Mites and Ticks

The mite epidemic, the epidemic of the biting mites, that drive you crazy, that keeps you up at night, or wakes you up in the middle of the night… the mites that get in your nose and into your eyes, and into your throat… those are also on this page…

Mites

Mites are among the most diverse and successful of all the invertebrate groups. They have exploited an incredible array of habitats, and because of their small size (most are microscopic) go largely unnoticed. Many live freely in the soil or water, but there are also a large number of species that live as parasites on plants, animals, and some that feed on mold.

There are over 45,000 described species of mites. Scientists believe that we have only found 5% of the total diversity of mites. Mites are believed to have existed for around 400 million years.

Mites cause several forms of allergic diseases, including hay fever, asthma and eczema and are known to aggravate atopic dermatitis. Mites are usually found in warm and humid locations, including beds. It is thought that inhalation of mites during sleep exposes the human body to some antigens that eventually induce hypersensitivity reaction. Dust mite allergens are thought to be among the heaviest dust allergens. However not all types of mites are infectious including Alaskozetes antarcticus an arctic inhabiting mite. Certain mites can also serve as vectors of disease.

Mites and ticks have 4 pair of legs and a broadly joined cephalothorax and abdomen, which gives the appearance of one body segment. There are over 200 families of mites and some experts feel over a million species, most of which are not discovered. They typically exhibit 4 stages of development, namely the egg, larva, nymph and adult. The larval stage bears 3 pair of legs while the nymph and adult possess 4. Their life cycles are normally brief (2 to 3 weeks) and correspondingly mites can build huge populations in a short period of time.

House Dust Mites.

The house dust mite (sometimes referred to by allergists as HDM), is a cosmopolitan in distribution. Dust mites feed on organic detritus such as flakes of shed human skin and flourish in the stable environment of dwellings. They mites are a common cause of asthma and allergic symptoms worldwide. Some of the digestive enzymes (notably proteases) produced by the house mite persist in their fecal matter, and can be strongly allergenic.

The European house dust mite (Dermatophagoides pteronyssinus) and the American house dust mite (Dermatophagoides farinae) are two different species, but are not necessarily confined to Europe or North America; a third species Euroglyphus maynei also occurs widely.

The body of a house dust mite is just visible against a dark background in normal light. A typical house dust mite measures 420 micrometers in length and 250-320 micrometers in width. Both male and female adult house dust mites are creamy blue and have a rectangular shape. The body also contains a striated cuticle. Like all acari house dust mites have eight legs (except 3 pairs in the first instar). Dust mites can be transported in dust bunnies or by minor air currents generated from normal household activities.

The average life cycle for a male house dust mite is 10 to 19 days. A mated female house dust mite can live for 70 days, laying 60 to 100 eggs in the last 5 weeks of her life. In a 10 week life span, a house dust mite will produce approximately 2000 fecal particles and an even larger number of partially digested enzyme-covered dust particles.

The house dust mite survives in all climates, even at high altitude. A person sheds about 1.5 grams of skin cells and flakes every day (approximately one pound per year), which is enough to feed roughly a million house dust mites under ideal conditions. If trying to control house dust mites, humidity should be kept low. House dust mites thrive in the indoor environment provided by homes, specifically in bedrooms and kitchens. They survive well in mattresses, carpets, furniture and bedding, with figures around 188 mites per gram of dust. Even in dry climates, house dust mites survive and reproduce easily in bedding (especially in pillows), deriving moisture from the humidity generated by human breathing, perspiration, and saliva.

House dust mites consume minute particles of organic matter. Like all acari, house dust mites have a simple gut; they have no stomach but rather diverticulae, which are sacs or pouches that divert out of hollow organs. Like many decomposer animals, they select food that has been pre-decomposed by fungi. House dust mites eat the same particle several times, only partially digesting it each time; between feedings, they leave particles to decompose further. Only when the particles are fully digested do they enter the dust mite’s fecal matter.

Allergens produced by house dust mites are among the most common causes of asthma. Some main signs of house dust mite allergies are itchiness, sneezing, inflamed or infected eczema, watering/reddening eyes, runny nose and clogging in the lungs. Avoidance of dust mites and their allergens is the best course of action for those with dust mite allergies. The use of bedding that acts as a barrier to the dust mite and its allergens is a good first step. The bedding should also be breathable and be able to withstand frequent washing. However, a home allergen reduction plan has been recognized as being an essential part to the management of asthma symptoms and therefore all aspects of the home environment should be considered (proper vacuuming, use of air cleaners, off-gassing from paint and cleaning products, etc). The Asthma and Allergy Foundation of America as well as the Asthma Society of Canada certify products that may be used in a home allergen reduction plan in a Program called Asthma and Allergy Friendly.

Most people who have dust mite allergy sneeze when they wake up in the morning. They will generally feel better as they leave their room for the day and then at night when they sleep, the cycle repeats again. Repeated exposure can lead to chronic and long lasting asthma.

It is commonly believed that the accumulated detritus from dust mites can add significantly to the weight of mattresses and pillows. While it is true that the fecal matter of dust mites will increase over time, there is no scientific evidence for these claims. Considering the size of these mites and their products it is doubtful that their presence could add to any measurable weight to a mattress.

Control. Allergy and asthma sufferers are also often advised to avoid feather pillows due to the presumed increased presence of the house dust mite allergen. The reverse, however, is true. A 1996 study from the British Medical Journal has shown that polyester fiber pillows contained more than 8 times the total weight of the mites and their products. Disodium octaborate tetrahydrate powder is often used to eradicate house dust mites.

A simple washing will remove most of the waste matter. Exposure to temperatures over 60 °C (140 °F) for a period of one hour or freezing, exposure to temperatures below 0 °C (32 °F), will typically prove fatal to house dust mites; a relative humidity less than 50 percent may also be fatal. Ten minutes in household clothes dryer at lethal temperatures has been shown to be sufficient to kill all the dust mites in bedding. House dust mites reproduce quickly enough that their effect on human health can be significant

Grocer’s Itch. Acarus siro. These mites infest a wide range of food products such as grain, milk products, dried fruits, straw and animal hides in both household and commercial situations. The most important mite in stored products is Acarus siro, a species found throughout the world. Is particularly a pest of processed cereal products rather than whole grain. It is quite small but readily visible to the naked eye. It prefers temperatures ranging from 24 to 332 C. It tends to develop most rapidly under humid conditions (greater than 60% but preferring 85%). The amount of damage is done to grain is directly related to moisture content; grain is only attacked when moisture content is 14% or better. The dermatitis encountered by food handlers infested with this mite is referred to as grocer’s itch. Other names for dermatitis caused by Acarus siro and other related mites are baker’s itch, dried-fruit mite dermatitis, wheat pollard itch and vanillism.

