Rat Mite Research Articles

Identification of Mites in Wild Rats in Simpang Limun Traditional Wet Market Area, Medan - Indonesia

Background: Among human diseases are infectious diseases transmitted by animals to humans, called zoonoses. Rats carry ectoparasites that act as biological vectors in the transmission of zoonoses. Mites are ectoparasites of rats that cause various zoonoses, namely murine typhus, rat mite dermatitis, and others. The study aims to identify species of wild rats in the study area based on their morphology and presentation of mite-infected rats and mite species in wild rats in Simpang Limun traditional wet market in Medan, Indonesia. Methods: This cross-sectional study used a purposive sampling technique. Primary data were collected in the Simpang Limun traditional wet market area of Medan, namely in the first area; M. Nawi Harahap Street, and the second area; Kemiri I Street. Every afternoon for four consecutive days, ten baited rat traps were deployed in each area. The captured rats were anesthetized, identified, and examined for mites by combing and then identified under a microscope. Results: From 65 total wild rat samples, the majority of species found was Rattus tanezumi 60 (92.3%), followed by Rattus norvegicus 5 (7.7%). The identified mite species were Laelaps echidninus (84.5%) and Laelaps nuttalli (15.5%). Conclusion: Nearly all of the wild rats found were of Rattus tanezumab species, and the most common mite species identified was Laelaps echinus in Medan's Simpang Limun traditional wet market area. This has a significant medical impact, resulting in increased potential for zoonosis transmission and indirectly to the surrounding residents in Medan's Simpang Limun traditional wet market area.

What's Eating You? Tropical Rat Mite (Ornithonyssus bacoti).

The tropical rat mite (Ornithonyssus bacoti) commonly infests wild and pet rodents, but they are not host specific. Bodily contact with wild or domesticated rodents is the most common source of infestation. Mites can live off many mammal hosts for a long period of time; therefore, living in quarters infested by mice can lead to mite exposure. Human infestation presents as urticarial, pruritic, cutaneous lesions that may be misdiagnosed as an arthropod bite, an infection, or contact dermatitis. Symptomatic relief of pruritus can be provided with a topical corticosteroid or antihistamine. The most effective treatment is an antiparasitic, such as permethrin cream, as well as extermination of rodents, mites, and any other pests in the patient's living space.

Identification and Control of an Ornithonyssus Bacoti Infestation in a Rodent Vivarium by Using Molecular Diagnostic Techniques.

Ornithonyssus bacoti, commonly known as the tropical rat mite, is a zoonotic ectoparasite that occasionally infests research rodent colonies. Most infestations have been attributed to wild rodents that harbor the mite and spread it to research animals, often during building construction or other activity that disrupts wild rodent populations. Although infestation may be clinically silent, severe outbreaks have been reported to cause pruritis, dermatitis, decreased reproductive performance, and anemia in rodents. In mid-2020, our institution experienced increased activity of wild mice, which were found to be infested with O. bacoti, diagnosed by microscopic exam and confirmed by fur swab PCR analysis. We elected to add O. bacoti to our quarterly health monitoring exhaust air dust (EAD) testing PCR panel, increase wild mouse control measures, and treat the environment with a sustained-release synthetic pyrethroid spray in an attempt to prevent colony animal infestation. Initial quarterly EAD health monitoring results in September of 2020 were negative for O. bacoti. However, in early 2021, multiple IVC racks tested positive for O. bacoti at quarterly testing. Treatment consisted of providing permethrin-soaked nesting material and surface spray treatment of the room and hallway with a sustained-release synthetic pyrethroid. Historically in the literature, O. bacoti outbreaks of research mice were not identified until mite burden was high enough to cause dermatitis on animal care workers. Due to modern molecular diagnostics and proactive PCR-based health monitoring surveillance, we were able to identify the outbreak earlier than would have otherwise been possible. To the best of our knowledge, this is the first report to successfully identify O. bacoti using environmental health monitoring PCR techniques. This outbreak demonstrates the importance of screening for O. bacoti in facilities with the potential for wild rodent infestation and highlights unique considerations when managing O. bacoti infestations. In addition, a novel permethrin-soaked enrichment item was developed for cage-level treatment.

