Kvægsovesyge martrer mange afrikanske småbønder og kan koste i forvejen fattige mennesker deres levevej – men nu melder forskere om nye opdagelser
JOHANNESBURG, 20 May 2011 (IRIN): New research on sleeping sickness in African cattle is holding out the possibility that in the not too distant future Africa could start seeing the introduction of cattle resistant to sleeping sickness – a disease which kills billions of dollars worth of livestock (tamkvæg) every year.
The research claims to have isolated two genes critical in the development of disease-resistant cattle.
Harry Noyes, lead author of a paper on this published in the Proceedings of the National Academy of Sciences of the USA (PNAS) on 16 May, told IRIN their research had been prompted by the fact that while East African humped cattle breeds (zebu-kvægracer) are susceptible to (modtagelige for) trypanosome parasites which cause sleeping sickness, the N’Dama, a humpless (pukkelløs) West African breed, is not seriously affected by the disease.
African animal trypanosomosis – also known as `nagana’ (Zulu: “to be depressed”) or tryps – is transmitted through the bite of an infected species of the tsetse fly and is endemic (findes i) from Senegal to Tanzania, and Chad to Zimbabwe (an area almost the size of the USA).
– The humped cattle originated in India, where the tsetse fly is not found, while N’Dama, which probably had been exposed to the trypanosome parasite for thousands of years had developed a mechanism to control the impact of the disease, explained Noyes, a senior researcher at Liverpool University.
Over the past two decades the researchers found at least 10 genes which control the impact of the disease in the N’ Dama breed.
– Out of those resistant genes we isolated what we feel are the two most significant ones for our purposes, said Steve Kemp, a geneticist with the Nairobi-based International Livestock Research Institute (ILRI), who also collaborated on the study.
Now that the scientists know what they are looking for, they have embarked on the task of isolating humped cattle breeds (racer) which also carry the two genes.
Over the next three years, ILRI intends to breed (fremavle) humped cattle varieties with at least one of the genes. The humped cattle breeds produce more milk than the N’Dama.
Decades away?
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