Rift Valley Fever Spreads to the Western Cape Province

Notwithstanding the strategic application of 40 000 doses of Rift Valley fever (RVF) vaccine sponsored by the Western Cape Department of Agriculture in the Murraysburg district of the Karoo, RVF has spread to the Beaufort West district in the Western Cape.

The first cases were detected on our northern border with the Northern Cape Province where 2 Jersey cattle died acutely. On post mortem examination a haemorrhagic syndrome was evident. In the 2nd case 12 young Merino lambs died acutely on a farm to the east of Beaufort West. Their post mortem findings were typical for RVF. Samples from both these cases were found positive for RVF by the Onderstepoort Veterinary Institute on Friday 26th March 2010.

Various other cases of deaths and abortions in the area are currently under investigation.

The local State Veterinarian that conducted the post mortem examinations has presumably also become infected. His symptoms include fever, severe headache, muscle aches and extreme eye pain with sensitivity to light. Blood samples have been taken to verify the cause of these symptoms. The vet is under medical supervision at home, his condition is stable.

Western Cape Health Minister, Theuns Botha, said Tygerberg Hospital's Infectious Diseases Unit is on standby. The Western Cape Department of Health has a contingency plan in place for communicable diseases such as Rift Valley Fever.

We expect the disease to extend in a westerly and south-westerly direction from Beaufort West. Areas in the Karoo with lush vegetation and large tracts of open water that favour the breeding of mosquitoes are deemed as high risk areas. The latest weather advisory indicates above normal expected rainfall for the next few weeks in the western parts of the Western Cape Province. It is thus possible that the infection may spread to the winter rainfall areas of the Swartland and possibly also to the Southern Cape.

Sheep and cattle farmers are advised not to let their stock graze in wet low-lying areas with large mosquito populations. The use of insecticidal and insect repellent remedies might be considered for valuable stock. As this is a viral disease, no specific treatment is available. Infected animals should be kept quiet, in the shade, with good feed and adequate water. Anti-inflammatory drugs and antibiotics might be indicated in certain cases. Stock owners should contact their private veterinarians in this regard.

Onderstepoort Biological Products are the sole manufacturers of Rift Valley fever vaccine. Currently only the live attenuated vaccine is in stock. This vaccine can cause abortions in pregnant animals but has the advantage that it confers life-long immunity on correctly vaccinated animals. As this is a live virus vaccine the recommendations for use should be strictly adhered to, to prevent adverse reactions or even infection in humans.

Vaccine is available from Onderstepoort Biological Products (Ltd) at telephone 012 522 1500 or fax 012 565 5260. The vaccine's full name is: Live Rift Valley fever vaccine with registration number G 0119 (Act 36/1947). It comes in bottles of 100 doses and the cost is approximately R 2.50 per dose.

Following the scare in November 2009 when positive cases of RVF were diagnosed in the Northern Cape, Western Cape Veterinary Services advised stock farmers in the Namaqualand and Swartland to vaccinate their animals. In excess of 90 000 doses of vaccine were subsequently distributed or administered by private veterinarians in the Swartland, West Coast and Ceres areas.

The Department of Agriculture has ordered a further 40 000 doses of live RVF vaccine that will be used strategically in the next weeks.

Stock farmers are again reminded that this is a Notifiable Animal Disease according to the Animal Diseases Act, 1984 (Act 35 of 1984). Any suspicion of this disease must consequently be reported to an Animal Health Technician, Private Veterinarian or State Veterinarian. The human form of RVF infection is also reportable to the Department of Health.