Isolation of Mycobacterium spp. from Milking Buffaloes and Cattle in Nepal

Abstract

ABSTRACT. In Nepal, mycobacterial isolates obtained from the milk and feces of buffaloes and cattle that were positive for the single intradermal cervical tuberculin (SICT) tests were genetically identified. A total of 36 mycobacterial strains were isolated from 39% of the buffaloes (14 of 36) and 34% of the cattle (11 of 32). Of the 36 strains, 13 were identified as M. bovis, and these strains were isolated from 17% of the buffaloes (6 of 36) and 16% of the cattle (5 of 32). M. bovis was isolated from both the milk and feces of one buffalo and one cattle, the milk alone of three buffaloes and three cattle, and the feces alone of two buffaloes and one cattle. These results suggest that milking buffaloes and cattle infected with M. bovis exist in Nepal. The remaining 23 strains were atypical mycobacteria. A program for the elimination of bovine tuberculosis should be implemented as soon as possible, and the public health education and proper hygienic practices may be required. KEY WORDS: buffalo, cattle, isolation, mycobacteria, Nepal.J. Vet. Med. Sci. 69(8): 819-825, 2007 In humans and animals, mycobacteria such as those belonging to the Mycobacterium tuberculosis complex (M. tuberculosis, M. bovis, M. africanum, M. canettii, and M. microti) cause serious diseases, and atypical mycobacteria cause opportunistic infections. Many species of mycobacteria have been identified and it has been suggested that many unknown atypical mycobacteria species exist [10,20,24]. In developing countries, M. tuberculosis is one of the most common causes of human tuberculosis. In humans, however, M. bovis infection exists and a large population of unknown causes may be attributable to M. bovis [2]. In addition, ruminant animals such as cattle and buffaloes are thought to be the reservoirs of M. bovis [2,3,5,9,18,19]. Previously, we had examined the results of the single intradermal cervical tuberculin (SICT) test was carried out by injection tuberculin into the skin of the neck of a large number of cattle and buffaloes in Nepal. We found that approximately 5% of these animals had a history of M. bovis infection, and that food products from these animals were being consumed daily in the country [21]. However, this study did not determine the M. bovis strain that was responsible for the infection.Recently, mycobacterial species were genetically identified by using rpoB gene analysis [10,11]. In addition, M. tuberculosis and M. bovis were identified by using the hypothetical protein "Rv1506c" [1]. In this study, we applied a genetic method such as sequence homology of the rpoB gene to the identification of the species of the isolates, and investigated the prevalence of mycobacteria in the milk and feces of SICT test-positive milking buffaloes and cattle. We also performed sequence and phylogenetic analyses of their rpoB gene. MATERIALS AND METHODS Samples:From September to October in 2003, we collected the milk and fecal samples from 36 buffaloes and 32 cattle that were SICT test-positive. The animals were selected from the Kathmand...

Perspectives on the History of Bovine TB and the Role of Tuberculin in Bovine TB Eradication

“…Some of the South American countries, many of which have had voluntary programmes for a number of years, are at this time considering implementation of national compulsory programmes. In other countries, particularly in the developing world, the issue is still being debated [38, 39]. Most Member States of the EU, having commenced bTB eradication programmes with a high disease incidence, are now recognised as officially TB free under the trading directive [72].…”

“…Francis quotes incidences of 0.5–19.5% in tuberculous cows and 5–31% in cows with generalized tuberculosis [35]. Analysis of milk in countries with no bTB eradication programme continues to show similar levels of M. bovis detection [38, 39]. Even in countries with a bTB eradication programme where unpasteurised milk is routinely fed to calves on farm, a high prevalence of infection within those calves will indicate the probable presence of one or more cows with M. bovis in milk and require appropriate follow-up epidemiological investigation [19].…”

Risk factors of bovine tuberculosis in cattle in rural livestock production systems of Ethiopia

“…A high prevalence of M. bovis was found in a recent abattoir survey in Chad in culture-positive mammary glands and in young tuberculin-positive animals (Müller B, personal communication). Jha et al (2007) isolated M. bovis in milk and faeces from milking buffaloes and cattle in Nepal. This indicates that transmission to young animals by milk should not be neglected.…”

Status of tuberculosis in bovine animals raised by tuberculosis infected patients in Western Chitwan, Nepal

“…Of the 36 strains isolated, 13 were identified as M. bovis. 13 In our study 24% of the tuberculosis patients had habit of raw milk consumption. Thus, it is possible for M. bovis infection to be transmitted to such people in study area and also in other part of Nepal via dairy product.…”