Abstract:
Responses to tuberculin in Zebu cattle of
the transhumant pastoral farming system in Karamoja
region and Nakasongola district in the north-eastern
and mid-central regions in Uganda, respectively, were
investigated using a comparative intradermal tuberculin
skin test. Of the 1864 cattle tested from 30 large
units (superherds) in Karamoja and 7 herds in Nakasongola,
a total of 28 animals from 19 herds (51.4%)
tested positive. Inter-district tuberculin reactor prevalence
variations seemed to be influenced by climate,
with impact on both the management patterns and transmissibility
of agent. High herd tuberculin reactor preva-lence (51.4%) was attributed to widespread contacts
and mixing of animals between herds. Low individual
animal tuberculin test positivity (mean=1.4%) was
attributed to low transmissibility of the agent under
the Karamoja climate, which is semi-arid, and to increased
resistance due to non-specific response to environmental
mycobacteria and natural selection, since
there was no active control against bovine tuberculosis.
Owing to similarities in management practices in
Karamoja and widespread risk factors, it was difficult
to identify which were more important, but variations
in sources of drinking water pointed to provision of
lake and borehole water during dry season as reducing
the risk. Positive bovine tuberculin reactor prevalence
and skin reactor status were related to age.