Zoonotic vector-borne bacteria in wild rodents and associated ectoparasites from Tunisia.

Wild rodents are considered as potential carriers of several zoonotic vector-borne bacteria but their epidemiology is poorly understood in Tunisia. A total of 305 biological samples (100 spleens, 100 livers, 100 kidneys, and 5 pooled ectoparasites (Xenopsylla cheopis, Laelaps echidninus, Ornithonyssus sp., Hoplopleura sp. and eggs of the rat fleas)) were collected from 100 wild rodents from three Tunisian governorates. Molecular screening was performed to reveal infections with main vector-borne bacteria. Captured rodents belonged to three rodent genera and species including Rattus rattus (n=51, 51%), Meriones shawi (n=24, 24%) and Mus musculus (n=25, 25%). Examined rodents were found to be heavily infested by the rat flea X. cheopis (n=32, 47%) and the rat mite L. echidninus (n=22, 32.3%). However, the rat mite Ornithonyssus sp. (n=13, 19.1%) and the rat lice Hoplopleura sp. (n=1, 1.5%) were rarely identified. Based on 16S rRNA and msp4 genes, infection with Anaplasmataceae bacteria was detected in six specimens of R. rattus and one M. shawi. Pathogenic A. phagocytophilum (n=1), A. phagocytophilum-like 1 (Anaplasma sp. Japan) (n=1), and A. ovis (n=5) were identified. On the basis of ompB, ompA and gltA genes, infection with Rickettsia spp. was identified in three specimens of R. rattus and one of M. shawi. Five Rickettsia species of the spotted fever group, corresponding to R. monacensis, R. helvetica, R. massiliae, R. africae, and R. aeschlimannii, were detected in mixed infections. Bartonella henselae DNA was also found in two R. rattus, based on rpoB partial sequences. All revealed Anaplasma, Rickettsia and Bartonella bacteria were detected in spleen samples. Ehrlichia, Coxiella and Borrelia spp. were not identified in any of the tested samples. In Tunisia, this is the first report indicating infections with Anaplasma, Rickettsia and Bartonella spp. in wild rodents, particularly present alongside domestic livestock and human. This represents a serious risk of potential bacterial transmission. Thus, controlling rodent population in animal herds, residential areas and sensitizing local people to this risk seem absolutely necessary.

Distribution and Host Selection of Tropical Rat Mite, Ornithonyssus bacoti, in Yunnan Province of Southwest China.

