Co-occurrence of Eutrombicula alfreddugesi and Oswaldofilaria chabaudi in Tropidurus torquatus and first report of microfilariae in the chigger mite: possible evidence of a lifecycle pathway?

While much attention has been paid to vector-borne filariasis, diseases that threaten millions of people in tropical and subtropical countries, the literature on host-parasite associations and transmission strategies of filarial nematodes in wildlife is scarce. Here, we report the co-occurrence of chigger mites (Eutrombicula alfreddugesi) and onchocercid nematodes (Oswaldofilaria chabaudi) parasitizing the lizard Tropidurus torquatus in the State of Minas Gerais, Brazil. Examination of chiggers established, for the first time, the occurrence of microfilariae in trombiculid mites (Trombiculidae). These larvae were morphologically similar to those recovered from adult females of O. chabaudi. The current evidence suggests that chiggers do not play a role in the transmission of filarioid nematodes, but rather act as accidental or dead-end hosts. Nevertheless, considering the polyphagous nature of trombiculid mites, similar to blood-sucking insects involved in the transmission of several infectious diseases, further studies may shed light on the potential role of chiggers as vectors of filarioids.

Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species.

BACKGROUND: Scrub typhus is an emerging vector-borne zoonosis, caused by Orientia spp. and transmitted by larvae of trombiculid mites, called chiggers. It mainly occurs within a region of the Asia-Pacific called the tsutsugamushi triangle, where rodents are known as the most relevant hosts for the trombiculid vector. However, the reservoir(s) and vector(s) of the scrub typhus outside Asia-Pacific are unknown. The disease has recently been discovered on and is considered endemic for Chiloé Island in southern Chile. The aim of the present work was to detect and determine the prevalence of chiggers on different rodent species captured in probable sites for the transmission of orientiae responsible for scrub typhus on Chiloé Island in southern Chile and to molecularly examine collected chiggers for the presence of Orientia DNA. METHODOLOGY/PRINCIPAL FINDINGS: During the austral summer 2018, rodents were live-trapped in six sites and examined for chigger infestation. All study sites were rural areas on Chiloé Island, previously identified as probable localities where human cases acquired the scrub typhus. During a total of 4,713 trap-nights, 244 rodents of seven species were captured: the most abundant was Abrothrix olivacea. Chiggers were detected on all seven rodent species with a 55% prevalence rate. Chiggers showed low host specificity and varied according to site specific host abundance. Three genera of trombiculids were identified. Herpetacarus was the most abundant genus (93%), prevalent in five of the six sites. Infestation rates showed site specific differences, which were statistically significant using a GLM model with binomial errors. Molecular analyses proved that 21 of 133 (15.8%) mite pools were positive for Orientia species, all of them belonged to the genus Herpetacarus. CONCLUSIONS/SIGNIFICANCE: This study firstly reports the presence of different rodent-associated chigger mites positive for Orientia sp., in a region endemic for scrub typhus in southern Chile. Herpetacarus and two other genera of mites were found with high infestation rates of rodents in sites previously identified as probable exposure of scrub typhus cases. A substantial percentage of mite pools were positive for Orientia DNA, suggesting that chigger mites serve as vectors and reservoirs of this emerging zoonosis in South America.

Trombiculiasis: not only a matter of animals!

Trombiculiasis represents a striking emerging infestation in humans. In fact, modified lifestyles and easy and quick traveling around the globe, together with the altered ecology and habits of the parasite Neotrombicula autumnalis, make this original epizoonosis an extraordinary example of synanthropic dermatosis. We present an additional clinical image of this unusual parasite transmission from animals to humans occurring in a trekker in Calabria, Italy.

Emergence of Schoengastiella ligula as the vector of scrub typhus outbreak in Darjeeling: has Leptotrombidium deliense been replaced?

BACKGROUND: Following a suspected outbreak of scrub typhus in Kurseong, Darjeeling, the Armed Forces Medical College, Pune was requested by the National Institute of Epidemiology and the State authorities to undertake investigation of the ongoing scrub typhus outbreak and suggest containment measures. MATERIALS AND METHODS: The epidemic team undertook clinical, entomological and serological studies to understand the local disease pattern and delineate high risk areas, host diversity by rodent trapping using Sherman traps, mite fauna diversity, abundance and vector species identification by phase contrast microscopy for preparation of electronic database and rodent and human serological studies by Weil Felix and PCR. RESULTS: The results indicate no association of scrub typhus with age and sex (P=0.37 and 0.74 respectively). The maximum cases occurred amongst the tea garden workers (73%) in the age group of 25-44 years. The predominant clinical presentation was fever (100%) with headache (75%), lymphadenopathy (45%) and presence of eschar (76.7%). The dominant host species (50% of trapped rodents) was shrew Suncus murinus, the index animal for scrub typhus, which contributed maximally to the vector abundance (52.96%) with a chigger index of 61.56. The trombiculid mite Schoengastiella ligula was the vector species much against the expected mite vector Leptotrombidium deliense, in the area. The study found the presence and abundance of vector species which corroborated well with the occurrence of cases in the various localities within the subdivisions. CONCLUSION: The study thus establishes Schoengastiella ligula as the vector of scrub typhus outbreak in Kurseong, Darjeeling. Preventive and containment measures with emphasis on reduction of man - vector contact were suggested to the state authorities to contain the outbreak.

