As of 15 March 2010, a total of 21 human laboratory confirmed cases of River Valley fever have been confirmed, all acquired in Free State, with two deaths. This brings a total to 22 human cases of Rift Valley fever, with one in Northern Cape.
Most of these cases reported direct contact with Rift Valley fever infected livestock and or linked to farms with confirmed animal cases of Rift Valley fever. The human cases are: farmers, veterinarians and farm workers. Additional suspect cases are currently being tested.
Outbreak investigations by the Department of Health and the Department of Agriculture, Forestry and Fisheries are ongoing, and are being supported by the South African Field Epidemiology and Training Programme (SA-FELTP) and National Institute for Communicable Diseases (NICD).
While there is no specific treatment, the majority of persons affected will recover completely. People should avoid contact with the tissues of infected animals, refrain from drinking unpasteurised milk and prevent mosquito bites to avoid becoming infected. Farmers and veterinarians should wear protective clothing when handling sick animals or their tissues. There is no routine vaccine available for humans.
An ongoing outbreak of Rift Valley fever affecting sheep, goats and cattle on farms is also spreading within the Free State, Eastern Cape and Northern Cape provinces.
Affected farms are primarily clustered within Free State (initially in Lejweleputswa district, Bultfontein area). However, animal cases of Rift valley fever have been confirmed in all districts with spill over into Eastern Cape and Northern Cape.
Rift Valley fever is a viral disease that can cause severe disease in a low proportion of infected humans. The virus is transmitted by mosquitoes and causes outbreaks of abortion and deaths of young livestock (sheep, goats and cattle). Humans become infected from contact with infected tissues of livestock and less frequently from mosquito bites. In sub-Saharan Africa the mosquitoes which transmit the virus do not enter human dwellings but feed on livestock outdoors at night. The disease occurs throughout Africa and Madagascar when exceptionally heavy rains favour the breeding of the mosquito vectors.
Clinical features in humans
Typically illness is asymptomatic or mild in the vast majority of infected persons, and severe disease would be expected to occur in less than one percent of infected persons.
Key symptoms:
* The incubation period (interval from infection to onset of symptoms) for Rift valley fever varies from two to six days.
* Sudden onset of flu-like fever and or muscle pain.
* Some patients develop neck stiffness, sensitivity to light, loss of appetite and vomiting
* Symptoms of Rift Valley fever usually last from four to seven days, after which time the immune response becomes detectable with the appearance of antibodies and the virus gradually disappears from the blood.
Severe form of Rift Valley fever in humans includes:
* vision disturbances
* intense headache, loss of memory, hallucinations, confusion, disorientation, vertigo, convulsions, lethargy and coma and
* haemorrhagic fever.
The public living in the affected areas is encouraged to seek medical attention at their nearest health facilities, should they have any of the above symptoms.
Enquiries:
Charity Bhengu
Cell: 083 679 7424
For interviews:
Frew Benson
Cell: 082 372 4199
Issued by: Department of Health
15 March 2010
