Bartonella species in bat flies (Diptera: Nycteribiidae) from western Africa.

Bat flies are obligate ectoparasites of bats and it has been hypothesized that they may be involved in the transmission of Bartonella species between bats. A survey was conducted to identify whether Cyclopodia greefi greefi (Diptera: Nycteribiidae) collected from Ghana and 2 islands in the Gulf of Guinea harbour Bartonella. In total, 137 adult flies removed from Eidolon helvum, the straw-coloured fruit bat, were screened for the presence of Bartonella by culture and PCR analysis. Bartonella DNA was detected in 91 (66·4%) of the specimens examined and 1 strain of a Bartonella sp., initially identified in E. helvum blood from Kenya, was obtained from a bat fly collected in Ghana. This is the first study, to our knowledge, to report the identification and isolation of Bartonella in bat flies from western Africa.

Temporal and spatial patterns of Bartonella infection in black-tailed prairie dogs (Cynomys ludovicianus).

We describe the temporal dynamics and spatial distribution of Bartonella in black-tailed prairie dogs (Cynomys ludovicianus) based on a longitudinal study conducted in 20 black-tailed prairie dog (BTPD) colonies in Boulder County, CO from 2003 to 2005. Bartonella infection was widely distributed in all colonies with an overall prevalence of 23.1%, but varied by colony from 4.8% to 42.5% and by year from 9.1 to 39.0%, with a marked increase in Bartonella activity in 2005. Levels of bacteremia varied from 40 to 12,000 colony forming units (CFU) per milliliter of BTPD blood, but were highly skewed with a median of 240 CFU. Bartonella infection rates were unimodal with respect to BTPD body mass, first increasing among growing juveniles, then declining among adults. Infection rates exhibited a sigmoidal response to body mass, such that 700g may prove to be a useful threshold value to evaluate the likelihood of Bartonella infection in BTPDs. Bartonella prevalence increased throughout the testing season for each year, as newly emerged juveniles developed bacteremia. Data from recaptured animals suggest that Bartonella infections did not persist in individual BTPDs, which may explain the relatively low prevalence of Bartonella in BTPDs compared to other rodent species. No association was found between Bartonella prevalence and host population density. Prevalence did not differ between males and females. The spatio-temporal pattern of Bartonella infection among colonies suggests epizootic spread from northern to central and southern portions of the study area. The potential significance of the BTPD-associated Bartonella for public health needs to be further investigated.

[Molecular genetic methods of typing of the Bartonellae].

The primer systems for the PCR detection of four house-keeping genes of bartonellae in clinical material were developed and tested. The tactics of the species RFLP typing was also developed and tested. The scheme of the species RFLP typing of bartonellae was tested using as an example two strains for the first time isolated in Russia from patients with endocarditis and fever of uncertain origin. The results of the typing were supported by sequencing of the amplicons obtained. According to the sequencing the isolates were attributed to the sub species Bartonella vinsonii, subsp. arupensis. The necessity of molecular epidemiological analysis of bartonelloses in Russia was substantiated.

A survey of zoonotic pathogens carried by Norway rats in Baltimore, Maryland, USA.

Norway rats (Rattus norvegicus) carry several zoonotic pathogens and because rats and humans live in close proximity in urban environments, there exists potential for transmission. To identify zoonotic agents carried by rats in Baltimore, Maryland, USA, we live-trapped 201 rats during 2005-2006 and screened them for a panel of viruses, bacteria, and parasites. Antibodies against Seoul virus (57.7%), hepatitis E virus (HEV, 73.5%), Leptospira interrogans (65.3%), Bartonella elizabethae (34.1%), and Rickettsia typhi (7.0%) were detected in Norway rats. Endoparasites, including Calodium hepatica (87.9%) and Hymenolepis sp. (34.4%), and ectoparasites (13.9%, primarily Laelaps echidninus) also were present. The risk of human exposure to these pathogens is a significant public health concern. Because these pathogens cause non-specific and often self-limiting symptoms in humans, infection in human populations is probably underdiagnosed.

Experimental evidence of host specificity of Bartonella infection in rodents.