Another common mite in stored products is the cosmopolitan Tyrophagus putrescentiae. It is particularly a problem in food with high protein content, namely cheese, ham, seeds, dried eggs, nuts and fish. These mites feed primarily on fungi that tend to thrive on foods stored at warm temperatures. Under these conditions they can complete one generation in as little as one week and reach huge populations in a month.

Ear Mites.

This is a group of parasitic mites that attack a variety of animals, including cats, dogs and rabbits. In these animals, infestations are limited to the ears and the mites are typically found feeding in the outer ear canals. As do most parasitic arthropods, ear mites are host-specific and no species attack humans. In rabbits, infestations can become serious if left uncontrolled; the result can be bleeding, secondary infection and possible death. An infestation is easily recognized by a layer of dried ooze on the inner side of the ear. If this crusty ooze is removed, large numbers of mites can be found feeding on ear tissue.

Adult female ear mites are microscopic, pale mites with cup-like structures at the tips of the front four legs and long setae at the tips of the hind four legs. Male ear mites are smaller and have cup-like structures at the tips of all eight legs. Males have a pair of copulatory suckers on the lower rear. The third pair of legs has especially long setae near the tip. The fourth pair of legs of male and female ear mites is noticeably smaller than the other legs. The egg is soft, sticky and pearly white at first, but soon dries and sticks to the substrate. The larvae are microscopic, pale mites with three pairs of legs. The front four legs have cup-like structures at the tips and the hind two legs have long setae at the tips. The protonymph has four pairs of legs with cup-like structures at the tips of the first four legs. The last two legs are very small. Deutonymphs have only three pairs of legs and two small bumps on the rear called copulatory tubercles. This stage has cup-like structures on the front four legs and long setae on the hind two legs.

Ear mites are found wherever their host animals occur. They have been found in 2.5 to 3.5% of dogs sampled in one study. Another sample of 113 hounds revealed that 77% were infested. In a survey of dog kennels, 33% of the dogs kept there were infected with ear mites. Of randomly selected cats, 20.2 to 28.4% were infested by these mites. It has been estimated that 75% of all long-haired cats are infested with ear mites. These mites have also been collected from the ears of foxes, ferrets, and hedgehogs.

Ear mites evidently pierce the lining of the auditory canal or somehow cause excessive production of earwax which becomes fouled with blood and bacteria. Crusts of earwax and blood form in the auditory canal and outer ear. Host animals scratch their ears excessively which causes loss of hair and scabbing. Secondary bacterial infections sometimes cause fever, depression and sullen, ill-tempered behavior. The ears of infected animals have a noticeable foul odor. Heavily infected animals often shake their heads constantly or run in circles in the direction of the most heavily infected ear. The most spectacularly bizarre behavior occurs when heavily infected dogs or cats are brought out of the cold into a warm room. These poor animals apparently “go berserk” with “spasmodic fits.” Symptoms tend to be less severe on older host animals.

Ear mites are passed from one animal to another when mites are dislodged during violent shaking of the head onto nearby animals or contact between animals, especially while nursing. However, it has been shown that ear mites also crawl about on the body of infested animals and that they can survive off of the host as long as hair and other detritus from the host animal are present. Thus, this mite passes from host to host with ease in confined quarters. Adult mites live about four weeks. Eggs hatch in 3 to 4 days and each active developmental stage lasts about one week and is followed by a 24 to 36 hour resting stage. Development from egg to egg laying female takes about three weeks. Ear mites tend to wedge under the edges of scabs for shelter.

Ear mites can be reared successfully from cells, hair, and dried earwax scraped from the ears of host animals. Once the ears of infested animals are secondarily infested with bacteria, the mites leave the suppurating area and tend to infest the outer ear or skin around the eyes. These facts indicate that ear mites do not feed on fluids.

Because ear mites pass readily from one animal to another in confined quarters, one might consider boarding a pet with a neighbor rather than a commercial kennel should it be necessary to leave the animal. Pets which have a fetid odor associated with the ears or which shake or scratch their ears excessively should be examined for signs of ear mites. If the inside of the outer ear is dark with dried scabs and the auditory canal is filled with dark, thick earwax, the chances are great the pet is infested. Examination of material from the ears by a veterinarian will confirm the presence or absence of ear mites. One type of treatment consists of washing the auditory canal with an alcohol based solution of “ear cleaner.” After the pet has removed the solution by violent shaking of the head, an emulsion of a miticide, antibiotics and mineral oil is dropped into the auditory canal to kill the mites, stop any secondary bacterial infection and to soothe the ears. Such a treatment should be applied several times as prescribed by the veterinarian. If a pet has mild symptoms, the application of mineral oil alone to the auditory canal is sufficient to control ear mites.

Scabies Mange Mites.

Sarcoptes scabei is a parasitic mite that attacks a wide variety of mammals; however, there are many varieties, with each type being host-specific. For example, the variety of scabies that attacks humans does not infest other animals. Similarly the scabies mites that attack dogs do no infest humans. The human scabies mite is almost invisible to the naked eye (about 1/60 inch), cylindrical in shape, and has golf tee-shaped suckers on the tips of the legs.

The life cycles of male and female human scabies mites are somewhat different. A young female adult will crawl over the human body until she reaches soft wrinkly skin and, within two to three minutes, bores inward, forming a tunnel about 3/4″ in length and parallel to the skin surface. She feeds on body juices and lays eggs (up to 20 per female) in the burrows. With close inspection mature females can be seen in the burrows. As a result of this activity, pimple-like structures develop which eventually rupture after a day or two, releasing the eggs on the skin. Once hatched, the larval and nymphal stages crawl over the skin and periodically feed in sebaceous glands and hair follicles. Male mites also feed in these areas. Generally it takes about two weeks to complete the life cycle from egg to adult.

Scabies is nearly always acquired by skin-to-skin contact with an infested individual. The contact may be quite brief such as holding hands. Frequently it is acquired from children, and sometimes it is sexually transmitted. Occasionally scabies is acquired via bedding or furnishings, as the mite can survive for a few days off its human host.

The majority of the mites (63%) are found on the hands (especially between the fingers) and wrists and about 11% on the elbows. In women the mites are often found burrowing beneath and around the breasts and nipples. In young children, whose skin is still soft, the mites can be found all over the body and frequently on the legs.

There are no obvious symptoms for the first 30 days after infestation. During that period, treatments are not necessary. However, subsequently, an intense rash and itching begins to occur over many areas of the body, in some cases even in areas where the mites are not found. The itch is characteristically more severe at night and affects the trunk and limbs. It does not usually affect the scalp. Itching can become so intense that the infested person loses sleep and can be affected mentally. Blisters and pustules on the palms and soles are characteristic of scabies in infants. Secondary infection commonly complicates scabies and results in crusting patches and scratched pustules. After about 100 days the mite population drops off and symptoms of the infestation begin to disappear.

