Descriptive Epidemiology of and Response to the High Pathogenicity Avian Influenza (H5N8) Epidemic in South African Coastal Seabirds, 2018.

High pathogenicity avian influenza (HPAI) clade 2.3.4.4b H5N8 virus was detected in coastal seabirds in late 2017 in South Africa, following a devastating epidemic in the commercial poultry and ostrich industries. By May 2018, the infection had been confirmed in fifteen seabird species at 31 sites along the southern coast, with the highest mortality recorded in terns (Family , Order ). Over 7,500 positive or suspected cases in seabirds were reported. Among those infected were three endangered species: African penguins ( Linnaeus, 1758), Cape cormorants ( Wahlberg, 1855), and Cape gannets ( Lichtenstein, 1823). The scale and impact of this outbreak were unprecedented in southern African coastal seabirds and raised logistical challenges in resource allocation, risk mitigation, and outbreak response. It required the collaboration of multiple stakeholder groups, including a variety of government departments and nongovernmental organizations. With another HPAI outbreak in South African seabirds in 2021 and major incursions in seabird species in the northern hemisphere in 2022, it is vital to share and consolidate knowledge on the subject. We describe the epidemic, the lessons learned, and recommendations for developing contingency plans.