First evidence of circulation of multiple arboviruses in Algeria.

Background: Algeria like other North African countries is experiencing recurrent episodes of West Nile Virus (WNV) emergences and new health threats associated with the introduction of Aedes albopictus in 2010 are to be feared. To improve the surveillance of mosquito-borne pathogens, we performed a study using innovative tools based on multiplex molecular methods. Methods: We combined two approaches: a high-throughput chip based on the BioMark Dynamic array system to detect arboviruses in mosquitoes, and a set of immunologic methods (ELISA, microsphere immunoassays (MIA) and virus microneutralization tests (MNT)) for serological surveys in animal hosts. We investigated two distinct regions: a first zone located in the coastal humid region and a second one in the Saharan desert region. Principal findings: We collected a total of 1,658 mosquitoes belonging to nine different species and found predominantly Culex pipienss. l. (56.5%) and Cx. perexiguus (27.5%). From 180 pools of 10 mosquitoes, we detected four arboviruses: Banna virus (BAV), chikungunya virus (CHIKV), Sindbis virus (SINV), and Usutu virus (USUV). Moreover, we examined 389 blood samples from equids and poultry and found that 52.4% were positive for flavivirus antibodies in ELISA, while 30.8% were positive for WNV and two chickens and two equids were positive for USUV by MNT and MIA respectively. Conclusions: To our knowledge, this is the first report of five arboviruses circulating in Algeria, with three reported for the first time (CHIKV, BAV, and USUV). Our study brings evidence that reinforcing surveillance using more discriminant tools may help in anticipating future emergences and propose adapted control measures. Author summary: Arboviruses are a significant threat to public health because of their epidemic and zoonotic potential. The geographical distribution of mosquito-borne diseases such as West Nile Fever has expanded over the last decades. Countries of the Mediterranean region are not spared. In this context, surveillance of the circulation of such viruses needs to be achieved before the appearing of human or animal cases. The aim of our study was to use innovative and highly efficient tools to highlight the circulation of arboviruses in mosquito vectors, animal reservoirs or exposed animals in Algeria. A total of 1,658 mosquitoes belonging to nine different species were collected and screened for arboviruses usinghighthroughput chips based on the BioMark Dynamic arrays system, capable of screening various arboviruses in a single experiment. Moreover, we analyzed 389 blood samples from equids and poultry using 3 different serologic methods. Our results bring, for the first time in Algeria, evidence of the cryptic circulation of 5 arboviruses: West Nile virus, chikungunya virus, Usutu virus, Sindbis virus and for the first time out of the Asian region, Banna virus. This approach, as an early warning system, is enabling for an early detection of pathogens circulation above-threshold before disease appearance in humans. [ABSTRACT FROM AUTHOR]