Molecular detection of Rickettsia genus in chigger mites (Trombidiformes: Trombiculidae) collected on small mammals in southeastern brazilian / Detecção molecular do gênero Rickettsia em ácaros trombiculídeos (Trombidiformes: Trombiculidae) coletados em pequenos mamíferos do sudeste brasileiro

Abstract Chiggers are ectoparasites of vertebrates and may cause trombiculiasis or transmit pathogens to their hosts. Specimens collected from rodents and marsupials were morphologically identified as Herpetacarus hertigi, Eutrombicula tinami, Kymocta sp., Quadraseta brasiliensis, Quadraseta falconensis, Quadraseta flochi, Quadraseta mackenziei, Quadraseta pazca, Quadraseta trapezoides, Quadraseta sp., Serratacarus sp., and Trombewingia bakeri. These mites were submitted individually to molecular analyses for the detection of bacteria of the genus Coxiella, Hepatozoon and Rickettsia. Samples were positive to Rickettsia only. Obtained sequences for the gltA (350 pb) and ompA (488 pb) genes were identical to "Candidatus Rickettsia colombianensi", a species previously detected in ticks. In addition, molecular identification of mites based on 18S rDNA sequences are provided for H. hertigi, Kymocta sp., Q. brasiliensis, Q. pazca, Q. trapezoides, Quadraseta sp., and T. bakeri for the first time. This is the first report of the detection of a Rickettsia sp. in chigger mites collected on rodents in Brazil.

Resumo Os trombiculídeos são ectoparasitas de vertebrados e podem causar trombiculíase ou transmitir patógenos ao hospedeiro. Exemplares coletados em roedores e marsupiais foram identificados morfologicamente como Herpetacarus hertigi, Eutrombicula tinami, Kymocta sp., Quadraseta brasiliensis, Quadraseta falconensis, Quadraseta flochi, Quadraseta mackenziei, Quadraseta pazca, Quadraseta trapezoides, Quadraseta sp., Serratacarus sp. e Trombewingia bakeri. Estes ácaros foram submetidos individualmente à análise molecular para detecção de bactérias dos gêneros Coxiella, Hepatozoon e Rickettsia. Amostras foram positivas somente para Rickettsia. Sequências obtidas para os genes gltA (350 pb) e ompA (488 pb) foram idênticas à "Candidatus Rickettsia colombianensi", uma espécie anteriormente detectada em carrapatos. Além disso, foram fornecidas sequências de DNA 18S para identificação molecular de H. hertigi, Kymocta sp., Q. brasiliensis, Q. pazca, Q. trapezoides, Quadraseta sp. e T. bakeri. Este é o primeiro registro da detecção de Rickettsia em ácaros trombiculídeos coletados em roedores do Brasil.

Blankaartia sinnamaryi (Trombidiformes: Trombiculidae) parasitizing birds in southeastern Brazil, with notes on Rickettsia detection / Blankaartia sinnamaryi (Trombidiformes: Trombiculidae) parasitando aves no sudeste do Brasil, e notas sobre a detecção de Rickettsia

Abstract The larvae of the family Trombiculidae are ectoparasites of vertebrates, including birds. The bite of some species can cause deep lesions and severe skin reactions in the host, these can lead to dermatitis, popularly known as trombiculiasis. A morphological study of chiggers collected on birds from the state of Minas Gerais in Southeastern Brazil discovered Blankaartia sinnamaryi-infestation on Passeriformes birds. Molecular studies of the disclosed the 18S rDNA sequences of the mite, and the detection of a Rickettsia sp. in this chigger mite species.

Resumo As larvas da família Trombiculidae são ectoparasitas de vertebrados, incluindo aves. A picada de algumas espécies pode causam lesões profundas e reações cutâneas graves no hospedeiro, estas podem levar a dermatites, popularmente conhecidas como trombiculíases. Por meio de um estudo morfológico dos espécimes coletados parasitando aves do estado de Minas Gerais, Sudeste do Brasil relatou a infestação por Blankaartia sinnamaryi em aves Passeriformes. Além disso, nós fornecemos sequências de rDNA 18S desses ácaros e a detecção de uma espécie de Rickettsia sp. nesta espécie de trombiculídeo.

