A lot of enomologysts, doctors, and pest control operators assume a variety of things about biting mites. Some false assumptions include: they can be seen on the patient; they will take a long time to reproduce to such levels that create discomfort; the original host must be dead for the mites to attack humans; mites will leave the host (human or animal) once it has bitten; humans cannot act as fomites (taking the mites to a new household or environment); you only need to apply insect repellant at night; if only one person is bothered in a household of many people, a non-anthropod cause must be found; mites can only survive a few days or weeks at the most without their original host .
The following research articles indicate that Tropical Rat Mites will readily attack humans even when its original host is present (Fox, Hill, Olson, Pratt); they can live for more than two months without a blood meal (Scott); a rat will carry sufficient numbers of mites on its person to build an entirely new colony of mites (thus a dead rat, exposed pet, or human can act as a fomite for a non-infested rat population) (Williams); when humans are attacked by Tropical Rat Mites, these mites may remain on the person and in their clothes as they go about their business continuing to crawl, bite, and cause discomfort (Angel);
Tropical Rat Mites can reproduce at incredible rates if the conditions are appropriate-to 1000 specimens in one week on one rat (Williams)-or as in the cases of the transgenic mice and the animal house in Texas in which large populations of rodents were swarmed by tens of thousands if not millions of mites leading to the death of a number of rodents from exsanguination (loss of blood) and great discomfort for laboratory personnel (Olson, Hill); Tropical Rat Mites can be selective of their host even among rats, by extension they can be selective of human hosts sometimes only bothering one person in a household (Olson); and in most academically reported cases, the mites were not readily visible to either the doctor or patient and it took additional investigation to assertain that Tropical Rat Mites were indeed present and the rats and mites needed to be eradicated-often this involved finding the original host rather than finding mites (Baumstark, Beck, etc.).
- Angel, Tiffany A. , James Nigro, and Moise L. Levy. "Infestations in the Pediatric Patient." Pediatric Clinics of North America 47 (2000).
This article discusses various skin infestations of human children, including the chicken mites, northern fowl mites, and tropical rat mites. Excerpt from article: "Treatment for infestation with all members of the Gamasidae family is the same. Because some of these mites may remain on clothing or the skin, the human host should be treated with one application of 1% lindane lotion or 5% permethrin cream, and all clothing and linens should be washed in hot water. Topical corticosteroids and oral antihistamines provide symptomatic relief. The source of the infestation should be located and treated, eliminated, or avoided." Link.
- Baumstark, J., W. Beck, H. Hofmann. "Outbreak of Tropical Rat Mite (Ornithonyssus bacoti) Dermatitis in a Home for Disabled Persons" Dermatology 215 (2007): 66-68.
Five mentally handicapped individuals living in a home for disabled persons in Southern Germany were seen in our outpatient department with pruritic, red papules predominantly located in groups on the upper extremities, neck, upper trunk and face. Over several weeks 40 inhabitants and 5 caretakers were affected by the same rash. Inspection of their home and the sheds nearby disclosed infestation with rat populations and mites. Finally the diagnosis of tropical rat mite dermatitis was made by the identification of the arthropod Ornithonyssus bacoti or so-called tropical rat mite. The patients were treated with topical corticosteroids and antihistamines. After elimination of the rats and disinfection of the rooms by a professional exterminator no new cases of rat mite dermatitis occurred. The tropical rat mite is an external parasite occurring on rats, mice, gerbils, hamstersand various other small mammals. When the principal animal host is not available, human beings can become the victim of mite infestation. (Abstract not mine.) Link.
- Beck, W. and Pfister, K. "Occurrence of a house-infesting tropical rat mite (Ornithonyssus bacoti) on murids and human beings in Munich: 3 case reports." Wiener Klinische Wochenschrift 116 (2004): 65-68.
In Germany there is little information available concerning the distribution of the tropical rat mite (Ornithonyssus bacoti) in rodents. A few case reports show that this haematophagous mite may also cause dermatitis in man. All developmental stages are exclusively blood feeders. Three children (4, 11 and 15 years old) from the same family, a 23-year-old medical student and a 17-year-old dental technician were attacked by the tropical rat mite. The patients' conditions had previously been diagnosed as allergic dermatitis and treated by several antiphlogistic agents without success. The conclusive diagnosis of tropical rat mite dermatitis was based on the identification of O. bacoti in the flats of the patients (associated with gerbil husbandry) and in the dental practice. The diagnosis of rat mite dermatitis requires the detection of the parasite, which is more likely to be found in the environment of its host than on the host's skin. (Abstract not mine.) Link.
