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Serologic survey for selected infectious disease agents in swift and kit foxes from the western United States.

A serologic survey of swift fox (Vulpes velox) and kit fox (V. macrotis) from the western USA was conducted for 12 infectious diseases. Samples from swift fox were collected between 1987 and 1992 from Colorado (n = 44), Kansas (n = 10), and Wyoming (n = 9). Samples from kit fox were collected in California (n = 86), New Mexico (n = 18), Utah (n = 9), and Arizona (n = 6). Overall antibody prevalence rates were 33 of 110 (30%) for canine parvovirus (CPV), 9 of 72 (13%) for canine distemper virus (CDV), 23 of 117 (20%) for vesicular stomatitis New Jersey, 16 of 117 (14%) for vesicular stomatitis Indiana, six of 117 (5%) for Cache Valley virus, five of 117 (4%) for Jamestown Canyon virus, one of 97 (1%) for rabies virus, one of 117 (1%) for Colorado tick fever virus, and one of 117 (1%) for western equine encephalitis virus. In addition, antibodies were not found to Yersinia pestis, Francisella tularensis, and Borrelia burgdorferi in serum from 25 Colorado swift fox. Adult swift fox from Colorado had serologic evidence of exposure to CPV more often than juveniles. No juvenile swift fox from Colorado had serum antibodies to CDV. There were season-specific differences in serum antibody prevalence for CPV for swift fox from Colorado. No viruses were isolated from ectoparasites or fox from Colorado.

Animals↗

Genus Coltivirus (family Reoviridae): genomic and morphologic characterization of Old World and New World viruses.

We report a genomic and morphologic study of the European Eyach (EYA) virus (genus Coltivirus, family Reoviridae) and a comparative analysis with the American Colorado tick fever (CTF) virus (the type species of the genus). The previously established, but distant, antigenic relationship between these viruses was strengthened by genetic findings (presence of cognate genes, amino acid identity between 55 and 88%, similar conserved terminal motifs, suspected read-through phenomenon in segment 9 of both viruses) and by indistinguishable ultramicroscopic morphologies. Moreover, putative constitutive modifying enzyme activities were suspected to be carried out by homologous viral proteins (RNA-dependent RNA polymerase, methyl/guanylyl transferase, NTPase). These findings, together with the comparative analysis to genomes of southeast Asian isolates, support the recent classification of arboviruses with 12 segments of dsRNA within two distinct genera (genus Coltivirus and genus Seadornavirus) and raise interesting questions about the evolutionary origins of coltiviruses. The previously proposed hypothesis that EYA virus was derived from an ancestral virus introduced in Europe with the migration of lagomorphs from North-America, would imply a divergence date between American and European isolates of over 50 million years ago (MYA). This analysis allows for the first time to propose an evolutionary rate for virus dsRNA genomes which was found to be in the order of 10(-8) to 10(-9) mutations/nt/year, a rate similar to that of dsDNA genomes.

Americas↗

[Genetic identification of rickettsiae of the tick-borne spotted fever group, isolated in the foci of tick-borne rickettsiosis].

A total of 25 rickettsial cultures of the tick-borne spotted fever (TBSF) group from the collection of the Research Institute of Infections in Omsk, isolated from different sources in the territory of the Russian Federation (from the Urals to the Far East) during the period of 1954-2001) were studied by the methods of genetic analysis. The fragments of the gene coding the outer-membrane protein of 190 kD (ompA) and synthetase citrate (gltA) of the rickettsiae under the study were sequenced. 23 isolates were identified as R. sibirica, among them 3 isolates obtained from patients, 16 isolates obtained from Dermacentor ticks, 2 isolates from Haemaphysalis concinna and 2--from Ixodes persulcatus. The strain Primorye 32/84, isolated from D. silvarum ticks in the Far East and earlier identified as S. sibirica by the results of the PCR-RFLP analysis proved to be a genovariant Rickettsia spBJ-90, i.e. close to this species. Strain Karpunino 19/69, isolated in the Kurgan region, was identified as R. slovaca. The results obtained extended our notions of the spectrum of rickettsiae group TBSF in Russia as well as their vectors.

