Bats are a natural reservoir of many pathogenic and non-pathogenic viruses with the chance of spill over via the intermediate host and/ directly to human. The number of zoonotic and deadly viruses especially RNA viruses originated from bats is remarkable. The recent outbreak of COVID 19 or SARS-Cov-2 is the novel or new version of continuation of virus spill over the last few decades. The previous outbreaks as such MERS, SARS predominantly infect human respiratory systems with limited human to human transmission capability. The human interface with wildlife along with deforestation, urbanization, overgrown population, bush meat hunting, wildlife trade significantly increase the reassortment of bat originated virus with other intermediate host to jump in to human species. In this review, we discussed the history of bat borne pathogen and the triggering factors that impose their spill over to human for generating current and future pandemics.
West Nile virus (WNV) is a vector-borne zoonotic disease maintained in a sylvatic cycle involving mosquito vectors and birds. To detect West Nile virus (WNV) and other flavivirus infections in wild resident and migratory birds, we tested 184 samples from 19 identified species within nine families collected during 2012-2016 from four districts in Bangladesh. We tested serum samples for the immunoglobulin G (IgG) antibody to WNV using competitive Enzyme-Linked Immunosorbent Assay (c-ELISA), whereas tracheal and cloacal swabs subjected to consensus PCR for the detection of the flavivirus RNA. Overall, 11.9% (n=22; 95% CI: 0.07-0.16) samples were seropositive, including 15.9% migratory wild birds and 10.7% resident wild birds. Tufted duck showed 28.5% sero-positivity, whereas crows showed 12.5% sero-positivity. None of the swab samples was positive for flavivirus RNA infection. These study findings suggest that wild birds of Bangladesh may carry WNV. We recommend continued surveillance for early detection and to better understand the epidemiology of WNV and other flavivirus circulation in both birds and mosquitoes in Bangladesh.