Mosquito vector competence for dengue is modulated by insect-specific viruses.

Aedes aegypti and A. albopictus mosquitoes are the main vectors for dengue virus (DENV) and other arboviruses, including Zika virus (ZIKV). Understanding the factors that affect transmission of arboviruses from mosquitoes to humans is a priority because it could inform public health and targeted interventions. Reasoning that interactions among viruses in the vector insect might affect transmission, we analysed the viromes of 815 urban Aedes mosquitoes collected from 12 countries worldwide. Two mosquito-specific viruses, Phasi Charoen-like virus (PCLV) and Humaita Tubiacanga virus (HTV), were the most abundant in A. aegypti worldwide. Spatiotemporal analyses of virus circulation in an endemic urban area revealed a 200% increase in chances of having DENV in wild A. aegypti mosquitoes when both HTV and PCLV were present. Using a mouse model in the laboratory, we showed that the presence of HTV and PCLV increased the ability of mosquitoes to transmit DENV and ZIKV to a vertebrate host. By transcriptomic analysis, we found that in DENV-infected mosquitoes, HTV and PCLV block the downregulation of histone H4, which we identify as an important proviral host factor in vivo.

Habitat modification and seasonality influence avian haemosporidian parasite distributions in southeastern Brazil.

Habitat modification may change vertebrate and vector-borne disease distributions. However, natural forest regeneration through secondary succession may mitigate these effects. Here we tested the hypothesis that secondary succession influences the distribution of birds and their haemosporidian parasites (genera Plasmodium and Haemoproteus) in a seasonally dry tropical forest, a globally threatened ecosystem, in Brazil. Moreover, we assessed seasonal fluctuations in parasite prevalence and distribution. We sampled birds in four different successional stages at the peak and end of the rainy season, as well as in the middle and at the end of the dry season. A non-metric multidimensional scaling analysis revealed that bird communities in the pasture (i.e., highly modified) areas were different from those in the early, intermediate, and late successional areas (secondary forests). Among 461 individual birds, haemosporidian prevalence was higher in pasture areas than in the more advanced successional stages, but parasite communities were homogeneous across these areas. Parasite prevalence was higher in pasture-specialists birds (resilient species) than in forest-specialists species, suggesting that pasture-specialists may increase infection risk for co-occurring hosts. We found an increase in prevalence between the middle and end of the dry season, a period associated with the beginning of the breeding season (early spring) in southeastern Brazil. We also found effects of seasonality in the relative prevalence of specific parasite lineages. Our results show that natural forest recovery through secondary succession in SDTFs is associated with compositional differences in avian communities, and that advanced successional stages are associated with lower prevalence of avian haemosporidian parasites.

Searching for putative avian malaria vectors in a Seasonally Dry Tropical Forest in Brazil.

BACKGROUND: Haemosporidian parasites of the genera Plasmodium and Haemoproteus can have detrimental effects on individual birds and populations. Despite recent investigations into the distribution and richness of these parasites and their vertebrate hosts, little is known about their dipteran vectors. The Neotropics has the highest diversity of mosquitoes in the world, but few studies have tried to identify vectors in this area, hampering the understanding of the ecology of avian malaria in the highly diverse Neotropical environments. METHODS: Shannon traps and active collection were used to capture 27,110 mosquitoes in a Seasonally Dry Tropical Forest in southeastern Brazil, a highly endangered ecosystem. RESULTS: We screened 17,619 mosquito abdomens from 12 different species and several unidentified specimens of Culex, grouped into 1,913 pools, for the presence of haemosporidians. Two pools (out of 459) of the mosquito Mansonia titillans and one pool (out of 29) of Mansonia pseudotitillans were positive for Plasmodium parasites, with the detection of a new parasite lineage in the former species. Detected Plasmodium lineages were distributed in three different clades within the phylogenetic tree revealing that Mansonia mosquitoes are potential vectors of genetically distant parasites. Two pools of Culex spp. (out of 43) were positive for Plasmodium gallinaceum and closely related lineages. We found a higher abundance of these putative vectors in pasture areas, but they were also distributed in areas at intermediate and late successional stages. One pool of the mosquito Psorophora discrucians (out of 173) was positive for Haemoproteus. CONCLUSIONS: The occurrence of different Plasmodium lineages in Mansonia mosquitoes indicates that this genus encompasses potential vectors of avian malaria parasites in Brazil, even though we did not find positive thoraces among the samples tested. Additional evidence is required to assign the role of Mansonia mosquitoes in avian malaria transmission and further studies will add information about evolutionary and ecological aspects of avian haemosporidia and untangle the diversity of their vectors in Brazil.