Monthly Occurrence of Vectors and Reservoir Rodents of Scrub Typhus in an Endemic Area of Jeollanam-do, Korea

Monthly surveys were conducted to investigate the occurrence of chigger mites and seroprevalence of scrub typhus among small mammals in Jeollanam-do, the southwestern part of Korea, from November 2006 through October 2007. Fifty-eight small mammals, including 57 Apodemus agrarius (98.3%) and 1 Crocidura lasiura (1.7%), were captured, and a total of 4,675 chigger mites representing 4 genera and 8 species were collected from them. The chigger infestation rate among small mammals was 69.0%. The most predominant species in A. agrarius was Leptotrombidium scutellare (54.0%), followed by Leptotrombidium pallidum (39.4%), Leptotrombidium orientale (4.4%), Leptotrombidium palpale (1.1%), Neotrombicula tamiyai (0.6%), Eushoengastia koreaensis (0.3%), Neotrombicula gardellai (0.3%), and Cheladonta ikaoensis (<0.1%). The chigger index of A. agrarius was the highest in October (740.0), followed by November (242.0), September (134.6), March (98.3), February (38.2), January (35.3), December (34.5), April (30.8), and May (1.7). The average antibody positive rate of scrub typhus in wild rodents was 50.0%. The seropositive rates were high in October (100.0%) and November (83.3%), whereas those in other months were relatively low (28.6-57.1%). The chigger index of L. scutellare rapidly increased in September to form an acuminate peak in October, followed by a gradual decline. These results suggest that the outbreak of scrub typhus in the southwestern part of Korean peninsula is mostly due to L. scutellare.

Acute reversible hearing loss in scrub typhus.

Scrub typhus usually presents as pyrexia with or without multiple organ involvement. Acute hearing loss occurs in about one third of cases and is a useful clue toward the diagnosis. We present two cases of scrub typhus with acute reversible hearing loss from an endemic area. The diagnosis was confirmed by nested PCR.

Characterization of Orientia tsutsugamushi strains isolated in Shandong Province, China by immunofluorescence and restriction fragment length polymorphism (RFLP) analyses.

In order to identify the characteristics of the Sta56 gene of the 23 isolates of Orientia (O.) tsutsugamushi isolated in Shandong Province, indirect immunofluorescence assay (IFA) was used to identify the gene type of 23 strains O. tsutsugamushi isolated from scrub typhus patients, chigger mites, and rodents. Restriction fragment length polymorphism (RFLP) analysis was also used to analyze the restriction profiles of the Sta56 gene PCR amplification products of the 23 isolated strains of the O. tsutsugamushi; the results were compared with those acquired by nested PCR. By IFA, 21 of the 23 isolates belonged to the Gilliam type, and 2 to the Karp type. Using RFLP analysis, 21 strains had similar restriction profiles to the Japan Kawasaki strain, but they had no restriction site Hha I, and thus had some difference in gene sequence compared with the Japan Kawasaki strain. The other 2 strains had similar restriction profiles to Karp. These results were identical to that acquired by nested-PCR. In Shandong Province, the gene types of epidemic O. tsutsugamushi strains were similar to the Japan Kawasaki type, but had some differences in gene sequence. In addition, Karp also existed.

Scrub typhus during pregnancy: a case report and review of the literature.

Scrub typhus is a rickettsial disease that is uncommon during pregnancy. We report a case of a 33-year-old woman, G1P0, 29 weeks pregnancy who presented to hospital with high fever, chill and headache for two weeks. Her diagnosis of scrub typhus was confirmed by serum immunofluorescent assay. She was successfully treated with chloramphenicol, but preterm delivery occurred. Her infant died from respiratory distress syndrome. No vertical transmission was demonstrated in this case. Scrub typhus should be listed in the differential diagnosis of acute febrile illness in pregnant women, who either live in, or return from, endemic areas. Chloramphenicol can be used safely during pregnancy if it is not circulating at the time of delivery.

Epidemiological studies on host animals of scrub typhus of the autumn-winter type in Shandong Province, China.