Simple SummaryThe tropical rat mite (Ornithonyssus bacoti) is a transmission vector of rickettsia pox and a potential vector of hemorrhagic fever with renal syndrome (HFRS). This article reports the distribution and host selection of O. bacoti in Yunnan Province of Southwest China. The original data came from the investigations in 39 counties of Yunnan. The prevalence (PM), mean abundance (MA) and mean intensity (MI) were calculated to reflect the infestations of the dominant rat hosts with O. bacoti mites. The patchiness index and Taylor’s power law were used to measure the spatial distribution of the mites. A total of 4121 O. bacoti mites were identified from 15 species of small mammal hosts in 27 of the 39 investigated counties, and 99.20% of them (4088/4121) were found on rodents. The majority of total O. bacoti mites was found in the flatland landscape (91.28%) and indoor habitat (73.48%). Moreover, 51.78% and 40.09% of O. bacoti mites were identified from Rattus tanezumi and R. norvegicus, the two synanthropic rat species. The mites had some host-specificity, with a preference to two dominant hosts (R. tanezumi and R. norvegicus), and they were of aggregated distribution on R. tanezumi.(1) Background: As a species of gamasid mite, the tropical rat mite (Ornithonyssus bacoti) is a common ectoparasite on rodents and some other small mammals. Besides stinging humans to cause dermatitis, O. bacoti can be a vector of rickettsia pox and a potential vector of hemorrhagic fever with renal syndrome (HFRS). (2) Objective: The present study was conducted to understand the host selection of O. bacoti on different animal hosts and the distribution in different environmental gradients in Yunnan Province of Southwest China. (3) Methods: The original data came from the investigations in 39 counties of Yunnan, between 1990 and 2015. The animal hosts, rodents and some other small mammals were mainly trapped with mouse traps. The O. bacoti mites on the body surface of animal hosts were collected and identified in a conventional way. The constituent ratio (Cr), prevalence (PM), mean abundance (MA) and mean intensity (MI) were used to reflect infestations of animal hosts with O. bacoti mites. The patchiness index and Taylor’s power law were used to measure the spatial distribution pattern of O. bacoti mites on their hosts. (4) Results: A total of 4121 tropical rat mites (O. bacoti) were identified from 15 species and 14,739 individuals of hosts, and 99.20% of them were found on rodents. More than half of O. bacoti mites (51.78%) were identified from the Asian house rat (Rattus tanezumi), and 40.09% of the mites from the Norway rat (R. norvegicus) (p < 0.05). The infestations of R. tanezumi (PM = 7.61%, MA = 0.40 and MI = 5.31) and R. norvegicus (PM = 10.98, MA = 1.14 and MI = 10.39) with O. bacoti mites were significantly higher than those of other host species (p < 0.05). The infestations of two dominant rat hosts (R. tanezumi and R. norvegicus) with O. bacoti mites varied in different environmental gradients (latitudes, longitudes, altitudes, landscapes and habitats) and on different sexes and ages of the hosts. The prevalence of juvenile R. norvegicus rats with O. bacoti mites (PM = 12.90%) was significantly higher than that of adult rats (PM = 9.62%) (p < 0.05). The prevalence (PM = 38.46%) and mean abundance (MA = 2.28 mites/host) of R. tanezumi rats with O. bacoti mites in the high latitude were higher than those in the low latitudes (p < 0.05). The majority of the total collected 4121 O. bacoti mites was found in the flatland landscape (91.28%) and indoor habitat (73.48%) (p < 0.05). The PM (10.66%) and MA (0.49 mites/host) of R. tanezumi rats with O. bacoti mites were significantly higher in the indoor habitat than in the outdoor habitat (p < 0.05). The tropical rat mites showed an aggregated distribution pattern on their first dominant host, R. tanezumi. Conclusion: The tropical rat mite (O. bacoti) is a widely distributed species of gamasid mite in Yunnan Province, Southwest China, and its dominant hosts are two synanthropic species of rats, R. tanezumi and R. norvegicus. It is mainly distributed in the flatland landscape and indoor habitat. It has some host-specificity, with a preference to rodents, especially R. tanezumi and R. norvegicus. The O. bacoti mites are of aggregated distribution on R. tanezumi rats.

DISEASE AND PATHOLOGICAL CONDITIONS OF AN ENDANGERED RODENT, MICROTUS CALIFORNICUS SCIRPENSIS, IN A CAPTIVE-REARING FACILITY AND IN THE WILD.

Causes of morbidity and mortality and a survey of infectious disease agents were collated from wild and colony-raised endangered Amargosa voles (Microtus californicus scirpensis). Six voles from the wild and 295 voles in the captive-breeding colony were included in the study upon identification of an infectious agent during screening, identification of clinical signs of disease, or finding a pathological condition or infectious agent on necropsy. Findings included 28 significant or incidental pathological conditions of seven organ systems and 19 parasitic, viral, bacterial, or fungal agents. Several voles captured in the wild had fungal osteomyelitis of the tail that disseminated systemically in a vole brought from the wild to the colony and may have been caused by a Penicillium sp. Three voles reintroduced from the colony to the wild experienced inanition and subsequent severe hepatic and moderate renal tubular lipidosis. The most common significant pathological conditions in colony-reared voles were chronic interstitial nephritis with proteinosis; cardiomyopathy; trichobezoars that, in intestines or cecocolic junctions, sometimes induced local rupture or infarction with peritonitis; multifocal gastrointestinal ulceration and colibacillosis; acute renal tubular necrosis or nephritis; sepsis; hepatic and renal lipidosis; molar apical elongation sometimes progressing to invasion of the calvarium; and mammary tumors. Uncommon diagnoses included intervertebral disc disease; microvascular dysplasia; and multifocal bacterial abscessation. Common or clinically important infectious agents included Demodex sp. mites in hair follicles, Demodex sp. in esophageal mucosa, and an outbreak of tropical rat mites thought to have been introduced via the straw bedding; gastrointestinal Helicobacter sp.; attaching and effacing Escherichia coli; and Citrobacter braakii, a possible zoonotic bacterium. This survey of species-specific diseases and pathogens was possible because the established health surveillance program that is part of the species recovery plan allowed for monitoring of voles throughout the duration of their natural life spans in captivity.

