Mycobacterium bovis detection from milk of negative skin test cows
- 1Departamento de morfofisiologia veterinária, Centro de ciências agrárias, Universidade Federal do Piauí, Campus Socopo, Brasil
- 2Laboratório de Bacteriologiaveterinária, Departamento de microbiologia e parasitologia, UniversidadeFederal Fluminense, Niterói, Brasil
- 3Laboratório de análises bacteriológicas de alimentos, Universidade Federal do Mato Grosso, Cuiabá, Brasil
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Mycobacterium bovis is the bovine tuberculosis (bTB) agent, which is still an important infection in bovine herds. Apart from this, bTB is also a zoonotic disease, and human beings can be infected by the consumption of non-pasteurised milk and its derivatives (Michel and others 2010). Hence, bTB is still endemic worldwide (Humblet and others 2009).
The single intradermal test (SIT) is a worldwide diagnosis test, which is known to lack from both sensitivity and specificity (de la Rua-Domenech and others 2006). In order to augment the specificity of this test, a single intradermal comparative cervical tuberculin (SICCT) test is often recommended for animals with inconclusive results at an SIT (Medeiros and others 2010). Although the SICCT test represents an advance in terms of increase in specificity, few advances were made in order to augment the sensitivity of intradermal tests, referred to be 80–93 per cent (de la Rua-Domenech and others 2006). Another important limitation of the intradermal tuberculin test (ITT) refers to anergy, when animals in late stages of the disease present undetectable cellular immune response and are consequently false-negative to the intradermal tests (Medeiros and others 2010).
Even during an outbreak, once a cow is classified as negative by ITT, there is no recommendation for additional tests. Since ITT-negative animals are not slaughtered, additional investigation of these cows may be impaired by the difficulty in obtaining samples from live animals. Nevertheless, that assumption would …