Tuberculosis in Zambia: spread, control of infection

Tuberculosis in Zambia: spread, control of infection

In Zambia, the incidence of all forms of human tuberculosis is estimated to be 444 per 100,000. There is also a high incidence of HIV and AIDS in the country. In the Kafue area, a high incidence of Mycobacterium bovis in both cattle and the Kafue lechwe antilope has been detected. This bacterium can infect humans and has been found in humans in the studied region of Namwala. Mycobacterium tuberculosis, which is the main cause of human tuberculosis, has also been detected in cattle in this region.


Human tuberculosis is caused by bacteria belonging to the Mycobacterium tuberculosis complex. Sidney Malama's doctoral research shows that Mycobacterium tuberculosis, which is the most prevalent tuberculosis bacterium in humans, also occurs in cattle in Namwala. In other words, this bacterium is zoonotic. Malama has detected a large degree of genetic variation amongst M. tuberculosis in humans in this area of Zambia and has also found that M. tuberculosis bacteria isolated from humans and cattle respectively are related. The fact that this bacterium is found in cattle means that these animals can be a reservoir for human tuberculosis and that humans can become infected with both M. bovis and M. tuberculosis by drinking unpasteurised milk and eating meat that has not been properly tested.

Malama used a standard 15 MIRU-VNTR loci-method for the genotyping of M. tuberculosis when he studied the epidemiology of M. tuberculosis in the Namwala district. However, this method has drawbacks when it comes to studying M. bovis in this area because some loci recommended by the European Reference Laboratory (EURL) for M. bovis are not suitable for genotyping the bacterium in Zambia.

Sidney Malama's research shows that cross infection of both M. tuberculosis and M. bovis occurs between humans and animals in this region. Finds of similar genotypes of M. tuberculosis in humans and cattle and of M. bovis in humans, cattle and Kafue lechwe in Namwala indicate that the same tuberculosis bacteria are circulating between humans and animals. Health authorities, wildlife managers and cattle owners must work together to stop zoonotic tuberculosis in Namwala and the bordering areas in Kafue. M. bovis has also been isolated from humans only suffering from tuberculosis of the lungs and this may suggest that the bacterium is transmitted between people and not just between cattle and humans.

Malama comes to the conclusion that zoonotic tuberculosis is a considerable threat to public health in Zambia and that a "One Health" approach adapted to local needs is required in order to control the spread of infection in the area.


Source :      2014/2/18 09:14

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