CASES OF TICK-BORNE DERMATITIS, CAUSED BY ORNITHONYSSUS BACOTI, IN MEDICAL WORKERS

Introduction. The article presents data on cases of tick-borne dermatitis in medical workers caused by rat mites Ornithonyssus bacoti in unfavorable sanitary conditions. The goal is to consider the cause-effect relationship in the formation of tick-borne dermatitis as an industrial-conditioned disease. Material and methods. The clinical examination of 23 employees - female medical workers (doctors, nurses) aged from 28 to 56 years was carried out. Results. As a result of clinical examination, medical employees working in the department of a medical hospital on the first floor of the building were found to have complaints of severe itching, not associated with the time of day and the appearance of rashes in the form of roseola, small nodules in areas with thin and delicate skin, with serous or bloody crust on the top, mainly in the places of close contact with the laundry, where it fits snugly (especially the straps, collar, belt). On weekends, the improvement was noted, the itch subsided, and on returning to work the manifestations of the disease resumed. The medical staff at the workplace had contact with rat mites, triggered by the spontaneous mass infiltration of Ornithonyssus bacoti shortly after in the basement of the hospital located under this deratization department, when the main feeder-rat was destroyed and the mites were forced to look for the food, motor activity, leave the nest of rodents and crawl into the premise on the ground floor, preferring insulated places, concentrating in the crevices of the floor, walls, furniture, and there was an attack of ticks on a human. At the same time, employees working in the department did not depend on the profession, it was also noted among doctors and nurses. Conclusions. Given that the nature of the work in the performance of their duties at the workplace, medical personnel should not have direct contact with animals and substrate that can be infected with rat mites, as well as the occurrence of the disease soon after the deratization in the hospital, the mass and uniformity of the appearance of rashes allow to consider rat tick-borne dermatitis as an industrial-conditioned disease.

Prevalence and zoonotic risk of tropical rat mite (Ornithonyssus bacoti) in exotic companion mammals in southern Italy

Exotic companion mammals are popular pets worldwide. They are a potential source of zoonotic infections transmissible to their owners. To determine the prevalence and zoonotic risks of tropical rat mite (Ornithonyssus bacoti) in exotic companion mammals in Italy. The records of 782 exotic pet mammals seen in multiple veterinary clinics (n=20), pet shops (n=10) and private breeders (n=2) around Naples (Italy) were searched. The isolation of O.bacoti was the only inclusion criterion. Relative (in the subgroups) and absolute prevalence (in the entire population sampled) of clinical signs in pets and owners were calculated. The prevalence of clinical signs in pets and their owners was also calculated based on their housing (pet shops versus private housing) using Fisher's exact test. A P-value < 0.05 was considered significant. Seventy seven records (9.8%) of animals infested were identified. Of those, 33.8% (26 of 77) were hamsters, 25.9% (20 of 77) gerbils, 11.7% (nine of 77) guinea pigs, 7.8% (six of 77) rabbits, 7.8% (six of 77) degus, 5.2% (four of 77) kangaroo mice, 2.6% (two of 77) hedgehogs, 2.6% (two of 77) squirrels and 2.6% (two of 77) were sugar gliders. The frequency of owners affected by the rat mite dermatitis was very high in gerbils (20 of 20), hamsters (21 of 26) and guinea pigs (seven of nine). The results of the present survey indicate that exotic pet mammals may serve as an active reservoir for O.bacoti infestation. The results of this study also suggest a lack of species specificity for O.bacoti when favourable conditions are present (overcrowding).

