ABSTRACT
Influenza D virus (IDV) was first isolated in 2011 in Oklahoma, USA from pigs presenting with influenza-like symptoms. IDV is known to mainly circulate in ruminants, especially cattle. In Africa, there is limited information on the epidemiology of IDV, although the virus has likely circulated in the region since 2012. In the present study, we investigated the seropositivity of IDV among domestic ruminants and swine in West and East Africa from 2017 to 2020. Serum samples were analyzed using the hemagglutination inhibition (HI) assay. Our study demonstrated that IDV is still circulating in Africa, with variations in seropositivity among countries and species. The highest seropositivity was detected in cattle (3.9 to 20.9%). Our data highlights a need for extensive surveillance of IDV in Africa in order to better understand the epidemiology of the virus in the region.
Subject(s)
Orthomyxoviridae Infections/epidemiology , Orthomyxoviridae Infections/immunology , Ruminants/immunology , Ruminants/virology , Thogotovirus/immunology , Thogotovirus/pathogenicity , Africa, Eastern/epidemiology , Africa, Western/epidemiology , Animals , Cattle , Cattle Diseases/epidemiology , Cattle Diseases/immunology , Cattle Diseases/virology , Female , Male , Seroepidemiologic Studies , Swine , Swine Diseases/epidemiology , Swine Diseases/immunology , Swine Diseases/virologyABSTRACT
Sub-Saharan Africa was historically considered an animal influenza cold spot, with only sporadic highly pathogenic H5 outbreaks detected over the last 20 years. However, in 2017, low pathogenic avian influenza A(H9N2) viruses were detected in poultry in Sub-Saharan Africa. Molecular, phylogenetic, and antigenic characterization of isolates from Benin, Togo, and Uganda showed that they belonged to the G1 lineage. Isolates from Benin and Togo clustered with viruses previously described in Western Africa, whereas viruses from Uganda were genetically distant and clustered with viruses from the Middle East. Viruses from Benin exhibited decreased cross-reactivity with those from Togo and Uganda, suggesting antigenic drift associated with reduced replication in Calu-3 cells. The viruses exhibited mammalian adaptation markers similar to those of the human strain A/Senegal/0243/2019 (H9N2). Therefore, viral genetic and antigenic surveillance in Africa is of paramount importance to detect further evolution or emergence of new zoonotic strains.
