Search

Background: Bartonella species are fastidious gram-negative vector-borne bacteria with a wide range of mammalian reservoirs. While it is understood that some species of Bartonella are human pathogens, the extent of human exposure to Bartonella species (both pathogenic and nonpathogenic) is yet to be fully understood. Materials and Methods: To this end, residual sera from participants enrolled in undifferentiated fever studies in Cambodia, Ghana, Laos, and Peru were screened for the presence of IgG antibodies against Bartonella quintana and Bartonella henselae , using the FOCUS diagnostics Dual Spot- Bartonella IgG Immunofluorescence assay. Forty-eight patients with suspected or confirmed Bartonella bacilliformis exposure or infection in Peru were screened to assess cross-reactivity of the FOCUS assay for IgG against other Bartonella species . Results: Ten of 13 patients with confirmed B. bacilliformis infection were Bartonella -specific IgG positive, and overall, 36/48 of the samples were positive. In addition, 79/206, 44/200, 101/180, and 57/100 of the samples from Peru, Laos, Cambodia, and Ghana, respectively, were Bartonella -specific IgG positive. Furthermore, ectoparasite pools from Cambodia, Laos, and Peru were tested using quantitative real-time PCR (qPCR) for the presence of Bartonella DNA. Of the sand fly pools collected in Peru, 0/196 were qPCR positive; 15/140 flea pools collected in Cambodia were qPCR positive; while 0/105 ticks, 0/22 fleas, and 0/3 louse pools collected in Laos tested positive for Bartonella DNA. Conclusion: Evidence of Bartonella in fleas from Cambodia supports the possibility that humans are exposed to Bartonella through this traditional vector. However, Bartonella species were not found in fleas, ticks, or lice from Laos, or sand flies from Peru. This could account for the lower positive serology among the population in Laos and the strictly localized nature of B. bacilliformis infections in Peru. Human exposure to the Bartonella species and Bartonella as a human pathogen warrants further investigation.

Rickettsia species cause rickettsioses, which are zoonotic diseases found worldwide, and are transmitted by arthropods such as lice, fleas, ticks, and mites. In Thailand, flea infestations are common among cats and dogs. This study aimed at determining the exposure to spotted fever group rickettsiae (SFGR) of cats in surrounding areas of Rajabhat Maha Sarakham University, Muang district, Maha Sarakham province and rickettsial infection among cat fleas, Ctenocephalides felis, collected from dogs of the surrounding area of Waeng Noi district, Khon Kaen province. Forty-two cat sera were assessed for IgG antibody titers against SFGR by a group-specific enzyme-linked immunosorbent assay. The prevalence of seroreactive cats was 4.76% (2/42). DNA preparations from 23 individual cat fleas from three dogs were assessed by Rickettsia genus-specific, group-specific, and species-specific quantitative real-time PCR (qPCR) assays. Positive results were confirmed by ompB gene fragment sequencing. Twenty-one of 23 cat fleas were positive for Rickettsia asembonensis , and the other two DNA preparations were negative for rickettsial DNA. This study's finding indicates that companion cats and dogs in Northeast Thailand are exposed to SFGR and that exposure may be due to infection with R. asembonensis, an organism known to infect humans, monkeys, and dogs. Clinicians for humans and animals in Northeast Thailand should be aware of rickettsial infections among their patients.

Cat fleas ( Ctenocephalides felis ) are the most prevalent ectoparasites of pet animals with cosmopolitan distribution, obligatory hematophagous, and may prey on humans to receive bloodmeals. We studied the microbiota of 100 flea-pools, containing C. felis , and collected from equal number of cats and dogs in the region of Attica, Greece, including Athens. The 16S metagenomics technique detected Brucella spp. nucleotide sequence that was identified as Brucella melitensis DNA by a real-time PCR, in five flea-pools, corresponding to five cats, one owned and the remaining four stray, residing in semiurban and urban areas, respectively. No definite conclusions can be drawn as to the pathway that led to the presence of B. melitensis in common fleas parasitizing cats. We suspect flea or cat contact with wild rodents, ubiquitous in various environments, which participate in the B. melitensis biology. The proximity of the cats and their fleas with humans and previous observations of flea potential to transmit B. melitensis in laboratory animals warrant a more elaborate research as to the vectorial dynamics, the ecological pathways resulting in pathogen carriage, and the risk for public health.

We examined fleas collected from black-tailed prairie dog (Cynomys ludovicianus) burrows from 2009 through 2011 in five national park units east of the known distribution of active plague across the northern Great Plains for the presence of Yersinia pestis. Across all national park units, Oropsylla tuberculata and Oropsylla hirsuta were the most common fleas collected from prairie dog burrows, 42.4% and 56.9%, respectively, of the 3964 fleas collected from burrow swabbing. Using a nested PCR assay, we detected 200 Y. pestis-positive fleas from 3117 assays. In total, 6.4% of assayed fleas were Y. pestis positive and 13.9% of prairie dog burrows swabbed contained Y. pestis-positive fleas. Evidence of the presence of Y. pestis was observed at all national park units except Devils Tower National Monument in Wyoming. We detected the presence of Y. pestis without large die-offs, i.e., enzootic sylvatic plague, east of the known distribution of active plague and near the eastern edge of the present distribution of black-tailed prairie dogs. This study, in combination with previous work suggests that sylvatic plague likely occurs across the range of black-tailed prairie dogs and should now be treated as endemic across this range.

