Three more people have been infected with Rift Valley fever, bringing the total to 63 of laboratory confirmed human cases since the first incident on 13 February 2010. The mortality rate remains unchanged at two.
The National Institute of Communicable Disease (NICD) reported this morning that of the 63 cases of infected people, 54 cases and two deaths are from Free State, four in Eastern Cape and five in Northern Cape.
Direct contact with Rift Valley fever infected livestock and or linked to farms with confirmed animal cases of Rift Valley fever, remain the main risk factor for the infection. 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, supported by the South African Field Epidemiology and Training Programme (SAFELTP) and NICD.
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 and Gauteng.
The Department of Agriculture in Free State has started the vaccination of animals, to contain the spread of the virus.
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). It is important to note that, humans become infected from contact with infected tissues of livestock and less frequently from mosquito bites. 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 and
* 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.
Preventive measures:
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.
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Charity Bhengu
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Charles Mugero
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Issued by: Department of Health
27 March 2010
