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Bug Bites


Resolving the cause of 'bug' bites may not always be simple. There are only a few arthropods in California which will cause ongoing bites. However, there are a number of other conditions and combination of conditions that may cause similar symptoms. For example certain environmental, medical or physical conditions may contribute to the 'bites' attributed to bugs. In many cases it is a matter of elimination. The following is an attempt to summarize the various factors involved in resolving a bug bite condition.

The first step is to determine if an insect or other arthropod is causing the problem. Entomologists, public health officials, or trained pest control operators should be able to determine if a biting insect is present. The only arthropods likely to cause ongoing problems include mites, fleas, lice and bed bugs. Many times the description of the bites would indicate the species of biting arthropod.

Abdomen Bites

Rodent and bird mites cause small pimple-like bites, which itch intensely for 2 to 7 days. The actual bite is often felt but the bite manifestations may take up to 10 hours to appear. The bite mark remains for 2 to 3 weeks. Bites tend to cluster under constrictions such as the belt line, armpits and under breasts.

picture showing bed bug bites

Head lice are only found on the hairs of the head. Body lice will bite anywhere on the body but are associated with poor personal hygiene.

Flea bites vary from person to person but tend to form itchy lumps. Bites tend to be on the lower legs often in groups of three.

Bed bug bites leave a large welt on the body, often forming a row of three bites. Bites are usually apparent in the mornings and itch for 2 to 4 days.

Mites: There are a variety of mites that are known to bite humans and cause irritation and itchy papules. These mites feed on blood and other fluids in the skin. Most of them only bite humans when the normal host is unavailable. They are mobile and do not remain on or in the skin. Only scabies mites remain in or on the host skin. Other mites know to cause contact dermatitis include a variety of grain mites.

  • Rodent mites: Most actual bug bite complaints are due to rodent mites, primarily the Tropical rat mite (Ornithonyssus bacoti). These mites are very small and difficult to see. Removing and excluding rodents from the property is the permanent solution. Without a host, the mites will disperse or die within 3 weeks. Treating the property for mites especially around rodent nesting areas may provide relief.
  • Bird mites: Fowl mite, Ornithonyssus sylviarum, and sparrow mite, Pellonyssus passeri are found primarily in the nesting material. Removing and excluding birds from nesting on or in the structure will eliminate the mite infestation.
  • Dog (Cheyletiella yasguri) and Cat (C. blakei) mites are found on pet dogs, cats, rabbits and bedding material. Treat pets and bedding area with a registered miticide. Consult with a veterinarian.
  • Grain mites: This group of mites (ie. Straw itch mite, Pyemotes tritici) tend to be associated with damp or mouldy food products, grains or hay. Find infested product and discard.
  • Mites found outdoors: There are a number of types of mites found in gardens which may bite humans. Humans are an accidental host. Bites may be painful and leave a mark.
  • Chigger mites: Chiggers are not common in Alameda County. Chiggers may be encountered in native Californian habitats. The six-legged larva normally feeds on rodents and birds, but will attach to humans and feed. The bite causes an inflamed, harden area which itches intensely.
  • Scabies: Sacoptes mites (Sarcoptes sp.) are the only group that lives in the skin. The lesions are distinctive and tend to be concentrated between the fingers of the hands and genital areas. Itching caused by scabies is intense. Consult a physician for recommendations and treatment.

Insects: Quite a number of insects bite or feed on humans. In most cases humans are an accidental or opportunistic host or food source. Humans are the host animal for the Human Bedbug (Cimex lectularis ), and the Head and Body louse.

  • Fleas: Fleas feed on warm-blooded animals such as opossums, raccoons, rats, dogs and cats. Remove and exclude wildlife from the structure, if present. Treat infested areas with registered pesticides. Treat pets per veterinarian's recommendation. Flea bite symptoms appear 4-6 hours or more after initial bite.
  • Bedbugs (Cimex lecturarus): Bedbugs are increasing in occurrence nationwide as well as in Alameda County. The Human Bedbug feeds on human blood. Though some people do not react to the bite, in others large "welts" will form at the bite site. The Bedbug will take multiple feedings, leaving numerous bites. Most of the Bed bugs will live near the human host though they can harbor anywhere in the dwelling. Signs of bedbugs include blood (fecal) spots on bed sheets, mattress seams, bed frame or other areas, cast skin casings and live bugs. Controlling Bedbugs is time-consuming, and can be expensive. Basically, every conceivable Bedbug harborage site must be treated as well as all personal items.
    • There are closely-related bugs associated with birds and bats which may also cause a problem. If bird or bat bugs are suspected, again as with mites, exclude birds or bats from property.
  • There are a number of other insects that occasionally bite humans. Outdoor insects: Thrips are a tiny insect found outdoors which can cause a painful bite. Plant and seed bugs may bite. The assassin bug feeds on mammals and can cause a painful bite as well as induce anaphylactic shock. Horse and deer flies inflict a painful bite. Mosquitoes and biting gnats and midges also bite humans. Most of these insects are quite visible and easy to identify. An uncommon insect found indoors which can cause an irritating bite is the wingless parasitic wasp (Bethylid wasp). This wasp parasitizes stored product beetles. Hairs from carpet beetle larvae may cause a sensation of being bitten.
images showing different bugs