Treatment consists of elimination of the mites from the body and treatment of recently worn clothing and bedding. The mites are totally host dependent and cannot live off the host for more than a day or two. Pesticide lotions can be used to kill those mites on the body. Kwell lotion was the standard for control for many years. However due to possible negative side effects of the active ingredient, it has been mostly replaced with more effective products. Recently used clothing or bedding should be laundered, ironed or sealed in large plastic bags for a few days. Symptoms will not disappear completely for a few weeks after the mites are eliminated. This is significant because it is probably not a good idea to over-treat an infestation of these mites. One of our grandkids contacted scabies and the kids next door had the same problem. We instructed the neighbor how to treat her kids. About a week later she indicated that the symptoms had not disappeared and wanted to retreat her kid. This is not a good idea as exposing children too frequently to the prescribed pesticide can lead to overmedicating. Therefore it’s important to know and to follow the directions for such direct contact treatments.

It should be mentioned that medical doctors frequently misdiagnose scabies mite infestations. As discussed above, several of the neighbors of the lady suffering from delusory parasitosis were convinced by her that they had scabies and were actually diagnosed and treated for them. I was once suffering from itching of the skin and went to a M. D. who immediately, upon hearing my symptom, stated that I had scabies and prescribed Kwell. I told him that I really didn’t have any of the other symptoms other than itching. His response was “sometimes there are no other symptoms,” which may or may not be true. The point is that he didn’t even look at me. Upon hearing “itching” he stepped back about two feet (they are fairly contagious) and muttered “scabies.” After using the Kwell with no relief, I consulted a dermatologist who correctly diagnosed my problem as dry skin.

I was recently contacted by a convalescent home about a scabies infestation. They had approximately 100 patients half of which were diagnosed with scabies. This was a real problem. Public Health had quarantined the hospital because this is a communicable disease. Of course this was devastating and confusing to the older residents as their relatives couldn’t visit them. The people who worked there were very concerned and fearful that they might carry the disease home with them and give it to their own families. With this in mind, the hospital wanted me to come up with a viable treatment program. Treatment was several fold. Everyone involved had to be treated with Kwell lotion-the chemical that at that time was preferred. Treatment included all the patients and individuals who worked there as symptoms of an active infestation do not appear immediately. There was no need to treat the premises itself as the mites are host-dependent and can only live off the host for a day or two. However, recently worn clothing and bedding had to be treated as a potential source of infestation. We considered sending these to a commercial laundry, but that created the potential of infesting the individuals who worked there. Instead, we took all the clothing and bed sheets and sealed them in large trash bags for three days, keeping in mind that the mites can only survive off the host for a day or two.

As previously mentioned control is 2 fold, namely elimination of the infestation on the body and those scabies found on recently worn clothing or bedding. A number of chemicals have been historically used for control of this mite.

Permethrin 5% is topical medication of choice. Toxicity may resemble allergic reactions. It is usually applied to the skin before bedtime and left on for about 8 to 14 hours, then showered off in the morning. Package directions or doctor’s instructions should be followed, but one application is normally sufficient to cure an infection.

Lindane lotion (e.g. Kwell) is approved in the U.S. for use as a second-line treatment where first-line medications like permethrin have either failed, are not well tolerated or otherwise contraindicated. It is illegal in 17 other countries, and 33 more countries have restricted its use. Though rare, serious side effects have resulted from product misuse. The FDA has confirmed 3 deaths that all involved use of lindane not in accordance with the label, including excessive topical applications and oral ingestions.

There is some evidence that a 10% sulfur ointment in petroleum jelly applied topically is effective. It is cheap and readily available over-the-counter. It also has the advantage of being able to be used in pregnant women and infants under two months of age.

Neem oil is deemed very effective in the treatment of scabies although only preliminary scientific proof exists which still has to be corroborated, and is recommended for those who are sensitive to permethrin, a known insecticide which might be an irritant. Also, the scabies mite has yet to become resistant to neem, so in persistent cases neem has been shown to be very effective.

A single dose of Ivermectin has been reported to reduce the load of scabies but another dose is required after 2 weeks for full eradication. In 1999, a small scale test comparing topically applied Lindane to orally administered Ivermectin found no statistically significant differences between the two treatments. As Ivermectin is easily administered (not requiring a rub down of the whole body like lindane or permethrin twice per treatment), compliance is much better. Ivermectin is used in eradication programs of many parasites of both human and animal. Side effects may include mild abdominal pain, nausea, vomiting, myalgia and/or arthralgia, which subside. The product is considered safe for use in children over five months of age.

There is no vaccine available for scabies, nor are there any proven causative risk factors. Therefore, most strategies focus on preventing re-infection. All family and close contacts should be treated at the same time, even if asymptomatic. Cleaning of environment should occur simultaneously, as there is a risk of reinfection. Therefore it is recommended to wash and hot iron all material (such as clothes, bedding, and towels) that has been in contact with scabies infestation.

Cleaning the environment should include: treatment of furniture and bedding; vacuuming floors, carpets, and rugs; disinfecting floor and bathroom surfaces by mopping; cleaning the shower/bath tub after each use; and daily washing of recently worn clothes, towels and bedding in hot water, drying in a hot dryer and steam ironing. Itchiness during treatment

Options to combat itchiness include antihistamines such as chlorpheniramine.

Arthropod bites can be mistaken for mite bites. Some arthropods that commonly bite humans are chiggers, also known as redbugs (Eutrombicula alfreddugesi ); mosquitoes; cat fleas and bedbugs. Chigger bites commonly occur beneath areas of restrictive clothing such as belts, underwear, and socks. Morphologically, the chigger bite resembles the scabies bite except that the chigger itself frequently appears as a tiny red dot in the center of the urticarial lesion. Chigger bites are usually few in number, compared with the large number of scabies bites on many patients. Chiggers do not burrow; they feed at the base of a hair follicle or in a pore. The bites commonly cause itching in three to six hours, and dermatitis develops in 10 to 16 hours. In the South, chiggers are active virtually year-round and commonly are encountered in woodlands and along swamps. Chiggers feed on skin tissue over a period of several days. Mosquito bites are usually associated with itchy wheals of short duration. They are generally found on uncovered portions of the body and do not tend to be grouped. Considerable variation in clinical appearance can be noted in the bites of the 160 species of U.S. mosquitoes.

Cat-flea ( Ctenocephalides felis ) bites usually are located only on the lower extremities of the body–the legs and ankles. The lesions are grouped, itchy, and raised, with a central round minute spot differing in color from the surrounding tissue. Secondarily infected lesions are commonly found. Generally the patient is aware of having been bitten. Bedbug ( Cimex lectularius) bites are usually found upon arising in the morning. They appear as grouped, itchy papules around the waist or on other areas not covered by clothing. Because of their complex nutritional requirements, bedbugs–which emit an offensive odor–come in contact with their human host only during feeding. During feeding, injected saliva produces an allergic reaction. The reaction causes delayed swelling, itching, and burning that may continue for seven days or longer.