Contribution to the knowledge of the phlebotomine sand flies fauna (Diptera: psychodidae) of Timóteo municipality, Minas Gerais, Brazil.

An investigation of the phlebotomine sandfloy fauna in the municipality of Timóteo, Minas Gerais State, Brazil, was undertaken with New Jersey traps placed in seven neighborhoods from December 2005 to January 2006. A total of 2,289 phlebotomine sandfloy specimens were recorded. Nyssomyia whitmani (Antunes & Coutinho) (48.1%), Nyssomyia intermedia (Lutz & Neiva) (36.8%) and Micropygomyia quinquefer (Dyar) (7.1%) were the most abundant species sampled. Some sandfloy species that play a role in the transmission of Leishmania Ross in the State of Minas Gerais were recorded and their importance to public health is highlighted. Pintomyia bianchigalatiae (Andrade Filho, Aguiar, Dias & Falcão), Micropygomyia capixaba (Dias, Falcão, Silva & Martins), Micropygomyia schreiberi (Martins, Falcão & Silva) and Psathyromyia pascalei (Coutinho & Barretto) are recorded for the first time in the municipality of Timóteo, and Pressatia choti (Floch & Abonnenc) is recorded for the first time in the State of Minas Gerais.

Contribution to the Knowledge of the Phlebotomine Sand Flies Fauna (Diptera: Psychodidae) of Timóteo Municipality, Minas Gerais, Brazil / Contribuição para o Conhecimento da Fauna de Flebotomíneos (Diptera: Psychodidae), do Município de Timóteo, MG

An investigation of the phlebotomine sandfloy fauna in the municipality of Timóteo, Minas Gerais State, Brazil, was undertaken with New Jersey traps placed in seven neighborhoods from December 2005 to January 2006. A total of 2,289 phlebotomine sandfloy specimens were recorded. Nyssomyia whitmani (Antunes & Coutinho) (48.1 percent), Nyssomyia intermedia (Lutz & Neiva) (36.8 percent) and Micropygomyia quinquefer (Dyar) (7.1 percent) were the most abundant species sampled. Some sandfloy species that play a role in the transmission of Leishmania Ross in the State of Minas Gerais were recorded and their importance to public health is highlighted. Pintomyia bianchigalatiae (Andrade Filho, Aguiar, Dias & Falcão), Micropygomyia capixaba (Dias, Falcão, Silva & Martins), Micropygomyia schreiberi (Martins, Falcão & Silva) and Psathyromyia pascalei (Coutinho & Barretto) are recorded for the first time in the municipality of Timóteo, and Pressatia choti (Floch & Abonnenc) is recorded for the first time in the State of Minas Gerais.

Foi realizada uma investigação sobre a fauna de flebotomíneos no município de Timóteo, MG, com a instalação de armadilhas do tipo New Jersey, em sete bairros, entre dezembro de 2005 e janeiro de 2006. O total de 2.289 espécimes de flebotomíneos foi registrado. Nyssomyia whitmani (Antunes & Coutinho) (48,1 por cento), Nyssomyia intermedia (Lutz & Neiva) (36,8 por cento) e Micropygomyia quinquefer (Dyar) (7,1 por cento) foram as espécies mais abundantes. Algumas espécies de flo ebotomíneos incriminadas como transmissoras de Leishmania em Minas Gerais foram registradas e a importância destas para saúde pública é destacada. Neste trabalho faz-se o primeiro registro de Pintomyia bianchigalatiae (Andrade Filho, Aguiar, Dias & Falcão), Micropygomyia capixaba (Dias, Falcão, Silva & Martins), Micropygomyia schreiberi (Martins, Falcão & Silva) e Psathyromyia pascalei (Coutinho & Barretto) para Timóteo. Pressatia choti (Floch & Abonnenc) é registrada pela primeira vez para Minas Gerais.