Johannesburg — THE National Institute for Communicable Diseases yesterday confirmed the deaths of two people in the Free State who had contracted river valley fever, an airborne disease that is affecting sheep, goats and cattle around the country.

The institute has warned that the disease "could quickly spread" to other farming communities and urged people to avoid contact with the tissue of infected animals, not to drink unpasteurised milk, and avoid mosquito bites.

It also urged farmers and veterinarians to wear protective clothing when handling sick animals, saying no vaccine was available for humans yet.

The institute said two farm workers had died in the Free State. A total of 22 infections were confirmed in the Free State and Northern Cape.

Lucille Blumberg, head of the institute's epidemiology and outbreak response unit, said people were contracting the virus through direct or indirect contact with tissues of infected livestock.

River valley fever is a viral disease that can cause an outbreak of abortions and deaths of young livestock, predominantly sheep, goats and cattle. Humans can become infected from contact with infected tissues of livestock, and less frequently from mosquito bites.

Mild symptoms in human cases can last from two to six days and include a sudden onset of flu -like fever and muscle pains, neck stiffness, sensitivity to light, vomiting and loss of appetite.

Blumberg said severe symptoms included vision disturbances, headache, memory loss, hallucinations, confusion, disorientation, vertigo, convulsions, lethargy and coma, and haemorrhagic fever. Deputy Health Minister Molefi Sefularo said his department and the Department of Agriculture, Forestry and Fisheries were investigating the outbreak.