DISEASE ▶▶▶
Insights and alert for the southern hemisphere
An outbreak of H5 avian influenza has been confirmed in a commercial layer flock in Johannesburg, South Africa. Meanwhile, Poultry World discusses the outbreak that has affected the poultry industry in Europe and Asia with Dr David E. Swayne at the USDA. We find out what makes this virus different and ask for his advice for the poultry sector in the southern hemisphere.
BY NATALIE BERKHOUT T
he farm, where 300 birds died of avian influenza, was quarantined and the animal health depart- ments of the national and provincial Department of Agriculture Land Reform and Rural Development
(DALRRD) implemented the required control measures. The whole industry has been placed on high alert and the biose- curity contingency plans have been implemented. This is the first outbreak of avian influenza (H5) on a commer- cial farm in South Africa since the outbreak of highly patho- genic avian influenza (H5N8) in 2017. The outbreak had a sig- nificant impact on the layer industry and marginally affected the broiler industry. Poultry World discussed the outbreak with Dr David E. Swayne, laboratory director at the Southeast Poultry Research Laboratory at the US National Poultry Re- search Center Agricultural Research Service, USDA, who shared with us his expert opinion.
How serious is this outbreak compared to previous avi- an influenza outbreaks? The current outbreak strains in Europe and Asia are the H5Nx HPAI viruses that have a genetic origin from the initially iden- tified H5N1 High Pathogenicity Avian Influenza Virus (HPAIV) from the Guangdong province in China in 1996. This virus lin- eage has spread to many additional countries and changed by drift and shift. There have been changes in the haemag- glutinin (HA) protein due to mutations in the gene that have produced diverse HA structures which have necessitated a change in vaccine seed strains and also resulted in changes in
the biology of the virus infections in poultry and wild birds. These newest viruses are still highly lethal to poultry but vary in their ability to infect and cause severe disease and death in wild birds.
What makes this outbreak different to the previous one? This clade of virus has infected migratory waterfowl and spread across multiple countries in Europe and Asia with over- flow into domestic poultry, causing outbreaks in backyard and commercial poultry. This is similar to the outbreaks seen in the USA in 2014-2015. But many previous outbreaks with the 1996 lineage of HPAIV have not always spread by migratory birds. Just before avian influenza was detected, Poultry World had asked Dr Swayne what advice he had for the southern hemisphere, specifically South Africa, in preparation for win- ter. He mentioned increased surveillance of migratory birds and outdoor poultry for early HPAIV detection and the devel- opment of mitigation strategies to reduce its introduction into commercial poultry and to limit onward spread.
▶ POULTRY WORLD | No. 4, 2021
Dr David E. Swayne, DVM, PhD, DACVP, DACPV, labora- tory director at the Southeast Poultry Research Laboratory, US National Poultry Research Center, Agricultural Re- search Service, USDA.
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PHOTO: USDA
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