Serological Surveillance of Influenza D Virus in Ruminants and Swine in West and East Africa, 2017-2020.

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.

Field Postmortem Rabies Rapid Immunochromatographic Diagnostic Test for Resource-Limited Settings with Further Molecular Applications.

Functional rabies surveillance systems are crucial to provide reliable data and increase the political commitment necessary for disease control. To date, animals suspected as rabies-positive must be submitted to a postmortem confirmation using classical or molecular laboratory methods. However, most endemic areas are in low- and middle-income countries where animal rabies diagnosis is restricted to central veterinary laboratories. Poor availability of surveillance infrastructure leads to serious disease underreporting from remote areas. Several diagnostic protocols requiring low technical expertise have been recently developed, providing opportunity to establish rabies diagnosis in decentralized laboratories. We present here a complete protocol for field postmortem diagnosis of animal rabies using a rapid immunochromatographic diagnostic test (RIDT), from brain biopsy sampling to the final interpretation. We complete the protocol by describing a further use of the device for molecular analysis and viral genotyping. RIDT easily detects rabies virus and other lyssaviruses in brain samples. The principle of such tests is simple: brain material is applied on a test strip where gold conjugated antibodies bind specifically to rabies antigens. The antigen-antibody complexes bind further to fixed antibodies on the test line, resulting in a clearly visible purple line. The virus is inactivated in the test strip, but viral RNA can be subsequently extracted. This allows the test strip, rather than the infectious brain sample, to be safely and easily sent to an equipped laboratory for confirmation and molecular typing. Based on a modification of the manufacturer's protocol, we found increased test sensitivity, reaching 98% compared to the gold standard reference method, the direct immunofluorescence antibody test. The advantages of the test are numerous: rapid, easy-to-use, low cost and no requirement for laboratory infrastructure, such as microscopy or cold-chain compliance. RIDTs represent a useful alternative for areas where reference diagnostic methods are not available.

Evolution of Highly Pathogenic Avian Influenza A(H5N1) Virus in Poultry, Togo, 2018.

In 2015, highly pathogenic avian influenza A(H5N1) viruses reemerged in poultry in West Africa. We describe the introduction of a reassortant clade 2.3.2.1c virus into Togo in April 2018. Our findings signal further local spread and evolution of these viruses, which could affect animal and human health.

Surveillance for influenza viruses in poultry and swine, west Africa, 2006-2008.

To determine the extent of animal influenza virus circulation in Côte d'Ivoire, Benin, and Togo, we initiated systematic year-round active influenza surveillance in backyard birds (predominantly chickens, guinea fowl, and ducks) and pigs. A total of 26,746 swab specimens were screened by using reverse transcription PCR. Animal influenza prevalence was estimated at 0 (95% CIs for each of the 2 study years 0-0.04% to 0-1.48% [birds] and 0-0.28% to 0-5% [pigs]). In addition, 2,276 serum samples from the same populations were negative for influenza-specific antibodies. These data indicate that the environments and host populations previously identified as harboring high levels of influenza virus in Southeast Asia do not do so in these 3 countries. The combination of climate and animal density factors might be responsible for what appears to be the absence of influenza virus in the backyard sector of the 3 countries.