Abstract
Tuberculosis (TB) is endemic among humans in Nepal. Almost 50% of the >28 million population are infected and up to 90,000 are active cases (http://www.who-int/inf-new/tuber4.htm) (VIN editor: Link not accessible 1/5/21). Direct observed therapy short-course (DOTS) was instituted in 1996 and now reaches 75% of the population. Implementation of DOTS nation-wide is hampered by the logistics of reaching and servicing remote hill areas. Between 5,000 and 7,000 people die every year despite DOTS therapy; some of these deaths may be due to multidrug-resistant (MDR) or extensively drug-resistant (XDR) TB. Four drug resistance surveys have been carried out since 2005. MDR-TB rates of 2.9% (1.8–3.2%) among new cases and 11.7% (7.1–18.3%) among re-treatment cases were reported at the end of the fourth survey (http://www.searo.who.int/en/Section10/Section2097/Section2100_14801.htm).
Nepal has a mixed farming system, including over four million buffaloes and almost seven million cattle. Sporadic studies have identified a TB prevalence of 0–24% among cattle and 4.5 to 41% among buffalo. In a recent study Mycobacterium bovis (M. bovis) was isolated from 17% of buffalo and 16% of cattle positive on the single intradermal cervical test.1 There is no formal TB surveillance or control program for cattle or buffalo in Nepal. Although the World Health Organization recommends test and slaughter to eliminate bovine TB, Nepal is predominantly Hindu and the slaughter of cattle is forbidden.
The prevalence of M. bovis (BTB) infection in humans is unknown as TB diagnostic laboratories in Nepal (as in many countries) report positive culture results as “M. tuberculosis complex” but do not speciate. Risks of TB/BTB transmission from livestock to people exist through direct contact by farmers and slaughterhouse workers and consumption of contaminated meat and unpasteurized milk. Buffalo meat comprises over 64% of the total meat consumed in Nepal. In one study, tuberculosis was diagnosed in 14% of slaughtered buffaloes.2 Intensive livestock production is rare, and human beings live in close association with their farm animals providing increased opportunities for exposure.
Captive elephants in Nepal are cared for by humans, bred by wild elephant bulls, and graze with domestic livestock. Government-owned elephants patrol the Chitwan National Park (and other protected areas) and are essential for rhino counts and other conservation programs. Privately-owned elephants used for safaris in the parks generate tourist dollars that support conservation and local businesses.
TB has not yet been diagnosed in wild elephants, rhinos, or other wild mammals in Nepal but poses a significant threat. Controlling TB at the captive elephant interface may decrease transmission to the wild where it would be difficult if not impossible to control.
An elephant TB surveillance program was initiated in Nepal in 2006 following the postmortem diagnosis of TB in several captive elephants. To date, 164 captive elephants (79% of the population) have been tested using the ElephantTB STAT-PAK Assay® (Chembio Diagnostic Systems, Inc., 3661 Horseblock Road, Medford, NY 11763, USA). Nineteen elephants are receiving treatment for TB; one elephant has completed treatment, and one old elephant is under permanent quarantine. Culture-confirmation of TB infection has been unrewarding due to 1) difficulty in performing the trunk wash procedure, 2) sample contamination, and 3) limited laboratory capacity to process elephant samples. Investigation of alternative direct methods for diagnosis are being pursued.3 TB has not been detected in currently employed elephant caretakers tested by the public health system.
Tuberculosis will be a main focus of the newly established One Health-Nepal, spearheaded by the National Trust for Nature Conservation (a Nepal NGO) and the Zoological Society of London. Elephant Care International, the Cummings School of Veterinary Medicine at Tufts University, and the Institute of Agriculture and Animal Science are among the organizations that will collaborate to address cross-species TB issues in Nepal.
Acknowledgments
The authors gratefully acknowledge the support of the Department of National Parks and Wildlife Conservation, Government of Nepal, and the following partners: National Trust for Nature Conservation, WWF-Nepal, and the Zoological Society of London.
Literature Cited
1. Chandra, V., Y. Morita, M. Dhakal, B. Besnet, T. Sato, A. Nagai, M. Kato, K. Kozawa, S. Yamamoto, and H. Kimura. 2007. Isolation of Mycobacterium spp. from milking buffaloes and cattle in Nepal. J. Vet. Med. Sci. 69(8):819–825.
2. Joshi, D.D. 1986. Epidemiological situation of tuberculosis in Nepal. J. Inst. Med. 5:115–128.
3. Wilson, T., D. Akiyoshi, S. Desai, M. Bhandar, S. Paudel, P. Manandhar, S. Manandhar, S. Mikota, J. Mukherjee, and G. Kaufman. 2008. Development of a PCR diagnostic technique for differentiation of Mycobacterium species in elephant trunk wash samples in Nepal. Poster AAZV Annual Conference, Los Angeles, October 12–17, 2008.