A large number of Bartonella species and genetic variants were compared for their ability to cause bacteremia in different rodent species: the cotton rat (Sigmodon hispidus), white-footed mouse (Peromyscus leucopus), BALB/c mouse and Wistar rat. Experimental data supported field observations that host specificity can occur among certain Bartonella species and rodent species. Bacteremia could only be readily produced in cotton rats or white-footed mice if the strains used for inoculation were originally obtained from the same species or from a phylogenetically close species. A few Bartonella colonies could be observed in the blood of some BALB/c mice by 7 days after inoculation, but no evidence of the persistence of the infection was found. Host specificity suggests the possibility of a long co-speciation of Bartonella species with their rodent hosts. Host-parasite relationships measured by the duration and level of bacteremia and the minimal infectious dose may serve as additional criteria for classification of Bartonella isolates obtained from natural environments.

Prevalence of antibody to hepatitis E virus among rodents in the United States.

The recent identification of antibody to hepatitis E virus (HEV) in pigs, sheep, and cattle and characterization of an HEV isolated from domestic pigs suggest animal reservoirs for this virus. To investigate whether rodents might be a natural reservoir of HEV, the prevalence of anti-HEV was determined among a variety of species throughout the United States. Serum samples were obtained from 806 rodents of 26 species in 15 genera. Anti-HEV prevalence was assessed by 2 EIAs (mosaic protein- and 55-kDa protein-based), which gave concordant results. The highest prevalence of antibody was found in the genus Rattus (59.7%; 166/278). Overall, rodents from urban habitats had a significantly higher prevalence of anti-HEV than did animals captured from rural areas. A high prevalence of anti-HEV was found in animals captured on mainland versus barrier islands. The results from this study provide convincing evidence of widespread HEV or HEV-like infection in rodents of the United States.

Experimental infection of cotton rats with three naturally occurring Bartonella species.

The kinetics of infection and humoral immune response of laboratory-bred cotton rats (Sigmodon hispidus) challenged with three Bartonella spp. recovered from the blood of naturally infected cotton rats captured in Georgia (USA) are described. Bartonella spp. infection, as determined by bacteremia, occurred in all 18 cotton rats inoculated with live Bartonella of each species at either a low dose, 10(3) colony-forming units (CFU's), or high dose, 10(7) CFU. Cotton rats inoculated with lower doses of Bartonella spp. developed higher bacteremia that persisted for longer periods than in those inoculated with high doses. Peak bacteremia varied among Bartonella spp, ranging from 10(4) to 10(6) CFUs per 1.0 ml of blood. Antibody measured by immunofluorescence assays using species-specific antigens indicated more rapidly rising and higher antibody titers in cotton rats challenged with high doses vs. low doses and with inactivated bacteria vs. live bacteria. Each group of rats produced high IgG titers to the homologous challenge antigen; low or unmeasurable cross-reactivity was detected to heterologous Bartonella antigens. Exposure of cotton rats to a specific Bartonella sp. resulted in protection, as measured by detectable bacteremia, in eight of nine animals challenged with the same Bartonella sp. used initially; no evidence of resistance to secondary challenge with different Bartonella spp. was obtained. Cross-protection between Bartonella spp., isolated from the same rodent species, may not occur.

Isolation of Bartonella spp. from embryos and neonates of naturally infected rodents.

Embryos and neonatal offspring of wild-captured cotton rats (Sigmodon hispidus) and white-footed mice (Peromyscus leucopus) were tested for the presence of Bartonella spp. Isolates of Bartonella spp. were obtained from 18 of 31 embryos and 7 of 19 neonates from bacteremic dams of the two species; no isolates were obtained from material from non-bacteremic dams. Sequence analysis demonstrated that the isolates from embryos and neonates matched the phylogenetic group of Bartonella spp. isolates obtained from the mother. No antibodies to homologous Bartonella spp. antigens were detected in maternal and neonatal blood or embryonic tissue. These findings suggest the possibility of vertical transmission of Bartonella spp. among natural rodent hosts.

Distribution, diversity, and host specificity of Bartonella in rodents from the Southeastern United States.