- Charlesworth, E. N. and R. W. Clegern "Tropical rat mite dermatitis" Archives of Dermatology 113 (1977).
We had a patient with dermatitis caused by the bite of Ornighonyssus bascoti (Hirst), commonly referred to as the tropical rat mite. The bite of this mite resulted in a severely pruritic papular dermatitis in our patient. Accurate identification of the mite indicated the presence of rat infestation. Link. (Abstract not mine.) Link.
- Chung, Sang Lip. "Report: Outbreak of Tropical Rat Mite Dermatitis in Medical Students" International Journal of Dermatology 37 (1998): 591-594.
Background The tropical rat mite, Ornithonyssus bacoti (O. bacoti), is an ectoparasite on many rodents, but when the rodent is not available, humans may become the victim of the mite’s bite. The bite induces a nonspecific dermatitis; therefore, it is not easy to diagnose rat mite dermatitis unless the parasites are found.
Materials and methods: Ten cases of rat mite dermatitis were found in medical students who had studied in the same room of the library. Their nonspecific dermatitis consisted of small papules, and parasites were found in the skin or in the environment. The mites were collected and identified as O. bacoti, female. Histopathologic studies showed moderate perivascular lymphohistiocytic infiltrations intermingled with some eosinophils. The presence of rodents in or around the room was confirmed by the students, but there had been no preceding rodent eradication. Although the rats were not captured in the library, insecticides were sprayed, and no further problem with either mites or dermatitis developed during the follow-up period.
Conclusions: Rat mite dermatitis can occur in clusters that involve a common source of exposure to the rat mite epidemiologically. Prompt identification of rat mites and the eradication of mites and rodents from the environment can prevent further spreading of the disease. Link.
- Engel, P.M., J. Welzel, M. Maass, U. Schramm, H. H. Wolff. "Tropical rat mite dermatitis: case report and review." Clinical Infectious Diseases 27 (1998): 1465-9.
Six medical students inhabiting a centuries-old, rat-infested house in Lübeck, in northern Germany, were suffering from itching papules and seropapules. Prior to these patients' visit to our institute, their conditions had been diagnosed as pediculosis, scabies, or pulicosis and treated unsuccessfully with the antiparasitic agent lindane (0.3%). The final diagnosis, tropical rat mite dermatitis, was based on the identification of the arthropod Ornithonyssus bacoti, which has an unsegmented body with eight legs. No treatment was recommended, and the dermatitis disappeared within 2 weeks. Measures taken to prevent reinfestation included extermination of the rats and treatment of the rooms of the house with the acaricide benzyl benzoate. Because the mite O. bacoti spends a relatively short time on a host and penetrates the skin for feeding only, the application of an antiparasitic agent is not necessary. If indicated, treatment should be symptomatic. (Abstract not mine.) Link.
- Fox, J. G. "Outbreak of Tropical Rat Mite Dermatitis in Laboratory Personnel." Archives of Dermatology 118 (1982).
An outbreak of tropical rate mite (Ornithonyssus bacoti) dermatitis occurred in a group of research and animal technicians. The technicians were affected with an intense pruritic dermatitis after exposure to asymptomatic laboratory mice infested with the mite. Locating the resident host of the mite is critical in the successful elimination of the mite from the premises and in preventing further contact with and irritation to human occupants. (Abstract not mine.) Link.
- Haggard, Carl N."Rat Mite Dermatitis in Children." Pediatrics 15 (1955): 322-324.
DERMATITIS due to a specific etiologic agent, which responds immediately to therapy, is rather exceptional among eruptions in infancy.
Exploratory activities of toddlers often lead them to habitats and runways of rodents. Time belief that acariasis acquired by this direct manner may commonly be overlooked suggested that the present observations should be recorded.
