Dr Louis Greeff, a wildlife veterinarian who also farms in the Limpopo Bushveld, told delegates at the Wildlife Ranching SA conference in Pretoria this past weekend how he recently managed to save six cows infected with bovine malignant catarrhal fever (MCF, snotsiekte), a condition that is normally a death sentence for cattle.
By Jasper Raats, senior journalist at African Farming and Landbouweekblad
He explained that MCF is caused by a herpes-related virus found in both cattle and wildebeest.
Wildebeest can carry the virus without showing symptoms, but when exposed to stress – such as during drought, weaning or hunting – it can trigger the disease. In systems where wildebeest are overcrowded or where social tension is high, the risk of disease increases.
In an outbreak on his farm in August 2024, Greeff lost 12 cattle after a cold front caused stress in his herd. The experience forced him to rethink his management approach, leading to a series of experimental treatments – with remarkable results.
Early, Aggressive and Systematic Treatment
Greeff says early action is the key to success. He believes that as soon as there is any suspicion of infection, the entire herd should be treated immediately. He uses high doses of cortisone and other anti-inflammatory medicines to suppress the severe immune response caused by the virus.
He also administers vitamins A, D, E, C and B, along with antioxidants and moringa, a plant-based immune booster.
An unusual component of his treatment is the use of cannabis, specifically the THC-containing form, which he describes as an immune modulator. “I have saved six cows with this combination,” he says. “The virus itself doesn’t kill the animal – the body’s overreaction does. You have to reprogramme the immune system.”
Although controversial, Greeff says the cannabis treatment has worked remarkably well in early cases, particularly when used with nutritional support and antioxidants. He administers a finely chopped mixture according to body mass, which quickly improves appetite and behaviour.
He admits that this is not a formal scientific trial, but rather an experiment he conducted on his own animals, with good results.
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Nutrition, Water and Phosphates
Correcting nutritional imbalances, says Greeff, has been another major factor in his success. He discovered that hard water with high calcium levels can impair phosphate absorption, increasing stress and disease susceptibility. After testing the water and switching to the correct phosphate mixture (monocalcium phosphate instead of dicalcium phosphate), his losses dropped by 90%.
“Happy animals are healthy animals,” he says. “When their nutrition, water and minerals are in balance, you’ve already won half the battle against disease.”
Vaccine Not Available Yet
Despite the heavy economic toll of MCF, a vaccine is still not available to South African farmers. More than 10 years ago, Afrivet obtained a vaccine from the Moredun Research Institute in Scotland and tested it with Prof Moritz van Vuuren of the University of Pretoria’s Faculty of Veterinary Science.
Dr Peter Oberem, who was Afrivet’s CEO at the time, says that although the Moredun vaccine had to be frozen until shortly before use – making it difficult to handle – it proved successful in field trials on about 250 cattle. Van Vuuren also confirmed that the virus strain used in the vaccine is the same as that found in South Africa.
Onderstepoort Biological Products (OBP) signed a licence agreement with Moredun in 2021 to produce the vaccine locally. However, OBP’s staffing shortages and stringent state regulations have delayed registration, leaving thousands of animals unprotected each year. The Department of Agriculture’s Animal Health unit now reportedly insists that the vaccine be tested under insect-free conditions before release – but such facilities are not currently available.
“It’s frustrating,” Oberem says. “Thousands of cattle die every year from MCF, while the solution is within our reach. But government red tape makes it extremely difficult to protect our animals.”
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An Alternative Vaccine
Greeff, working with Prof Daan Goosen of Disease Control Africa, has started experimenting with an alternative vaccine against MCF. He has already vaccinated his own herd four times, with excellent results. In a group of 600 cows vaccinated during an outbreak, no new cases have been reported.
Although not yet officially registered, the vaccine shows great promise. “It costs me about R50 per cow per year, and I haven’t lost a single animal this year,” Greeff says.
He cautions that all vaccine use must be under veterinary supervision. The law prohibits its distribution without a prescription, and research on antibody responses is ongoing.
Interestingly, antibody tests show that even animals never vaccinated sometimes have built-up immunity – suggesting that the virus circulates quietly in herds and only flares up during stress.
Neighbourliness Saves Cattle
Greeff stresses that MCF is not just a cattle farmer’s problem or a game farmer’s problem, but a shared challenge. He and his neighbour worked together after their respective losses, counting their game and adjusting their wildebeest numbers per hectare. Greeff also gave his neighbour a series of vaccine doses, after which the outbreak came to an end.
According to Greeff, 60% of controlling the disease comes down to animal welfare and 40% to good neighbourliness. Neighbours should warn each other in advance about hunting, helicopter captures or the introduction of new animals to a herd – any event that could cause stress.
He says that in the Free State, outbreaks of MCF are increasingly linked to sheep. Stress in ewes and lambing groups, especially during shearing or lambing season, appears to activate the virus.
Buffaloes seem to be particularly susceptible to this strain of the disease. “Buffaloes and sheep simply don’t belong together,” Greeff says. “I’ve had several cases where buffalo bulls have died after eating feed contaminated by sheep.”
Greeff doesn’t claim to have cured the disease, but his results show that timely intervention, good nutrition and cooperation between neighbours can mean the difference between disaster and recovery.
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