AGRICULTURE NEWS - Agriculture and livestock production have always been important contributors to the SA economy.

Due to the burden of animal diseases, some of which are unique to Africa, South Africa has relied on several animal vaccines for more than 100 years to ensure effective livestock production. 

The local production of horse sickness and bluetongue vaccines have been able to keep horses and maintain a thriving wool industry. South Africa was the first country in the world to describe the viruses causing these two devastating diseases and developed these two vaccines around 1904.

Macro driver

The South African wool industry according to industry statistics, has more than 15 million wool sheep, of which 4 million sheep are owned by the emerging and communal sector. 

With a total production of around 45 million kg of wool per annum, more than 90% is exported, essentially to China, Italy, and other big international markets. 

SA produces 2-3% of the global production and about 12% of the world’s fine wool used for making clothing. This multibillion-rand industry relies on around 6 000 commercial and 4 000 communal wool producers in South Africa. The emerging sector produces about 13% of the national clip. More importantly, the wool industry employs 35 000 farm workers as well as 4 000 sheep shearers and wool handlers.

Peste des Petits Ruminants

This economic sector of our country could be in jeopardy due to serious animal diseases. One such disease is Peste des Petits Ruminants known globally as PPR, a disease caused by a virus of the same family as the causative agent of the now eradicated rinderpest.

PPR is currently one of the most important small ruminant (sheep and goats) diseases globally, which can cause massive negative economic and livelihood impacts. It has been named by the global animal health and livestock community as the next disease to be eradicated from our planet.

Currently, no cases have been seen in South Africa, but it poses a serious threat as it is spreading southward on the African continent. The disease is difficult to eradicate, without sustained coordinated efforts, thus resulting in catastrophic losses for the sheep and goat industries, and subsequently the livelihood of millions of people.

PPR is a severe, fast-spreading disease of mainly domestic small ruminants. It is characterized by the sudden onset of depression, fever, discharges from the eyes and nose, sores in the mouth, disturbed breathing and cough, foul-smelling diarrhea, and death. Young animals are most severely affected, and goats more than sheep.

High mortality

The virus can infect up to 90 percent of a flock, and the disease kills 30 to 70% of infected animals. PPR has spread rapidly in recent years, with more than 70 countries in Africa, the Middle East and Asia have to date confirming PPR within their borders, and many countries are at risk of the disease being introduced.

These regions are home to approximately 1.7 billion heads – roughly 80 percent – of the global population of sheep and goats.

Morocco is one of the very few countries that managed to eradicate the disease after the incursion but unfortunately suffered a resurgence a few years later. India and China have been battling with disease: In India, the PPR associated annual losses have been shown to vary between the US $653 million and $669 million (more than R10 billion!).

A massive outbreak in the susceptible small ruminant population in West DR Congo up to 2012 resulted in recorded deaths of 744,527 goats, which converted to a trade value of USD 35,674,600 (more than R565 million). These figures are probably an underestimate since the disease has since become endemic, causing further economic damage.

Moving south

South Africa is at great risk as the disease has spread southward in recent years on the African continent, reaching, and establishing itself already in Tanzania and Angola. There have been brief intrusions into Zambia which, were short-lived.

However, with the spread seen in other regions, including Asia and the Middle East, PPR may likely continue its spread south and reach South Africa. 

With a fully naïve population of sheep and goats in South Africa, its introduction will be devastating as high morbidity and mortality can be expected, thus compromising the lucrative wool industry, food security, and the tens of thousands of jobs in the sector.

Preventing its entry into South Africa should therefore be a priority, with a preparedness program including surveillance activities and rapid detection capacity. At the first indication of entry or imminent risk, two options could be considered for South Africa: stamping out or targeted slaughter of infected or exposed animals, and vaccination. With the disease not always being easy to detect, stamping out will be difficult to effectively implement.

Vaccines

Vaccines are available against PPR; the most widely used is an attenuated strain referred to as Nigeria 75/1. 

This vaccine, which has been very successful in controlling the disease, is produced by many vaccine manufacturers and is widely used in infected countries, including countries like China. 

Vaccination, clearly a critical tool for PPR, should be part of a well-structured control program. Given the PPR-free status of South Africa, a vaccination strategy will require serious considerations in terms of the approach to be adopted.

Once vaccinated, the animals become zero-positive and cannot be distinguished from infected animals based on the presence of antibodies. Once the disease has established itself, however, this becomes an academic issue as the aim is to protect animals from clinical infection.

In PPR-free countries like South Africa, the use of a DIVA vaccine would be advisable (DIVA vaccines distinguish vaccinated from infected animals).

South Africa needs to be prepared for the likely incursion by acquiring existent PPR vaccines or developing our own because of the potentially disastrous impact of the disease on the wool, sheep, and goat industries, but equally on both food security, employment, and South African economy, as a whole.

'We bring you the latest Garden Route, Hessequa, Karoo news'