Dog Mange.

This is persistent contagious skin diseases caused by parasitic mites. The term is sometimes reserved for the infestation of domestic animals. Another term used to describe mite infestation is acariasis. These mites embed themselves either in hair follicles or skin, depending upon the type of mange. They generally infect domestic animals, commonly dogs and other canines, but can also affect wild animals and even humans. Two types of mites produce canine mange, and each type has characteristic symptoms.

Demodectic Mange

Also called demodicosis or Red Mange, demodectic mange in dogs is caused by sensitivity to and overpopulation of Demodex canis as the animal’s immune system is unable to keep the mites under control. This is a mite that occurs naturally in the hair follicles of most dogs in low numbers around the face and other areas of the body. In most dogs, these mites never cause problems. However, in certain situations, such as an under-developed or impaired immune system, intense stress, or malnutrition, the mites can reproduce rapidly, causing symptoms in sensitive dogs that range from mild irritation and hair loss on a small patch of skin to severe and widespread inflammation, secondary infection, and-in rare cases-a life-threatening condition. Small patches of demodicosis often correct themselves over time as the dog’s immune system matures, although treatment is usually recommended.

Minor cases of demodectic mange usually do not cause much itching but might cause pustules on the dog’s skin, redness, scaling, hair loss, or any combination of these. It most commonly appears first on the face, around the eyes, or at the corners of the mouth, and on the forelimbs and paws. In the more severe form, hair loss can occur in patches all over the body and might be accompanied by crusting, pain, enlarged lymph nodes, and deep skin infections.

Demodectic mange is not generally contagious to people, other animals or even other dogs (except from mother to pup). However, the mite is zoonotic, and, upon infesting a human, will generally live in the hair follicles of the eyelashes and eyebrows. These mites thrive only on very specific hosts (dogs) and transmission usually occurs only from the mother to nursing puppies during the first few days after birth. The transmission of these mites from mother to pup is normal (which is why the mites are normal inhabitants of the dog’s skin), but some individuals are sensitive to the mites, which can lead to the development of demodectic mange.

These diseases in humans are usually called demodicosis which may have a rosacea-like appearance. Common symptoms include hair loss, itching and inflammation.

Some breeds appear to have an increased risk of mild cases as young dogs, including the Afghan Hound, American Staffordshire Terrier, Boston Terrier, Boxer, Chihuahua, Shar Pei, Collie, Dalmatian, Doberman Pinscher, Bulldog, English Bull Terrier, Miniature Bull Terrier, German Shepherd Dog, Great Dane, Old English Sheepdog, American Pit Bull Terrier, West Highland White Terrier, Rat Terrier, and Pug.

Demodectic mange also occurs in other domestic and wild animals. The mites are specific to their hosts, and each mammal species is host to one or two unique species of Demodex mites. There are two types of demodectic mange in cats. Demodex cati causes follicular mange, similar to that seen in dogs, though it is much less common. Demodex gatoi is a more superficial form of mange, causes an itchy skin condition, and is contagious amongst cats.

Localized demodectic mange is considered a common puppyhood ailment, with roughly 90% of cases resolving on their own with no treatment. Minor, localized cases are often treated with medicated shampoos and not treated with agents aimed at killing mites as these infestations often resolve within several weeks in young dogs.

Demodectic mange with secondary infection is treated with antibiotics and medicated shampoos as well as parasiticidal agents. Amitraz is a parasiticidal rinse that is licensed for use in many countries for treating canine demodicosis. It is applied weekly or biweekly, for several weeks, until no mites can be detected by skin scrapings.

Demodectic mange in dogs can also be managed with ivermectins, although there are few countries which license these drugs, which are given by mouth, daily, for this use. Ivermectin is used most frequently; collie-like herding breeds often do not tolerate this drug due to a defect in the blood-brain barrier, though not all of them have this defect. Other avermectin drugs that can be used include doramectin and milbemycin.

Cats with Demodex gatoi must be treated with weekly or bi-weekly sulfurated lime rinses. Demodex cati are treated similarly to canine demodicosis.

Sarcoptic Mange

Also known as canine scabies, sarcoptic mange is a highly contagious infestation of Sarcoptes scabiei canis, a burrowing mite. The canine sarcoptic mite can also infest humans and cats, pigs, horses, sheep and various other species.

These mites dig into and through the skin, causing intense itching and crusting that can quickly become infected. Hair loss and crusting frequently appear first on elbows and ears. Skin damage can occur from the dog’s intense scratching and biting. Secondary skin infection is also common. Dogs with chronic sarcoptic mange are often in poor condition.

Affected dogs need to be isolated from other dogs and their bedding, and places they have occupied must be thoroughly cleaned. Other dogs in contact with a diagnosed case should be evaluated and treated.

There are a number of parasiticidal treatments useful in treating canine scabies. Sulfurated lime rinses applied weekly or bi-weekly are effective. Selamectin is licensed for treatment by veterinary prescription in several countries; it is applied as a drip-on directly to the skin. Unlicensed, but frequently used, ivermectin, given by mouth for two to four weekly treatments; this drug is not safe to use on some collie-like herding dogs, however. Other ivermectin drugs are also effective, but none is licensed for use on dogs.

Veterinarians usually attempt diagnosis with skin scrapings from multiple areas, which are then examined under a microscope for mites. Sarcoptes, because they may be pressed t in relatively low numbers, and because they are often removed by dogs chewing at themselves, may be difficult to demonstrate. As a result, diagnosis in Sarcoptic mange is often based on symptoms rather than actual confirmation of the presence of mites. A common and simple way of determining if a dog has mange is if it displays what is called a “Pedal-Pinna reflex”, which is when the dog moves one of its hind legs in a scratching motion as the ear is being manipulated and scratched gently by the examiner; because the mites proliferate on the ear margins in nearly all cases at some point, this method works over 95% of the time.[5] It is helpful in cases where all symptoms of mange are present but no mites are observed with a microscope. In some countries, a serologic test is available that may be useful in diagnosis.

For demodectic mange, properly performed deep skin scrapings generally allow the veterinarian to identify the microscopic mites. However because the mite is a normal inhabitant of the dog’s skin, the presence of the mites does not conclusively mean the dog suffers from demodex. Rather abnormally high numbers of the mite are more useful. In breeds such as the West Highland White Terrier, relatively minor skin irritation which would otherwise be considered allergy should be carefully scraped because of the predilection of these dogs to demodectic mange. Skin scrapings may be used to follow the progress of treatment in demodectic mange.