Patterns of infestation by the trombiculid mite Eutrombicula alfreddugesi in four sympatric lizard species (genus Tropidurus) in northeastern Brazil.

We studied the parasitism by the chigger mite Eutrombicula alfreddugesi on four sympatric lizard species of the genus Tropidurus in Morro do Chapéu, Bahia state, Brazil: T. hispidus, T. cocorobensis, T. semitaeniatus and T. erythrocephalus. For each species, we investigated the patterns of infestation and analyzed to which extent they varied among the hosts. We calculated the spatial niche breadth of the chigger mite on the body of each host species and the distribution of mites along the hosts' bodies for each Tropidurus species. All four species of Tropidurus at Morro do Chapéu were parasited by the chigger mite, with high (97-100%) prevalences. Host body size significantly explained the intensity of mite infestation for all species, except T. erythrocephalus. The body regions with highest intensity of infestation in the four lizard species were the mite pockets. The spacial niche width of the chigger varied consistently among the four lizards species studied being highest for T. erytrocephalus and lowest for T. cocorobensis. We conclude that the distribution and intensity with which lizards of the genus Tropidurus are infested by Eutrombicula alfreddugesi larvae results from the interaction between aspects of host morphology (such as body size and the occurrence and distribution of mite pockets) and ecology (especially microhabitat use).

Rickettsia tsutsugamushi in chiggers (Acari: Trombiculidae) associated with rodents in central Thailand.

Chiggers were collected from rodents trapped at two military bases located 10 km apart in central Thailand. One site was swampy and nearly treeless and the other site was well-drained and partially wooded. Although 13 species of chiggers were collected, only three species were found to be positive for Rickettsia tsutsugamushi (Hayashi) Ogata using a direct fluorescent antibody test: Blankaartia acuscutellaris Walch (7.3% infected), Leptotrombidium delinese Walch (3.1% infected), and an undescribed species of Ascoschoengastia near A. indica Hirst (1.2% infected). This was the first record of R. tsutsugamushi in B. acuscutellaris. The Ascoschoengastia species occurred with equal frequency at the two study sites, L. deliense occurred more frequently at the well-drained site, and B. acuscutellaris occurred more frequently at the swampy site. Results suggest that there are important foci of scrub typhus in central Thailand and that B. acuscutellaris may be a vector in this area.

Tunguíase / Tunguiasis

O autor faz uma revisäo da história, morfológia, biologia, clínica e terapêutica da tunguíase. Relata suas observaçöes destacando nove casos generalizados tratados com tiabendazol

Ectoparasitos de roedores da regiäo urbana de Belo Horizonte, MG: III. Indices pulicidianos, anoplurianos e acarianos em Rattus Norvegicus norvegicus / Ectoparasites in rodents of the urban region of Belo Horizonte, MG: III. Fleas, anoplura and acari indices in Rattus norvegicus norvegicus

Indices pulicidianos, anoplurianos e acarianos, globais e específicos foram determinados para os ectoparasitos de Rattus norvegicus norvegicus capturados em zona urbana de Belo Horizonte, Minas Gerais, Brasil, no período de junho de 1980 a setembro de 1982. Tendo-se em vista os valores limites ou críticos atribuídos aos índices pulicidianos, sobretudo ao índice "cheopis" e propostos por diversos autores como medida complementar de vigilância epidemiológica para peste bubônica, a comunidade de Belo Horizonte poderia ter estado exposta a esta infecçäo, uma vez que os índices globais anuais de 0,3 a 2,4 e a pulga prevalente foi Xenopsylla cheopis (99,2%), com os maiores índices coincidindo com o final da estaçäo seca-fria. Em duas ocasiöes, a comunidade poderia ter permanecido altamente exposta à infecçäo, já que os índices-limites tolerados foram suplantados: 8,8 (outubro 1980) e 6,2 (setembro 1982). Sugere-se que medidas profiláticas como anti-ratizaçäo e desinsetizaçäo sejam eficazmente aplicadas ao final da estaçäo seca-fria, ou anteriormente à chegada das chuvas, sendo sucedidas pela desratizaçäo. Informaçöes sobre índices anoplurianos e acarianos säo importantes para que se possa, no exclusivas de roedores

A survey of scrub and murine typhus in the Ancol section of Jakarta, Indonesia.

Rickettsia tsutsugamushi was isolated from L. (L.) arenicola chiggers and three species of rats in an area of scrub and sedge along the Bay of Jakarta. This is the only finding in Indonesia of a cycle of the agent of scrub typhus associated with L. (L.) arenicola. A serologic survey of nearly 300 persons living in two kampungs near the site at which rickettsiae were recovered revealed one individual with antibodies to R. tsutsugamushi. Murine typhus, with a seropositivity rate of 6.5%, may be endemic at low levels.

[Revision of the mites of the genus Miyatrombicula (Trombiculidae) in the fauna of the USSR]. / Reviziia kleshchei roda Miyatrombicula (Trombiculidae) fauny SSSR.

6 species of the genus Miyatrombicula are recorded from the fauna of the USSR: M. esoensis, M. reptilica, M. muris, M. balcanica, M. caucasica, M. ramitensis sp. n. Characteristic of the genus, redescription of known and description of new species are given. Larvae of the mites parasitize in general small mammals. In addition, some of these species were found in West Europe, Japan and North America.