Animals↗

Prevalence of rickettsia-like organisms and spotted fever group rickettsiae in ticks (Acari: Ixodidae) from Zimbabwe.

The prevalence of rickettsia-like organisms in ticks from Zimbabwe was determined using the hemolymph test. Amblyomma hebraeum had the highest prevalence of rickettsia-like organisms. Other species with rickettsia-like organisms included Amblyomma sparsum, Amblyomma variegatum, Hyalomma marginatum rufipes, Ripicephalus simus, Haemaphysalis leachi, Amblyomma rhinocerotis, and Hyalomma truncatum. Ticks with no demonstrable rickettsia-like organisms infection were Boophilus decoloratus, Haemaphysalis spinulosa, Rhipicephalus appendiculatus, Rhipicephalus evertsi evertsi, and Rhipicephalus sanguineus. Polymerase chain reaction followed by restriction fragment-length polymorphism analysis on samples of hemolymph-positive ticks showed the agent of African tick-bite fever to be present in A. hebraeum, Rickettsia conorii to be present in Rhipicephalus simus and Haemaphysalis leachi, and a spotted fever group rickettsia similar to that in Hyalomma marginatum marginatum ticks from Morocco and Portugal to be present in Hyalomma marginatum rufipes.

Animals↗

Carbaryl resistance in Mexican strains of the southern cattle tick (Acari: Ixodidae).

Susceptibility to carbaryl in six Mexican strains of the southern cattle tick, Boophilus microplus (Canestrini), was evaluated with the Food and Agricultural Organization larval packet test. Tick strains from the cattle fever tick quarantine zone in Texas were more susceptible to carbaryl than to coumaphos or diazinon. Compared with the susceptible reference (Gonzalez) strain, Mexican tick strains demonstrated 10.9-59.5-fold resistance to carbaryl. Significant cross-resistance was found between carbaryl and the organophosphate acaricides coumaphos and diazinon. Bioassay results with synergists suggested that metabolic detoxification mechanisms did not play a major role in carbaryl resistance. Resistance to carbaryl was likely conferred by insensitive acetylcholinesterase. The implications of carbaryl resistance in tick eradication and control also are discussed.

Acetylcholinesterase↗

Immunogenicity of combination DNA vaccines for Rift Valley fever virus, tick-borne encephalitis virus, Hantaan virus, and Crimean Congo hemorrhagic fever virus.

DNA vaccines for Rift Valley fever virus (RVFV), Crimean Congo hemorrhagic fever virus (CCHFV), tick-borne encephalitis virus (TBEV), and Hantaan virus (HTNV), were tested in mice alone or in various combinations. The bunyavirus vaccines (RVFV, CCHFV, and HTNV) expressed Gn and Gc genes, and the flavivirus vaccine (TBEV) expressed the preM and E genes. All vaccines were delivered by gene gun. The TBEV DNA vaccine and the RVFV DNA vaccine elicited similar levels of antibodies and protected mice from challenge when delivered alone or in combination with other DNAs. Although in general, the HTNV and CCHFV DNA vaccines were not very immunogenic in mice, there were no major differences in performance when given alone or in combination with the other vaccines.

Animals↗

Tick-borne relapsing fever during pregnancy: a case report.

BACKGROUND: Tick-borne relapsing fever (TBRF) is uncommon. Vertical transmission in the gravid woman may result in spontaneous abortion, preterm delivery or perinatal mortality. We report a case in a pregnant woman who experienced a Jarisch-Herxheimer reaction (J-HR). CASE: A 24-year-old woman at 23 weeks' gestation had a relapsing fever of unknown origin and nonspecific complaints. Her peripheral blood smear demonstrated spirochetes consistent with TBRF caused by Borrelia. Treatment with antibiotics precipitated J-HR. Supportive measures and appropriate antibiotic therapy resulted in a clinical cure and normal term delivery. CONCLUSION: The diagnosis of TBRF should be considered in individuals with recurrent fevers, especially those who have been in mountainous regions where Borrelia hermsii exists. Individuals receiving antimicrobials should be closely monitored for a J-HR.

Adult↗

A method for extraction and analysis of high quality genomic DNA from ixodid ticks.