Environmental conditions: A variety of environmental factors can produce the false perception of insect bites.

  • One common condition is referred to as "paper mites". Paper chards and fibers under static buildup may penetrate the skin causing a sensation similar to a bite. Allergies due to pollens, molds and cockroach and mice infestations can cause reactions that can be mistaken for insect bites. Certain household products such as detergents, soaps and deodorants can cause skin sensations or reactions that can be mistaken for insect bites.

Medical conditions:

  • Medical conditions such as diabetes, liver disease, thyroid disorders, and pellagra can cause perceptions of parasitosis, dermatitis or hives. Certain medications can cause unusual skin sensations and itching as well as some dietary deficiencies.

Delusory Parasitosis (monosymtomatic hypochrondriacal psychosis): A delusion is a "false belief that cannot be corrected by reason. Or even by the evidence of the patient's own senses". Delusory parasitosis is a recognized medical condition characterized by an unfounded, yet unshakable, belief that live insects are present in the skin. Delusory parasitosis is not an uncommon condition. It is difficult to treat as there are a number of conditions which produce symptoms of delusory parasitosis such as emotional, stress/trauma, depression, psychological, physical or a combination. Finding the right medical specialist is difficult. Compounding this is that the sufferer is totally convinced that there is a bug or parasite present (delusion) and the only solution is to find this parasite.

The following description from the Physician's Guide to Arthropods of Medical Importance (J.A. Goddard, CRC Press, 1993) describes patterns and circumstances typical of delusory parasitosis:
Sometimes an initial and real insect infestation precedes and triggers the delusion. The "bugs" may appear and disappear while they are being watched; they enter the skin and reappear and invade the hair, nose, and ears. The patients claim that the "bugs" are able to survive repeated insecticidal sprays and the use of medicated shampoos and lotions. Frequently there is a history of numerous visits to medical doctors and dermatologist. Lesions may be present, although neurotic excoriation (self-inflicted skin wounds) may be the cause. Out of desperation the victim may move out of their home, only to report later that "bugs" have followed them there too. An affected person may be so positive of his infestation and give such a detailed description that other family members may agree with the patient. They may even be "infected" themselves, thus the delusion has been transferred.

A psychodermatologic disorder is a condition that involves an interaction between the mind and the skin. Psychodermatologic disorders fall into three categories: psychophysiologic disorders, primary psychiatric disorders and secondary psychiatric disorders. Psychophysiologic disorders (e.g., psoriasis and eczema) are associated with skin problems that are not directly connected to the mind but that react to emotional states, such as stress. Primary psychiatric disorders involve psychiatric conditions that result in self-induced cutaneous manifestations, such as trichotillomania and delusions of parasitosis. Secondary psychiatric disorders are associated with disfiguring skin disorders. The disfigurement results in psychologic problems, such as decreased self-esteem, depression or social phobia. Most psychodermatologic disorders can be treated with anxiety-decreasing techniques or, in extreme cases, psychotropic medications.

The first step is to determine if there is an insect or other arthropod infestation. If no infestation is found by a professional, then determine if there may be an underlining medical, neurological or dietary deficiency which may be the cause of the symptoms. The use of certain prescription drugs as well as illicit drugs (cocaine, methamphetamines) can cause the illusion of being infested by bugs. Stress, depression, or having had a traumatic experience may induce symptoms of delusory parasitosis possibly as a coping mechanism. Dealing with the stressful or traumatic experience should alleviate symptoms. If the sufferer does not fit into these categories, then delusory parasitosis should be suspected. The sufferer should consult with a medical professional such as a psychodermatogist, knowledgeable psychologist or psychiatrist. The help of a relative or close friend may be necessary to persuade the sufferer to consider this option.

For further details, refer to references below:

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