Responses to tuberculin among Zebu cattle in the transhumance regions of Karamoja and Nakasongola district of Uganda

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 prevalence (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.

Prevalence of bovine tuberculosis in cattle in the highlands of Cameroon based on the detection of lesions in slaughtered cattle and tuberculin skin tests of live cattle

“…However, and Oloya et al (2006) suggested that sex was a weak risk factor similarly to this study where non-significantly more female than male animals were affected. The chronic nature of bovine TB, low transmissibility of the disease in an extensive/ transhumance system and delayed onset of tuberculin positive response in adult and old animals has been attributed to the long incubation period of the disease, pre-allergenic status, and acquired and maternal immunity (Kazwala et al 2001b;Oloya et al 2006). These factors were also noted as important risk factors in this study.…”

“…In this study, animal environments were generally humid or wet and favourable for long survival of TB agents (Goodchild and CliftonHadley 2001;Philips et al 2003). However, contradictory results of lower bovine TB prevalence in cattle maintained in traditional pastoral systems in Uganda and Ethiopia were associated with the relatively dryer conditions of the environments (Oloya et al 2006;Ameni et al 2007;Inangolet et al 2008). Traditional pastoral systems in the tropics that create risks characteristic of intensive farming in relation to the transmission of bovine TB have been well documented (O'Reilly and Daborn 1995;Omer et al 2001;Ayele et al 2004).…”

“…This finding is in agreement with Inangolet et al (2008), who suggested high levels of infectiousness of bovine TB under the common cattle management practices and humid tropical conditions. However, inefficient close contact between diseased and healthy animals in extensive systems, dairy herds and large herds, and possibly a decrease in virulence and transmission capacity of the causal strains due to adverse weather (Oloya et al 2006), and low infectiousness of the local zebu cattle (Ameni et al 2006(Ameni et al , 2007Inangolet et al 2008), were also characteristics in the study environments. A better resistance or adapted tolerance to bovine TB infection of some local breeds have been suggested (O'Reilly and Daborn 1995;Ameni et al 2008), and could have been the reasons for the lower prevalence rates recorded among the Namchi, Guadali and White Fulani compared to the Red Mbororo cattle.…”

“…For both tests, the disease was more severe in the Western highlands compared to the Adamawa plateaux; age was a more significant risk factor than sex, and upgraded / exotic and Red Mbororo cattle showed the highest prevalence rates. Age and sex (Ameni et al , 2007Oloya et al 2006;Inangolet et al 2008), herd size and body condition , husbandry system and breed (Ameni et al 2006(Ameni et al , 2007, have been extensively reported as important risk factors influencing individual bovine TB prevalence rates. However, and Oloya et al (2006) suggested that sex was a weak risk factor similarly to this study where non-significantly more female than male animals were affected.…”

“…Age and sex (Ameni et al , 2007Oloya et al 2006;Inangolet et al 2008), herd size and body condition , husbandry system and breed (Ameni et al 2006(Ameni et al , 2007, have been extensively reported as important risk factors influencing individual bovine TB prevalence rates. However, and Oloya et al (2006) suggested that sex was a weak risk factor similarly to this study where non-significantly more female than male animals were affected. The chronic nature of bovine TB, low transmissibility of the disease in an extensive/ transhumance system and delayed onset of tuberculin positive response in adult and old animals has been attributed to the long incubation period of the disease, pre-allergenic status, and acquired and maternal immunity (Kazwala et al 2001b;Oloya et al 2006).…”