Currently, no published methods describe the extraction of high molecular weight genomic DNA from ixodid ticks (Acari: Ixodidae) and commonly used methods of extraction are not well adapted for use with members of this family. A method for extraction of minimally degraded genomic DNA from ixodid ticks that can be completed in one or two days is described. The method produces DNA which is of sufficient size (>24 kb) for use in Southern analysis and which is readily digestible by restriction endonucleases. Southern analysis using a cytochrome P450 gene probe, demonstrates the success of our method with genomic DNA extracted from two species of Ixodidae, the lone star tick, Amblyomma americanum (Linnaeus) and the cattle fever tick, Boophilus microplus (Canestrini).

Animals↗

Arbovirus infections in man in British Columbia.

During the summer of 1971, the first laboratory-proved cases of acute encephalitis in man due to any of the known arboviruses occurred in the south-central region of British Columbia. Five human cases of encephalitis with two deaths were diagnosed; three of these patients, including one of the fatalities, were proven in the laboratory to have contracted western equine encephalitis.During 1968 and 1969, a human serum survey undertaken in approximately 2000 life-long residents of the province discovered low levels of hemagglutinin-inhibiting and/or complement-fixing as well as neutralizing antibodies for western equine encephalitis, St. Louis encephalitis, Powassan encephalitis, California encephalitis and Colorado tick fever. Evidence of recent sub-clinical infection was detected in some cases.

Adolescent↗

[Tick-borne recurrent fever. Description of 5 cases].

BACKGROUND: Tick-borne relapsing fever (FRGT) is a worldwide zoonosis. The disease is caused by spirochetes of the genus Borrelia, and is transmitted to man by ticks of the genus Ornithodoros (O. erraticus in Spain). METHODS: 5 FRTG cases attended in our hospital in a 2 years period are described. Diagnosis was established in all cases by demonstration of borreliae in peripheral blood. Three Borrelia strains were isolated from blood of 3 of our patients and they are maintained by passages through mice. RESULTS: High fever, tachycardia and headache were noted in all cases accompanied in 2 of them by hepatosplenomegaly. Three of the patients complained of arthromyalgias or lumbar myalgia. Treatment with doxycicline was curative in all of them. CONCLUSIONS: FRGT incidence in our country is probably underestimated due to the low suspicion of the disease and the specificity of the clinical symptoms. The isolement of the causative Borrelia strain will allow the development of more specific serological tests necessary to establish the prevalence of this disease as well to assess its implication in chronic diseases, as is observed in other borreliosis (i.e. Lyme disease), that might be missed at this moment.

Adult↗

Molecular evidence for novel tick-associated spotted fever group rickettsiae from Thailand.

Ticks are of considerable medical and veterinary importance because they directly harm the host through their feeding action and indirectly through vectoring many bacterial pathogens. Despite many ticks being known from Thailand, very little is known about the bacteria they may harbor. We report here the results of a survey of tick-associated bacteria in Thailand. A total of 334 individuals representing 14 species of ticks in five genera were collected from 10 locations in Thailand and were examined for the human pathogens, Borrelia, Francisella, Rickettsia, and the common arthropod endosymbionts, Wolbachia, by polymerase chain reaction (PCR) assay using specific primers. Rickettsial DNA was detected in 30% (9/30) of Amblyomma testudinarium (Koch, 1844) collected from Khao Yai National Park, Nakhon Nayok Province and 16.84% (16/95) of Hemaphysalis ornithophila (Hoogstraal and Kohls, 1959) collected from Khao Yai National Park, Nakhon Nayok Province and Khao Ang Rue Nai Wildlife Sanctuary, Chachoengsao Province. Rickettsial DNA was not detected in any of the other tick species and no DNA of Borrelia, Francisella, or Wolbachia was detected in any of 14 tick species. Phylogenetic relationships among the rickettsiae detected in this study and those of other rickettsiae were inferred from comparison of sequences of the 17-kDa antigen gene, the citrate synthase gene (gltA), and the 190-kDa outer membrane protein gene (ompA). Results indicated that the three Thai rickettsiae detected in this study represent new rickettsial genotypes and form a separate cluster among the spotted fever group rickettsiae.

Animals↗