10.1 Diagnosis by clinical signs

discharge. Affected animals generally remain bright and alert and maintain a good appetite despite weakness and sluggishness [57]. Acute or subacute death may result from military tuberculosis, caused by rapid widespread dissemination, from pri-

Zoonotic tuberculosis in cattle is a public health concern worldwide. The preva-

Tuberculosis in cattle can be diagnosed in live animals and also during postmortem examination of dead or slaughtered carcasses. In live animals, clinical signs, tuberculin skin test, and gamma interferon assay can be used. At postmortem, pathological lesions and acid fast staining are preliminary tests while culture and

Raptured lesion (arrowed) in the left retropharyngeal lymph node of a tuberculosis patient infected by M.

lence is estimated at 0.5–1% in developed countries and 10–15% in developing countries [58]. In developing world, high levels of human immunodeficiency virus (HIV) and poverty, especially in Sub-Saharan countries, are contributing factors. Consumption of raw or undercooked products, and especially milk, from infected cattle is the main cause of nonpulmonary tuberculosis [59]. M. bovis is excreted in milk of about 1–2% of infected cattle in large numbers such that a single infected cow can contaminate bulk milk by 100 cows to cause infection in susceptible humans [60]. Social-cultural factors, for instance, the tradition by pastoral communities to consume raw blood and milk and raw or undercooked meat and meat products, are risk factors [1]. It is estimated that in Africa, 90% of milk is consumed either raw or fermented, thus increasing the risk of transmission [61]. Cervical lymphadenitis is the commonest manifestation of oral infection (Figure 3). Inhalation of infected dust particles or aerosols shed by infected cattle is the second important route especially in rural pastoralist communities. Abattoir workers, farmers, milkers, veterinarians, and animal handlers are also exposed to this mode of transmission [58, 62]. Infection in wildlife puts hunters, trappers, and zoo workers at risk. Trans-cutaneous transmission may occur through handling of

mary or secondary lesions through the hematogenous route.

9. Public health importance

Bacterial Cattle Diseases

infected carcasses [47].

10. Diagnosis

bovis. ©2018 JKN Kuria.

Figure 3.

72

DNA analysis are confirmatory.

Clinical diagnosis may be difficult due to the chronic nature of the disease and the wide variety of symptoms, resembling other chronic debilitating conditions. The disease should be suspected on the basis of history coupled with signs of progressive emaciation, in spite of good appetite, fluctuating temperature, chronic, and moist cough dysphagia and noisy breathing. Enlargement of supramammary lymph nodes may be observed. Differential diagnosis includes contagious bovine pleuropneumonia, pasteurellosis Trueperella pyogenes pneumonia, bovine lymphosarcoma, traumatic pericarditis, and fascioliasis [63]. Animals suspected of tuberculosis infection should be thoroughly examined by palpation of all superficial lymph nodes, the udder in females and percussion and auscultation of the pulmonary area.
