Understanding the 2023 avian influenza outbreak

The 2023 avian influenza outbreak has caused unprecedented damage to the poultry industry. Two strains of highly pathogenic avian influenza (HPAI) strains have caused outbreaks in South Africa this year.

An H5N? (partially typed) strain has caused 10 outbreaks, seven in the Western Cape and three in KwaZulu-Natal. A much more virulent HPAI H7N6 virus, which began at end of May, has caused 87 outbreaks on poultry farms, with the majority of outbreaks in Gauteng and a couple of affected farms in Mpumalanga, North West, and Limpopo provinces.

Just over eight million birds have been affected on the H7N6 affected properties, with approximately 208 000 deaths and close to 1,8 million birds being culled and disposed. Breeder and layer farms have been most affected, reducing the number of day-old chicks hatched to supply broiler farms, and the number of eggs being produced for the consumer market. Limited outbreaks have occurred on broiler farms, although the reduced supply of day-old chicks has created a shortage of chicken in the market.

Price inflation on eggs and chicken is a reality due to the shortage and price increases can be expected to continue in the short term. To alleviate the shortage, government is fast-tracking import permits for egg imports. The Minister of Agriculture, Land Reform, and Rural Development stated that South Africa will also fast-track the importation of vaccines in an attempt to halt the spread of avian influenza.

These outbreaks come at a time when the chicken industry has been under production pressure due to load-shedding, which has caused poor growth rates and subsequent overcrowding. Reports suggest that up to 10 million birds were culled due to the electricity blackouts at the beginning of 2023.

Avian influenza is on the rise globally; new outbreaks are reported regularly to the World Organisation for Animal Health (WOAH) from all parts of the world. For example, over the past week, outbreaks have occurred in Latvia, Spain, Belgium, Germany, the United States, United Kingdom, Finland, Norway, Brazil, Uruguay, and Israel.

Avian influenza rarely affects humans, and then only those in contact with live birds, i.e., eggs and chicken meat are not infectious.

Migratory wild birds, especially waterfowls, are the natural host and reservoir of avian influenza viruses, which they carry within their respiratory or intestinal tracts. Depending on the virus strain and the species of bird, the virus can be harmless or fatal to the wild bird. When birds have little or no symptoms of the virus, it allows them to spread the viruses between neighbouring countries or over long distances along their migratory pathways. Wild birds also play a major role in avian influenza virus’ evolution and maintenance during low seasons. 

The main wild species involved in the viral cycle of avian influenza are waterfowls, gulls, and shorebirds; however, the virus seems to pass easily between different bird species. Direct exposure of farmed birds to wild birds is a likely transmission route of the virus.  Therefore, it is critical to limit their exposure to wild birds to lessen the risk of introducing avian influenza into flocks. In birds, avian influenza viruses are shed in the faeces and respiratory secretions. They can all be spread through direct contact with secretions from infected birds, especially through faeces or through contaminated feed and water. Because of the resistant nature of avian influenza viruses, including their ability to survive for long periods when temperatures are low, they can also be carried on farm equipment and spread easily from farm to farm.