Face Mange Cats

Feline scabies is caused by a tiny mite called Notoedres cati. This mite affects cats very much like the sarcoptic mange mite affects dogs; in fact, their life cycles and treatments are very similar. While many cat owners do not realize that cats get mange, as veterinarians, we see and treat this on a regular basis. If your cat suffers from severe itching or hair loss on the head and neck, you should consider having her examined for this mange mite. The mites spend their entire life on a cat. The female mite burrows into the skin and lays eggs several times as she continues burrowing. These tunnels can actually reach the length of several centimeters. After she deposits the eggs, the female mite dies. In 3-8 days, the eggs hatch into larvae which have 6 legs. The larvae mature into nymphs which have 8 legs. The nymph then molts into an adult while it is still in the burrow. The adults mate, and the process continues. The entire life cycle requires 2-3 weeks.

Notoedres can infect cats of all ages, breeds, and colors. It infects both males and females and often will infect an entire litter of kittens. Because this mite is transmitted directly from cat to cat, it is more common in outdoor cats that come in contact with strays. The mite only lives a few days off of the cat, but transmission through grooming, boarding, and sharing bedding is possible. N. cati can also infest foxes, dogs and rabbits

The symptoms usually start with hair loss and itching on the ears and then spread rapidly to the face, eyelids, and neck. The mites can also spread to the feet and lower abdomen. This characteristic spread probably occurs from the cat’s habit of grooming, and sleeping curled up in a ball. As the disease progresses, the skin will become thickened, wrinkled, and covered with grayish/yellow crusts. Because of the intense itching, the infected cat will often scratch and irritate the skin causing secondary infections to develop. The surrounding lymph nodes may also become enlarged as the problem worsens. The characteristic itching and hair loss pattern help to diagnose Notoedric mange in the cat. Skin scrapings are performed to confirm the diagnosis. There are usually a large number of mites present on the skin and the resulting skin scrapings,

While the Notoedres mite can be killed with many of the same products used to treat dogs with scabies, most of them are NOT safe to use in a cat. Cats are much more sensitive to some of the insecticides that are safe to use in the dog. The current recommended treatment for cats is to clip all long hair and then bathe the cat with a gentle cleansing shampoo. After the shampoo, a 2 to 3% lime sulfur dip is applied to the entire surface of the cat. Some cats may require a sedative to be properly bathed and treated. This is repeated every seven days until the condition resolves and may require 6 to 8 weeks of treatment.

Some veterinarians have successfully used an amitraz dip to cure this disease, but this is an off-label use of this product and may make some cats sick. Recently, ivermectin has also been used successfully, much as it has been for sarcoptic mange in dogs. Ivermectin is not approved for use in cats, but under close veterinary care, it may provide a viable form of treatment. If there are multiple cats in the household it is often recommended that all cats in the household are treated because they may be harboring the mites. Unlike allergies, the intense scratching caused by Notoedres responds poorly to steroids.

Prevention is best accomplished by preventing your cat from coming in contact with stray or infected cats. Indoor cats are much less likely to contract this disease. Avoid boarding or grooming your cats at locations that do not provide good sanitation and insist that all grooming tools be disinfected between uses. At the first signs of infection, seek prompt treatment and isolate the infected cat from other cats in the household.

As with other mites in the Sarcoptes family, Notoedres can infect humans. The disease, though, is generally self-limiting, causing only temporary itching.

Human Follicle Mite.

Demodex is a genus of tiny parasitic mites that live in or near hair follicles of mammals. About 65 species of Demodex mites are known; they are among the smallest of arthropods.

Demodex folliculorum and Demodex brevis are typically found on humans. It is extremely rare to see a human infected with a different species of mite, such as Demodex canis, though a few instances have occurred. D. folliculorum was first described in 1842; D. brevis was identified as separate in 1963. D. folliculorum is found in hair follicles, while D. brevis lives in sebaceous connected to hair follicles. Both species are primarily found in the face, near the nose, the eyelashes and eyebrows, but also occur elsewhere on the body.

The adult mites are only between 0.3 mm and 0.4 mm long, with D. brevis slightly shorter than D. folliculorum. They have a semi-transparent elongated body that consists of two fused segments. Eight short segmented legs are attached to the first body segment. The body is covered with scales for anchoring itself in the hair follicle, and the mite has pin-like mouth-parts for eating skin-cells, hormones and oils (sebum) which accumulate in the hair follicles. The mite’s digestive system is so efficient and results in so little waste that there is no excretory orifice. The mites can leave the hair follicles and slowly walk around on the skin, at a speed of about 8-16 cm/hour, especially at night; they try to avoid light.

Female Demodex folliculorum are somewhat shorter and rounder than males. Both male and female Demodex mites have a genital opening, and fertilization is internal. Mating takes place in the follicle opening, and eggs are laid inside the hair follicles or sebaceous glands. The six-legged larvae hatch after 3-4 days, and it takes about seven days for the larvae to develop into adults. The total lifespan of a Demodex mite is several weeks. The dead mites decompose inside the hair follicles or sebaceous glands.

Older people are much more likely to carry the mites; it is estimated that about 1/3 of children and young adults, 1/2 of adults, and 2/3 of elderly people carry the mites. The lower rate of children may be due to the fact that children produce much less sebum. It is quite easy to look for one’s own Demodex mites, by carefully removing an eyelash or eyebrow hair and placing it under a microscope.

The mites are transferred between hosts through contact of hair, eyebrows and of the sebaceous glands on the nose. Different species of animals host different species of demodex; and demodex is not contagious between different species.

In the vast majority of cases, the mites go unobserved, without any adverse symptoms, but in certain cases (usually related to a suppressed immune system, caused by stress or illness) mite populations can dramatically increase, resulting in a condition known as demodicosis or Demodex mite bite, characterized by itching, inflammation and other skin disorders. Blepharitis (inflammation of the eyelids) can also be caused by Demodex mites.

There is some evidence linking demodex mites to some forms of the skin disease rosacea, possibly due to the bacterium Bacillus oleronius found in the mites.

Psoroptic Mange.

The mites in this family are known as the psoroptic mange mite. They have shorter legs than the sarcoptic mange mites and do not burrow under the skin. These mites inhabit the base of hairs and pierce the skin introducing toxic saliva with resultant inflammation. An exudate oozes out and forms a scab. The skin becomes hardened and thickened especially on the scalp of humans and in the ears of domestic animals.

Rickettsial Pox. This is an illness caused Rickettsia akari). Physician Robert Huebner and self-trained entomologist Charles Pomerantz played major roles in identifying the etiology of the disease after an outbreak in 1946 in a New York City apartment complex, documented in medical writer Berton Roueché’s short story, “The Alerting of Mr. Pomerantz.”

The initial outbreak of the disease took place in the Regency Park complex which had 69 apartment units organized in three groups each three stories in height, located in Kew Gardens, in the New York City. . Physicians who had seen patients starting in early 1946 had assumed that they were dealing with an atypical form of chickenpox, but the realization was made that they were dealing with a localized epidemic of unknown origins starting in the summer of that year. Physicians canvassed the residents of the building and found that there had been 124 cases of this disease from January through October among the 2,000 people living in the complex, reaching a peak of more than 20 cases reported in July. Individuals afflicted with the condition ranged in age from 3 months to 71, males and females were equally affected and the incidence among adults (6.5% of the 1,400 above age 15) exceeded that of children 14 and under (5.3%).

