The South African government urged farmers to intensify biosecurity measures after an avian influenza outbreak resulted in the deaths of more than 2.6 million birds.

Six of the nation’s nine provinces have been affected by the 50 HPAI H7 and 10 HPAI H5 sub-types of the virus, the Department of Agriculture said in a statement September 25. Poultry producers should immediately report suspicion of the disease to state veterinarians, it said.

Avian flu usually affects wild birds, but can sometimes infect commercial or domestic poultry. While it rarely causes disease in humans, according to South Africa’s National Institute for Communicable Diseases, there’s no treatment for the birds and the government requires farmers to cull poultry to control its spread.

Vaccines aren’t yet available in South Africa, but government talks to finalize access are at an advanced stage and registration of the medicines will be fast-tracked.

“The criteria under which vaccination will be permitted is almost in its final development, and only farms with good biosecurity and approved to vaccinate by the department will be given permission to vaccinate,” the department said.