CASE REPORT
A foundling home was being razed to make room for a new modern building. As portions of the house were torn down, occupants were moved to intact parts of the building. As the building proceeded, the need for rat extermination became increasingly great. About this time, adult occupants complained of itching rashes, and these failed to respond to a variety of common remedies. (Abstract not mine.) Link.
- Hill, William A , Mildred M Randolph , Keli L Boyd , and Timothy D Mandrell. "Use of permethrin eradicated the tropical rat mite (Ornithonyssus bacoti) from a colony of mutagenized and transgenic mice." Contemporary Topics in Animal Laboratory Science 44 (2005): 31-34.
The tropical rat mite, Ornithonyssus bacoti, was identified in a colony of mutagenized and transgenic mice at a large academic institution. O. bacoti is an obligate, blood-feeding ectoparasite with an extensive host range. Although the source of the infestation was likely feral rodents, none were found in the room housing infested mice. We hypothesize that construction on the floor above the vivarium and compromised ceiling integrity within the animal room provided for vermin entry and subsequent O. bacoti infestation. O. bacoti infestation was eliminated by environmental decontamination with synthetic pyrethroids and weekly application of 7.4% permethrin-impregnated cotton balls to mouse caging for five consecutive weeks. Visual examination of the macroenvironment, microenvironment, and colony for 38 days confirmed the efficacy of treatment. We noted no treatment-related toxicities or effects on colony production. (Abstract not mine.) Link.
- Katoch, R., S. Chatterjee, R. S. Telang, S. K. Khurana, R. K. Agnihotri. "Efficacy of EctoZee spray formulation against tropical rat mite (Ornithonyssus sp.)." Phytomedica 3 (2002).
A study was conducted to investigate the in vitro and in vivo efficacy of EctoZee against Ornithonyssus. For the in vitro study, live mites were collected by hand-picking from naturally-infested rats. After one hour, 240 mites were randomly divided into 8 groups of 30 mites each. Mites in groups 2 to 8 were placed in 30 ml culture tubes containing 6 × 6 cm Whatman filter paper impregnated with 0.5 ml of 0.25, 0.5, 1.0, 2.0, 4.0, 8.0 and 16.0% EctoZee formulation, respectively. Group 1 served as the untreated control. The mortality of mites in all the groups was noted after 20 hours. In the in vivo study, 2 adult and 6 newborn Wistar albino rats, severely infested with Ornithonyssus sp. were found in the laboratory. EctoZee (25%) spray formulation was evenly applied to the test animals. One of the adult animals died before any treatment was given. The in vitro study showed concentration-dependent mortality of the mites. The LC50 of Ornithonyssus was 5.112±0.334%. Application of EctoZee spray formulation in the in vivo study resulted in complete removal of mites by 24 hours. No reinfestation was noted during the subsequent days. Minor adverse reactions were observed in the adult rat, which subsided after 30 minutes of application, with no need for any antidote. The surroundings of the animal houses/cages were also devoid of mites during the subsequent days. Results suggest that EctoZee spray formulation is effective against Ornithonyssus sp. both in vivo and in vitro, without any significant adverse effects. (Abstract not mine.) Link.
- Newton, Hiram D. "Tropical Rat Mite Infestation." California and Western Medicine 57 (1942): 143.
A married woman of 39 years came to a physician on April 21, 1942. At first, the doctor suspected entymophobia, but upon inspection of the samples the patient brought and by consulting an entymologist at San Diego State College, the physician determined they were tropical rat mites and subsequently a rat infestation was found in the patient's home. Husband and infant child not affected by mites. The rats were killed, the floors powdered with flea powder, and pyrethrum cream was used on the patient. When the doctor asked pest control operators, they were familiar with the mite and had resorted to the use of cyanide gas to control infestations in large buildings--which reflects how difficult it is to destroy the mites. Abstract mine. Link.
- Olson, Theodore A. and Reynold G. Dahms. "Observations on the Tropical Rat Mite, Liponyssus bacoti, as an Ecto-Parasite of Laboratory Animals and Suggestions for Its Control." Journal of Parasitology 32 (1946): 56-60.