Typically individuals first have a small lesion at the site of a bite, which eventually leave a small scar. Lymph nodes become enlarged and about a week after the initial bite victims start to experience chills, fever and headaches, accompanied by a maculopapular rash. The rash lasts for about a week, with the full progress from the lesion being encountered until recovery typically occurs in three weeks. In the case of the initial New York discovery many residents had reported the presence of mice in and around the apartments, especially in the basements of the buildings near the incinerators, where living and dead mice were found.

Visiting the complex with pest-control specialist and self-trained entomologist Charles Pomerantz, the two peeled back wallpaper to find the walls swarming with mites which tenants had described that “the walls had movement”. The mites were collected and rickettsial strains were isolated from some of them, with the name Rickettsia akari given to the organism.

As indicate the house mouse is an urban reservoir of this disease with mites the vector. Humans acquire rickettsial pox when receiving a bite from the house mouse mite infected mite.

The first symptom is a bump formed by the bite, eventually resulting in a black, crusty scab. Many of the symptoms are flu-like including fever, chills, weakness and achy muscles but the most distinctive symptom is the rash that breaks out, spanning the infected person’s entire body. Rickettsial pox is generally mild and resolves within 2-3 weeks if untreated. There are no known deaths resulting from the disease.

Those dwelling in urban areas (which typically experience rodent problems) have a higher risk of contracting Rickettsial pox.

Pymotes Itch Mites.

There are two species of Pynotes mites that cause itch in humans, namely Pyemotes tritici, the straw itch mite and Pyemotes herfsi, the oak leaf gall mite. The former is parasitic on a variety of insects including pests of wheat, alfalfa and other crops. The mite is usually microscopic, but the gravid females are visible. Problems commonly exist when alfalfa straw or other agricultural commodities containing these pests and their parasites are brought in from the field. Straw itch mites are found in stored grain, dried beans and peas, wheat straw, hay and other dried grasses. The mites are actually beneficial because they attack insects that feed on stored grain and similar materials. The mites which bite individuals handling these materials result in dermatitis. The infested area itches, but some victims have an allergic reaction with a fever. Bites from these mites can be confused with chicken pox because of eruptions with both maladies

These mites have a very unusual life cycle. They wander continuously over the relatively giant body of a pregnant female feeding on her parasitically. The eggs hatch and 200 to 300 mites develop to adulthood within the enlarged female’s abdomen. They are released from her at a rate of about 50 a day. Only about 3% are males but they emerge first and remain clustered around the genital opening of the female. With the aid of their hind legs they drag newly emerging females through the opening even though they can exit on their own. Copulation is immediate and once eggs develop inside the new females they swell to many times their original size thus repeating the cycle.

Humans, particularly in grain growing areas, are bitten when handling infested straw, crops (beans, cotton, small grains) or crop residues, or similar materials harboring the mites and those who make dried plant arrangements. Straw itch mites can travel through the air, so anyone in these areas can be at risk. Bites occur more often when straw itch mites become separated from their insect hosts or their hosts become scarce, itch mites may bite other animals, and humans. A person who is severely infested may have thousands of bites from itch mites that cannot be detected by the naked eye. Fortunately, the mites cannot live on humans and do not remain long. There is no evidence that the bites transmit disease, nor that there is a person-to-person transmission of the mite.

Bites produce a rash which includes red welts with a small white pustule (head) at the center. The bite is not felt and can take from two to 24 hours for resulting welts to appear. Severe cases can cause infection, fever, vomiting, and joint pain. Severe itching and possible infection can occur if bites are scratched open. Itching may last up to a week or more and will normally disappear within a few weeks. The bites of straw itch mites are characteristically found on the trunk of the body and on the arms.

To prevent straw itch mite bites, avoid grassy areas and shower with plenty of soap after being in grassy or weedy areas. An insect repellent containing DEET is effective in preventing the bites. The best control strategy is to eliminate the mite’s host insects. If possible, clean storage areas thoroughly and treat with a pesticide, such as cyfluthrin. If necessary, stored commodities can be fumigated to disinfest them. Mite populations should decrease or completely disappear with the onset of the first frost. Many people believe the mites infest their beds or homes, but this is not true.

Oral antihistamines such as diphenhydramine and topical anti-itch creams such as hydrocortisone have been useful in alleviating the discomfort caused by the bites. In most cases the bites

Pyemotes herfsi, also known as the oak leaf gall mite or itch mite, is an ectoparasitic mite, identified in central Europe in 1936, whose presence in the United States was confirmed during the 1990s. The United States Centers for Disease Control estimated that during an outbreak in August 2004, 54% of the population of Crawford County, Kansas, or about 19,000 people, suffered from its bites. Other states in the US where humans have been affected during the 2000s are Nebraska, Oklahoma, Missouri, Tennessee Shelby County, Texas, and Illinois. Currently in August 2008 an outbreak is being reported in the northern suburbs of Cincinnati, Ohio by the Hamilton County Public Health Department.

This species has a biology very similar to the straw itch mite. The mites’ reported hosts have included Anobium punctatum, the pink bollworm, Grapholita molesta, Tineola bisselliella and various pests of stored grain, as well as humans and their pets. Their usual hosts in the United States are oak midge larvae. Newly emerged and mated females inject a neurotoxin containing saliva into their hosts, which paralyzes the host and enables the pregnant female mites to feed on the host’s hemolymph. A single mite can paralyze and kill an insect larva 166,000 times its own weight; within a few days, up to 250 adult mites emerge from the female. A life cycle can be completed within seven days. Conditions that are cooler and moister than average favor its population growth. Outbreaks of attacks on humans in the United States have been attributed to fluctuations in the supply of oak midge larvae.

The closely related straw itch mite (Pyemotes tritici), was initially suspected, as the culprit in the Kansas infestation but no specimens of this species were found. The reports indicated that the bites occurred on people after being outdoors in or near wooded areas. Based on this information, a search was initiated and resulted in the discovery of Pyemotes herfsi preying on midge larvae in leaf galls on pin oak trees.

Humans typically report itching from mite bites within 10 to 16 hours after contact. The victims often do not recall being bitten. The rash that results from the bites is usually described as a red patch with a small blister in the center, most often found on the neck, face, arms, or upper torso. A secondary bacterial infection sometimes arises when the bite is scratched. The suggested treatments include the application of calamine lotion, an antihistamine cream such as Benadryl, or a corticosteroid cream; a suggested preventive measure is the application of DEET before outdoor activity. Anecdotal reports from the Kansas outbreak, however, suggest that DEET might not provide complete protection against P. herfsi.

