Limit the spread of bluetongue

June 2023

Bluetongue disease is a non-contagious, insect-borne, viral disease in ruminants, mainly sheep and less frequently cattle. The virus does not affect humans, but the disease is caused by viruses transmitted by insects.

According to vetlink.co.za, outbreaks of bluetongue can result in significant losses due to the impact on livestock health, but also in the loss of livestock markets due to regulatory restrictions on animal movement to limit the spread of the disease.

The disease is characterised by fever, excessive salivation and swelling of the face and tongue. Some animals also develop foot lesions, resulting in lameness. Other symptoms may include difficulty in breathing, a nasal discharge and an ulcerated and/or inflamed snout, beak and ears. 

TREATMENT
In an article in Farmer’s Weekly (26 January 2023), Dr Danie Odendaal, director of the South African Veterinarian Network, stated that there is no treatment against the disease. “The aim of treating infected animals is to make them feel better until they have developed immunity against the virus. Vaccination is the most effective way to minimise losses and interrupt the cycle from an infected animal to vector.

In its March 2023 newsletter, the Red Meat Producers’ Organisation (RPO) mentioned that vaccination is without a doubt the best preventative measure against bluetongue. However, they shared some guidelines to keep in mind when vaccinations are not available: 

• Avoid unregistered drugs, vaccines and home remedies.
• Sheep can be sprayed over the head and legs with registered insecticides. The best products are those containing deltamethrin.
• The midges breed in moist areas such as wetlands and, if possible, such areas should be avoided, especially at night when the midges are active.
• Reduce contact between the midges that spread the virus and the sheep. Cattle are only slightly affected (or not affected at all) by the virus but are more susceptible to midges. If cattle and sheep graze together, midges will tend to prefer the cattle. Be aware that the virus can multiply in cattle.
• If possible, the herd and especially the most valuable animals such as rams should be kept in a sheltered barn from late afternoon until late morning. Openings can be covered with shade netting and sprayed with insect repellents.
• The treatment of affected sheep relies on good care, soft food and, if necessary, appropriate antibiotics and painkillers.

Remember the following:

• Previously vaccinated animals are less susceptible to the virus than young lambs, which will require special attention and care if they get sick.
• As the situation can vary between districts and farms, always consult your local vet.

SOURCES
RPO Newsletter, March 2023
https://vet360.vetlink.co.za/training/blue-tongue-in-cattle
https://www.farmersweekly.co.za/agri-news/south-africa/south-africa-is-sitting-on-a-bluetongue-timebomb/

Publication: June 2023

Section: Pula/Imvula

Author: PULA IMVULA EDITORIAL TEAM