Highly Pathogenic Avian Influenza A(H5N1) Clade 2.3.4.4b Virus in Poultry, Benin, 2021

International audience; In August 2021, we detected highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b viruses in poultry in southern Benin.

The isolates were genetically similar to H5N1 viruses of clade 2.3.4.4b isolated during the same period in Africa and Europe.

We also found evidence for 2 separate introductions of these viruses into Benin.Highly pathogenic avian influenza (HPAI) viruses represent a major threat to animal and public health.

HPAI A/Goose/Guangdong/1/96-lineage subtype H5N1 viruses first emerged in southern China in 1996, and their descendants have since evolved into different phylogenetic clades causing large outbreaks in poultry and wild birds worldwide (1).

Since first being detected in Nigeria in 2006, HPAI H5N1 viruses have been responsible for numerous outbreaks in many countries in Africa, causing high mortality in domestic and wild birds over the past 15 years (2,3).

Beginning in January 2021, outbreaks caused by HPAI H5N1 clade 2.3.4.4b virus have been reported in many countries in West Africa, including Mali, Nigeria, Niger, and Senegal (3).

Clade 2.3.4.4 H5 viruses are of particular concern because of their potential for reassortment and ability to cross the species barrier and infect new hosts, including humans, seals, and foxes (4,5).

In addition, increasing infectivity of these HPAI H5 viruses in humans could accelerate their adaptation to human-to-human transmission, which might increase the possibility for emergence of a novel influenza strain with pandemic potential (6).

In August 2021, HPAI H5N1 viruses were detected in poultry in the southern region of Benin.

In this study, we carried out genetic and antigenic analyses to investigate the origin of the virus and its relationship with viruses detected in neighboring countries.