The bites are not life-threatening, but a few individuals suffering 100 or more bites have undergone brief hospitalizations.

Chiggers.

Trombiculidae (pronounced /trɒmbɨˈkjuːlɨdiː/) is a family of mites called trombiculid mites (also called berry bugs; harvest mites; red bugs; scrub-itch mites; and, in their larval stage, chiggers). The term chigger is sometimes used to refer to a different animal, the Chigoe flea. Trombiculidae live in the forests and grasslands and are also found in low, damp areas where vegetation is rank such as woodlands, berry bushes, orchards, along lakes and streams, and even in drier places where vegetation is low such as lawns, golf courses, and parks. They are most numerous in early summer when grass, weeds and other vegetation are heaviest. A common species of harvest mite in Northern America is Trombicula alfreddugesi; in the UK the most prevalent harvest mite is Trombicula autumnalis.

Trombiculid mites are found throughout the world. In Europe and North America, they tend to be more prevalent in the hot and humid parts. In the more temperate regions, they are found only in the summer (in French, harvest mites are called aoûtat, or “August” flies. In the United States, they are found mostly in the southeast, the south, and the Midwest. They are not present, or barely found, in far northern areas, in high mountains and in deserts. In the British Isles, the species Trombicula autumnalis are called harvest mites, in North America the species Trombicula alfreddugesi, and the species Trombicula (eutrombicula) hirsti which are found in Australia and are commonly called the scrub-itch mite.

The length of the mite’s cycle depends on species and environment, but normally last 2 to 12 months (but may be longer). The number of cycles in a year depends on the region. For example, in a temperate region, there might only be 3 a year, but in tropical regions, the cycle might be continuous all year long. Adult mites overwinter in protected places such as slightly below the soil. Females become active in the spring, and once the ground temperature is regularly above 60 °F (15.6 °C), she lays eggs, up to 15 eggs per day in vegetation when soil temperatures are 60 °F (15.6 °C). It follows that from April through early autumn up until the first frost, humans are susceptible to chigger bites.The larvae congregate in groups on small clods of earth, in matted vegetation and even on low bushes and plants, where they have more access to a prospective host. The eggs are dormant for about six days, after which the non-feeding pre-larvae emerge, with only three pairs of legs. After about six days, the pre-larva grows into its larval stage.

The larvae, commonly called chigger, is tiny (0.007-0.008 in) in diameter, normally light red, covered in hairs, and move quickly relative to size. Chigger is also an alternate term for the chigoe flea (Tunga penetrans), a sand flea found in tropical and subtropical climates in the Americas and Africa. The name chigger originated as a corruption of chigoe. The larval stage is the only parasitic stage of the mite’s life cycle. They are parasites various animals, including amphibians, reptiles, birds, and mammals, and feed on skin. This often causes an intensely itchy red bump in humans (who are accidental hosts). Chiggers attach to the host, pierce the skin, inject enzymes into the bite which subsequently forms a hardened tube called a stylostome. Once formed the digested cell are sucked up through the hardened tube. They do not burrow into the skin or suck blood, as is commonly assumed. Itching from a chigger bite may not develop until 24-48 hours after the bite, so the victim may not associate this symptom with the bite itself. Tiny red welts are also formed due to this feeding. The red welt/bump on the skin is not where a chigger laid eggs, as is sometimes believed. The larva remains attached to a suitable host for 3 to 5 days before dropping off to molt into the nymph stage. There are three nymphl instars, namely the protonymph, deutonymph, and tritonymph. The protonymph is an inactive transitional stage. The active deutonymph develops an additional pair of legs (for a total of eight) subsequently re-entering inactivity during its transitional tritonymph phase before growing to adulthood. The deutonymph and adult are predatory feeding on small arthropods and their eggs and occasionally feeding on plant material. They live in soil, often found when digging in yards and gardens. Adults can be beneficial to human beings, since they often eat the eggs of other pests, such as mosquitoes.

Although chigger usually does not carry diseases in North American temperate climates, they are considered a dangerous pest in East Asia and the South Pacific because they vector Orientia tsutsugamushi,, a bacterium that causes scrub typhus, which is known alternatively as the Japanese river disease, scrub disease, or tsutsugamushi.

Chiggers typically feed around the ankles or behind the knees and tend to congregate where clothing comes in restrictive contact with the skin. They may crawl as high as the crotch. If someone were to sit or lie down in chigger-infested grass, their bites could occur all over the body. These mites do not burrow into the skin, but rather secrete digestive enzymes that dissolve tissue just under the skin. Chigger bites initially appear as small-reddened areas but soon develop into small water blisters. The accompanied itching can last up to 36 hours. Some people suffer from nausea.

Chiggers are more common in the South and other tropical or semitropical areas of the world, but can be encountered in most states. Individuals who live in chigger-infested areas may become somewhat immune to their bites. When a chigger feeds it injects saliva that causes the tissues to harden around its mouthparts. This hardened area is referred to as a feeding tube and functions to facilitate the chiggers feeding. However, if someone has a history of chigger bites, he or she may become hypersensitive to their saliva and when the chigger begins to feed, a massive hardened area (instead of the feeding tube) quickly develops. This, in turn, blocks the chigger’s ability to further feed. As a consequence little saliva is injected and typical symptoms do not develop.

Currently available treatments are few with applications of benzocaine the most effective. Prevention of infestation by this mite is the best strategy and is accomplished staying away from grasses and fields in chigger-infested areas. Also, placing socks outside of pant legs and applications of insect repellants are also effective. Chiggers are known to vector scrub typhus (Rickettsia tsutsugamushi). This disease is also known as Japanese river fever and is found primarily in Southeast Asia. It is fairly well controlled now, but was problematic during WWII, before antibiotics were routinely used.

Chigger bites commonly occur beneath areas of restrictive clothing such as belts, underwear, and socks. Morphologically, the chigger bite resembles the Pyemotes bite except that the chigger itself frequently appears as a tiny red dot in the center of the urticarial lesion. Chigger bites are usually few in number, compared with the large number of Pyemotes bites on many patients. Chiggers do not burrow; they feed at the base of a hair follicle or in a pore. The bites commonly cause itching in three to six hours, and dermatitis develops in 10 to 16 hours. In the South, chiggers are active virtually year-round and commonly are encountered in woodlands and along swamps. Chiggers feed on skin tissue over a period of several days.

Scrub typhus is transmitted by some species of trombiculid mites (“chiggers”, particularly Leptotrombidium deliense), which are found in areas of heavy scrub vegetation. The bite of this mite leaves a characteristic black eschar (piece of dead skin that is cast off from the surface) that is useful to the doctor for making the diagnosis. Scrub typhus is endemic to a part of the world known as the “tsutsugamushi triangle”, which extends from northern Japan and far-eastern Russia in the north, to northern Australia in the south, and to Pakistan and Afghanistan in the west.

