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A brewing storm for livestock disease?

RVF is associated with the rainy season and mosquito breeding (WRENmedia)
RVF is associated with the rainy season and mosquito breeding

2010 is the year of World Cup fever in South Africa. But, visiting fans have been warned of another potentially lethal fever present in the region: Rift Valley fever (RVF), a viral zoonotic mosquito-borne disease, currently circulating in livestock across five out of nine provinces in the country. Whilst it is unlikely that fans will contract the disease unless they are in direct contact with infected animals, 18 fatalities had been confirmed in South Africa, with 186 human cases of RVF reported by mid May.

Although endemic over much of Africa, RVF is seasonal and associated with the rainy season and mosquito breeding, and it is the rise in heavy rainfall that has resulted in increasing incidence of the disease. Livestock keepers suffer direct losses through death of their animals and a high rate of abortion, and are also affected by loss of trade and the impact of control measures.

RVF is only one of a number of transboundary livestock diseases, which impact on livestock keepers across the African continent. Pestes des Petit Ruminantes (PPR) is another viral disease but affecting sheep and goats; endemic to parts of West, Central and East Africa, in 2008 it also affected Morocco. Spread from one region to another by sick animals, it is feared that the incidence of PPR, and other similar diseases, is likely to increase in drier areas where fewer watering holes will increase the interaction both between livestock and also wildlife, that also often carry these diseases.

Climate and disease change

Transboundary diseases restrict trade (WRENmedia)
Transboundary diseases restrict trade

Delegates at a recent conference, Pastoralism and Climate Change Adaptation in Africa, organised by Climate Change Adaptation in Africa (CCAA) at Egerton University in Nakuru, Kenya, were told that climate change was altering disease distribution as vectors such as mosquitoes moved to new habitats, making prediction and control of disease outbreak difficult. "Imbalance caused by climate change has disrupted prediction models and altered geographical disease distribution making planning difficult," said Dr Florence Maichomo of the Kenya Agriculture Research Institute (KARI).

The economic and trade implications for African countries are severe as market restrictions are put in place to control spread of disease to new areas, and millions of dollars are spent on management of the diseases. Export markets for live animals and their products have also been lost both within and outside the continent as governments, mainly in the E.U., enforce bans for fear of disease spread. Kenya has also suffered regional losses, losing its markets in Yemen and Mauritius for export of beef and live animals. It was reported at the conference that the Kenya government is currently grappling with the feasibility of establishing disease-free zones to help protect its livestock trade.

Strengthening regional surveillance and control

Dr Maichomo went on to say "Disease surveillance and monitoring skills are weak in most regions. As herders migrate, traceability of infected animals becomes difficult while weak enforcement of cross-border movement of livestock worsens the situation. For instance, animals move freely between the remote border regions of Kenya, Uganda, Sudan and Ethiopia, making surveillance and monitoring nearly impossible as pastoralists pay little importance to international boundaries in their pursuit of pasture and water."

To curb further spread of transboundary disease, Maichomo recommended a number of measures including establishing a regional and sub-regional approach to disease spread, enhancement of data collection, increased capacity and more funding of veterinary bodies. A reassessment of existing prediction models was also required. "Institutions dealing with animal health need to harmonise their policies and regulatory mechanisms, and openly share data," she said.

Regional disease surveillance needs to be strengthened (WRENmedia)
Regional disease surveillance needs to be strengthened

Pan African Tsetse and Trypanosomiasis Eradication Campaign (PATTEC) initiative, established to control tsetse fly and the diseases caused by the fly, was cited as a good example of a regional initiative that needs to be replicated in tackling the problem of controlling livestock diseases at regional level. Maichomo acknowledged that East African countries were now collaborating more closely in information sharing and there were improvements in surveillance and monitoring but she stated that much more still needed to be done.

The global spread of transboundary diseases has much to do with international spread through increased movement of people and animals. However, climate change brings new uncertainties as geographical distribution of vectors may change and extreme weather events, resulting in flooding or drought, also affect the spread of diseases. For the millions of smallscale farmers dependent on livestock, climate change is likely to make their already precarious livelihoods even more challenging.

Written by: Maina Waruru

Date published: July 2010


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