ERADICATION OF A TROPICAL RAT MITE ( ORNITHONYSSUS BACOTI) INFESTATION FROM A CAPTIVE COLONY OF ENDANGERED AMARGOSA VOLES ( MICROTUS CALIFORNICUS SCIRPENSIS).

Staff at a university laboratory responsible for management of a captive insurance colony of endangered Amargosa voles ( Microtus californicus scirpensis) discovered an outbreak of tropical rat mites ( Ornithonyssus bacoti) infesting 106 voles. This bloodsucking mesostigmatid mite typically occurs in laboratory settings and can cause weight loss, wounds, or other negative impacts on health. The source of the infestation was likely feral rodents, and the route was suspected to be straw bedding. Twenty-nine of the 106 (27.4%) infested voles developed ulcerated dorsal skin lesions that resolved when treated with topical selamectin. A triad approach was implemented to eradicate the mites, consisting of environmental management, individual animal treatment, and training. Voles were moved individually into a clean room containing only autoclaved materials (including straw), cages were treated with permethrin-impregnated cotton, treatment order was instituted to avoid transferring mites, and voles coming from outside were quarantined. All animals in an infested room were treated with topical selamectin, and personnel were trained on risks and new procedures. No adverse effects from the use of selamectin were identified, and this efficient protocol does not require the long-term use of acaricides. This report documents infestation of an endangered rodent with an exotic parasite, safe use of permethrin and selamectin in this species, and comprehensive management to manage a large infestation.

Your Children Mite Not be Safe at School: An Outbreak of Biting Rat Mites at a Southern California Elementary School Campus

During May, 2017, the Orange County Mosquito and Vector Control District (OCMVCD) received anonymous calls from distressed school staff and parents of children attending an elementary school (Villa Park Elementary School, VPES) in Orange County, California, about an outbreak of pruritic dermatitis that was believed to be caused by biting arthropods. The incident received intense media coverage and led to a partial closure of the campus. With no identified culprit, OCMVCD interviewed VPES staff and surveyed the school property for vertebrate pests and their ectoparasites to determine the source of the outbreak. After thorough inspections of the exterior and interior of classrooms and a carefully-placed, glue-board trap survey, OCMVCD detected signs of significant roof rat activity (feces, rub marks, and harborage sites) throughout the campus and the presence of rat mites inside multiple classrooms. OCMVCD worked with other governmental agencies (Orange County Health Care’s Environmental Health, California Department of Pesticide Regulation’s School Integrated Pest Management Program, local city officials) and the VPES administration to educate parents about the vertebrate pests on the school grounds and the complexities of controlling the rat mite infestation during the school year. OCMVCD also identified deficiencies in the school’s pest control program and developed an integrated vector management plan to address the immediate and long-term health threats to prevent rodent and rat mite outbreaks in the future. This report details the investigation and methodology used to locate and eradicate the vertebrate and ectoparasite threats on the VPES campus and the challenges encountered during the process.

Outbreak and Eradication of Tropical Rat Mite (Acari: Macronyssidae) in a European Animal Facility.

A zoonotic, opportunistic out-break of tropical rat mite Ornithonyssus bacoti [Acari: Macronyssidae; Ornithonyssus bacoti (Hirst)] in an animal facility, is described. Immunocompetent mice [Mus musculus (Linnaeus)] and rat [Rattus norvegicus (Berkenhout)] strains in a conventional health status facility suffered from scratching and allopecia and staff members suffered from pruritic, erythemato-papular lesions, presumed to be allergic in origin. O. bacoti was identified and treatment with a 0.1% ivermectin solution led to its complete erradication. Safety assessment revealed no signs of acute toxicity in any animal strain. Following this inexpensive strategy, 7 wk after the initial dose, samples were negative for the presence of acari. At the time of this report, 26 months after diagnosis, O. bacoti remains undetected.