The aim of this work was to detect and identify Rickettsia species in ticks collected in rural areas of Villeta, Colombia. Tick specimens were collected from domestic animals and walls of houses in five rural villages of Villeta town and from humans in Naranjal village (same town). Moreover, a flea collected from the same area was also processed. DNA was extracted and tested by conventional, semi-nested, and nested PCR reactions targeting rickettsial genes. In the ticks collected from humans from Naranjal village, a nymph of Amblyomma cajennense sensu lato was amplified using primers for ompA and sequenced (100% identity with "Candidatus Rickettsia amblyommii"). Last, three amplicons from the Ctenocephalides felis flea, corresponding to gltA, ompB, and 16S rRNA genes, showed high identity with R. felis (98.5%, 97.3%, and 99.2%, respectively) and "Candidatus Rickettsia asemboensis" (99.7% and 100%, respectively). To our knowledge, these results correspond to the first molecular detection in Colombia of "Candidatus Rickettsia amblyommii" and "Ca. Rickettsia asemboensis" in fleas.

This study investigated the prevalence of Rickettsia spp. and Ehrlichia canis infection in dogs and their ectoparasites from rural and urban areas of two municipalities, Petrolina and Juazeiro, within a semiarid region (Caatinga biome) of northeastern Brazil, by immunofluorescence assay (IFA) and polymerase chain reaction (PCR). Overall, 12.1% (61/504) and 23.0% (116/504) of canine plasma samples had antibodies reactive to Rickettsia spp. and E. canis. E. canis DNA was detected by PCR in 8.3% (42/504) of canine blood samples, whereas no blood sample was positive for Rickettsia spp. The infection by E. canis was determined by PCR in 4.9% (14/285) Rhipicephalus sanguineus sensu lato (s.l.) ticks and by Rickettsia felis in 1.1% (3/285) and 40.6% (74/182) ticks and fleas, respectively. Multivariate regression analyses revealed that canine seropositivity to Rickettsia spp. was associated statistically with the variables "to reside in Petrolina" and "presence of ectoparasites." Our results indicate that canine infection by E. canis might be endemic in the Caatinga biome as it is in other Brazilian biomes. Although no previous serosurvey for Rickettsia spp. has been conducted on dogs from the Caatinga biome, our values are much lower than the ones reported for rural dogs from other Brazilian biomes. These differences are likely related to the semiarid climate of the aatinga biome, which minimizes the exposure of rural dogs to Amblyomma spp. ticks, the most common vectors of Rickettsia spp. in Brazil. Considering that dogs are excellent sentinels for human exposure to Rickettsia spp., we can infer that the risks of human acquiring tick-borne rickettsiosis in the Caatinga region of the present study are low. The rickettsial infection rates in fleas and ticks were not related to canine seropositivity; i.e., areas with higher Rickettsia infection rates in fleas had the lowest canine seroreactivity to Rickettsia spp.

Fleas were collected from live-captured small mammals to identify flea-borne pathogens, host associations, and seasonal prevalence of flea species, as part of the 65th Medical Brigade rodent-borne disease surveillance program at 20 military installations and training sites, Gyeonggi Province, Republic of Korea, 2005-2007. A total of 1251 fleas were recovered from 2833 small mammals. Apodemus agrarius, the striped field mouse, accounted for 93.1% (2,637/2,833) of all small mammals captured, followed by Crocidura lasiura (3.1%), Mus musculus (1.3%), Microtus fortis (0.7%), Myodes regulus (0.7%), Micromys minutus (0.5%), Rattus norvegicus (0.4%), Tscherskia triton (0.1%), Apodemus peninsulae (< 0.1%), Rattus rattus (< 0.1%), and Mogera robusta (< 0.1%). A total of 6/11 species of mammals captured were infested with fleas with infestation rates ranging from a high of 26.3% (A. agrarius and M. regulus) to a low of 5.3% (M. fortis). Flea indices among infested mammals were highest for R. norvegicus (2.50), followed by C. lasiura (2.20), A. agrarius (1.71), M. regulus (1.20), M. musculus (1.0), and M. fortis (1.0). The predominant flea species collected were Stenoponia sidimi (56.5%), followed by Ctenophthalmus congeneroides (38.3%) and Rhadinopsylla insolita (3.9%). The minimum field infection rates [number of positive pools/total number of fleas (600)] for Rickettsia typhi and for Rickettsia felis were 1.7% and 1.0%, respectively.