PLoS neglected tropical diseases
-
A 26 year-old female patient presented to the Tropical Medicine outpatient unit of the Ludwig Maximilians-University in Munich with febrile illness after returning from Southern Africa, where she contracted a bite by a large mite-like arthropod, most likely a soft-tick. Spirochetes were detected in Giemsa stained blood smears and treatment was started with doxycycline for suspected tick-borne relapsing fever. The patient eventually recovered after developing a slight Jarisch-Herxheimer reaction during therapy. ⋯ Fragments of the uvrA gene revealed genetic distance of 0.086 to B. hermsii in genetic analysis and only distant relations with classic Old World relapsing fever species. This revealed the presence of a novel species of tick-borne relapsing fever spirochetes that we propose to name "Candidatus Borrelia kalaharica", as it was contracted from an arthropod bite in the Kalahari Desert belonging to both, Botswana and Namibia, a region where to our knowledge no relapsing fever has been described so far. Interestingly, the novel species shows more homology to New World relapsing fever Borrelia such as B. parkeri or B. hermsii than to known Old World species such as B. duttonii or B. crocidurae.
-
Differential Susceptibilities of Aedes aegypti and Aedes albopictus from the Americas to Zika Virus.
Since the major outbreak in 2007 in the Yap Island, Zika virus (ZIKV) causing dengue-like syndromes has affected multiple islands of the South Pacific region. In May 2015, the virus was detected in Brazil and then spread through South and Central America. In December 2015, ZIKV was detected in French Guiana and Martinique. The aim of the study was to evaluate the vector competence of the mosquito spp. Aedes aegypti and Aedes albopictus from the Caribbean (Martinique, Guadeloupe), North America (southern United States), South America (Brazil, French Guiana) for the currently circulating Asian genotype of ZIKV isolated from a patient in April 2014 in New Caledonia. ⋯ This study suggests that although susceptible to infection, Ae. aegypti and Ae. albopictus were unexpectedly low competent vectors for ZIKV. This may suggest that other factors such as the large naïve population for ZIKV and the high densities of human-biting mosquitoes contribute to the rapid spread of ZIKV during the current outbreak.
-
The cat flea, Ctenocephalides felis, is prevalent worldwide, will parasitize animal reservoirs of plague, and is associated with human habitations in known plague foci. Despite its pervasiveness, limited information is available about the cat flea's competence as a vector for Yersinia pestis. It is generally considered to be a poor vector, based on studies examining early-phase transmission during the first week after infection, but transmission potential by the biofilm-dependent proventricular-blocking mechanism has never been systematically evaluated. In this study, we assessed the vector competence of cat fleas by both mechanisms. Because the feeding behavior of cat fleas differs markedly from important rat flea vectors, we also examined the influence of feeding behavior on transmission dynamics. ⋯ The normal feeding behavior of C. felis, more than an intrinsic resistance to infection or blockage by Y. pestis, limits its vector competence. Rapid turnover of midgut contents results in bacterial clearance and disruption of biofilm accumulation in the proventriculus. Anatomical features of the cat flea foregut may also restrict transmission by both early-phase and proventricular biofilm-dependent mechanisms.