A number of Bartonella isolates were obtained from seven species of rodents sampled from 12 geographic sites representing the major biotic communities of the southeastern United States. Bartonella were isolated from the blood of 42.2% of 279 tested rodents. The highest prevalence of infection typically occurred among the most commonly captured species in the rodent community. Four phylogenetic groups, uniting 14 genotypic variants of Bartonella, were identified by sequence analysis of the citrate synthase gene. The level of sequence homology between genotypic groups varied from 88.8% to 96.4%, and the degree of homology among variants within groups was > or = 97%. Cotton rats (Sigmodon hispidus) harbored up to three phylogenetic groups of Bartonella at a single site, and Bartonella of two phylogenetic groups were isolated from a single rodent. All the Bartonella isolated from three species of Peromyscus clustered in a single distinct phylogenetic group, suggesting some host specificity may occur. Mouse ascitic fluids produced in BALB/c mice inoculated with Bartonella of three phylogenetic groups demonstrated high indirect fluorescent antibody (IFA) titers to homologous antigens. However, use of eight Bartonella antigens in an IFA test with sera from 394 wild-caught rodents resulted in either little or extremely low titers of antibody.

Community structure and prevalence of hantavirus infection in rodents: a geographic division of the enzootic area in far eastern Russia.

The results of an extensive rodent trapping effort throughout the southern part of far eastern Russia and hantavirus antigen screening of tissues were used to develop a multifaceted approach for the geographic division of the enzootic territory of hantavirus. Four species of rodents (Apodemus agrarius, Apodemus peninsulae, Microtus fortis, and Clethrionomys rufocanus) comprised 88.5 percent of 10,595 captured rodents and 94.1 percent of 996 antigen-positive animals. Rodent fauna and the prevalence and distribution of hantavirus antigen-positive animals were compared among major biotic communities in the region. The species composition of the rodent communities and the predominant hantavirus reservoir species were used as criteria to define zones with similar enzootic characteristics.

Isolation and characterization of Whitewater Arroyo virus, a novel North American arenavirus.

Rodents are principal hosts for each of the well-characterized arenaviruses. Prior to the present study, Tamiami (TAM) virus was the sole arenavirus known to be indigenous to North America; it has been isolated only from southern Florida where its primary host is the cotton rat Sigmodon hispidus. Recently, arenavirus antibody was found in Neotoma albigula woodrats collected from the southwestern United States. The purpose of the present study was to isolate and characterize the arenavirus associated with N. albigula. Three isolates of a novel arenavirus (proposed name "Whitewater Arroyo," WWA) were recovered from two arenavirus antibody-positive N. albigula collected from Whitewater Arroyo in McKinley County, New Mexico. Two-way serologic tests indicated that WWA virus is antigenically distinct from other arenaviruses but most closely related to TAM virus. Phylogenetic analysis of nucleocapsid protein gene sequence data showed that WWA virus is a novel arenavirus that is genetically most closely related to TAM virus. The recovery of WWA virus from antibody-positive N. albigula suggests that WWA virus infection in this species can be chronic and thus that N. albigula is a reservoir host of the virus.

Prevalence of antibodies to arenaviruses in rodents from the southern and western United States: evidence for an arenavirus associated with the genus Neotoma.

The objectives of this study were to extend our knowledge of the geographic distribution and rodent host range of arenaviruses in North America. Sera from wild rodents collected from the southern and western United States were tested for antibody against Tamiami, Pichinde, Junin, and lymphocytic choriomeningitis viruses, using an indirect fluorescent antibody test. Antibody to at least one arenavirus was found in 220 (3.1%) of 7,106 rodents tested. The antibody-positive animals included Mus musculus from Florida and Texas; Neotoma albigula from Arizona, Colorado, and New Mexico; N. fuscipes and N. lepida from California: N. mexicana from Arizona, New Mexico, and Utah; N. stephensi from Arizona and New Mexico; and Oryzomys palustris and Sigmodon hispidus from Florida. Sigmodon hispidus seropositive for Tamiami virus were found only in Florida (156 [27.0%] of 578 tested), although 463 hispid cotton rats from outside that state were examined. High-titered antibodies to Tamiami virus were present in sera from S. hispidus, (geometric mean antibody titer [GMAT] of 1:792), whereas sera from Neotoma spp. reacted at high titer to both Tamiami (GMAT = 1:905) and Pichinde (GMAT = 1:433) viruses. The results suggest that arenaviruses are widely distributed in the southern United States and that one or more indigenous arenaviruses are associated with Neotoma spp. in North America.