Trypanosomiasis and droughts are probably the two largest limiting factors for cattle production in Africa. Trypanosomiasis has been estimated to cost between 1 and 4 billion US dollars per year to African farmers. Cattle are mainly used in the Europe and North America for meat and milk production in large scale intensive farms. Production systems in Africa vary from the pastoralists who live in semi-arid areas unsuitable for arable crops to the small dairy farmers who keep a couple of cows to produce milk for sale to pay for school fees, medicines and clothes. Cattle play a critical role in all these systems and live off grass and fodder crops that humans could not consume. They therefore make it possible for families to survive on smaller plots or in regions where crops will not grow. For these small farmers the loss of any animal is a serious blow and can mean taking children out of school or not being able to buy medicines. This film from the International Livestock Research Institute shows the impact on one African family when their animals died of trypanosomiasis.
In the west cattle have been intensively bred to maximize production of meat and milk. But these yields are only possible when abundant food and water is available for the animals. For the African farmer who lives with the ever-present risk of drought and disease it is more important that the animals survive than that they have high production. There are indigenous breeds of cattle such as N'Dama that can remain productive under moderate levels of trypanosomiasis infection. However they are unpopular with farmers because they are very temperamental and hard to manage. They are reluctant to be harnessed to a plow or cart and difficult to herd. In theory it should be possible to use the large range of natural responses to infection to breed cattle that are resistant to disease, highly productive and docile enough to pull a cart or a plow. However this needs sustained investment by government research stations over decades to develop these animals and then a highly developed agricultural extension system to maintain a supply of improved animals. This has not been achieved anywhere in Africa to date.
The parasites that cause nagana (trypanosomes) are common in African wild animals particularly in antelope, such as bushbuck and in wild pigs and warthogs and these wild populations act as a reservoir for the parasites. Tsetse flies bite these wild animals and then infect any domestic animals that they subsequently bite.
The presence of trypanosomes in wildlife means that the disease cannot be controlled by drug treatments alone and although the drugs samorin and berenil can be used for the prevention and treatment of nagana they are too toxic for use in humans and are also too costly for many African small-holders. An excellent film about how to treat African cattle with drugs is available from the ILRI film unit
Trypanosomiasis can be controlled very effectively by reducing the numbers of the tsetse flies that transmit the disease and by regularly treatment of infected animals. Tsetse flies breed very slowly producing only a single larvae every 4-5 days. The flies are easily attracted to coloured cloth traps which can be impregnated with insecticide. Well-maintained networks of these traps, such as the bi-conical trap shown on the right, have proved very effective for tsetse control, particularly in Southern Africa.
Tsetse control has been particularly successful in isolated areas such as the island of Zanzibar and the Ghibe valley of Ethiopia. However in the last three decades there has been a breakdown of the public and veterinary health infrastructure in many African countries and the traps have not always been maintained. This has resulted in a massive upsurge in human and animal cases of African trypanosomiasis. A continent-wide Programme Against African Trypanosomiasis (PAAT) has been established that approaches the problem of trypanosomiasis on a national level as part of a drive to reduce poverty and promote development in affected areas. The Pan African Tsetse and Trypanosome Eradication Programme (PAATEC) has also been established, but it is still uncertain whether there will be sufficient funding or political commitment to see this programme through.