In order to elucidate the host animals of scrub typhus in Shandong Province, epidemiological studies on host rodents of the autumn-winter type scrub typhus were carried out from 1995 to 2002 at four localities in the Shandong Province. Based upon ecological observations of the composition, seasonal fluctuation of animal hosts, isolation of Orientia tsutsugamushi, detection and identification of serotypes of antibodies to O. tsutsugamushi were conducted. Two thousand eight hundred and eighty-four rodents and insectivores were captured, including 2,055 Apodemus agrarius (71.26%), 408 Cricetulus triton (14.15%), 64 C. barabensis (2.22%), 12 Crocidura suaveolens (0.42%), 313 Rattus (R.) norvegicus (10.85%), 32 Mus (M.) musculus (1.11%). A. agrarius was predominant in the field and the seasonal fluctuation was correlated significantly to that of scrub typhus (r=0.810, p<0.005). R. norvegicus was predominant indoors. The average capture rate per year in the field was 12.76% from 1995 to 1997. Of the total 2,884 rodents and insectivores captured out- and in-doors, 527 were living rodents (including 335 A. agrarius, 119 C. triton, 6 C. barabensis, 2 C. suaveolens, 63 R. norvegicus and 2 M. musculus, and 15,467 chigger mites were collected from them. Two hundred and fifty-three of 335 A. agrarius were parasitized by chiggers, showing 75.52% (253/335) of the infestation rate and 17.53 of the chigger index; 106 C. triton were parasitized by chiggers, showing 89.08% (106/119) infestation rate and 75.93 of the chigger index. The average antibody positive rate of rodents was 14.78%. The seasonal change of the antibody positive rate was higher during December-February (the second year), and varied from 20% to 28%, but the level of antibodies remained relatively low (5.26-16.67%) during March-November. The results of serotyping with 47 antibody-positive sera were as followings: 39 sera were Gilliam types, 7 sera were Karp types, 1 serum was Kato type. Twelve strains of O. tsutsugamushi were isolated from A. agrarius (8 strains), C. triton (3 strains) and R. norvegicus (1 strain), out of the isolated 12 strains, 10 were Gilliam strains, 2 were Karp strains. A. agrarius and R. norvegicus were the main host animals in out- and indoors respectively.

Rickettsia tsutsugamushi strains found in chiggers collected in Thailand.

R. tsutsugamushi strains found in chiggers collected from 3 different sites throughout Thailand were antigenically characterized. Monotypic infections were observed in 76.7% of the chiggers. Karp was the most predominant strain, followed by TA716, TA763, TA686 and Kato. This study represents the first confirmed report of R. tsutsugamushi infection in 8 different chigger species in Thailand.

Virulence and antigenic properties of Rickettsia tsutsugamushi in a naturally infectei laboratory colony of Leptotrombidium (leptotrombidium) arenicola.

Over 1,200 isolations of R. tsutsugamushi were obtained over 7 generations of L. (L.) arenicola and no reproducible differences in virulence or antigenic markers could be detected among these isolations. The F8 generation yielded rickettsia with the same antigenic makeup and virulence properties as the original female parent mite. When these isolates were inoculated into mice they elicited the same predominant antibody specificities, i.e. they all produced antibody which reacted with the TA 763 and Karp strains. These were the same as the major antigens detected by direct fluorescent antibody staining of the isolates.

Numbers of Leptotrombidium (Leptotrombidium) deliense (Acarina: trombiculidae) and prevalence of Rickettsia tsutsugamushi in adjacent habitats of peninsular Malaysia.

Numbers of L. (L.) deliense larvae were determined in adjacent habitats over a 16 month period. Both R. argentiventer and R. tiomanicus were highly efficient hosts for L. (L.) deliense. R. argentiventer was host to significantly greater numbers of chiggers per rat than was R. tiomanicus. The 2 habitats were similar in numbers of chiggers collected. No consistent correlation was apparent between numbers of chiggers and any single weather factor, but the chigger population seemed to be adversely affected by a 2 month period during which total evaporation greatly exceeded total rainfall. Direct fluorescent antibody examination of tissues from unfed L. (L.) deliense showed that 2 of 420 larvae (0.5%) contained organisms morphologically resembling R. tsutsugamushi. Considering the vector load and numbers of chiggers being returned to the ground by a given host, a rate of 0.5% appeared adequate to account for the prevalence rate of R. tsutsugamushi observed in the 2 host species.