Tropical rat mite (Ornithonyssus bacoti) infestation in pet Syrian hamsters (Mesocricetus auratus) and their owner

Tropical rat mite <i>(Ornithonyssus bacoti)</i> infestation in pet Syrian hamsters (<i>Mesocricetus auratus</i>) and their owner

New Records of EctoparasitesEchinolaelaps echidninusandPolyplax spinulosaon Rodents with Serological Evidence of Flavivirus Infections at Mérida, Yucatán, México

Abstract. Two ectoparasites, spiny rat mite, Echinolaelaps echidninus (Berlese) (n = 27), and spined rat louse, Polyplax spinulosa (Burmeister) (n = 2), were recorded for the first time in Yucatan State and documented with photographs. The ectoparasites were identified mostly on black rat, Rattus rattus (L.), with serological evidence of flavivirus infection. Adult female E. echidninus was most common and found on black rat with serological evidence of yellow fever, Modoc, and Apoi viruses. We also reported for the first time the cat flea, Ctenocephalides felis (Bouche), on R. rattus. We discussed the potential for the arthropods to bite and transmit pathogens to humans.

Dermatitis by Tropical Rat Mite, Ornithonyssus bacoti (Mesostigmata, Macronyssidae) in Italian city‐dwellers: a diagnostic challenge

Editor Mesostigmata (Gamasida) is a suborder of mites within the order Parasitiformes.1 Some species can bite humans, typically causing pruritic, non-specific skin lesions. The mesostigmatic mites most commonly associated with cases of dermatitis are from the Macronyssidae and Dermanyssidae families.1 All are haematophagous non-burrowing mites of very similar size and shape, and can be seen with the naked eyed as they range from 0.5 to 1.5 mm in size.1 Adults are able to survive several weeks without a blood meal.1 The tropical rat mite, Ornithonyssus bacoti, Hirst (Macronyssidae) is one of these species. It can occur worldwide mostly as an ectoparasite of wild rats and mice,2, 3 but also pet and laboratory rodents may occasionally be the source of the mite.2, 4-6 As a nest parasite, it only visits its host to feed, mainly during the night; and then returns to its nearby hiding place during the day. In the absence of its natural host, human beings may become subject to mite infestation. Outbreaks of tropical rat mite (TRM) dermatitis have been reported in humans in urban areas in Europe, because of wild/pet rodent infestation of flats2-4 but also due to occupational exposure,5 including a single record from Italy.6 These scattered cases show that parasitization by the TRM is not obvious and skin lesions are usually misdiagnosed, unless the mite is discovered and correctly identified. To confirm this, we report an urban outbreak of TRM dermatitis diagnosed by identifying the parasite. In November 2013, veterinary entomologists from the Zooprofilactic Institute (IZSPB), Foggia were contacted to inspect a house for mites. Owner referred that her 2-year-old daughter suffered from multiple erythematous papules over a 9-month period. Cutaneous lesions were generalized but predominantly located in groups on the neck and body areas covered by clothes (trunk, upper extremities and abdomen) (Fig. 1). Her 71-year-old grandmother had also experienced the same symptoms after spending a single night in the child's home. Bites by arthropods/non-burrowing mites/wood-mite and Streptococcus spp. infection respectively, were diagnosed after two paediatric and two dermatological consultations. Symptomatic relief was also unsuccessful. Mites were detected in dust samples and in child's bedding, after careful investigation of the patient's living quarters by IZSPB staff. All of the parasites were identified as Ornithonyss bacoti based on morphological keys1 (Fig. 2). The source of the mites was a previously eliminated rats' nest in the living-room. Medical texts and parasitology manuals rarely mention mesostigmatic mites in association with human parasitization; detection and correct identification of these ectoparasites is also difficult. This makes it a challenge for physicians, including dermatologists, to recognize epizoonotic mite-associated dermatitis, including skin disorders caused by O. bacoti. This inevitably leads to failures in treatment. In addition to O. bacoti, mestostigmatic avian mites such as Ornithonyssus sylviarum and Ornithonyssus bursa (Macronyssidae), and more frequently Dermanyssus gallinae (Dermanyssidae) can be associated with urban dermatitis in Europe,2, 7, 8 including Italy.9 When unexplained pseudoscabious eruptions occur on patients in urban areas, investigation for mesostigmatic mites should always be undertaken. If small rodents are held as pets, animals and their bedding should be carefully examined by a veterinarian. Diagnosis and treatment of these infestations require accurate anamnesis, detection and identification of the parasite, removal of the source and disinfestation. As studies suggest that the rat mite may be a reservoir of various zoonotic pathogens and a vector of Bartonella henselae,10 its early diagnosis remains crucial. Dermatitis by mesostigmatic mites, including the TRM dermatitis, are without doubt more frequent than one might expect. Increased physicians awareness of the possible role of these ectoparasites in urban infestations of humans, and applying the One Health approach will be essential for diagnosis, treatment and prevention.