Article points out that the tropical rat mite was first observed in Egypt in 1913. The article follows an incident in an animal house in Texas in 1945. In the incident, the animal house is so infested with tropical rat mites that many laboratory animals die from exsanguination (loss of blood). The scientists observe the mites choosing one rodent host over the others to swarm, killing it, and then moving on to the next host (although apparently many hosts were being swarmed at the same time). The mites reproduced so quickly and were so numerous that the swarm was both converging on the rodents and away from them as they were full of blood. The investigative team found that DDT was the best way to destroy the mites. (Abstract mine.) Link.
- Philip, Cornelius B. and Lyndahl E. Hughes. "The Tropical Rat Mite, Liponyssus Bacoti, as an Experimental Vector of Rickettsialpox." American Journal of Tropical Medicine 1948 (5): 697-705.
Preliminary tests have shown that the tropical rat mite, Liponyssus bacoti, can transmit the agent of rickettsialpox, Rickettsia akari, from mouse to mouse, though present observations do not indicate it to be an efficient vector. In the early tests no attempt was made to prevent test mice from eating the mites, but in one successful transmission to baby mice this could not have occurred. Infection was demonstrated in nymphal progeny, indicating transovarial passage of the agent. The agent was shown to persist in a colony for at least 34 days, and in dead mites for at least short periods.
Though the disease is not now known beyond the limits of New York City, the host habits and much more widely known distribution of I. bacoti compared to that of the presently known natural vector, Allodermanyssus sanguineus, suggest the former is of potential importance in planning control measures or in surveying future foci. (Abstract not mine.) Link.
- Pratt, Harry D. and Newell E. Good. "Distribution of Some Common Domestic Rat Ectoparasites in the United States." Journal of Parasitology 40 (1954): 113-129.
Article discusses a variety of rat ectoparasites. Tropical rat mites are noted to be one of the only rat mites that will readily attack humans even when its host is present. It's distribution is mainly in the Southern States in the United States, however, it has been reported to the CDC in all states including Alaska. (Abstract mine.) Link.
- Scott, J. Allen. "Longevity of Tropical Rat Mites Kept Without Food." Journal of Parasitology 35 (1949): 434.
When a laboratory was infested with Tropical Rat Mites, the laboratory personnel inadvertantly had some mites left over in a glass implement. The personnel decided to make in impromtu experiment and observe how long the mites would survive. The last mite died at about 63 days without a blood meal. (Abstract Mine.) Link.
- Skirnisson, Karl. "The Tropical Rat Mite, Ornithonyssus Bacoti, Attacks Humans In Iceland." Laeknabladid 12 (1987): 991-993.
In the summer of 2001 the obligate, intermittent tropical rat mite Ornithonyssus bacoti attacked humans in an Icelandic household where infected Mongolian gerbils (Meriones unguiculatus), bought in a local pet shop, had been kept for few months. After a rapid proliferation the mite started attacking the humans living in the house. A boy sharing room with the pets suffered from extensive dermatitis. Optimal conditions for O. bacoti are at 24-26 degrees C and a relative humidity of 47%. Similar conditions frequently occur indoors in Icelandic premises. Therefore, if O. bacoti has been noticed indoors, necessary measures should be undertaken to immediately eliminate the pest. Link.
- Theis, J., M. M. Lavoipierre, R. LaPerriere and H. Kroese "Tropical rat mite dermatitis. Report of six cases and review of mite infestations." Archives of Dermatology 117 (1981).
Six cases of tropical rat mite (Ornithonyssus bacoti) dermatitis are presented. The patients experienced papular urticaria, and mites were found on and identified in several of the patients. The presence of rodents in or around the home was confirmed in most cases. The role of other parasitic mites found on bats, birds, and snakes is reviewed. The importance of obtaining a history of rodent activity or exposure to other animals is emphasized when considering the cause of arthropod bites. (Abstract not mine.) Link.
- Williams, Roger. W. "The Laboratory Rearing of the Tropical Rat Mite, Liponyssus Bacoti." Journal of Parasitology 32 (1946): 252-256.
Article discusses ways in which a laboratory can raise tropical rat mites. A ferral rat carries sufficient quantities of mites on it's person to be able to establish a proper laboratory colony. The mites on the rat (not in nest) were able to reproduce to over 1000 specimens within one week. Article also discusses rat mites as a vector for worms. (Abstract mine.) Link.
birdmites.org has a similar collection of research and abstracts for bird mites: Link.
