RESUMO
Few studies have been able to provide experimental evidence of the ability of fleas to maintain rodent-associated Bartonella infections and excrete these bacteria. These data are important for understanding the transmission cycles and prevalence of these bacteria in hosts and vectors. We used an artificial feeding approach to expose groups of the oriental rat flea (Xenopsylla cheopis Rothschild; Siphonaptera, Pulicidae) to rat blood inoculated with varying concentrations of Bartonella elizabethae Daly (Bartonellaceae: Rhizobiales). Flea populations were maintained by membrane feeding on pathogen-free bloodmeals for up to 13 d post infection. Individual fleas and pools of flea feces were tested for the presence of Bartonella DNA using molecular methods (quantitative and conventional polymerase chain reaction [PCR]). The threshold number of Bartonellae required in the infectious bloodmeal for fleas to be detected as positive was 106 colony-forming units per milliliter (CFU/ml). Individual fleas were capable of harboring infections for at least 13 d post infection and continuously excreted Bartonella DNA in their feces over the same period. This experiment demonstrated that X. cheopis are capable of acquiring and excreting B. elizabethae over several days. These results will guide future work to model and understand the role of X. cheopis in the natural transmission cycle of rodent-borne Bartonella species. Future experiments using this artificial feeding approach will be useful for examining the horizontal transmission of B. elizabethae or other rodent-associated Bartonella species to naïve hosts and for determining the viability of excreted bacteria.
Assuntos
Bartonella/fisiologia , DNA Bacteriano/análise , Insetos Vetores/microbiologia , Xenopsylla/microbiologia , Animais , Fezes/químicaRESUMO
The plague is an infectious disease that has transcended through history and has been responsible for three pandemics with high mortality rates. During the third pandemic that started in Hong Kong (1894), the disease spread through maritime routes to different regions in the world, including South America. In this region, approximately 16 million people are thought to be at risk in relation to this disease due to specific situations like human-rodent coexistence inside houses in rural areas, homes built with inadequate materials that are vulnerable to invasion by these animals, inappropriate storage of crops and an increase in rainfall and deforestation, which allows for the displacement of wild fauna and man invasion of the natural foci of the disease. Between 1994 and 1999, five countries: Bolivia, Brazil, Ecuador, Peru and the United States of America, reported approximately 1,700 cases with 79 related deaths. In Colombia we have historical data about an "infectious pneumonia" with high mortality rates that occurred during the same months, for three consecutive years (1913 to 1915) in the departments of Magdalena, Atlántico and Bolívar, located in the Colombian Atlantic coast, which suggested plague, but could not be confirmed.
Assuntos
Surtos de Doenças/história , Peste/história , África/epidemiologia , Microbiologia do Ar , Doenças dos Animais/diagnóstico , Doenças dos Animais/epidemiologia , Doenças dos Animais/microbiologia , Animais , Ásia/epidemiologia , Análise por Conglomerados , Colômbia/epidemiologia , Reservatórios de Doenças , Vetores de Doenças , História do Século XV , História do Século XIX , História do Século XX , História do Século XXI , História Antiga , História Medieval , Humanos , Mordeduras e Picadas de Insetos/microbiologia , Animais de Estimação/parasitologia , Peste/diagnóstico , Peste/transmissão , Peste/veterinária , Roedores/parasitologia , Estudos Soroepidemiológicos , Testes Sorológicos , Navios , América do Sul/epidemiologia , Estados Unidos/epidemiologia , Infecção dos Ferimentos/microbiologia , Xenopsylla/microbiologia , Yersinia pestis/fisiologiaRESUMO
BACKGROUND: Entomopathogenic fungi, particularly those belonging to the genera Metarhizium and Beauveria have shown great promise as arthropod vector control tools. These agents, however, have not been evaluated against flea vectors of plague. FINDINGS: A 3-h exposure to the fungi coated paper at a concentration of 2 × 108 conidia m-2 infected >90% of flea larvae cadavers in the treatment groups. The infection reduced the survival of larvae that had been exposed to fungus relative to controls. The daily risk of dying was four- and over three-fold greater in larvae exposed to M. anisopliae (HR = 4, p<0.001) and B. bassiana (HR = 3.5, p<0.001) respectively. Both fungi can successfully infect and kill larvae of X. brasiliensis with a pooled median survival time (MST±SE) of 2 ± 0.31 days post-exposure. CONCLUSION: These findings justify further research to investigate the bio-control potential of entomopathogenic fungi against fleas.