Preliminary Survey of Ectoparasites and Associated Pathogens from Norway Rats in New York City.

The Norway rat (Rattus norvegicus) is a reservoir of many zoonotic pathogens and lives in close proximity to humans in urban environments. Human infection with rodent-borne disease occurs either directly through contact with a rat or its excreta, or indirectly via arthropod vectors such as fleas and ticks. Here, we report on the diversity and abundance of ectoparasitic arthropod species and associated pathogenic bacteria from 133 Norway rats trapped over a 10-mo period in Manhattan, New York, NY. Norway rats were host to the tropical rat mite [Ornithonyssus bacoti (Hirst)], the spiny rat mite (Laelaps echidnina Berlese), Laelaps nuttalli Hirst, the spined rat louse [Polyplax spinulosa (Burmeister)], and the Oriental rat flea [(Xenopsylla cheopis) (Rothschild)], with an average of 1.7 species per individual. A flea index of 4.1 X. cheopis was determined, whereas previous studies in New York City reported 0.22 fleas per rat. Multiple species of pathogenic Bartonella were identified from Oriental rat fleas that were related to Bartonella tribocorum, Bartonella rochalimae, and Bartonella elizabethae. However, no evidence of Yersinia pestis or Rickettsia spp. infection was detected in fleas. The identification of multiple medically important ectoparasite species in New York City underscores the need for future efforts to fully characterize the diversity and distribution of ectoparasites on Norway rats, and assess the risk to humans of vector-borne disease transmission.

Dermatoses associated with mites other than sarcoptes

Mites are arthropods of the subclass Acari (Acarina). Although Sarcoptes is the mite most commonly recognized as a cause of human skin disease in the United States, numerous other mite-associated dermatoses have been described, and merit familiarity on the part of physicians treating skin disease. This review discusses several non-scabies mites and their associated diseases, including Demodex, chiggers, Cheyletiella, bird mites, grain itch, oak leaf itch, grocer's itch, tropical rat mite, snake mite, and Psoroptes.

Use of scanning electron microscopy to confirm the identity of tropical rat mite (Ornithonyssus bacoti): the cause of rat mite dermatitis.

Cutaneous lesions in human patient due to the bite of rat mite Ornithonyssus bacoti are frequently misdiagnosed as allergies, fungal infection, or bacterial infection. Bite lesions in the personnel working in a Laboratory Animal facility which was infested with O. bacoti is reported here along with its therapeutic management. Diagnosis of the parasites obtained from the clothing of the personnel and later from the infested mice colony was based on preliminary light microscopy and confirmed by scanning electron microscopy. The mean length and breadth of adult female mite were 1.13mm ×0.63mm. The body is hairy, unsegmented and has four pairs of legs. The gnathostoma has long pointed chelicerae and pedipalp. The dorsal surface has one dorsal shield, and the ventral surface has three shields- sternal, genital and anal shield. Treatment of dermatitis involved antihistaminic drugs for a period of 3-5days. The skin lesion, characterized by papular erythema, tends to disappear within a period of 4-5days of antihistaminic treatment. In untreated cases, the lesions disappeared within 7-10days. Tropical rat mite O. bacoti Hirst, 1931 was identified to be the cause of infestation in the laboratory mice colony of Pasteur Institute of India, Coonoor, Tamil Nadu, predisposing the animal handlers to be temporary host.

