Preliminary investigation of Culicidae species in South Pantanal, Brazil and their potential importance in arbovirus transmission

Abstract

In view of the high circulation of migratory birds and the environmental and climatic conditions which favor the proliferation of arthropods, the Brazilian Pantanal is susceptible to circulation of arboviruses. However, the amount of data concerning arbovirus vectors in this area is scarce; therefore the aim of this study was to conduct a preliminary investigation of Culicidae species in the Nhecolândia Sub-region of South Pantanal, Brazil and their potential importance in the arbovirus transmission. A total of 3684 specimens of mosquitoes were captured, 1689 of which caught in the rainy season of 2007, were divided into 78 pools and submitted to viral isolation, Semi-Nested RT-PCR and Nested RT-PCR, with a view to identifying the most important arboviruses in Brazil. Simultaneously, 70 specimens of ticks found blood-feeding on horses were also submitted to the same virological assays. No virus was isolated and viral nucleic-acid detection by RT-PCR was also negative. Nevertheless, a total of 22 Culicidae species were identified, ten of which had previously been reported as vectors of important arboviruses. The diversity of species found blood-feeding on human and horse hosts together with the arboviruses circulation previously reported suggest that the Nhecolândia Sub-region of South Pantanal is an important area for arbovirus surveillance in Brazil.

Neutralising antibodies for West Nile virus in horses from Brazilian Pantanal

“…All mosquito species identified in the present study were previously reported in the Nhecolândia sub-region (Pauvolid-Corrêa et al 2010a). Moreover, the nondetection of Flavivirus and Alphavirus RNA in the O. scapularis pool that caused CPE in C6/36 cells implied a virus identity that was not related to WNV, SLEV or alphaviruses, which would have been indicated by the RT-PCR.…”

“…The Brazilian Pantanal was selected as a suitable place for the study of WNV circulation because of the following factors: (i) natural foci of WNV infections have been mostly described in wetland ecosystems, such deltas and flood plains, as reported in France (Joubert et al 1970), Venezuela (Bosch et al 2007), Romania (Tsai et al 1998) and Italy (Autorino et al 2002), (ii) the local movement of migratory birds (Nunes & Tomas 2008), (iii) the unsuccessful efforts of the detection of WNVspecific antibodies in the free-ranging birds in Brazilian coastal areas (MS 2003(MS , 2004, (iv) the recent detec-tion of arbovirus vectors blood-feeding on human and equine hosts in the area (Pauvolid-Corrêa et al 2010a) and, finally, (v) the serological evidence of arbovirus activity in the area (Iversson et al 1993), which includes St. Louis encephalitis virus (SLEV) (Pauvolid-Corrêa et al 2010b), a species that is antigenically related to WNV (Smithburn 1942). In view of these data, the hypothesis that the Brazilian Pantanal is one of the most susceptible areas to WNV circulation in Brazil (Pauvolid-Corrêa & Varella 2008) seemed promising.…”

Serologic evidence of the recent circulation of Saint Louis encephalitis virus and high prevalence of equine encephalitis viruses in horses in the Nhecolândia sub-region in South Pantanal, Central-West Brazil

“…Because its biological plasticity, the hematofagia on horses by this acrodendrophilic species was considered and MAYV investigation in horses was conducted. However, in a recent preliminary investigation conducted in the same sub-region of our study, of a total of 22 Culicidae species identified, the Haemagogous spp were not captured (Pauvolid-Corrêa et al 2010).…”

“…Wetland ecosystems like the Brazilian Pantanal, which have high movement of migratory birds (Nunes & Tomas 2004), diversity of arbovirus vectors (Pauvolid-Corrêa et al 2010) and arbovirus circulation (Iversson et al 1993), present favorable conditions for reservoirs, which can sustain arbovirus circulation in imperceptible enzootic cycles (Pauvolid-Corrêa & Varella 2008).…”

Nhumirim virus, a novel flavivirus isolated from mosquitoes from the Pantanal, Brazil

“…As a result, the interpretive value of serological studies can be limited, resulting in an incomplete appreciation of the breadth of circulating flaviviruses. Few studies in the Brazilian Pantanal have attempted arbovirus detection directly in arthropods, and these have focused primarily on mosquitoes [11, 13, 15]. However, modern molecular techniques have facilitated virus detection and characterization, and as a result, many new flaviviruses have been discovered recently worldwide [16–19].…”