The precise incidence of the disease is unknown, as diagnostic facilities are not available in much of its native range. In rural Thailand and in Laos, murine and scrub typhus accounts for around a quarter of all adults presenting to hospital with fever and negative blood cultures. The incidence in Japan has fallen over the past few decades, probably due to decreasing exposure, and many prefectures report fewer than 50 cases per year. It affects females more than males in Korea, but not in Japan.

Symptoms include fever, headache, muscle pain, cough, and gastrointestinal symptoms. More virulent strains of O. tsutsugamushi can cause hemorrhaging, intravascular coagulation. Macuopapular rash, eschar, splenomegaly and lymphadenopathies are typical signs. Leukopenia and abnormal liver function tests are commonly seen in the early phase of the illness. Pneumonitis, encephalitis, and myocarditis occur in the late phase of illness. Acute scrub typhus appears to improve viral loads in patients with HIV. This interaction is refused by an in vitro study.

In endemic areas, diagnosis is generally made on clinical grounds alone. Where there is doubt, the diagnosis may be confirmed by a laboratory test such as serology.

Without treatment, the disease is often fatal. Since the use of antibiotics, case fatalities have decreased from 4%-40% to less than 2%. The drug most commonly used is doxycycline; but chloramphenicol is an alternative. There are currently no licensed vaccines available.

Severe epidemics of the disease occurred among troops in Burma and Ceylon during World War II (WWII). Several members of the U.S. Army’s 5307th Composite Unit (Merrill’s Marauders) died of the disease; and in 1944, there were no effective antibiotics or vaccines available. The disease was also a problem for US troops stationed in Japan after WWII, and was variously known as “Shichitō fever” (by troops stationed in the Izu Seven Islands) or “Hatsuka fever” (Chiba prefecture).

Delusory Parasitosis.

This is a paranoia, or irrational fear, of small creepy non-existent creatures. Because mites are so small, this condition is often diagnosed as a mite infestation. This phenomenon is more common than one might expect. Frequently, people who are inflicted with this malady are quite normal in all other phases of life and lead productive lives.

I was quite unaware of this phenomenon until one day a man in his mid 40’s walked into my office and indicated that the UCLA Medical Center had referred him to me. He indicated that he and his home were infested with small ’bugs’ that he could not eradicate. After a short discussion he reached out into the air and indicated I had them in my office also. I responded that he must have brought them with him. He further stated that he had captured some and placed them on a piece of scotch tape. He related collecting each ‘critter.’ The first had bitten him on the leg and then disappeared under his skin, but he dug it out with a sewing needle. The second was on his pants cuff and bit him on the ankle. The third was found swimming around in his toothpaste. After considerable discussion we examined each ’critter’ with a microscope. Needless to say, none resembled an insect or mite. Indeed, they were small grains of sand, pieces of lint and so on. However, even after this close inspection and work over a several-week-period, he could not be persuaded that the attacking creatures were imaginary. The situation became so bad that he convinced his wife that she was also infested. They couldn’t get them out of their home even though several exterminators were called. Because of the “infestation”, the home was eventually sold at a considerable loss. Eventually, partly because of the turmoil, their marriage ended in divorce.

There have been many similar situations since then. One of the most unusual occurred a few years ago when a city official from Mission Viejo (Orange County) called me and indicated that he had a whole neighborhood infested with scabies mites (see below). Scabies are parasitic mites that commonly infest humans. At the time this didn’t seem questionable because a number of the people had been to medical doctors and had been treated for this mite. These treatments didn’t seem to solve the problem, so I was brought in as a consultant. The main problem was centered on one particular resident. This woman apparently had convinced much of the neighborhood of the widespread infestation. She was using very drastic measures to try to eliminate these mites from her house and family. She would use lye to scrub down the beds on a weekly basis. On several occasions she washed her kids down with gasoline. Of course, upon hearing this, I began to realize that the whole situation was more than a little irrational. The final clincher was when she indicated that the whole problem started when she brought a potted plant back from Arizona and, while it was sitting in her bathroom, a pod grew out of it and blew these tiny critters all over the neighborhood.

A colleague from NCSU, Mike Waldvogel, reports similar experiences. He states he has received a variety of imaginary critters in vacuum cleaner bags, pillows, panty hose, skin samples, glue boards (like the one you use for catching mice) and (the one he described as the ultimate) a bottle (formerly a pint gin bottle) that was labeled ” after douching.” Needless to say that one wasn’t opened! Neither were the vacuum cleaner bags, as they usually contain pesticide-laden dust from over-treated carpets.

All of these cases have had several symptoms in common. The ’critters’ typically fly through the air, crawl on the skin, frequently appear and disappear in the skin, make clicking noises and can be found in soap and toothpaste. Generally, inflicted individuals have gone to several medical doctors to no avail and can almost never be persuaded that the pests are imaginary.

Bitting Mites.

Several types of mites are associated with cases of skin dermatitis in humans. The tropical rat mite, Ornithonyssus bacoti, is one of the most commonly encountered species closely followed by the house mouse mite and the spiny rat mite. As their names imply these are typically parasites on rodents. The tropical fowl mite, Ornithonyssus bursa, and northern fowl mite, Ornithonyssus sylviarum, both associated with domestic or wild birds, can also be found in homes.

The tropical rat mite is a parasite of rats and inhabits the area in and around the rat’s nesting area. Although none of these species are truly parasitic on humans or pets, they will readily bite humans. Some people are unaffected by the bites while others will experience itching and dermatitis. The bite is normally pimple sized that itches for up to a week or so. The bite mark may last as long as three weeks. The bites can be randomly found on the body but often are found under areas where clothes constrict the body or areas such as under armpits and breasts. Scratching may lead to secondary bacterial infections. Fortunately rat mites do not vector disease. Rat mites are very small, approximately the size of a period. They move about quite actively and will enter the living areas of a home when their host, rats or birds, have left or have died. Heavy infestations may cause some mites to search for additional food sources. The protonymphs and females suck blood, and are often distended after feeding. A complete generation usually takes about two weeks. Unfed females may live ten days or more after rats have been eliminated. Rodent mites are normally associated with the roof rat (Rattus rattus), but are also found to the Norway rat, (R. norvegicus) and House mouse (Mus musculus). The occurrence of the rat mite has increased considerably in recent years causing distress and discomfort to many residents.

The solution to a mite infestation is to eliminate their hosts, rats or birds. The mites will survive only 2 to 3 weeks without their hosts. Mites cannot complete their life cycle on humans. Rodent control including rat proofing is the permanent solution for a rodent mite infestation. Pesticide treatments are advisable to prevent further bites from occurring but must be used in combination with bird or rodent control. Pesticides may be applied prior or concurrently with rodent control and exclusion. Repeat treatments may be necessary depending on the pesticides used.