Ectoparasites and Gastrointestinal Helminths of House Mice (Mus musculus) from Poultry Houses in Northwest Iran

Studies of rodent parasites are very important in relation to human and veterinary medicine and biology. Previous studies have demonstrated that the rate of infestation with ectoparasites and infection with nematodes, cestodes, and trematodes differs among locations. We surveyed the ectoparasites and endoparasites of 77 Mus musculus (house mice) collected from 41 poultry houses between April and December 2010 in northwest Iran. The rates of infection with ectoparasites and gastrointestinal helminths were 23.4 and 55.8%, respectively. We collected the ectoparasites Dermanyssus gallinae (prevalence 78%), Ornithonyssus bacoti (prevalence 11%), Polyplax serrate (prevalence 6%), and Myocoptes musculinus (prevalence 5%). We collected the gastrointestinal helminths Syphacia obvelata (prevalence 42%), Aspiculuris tetraptera (prevalence 19%), Syphacia muris (prevalence 18%), Cysticercus fasciolaris (prevalence 15%), and Hymenolepis diminuta (prevalence 5%). The chicken mite, Dermanyssus gallinae, and the tropical rat mite, Ornithonyssus bacoti are potential vectors of zoonotic pathogens. Hymenolepis diminuta can infect humans, and highlights the importance of house mice in certain zoonoses and suggests a more robust need for mouse control in the poultry houses.

Häufung von Ornithonyssus bacoti (Tropische Rattenmilbe) Infestationen bei Heimnagern und ihren Besitzern in den Kantonen Zürich und Graubünden

In spring 2009 several cases of infestation with Ornithonyssus bacoti («tropical rat mite») in pet rodents have been diagnosed at the Institute of Parasitology, University of Zurich. Although adequate animal hosts were present, owners also became victims of mite infestation. The owners presented cutaneous lesions such as pruritic red papules partly with a central vesicle, predominantly disposed in groups. Particularly children with close body contact to their pet rodents were strongly affected. Because the definite diagnosis was usually yielded at a late time-point, the medical treatment remained unsatisfactory in some cases. The mite-infestation of the pets was mostly detected after the owners also became affected. The owners noticed merely non-specific signs such as increased restlessness, itching and shaggy coat on their animals. Efficient healing was achieved only if the parasites were completely eliminated, i.e. also the pets were treated, the cages cleaned and the apartments professionally disinfested. A definite diagnosis of «Infestation with Ornithonyssus bacoti» is only possible by means of morphological identification on an isolated mite, which is most likely to be found in the environment of the animals. Pet owners should be informed about the zoonotic potential of O. bacoti.

Tropical rat mites (Ornithonyssus bacoti) – serious ectoparasites

In Germany there is limited information available about the distribution of the tropical rat mite (Ornithonyssus bacoti) in rodents. A few case reports show that this hematophagous mite species may also cause dermatitis in man. Having close body contact to small rodents is an important question for patients with pruritic dermatoses. The definitive diagnosis of this ectoparasitosis requires the detection of the parasite, which is more likely to be found in the environment of its host (in the cages, in the litter or in corners or cracks of the living area) than on the hosts' skin itself. A case of infestation with tropical rat mites in a family is reported here. Three mice that had been removed from the home two months before were the reservoir. The mites were detected in a room where the cage with the mice had been placed months ago. Treatment requires the eradication of the parasites on its hosts (by a veterinarian) and in the environment (by an exterminator) with adequate acaricides such as permethrin.