Prevalence and Factors Associated with Mycobacterium tuberculosis Transmission in Domestic Elephants and Human Contacts, Thailand, 2012 - การสำรวจความชุกของการติดเชื้อวัณโรค และปัจจัยที่ มีผลต่อการติดเชื้อในคนที่ใกล้ชิดกับช้างเลี้ยง ประเทศไทย ปี 2555

Abstract

We conducted a study in an elephant village in Surin Province to assess the prevalence of TB in elephant keepers
and their family members, to identify factors associated with TB infection and to recommend strategies for prevention and
control of disease transmission between humans and animals. The study methods included (1) a survey using structured
questionnaire to interview mahouts to collect data on history of illness and routine activities with their elephants; (2) a
laboratory-screening for TB included tuberculin skin test (TST) and chest radiography CXR). during 1 October – 2
November 2012. A laboratory-confirmed case was identified by sputum smear positive AFB and culture positive for M.
tuberculosis. This study used data on trunk-wash culture and serum antibody tests (Elephant TB STAT-PAK kit) for TB
in elephants which were conducted by Thailand Zoological Park Organization. It was found that among 291 elephant
keepers surveyed, 160 (60.2%) were positive reaction or TST e” 10 mm. We found 89 (30.6%) had abnormal CXR
and 26 (8.9%) met a suspected TB case definition, 3/19 (15.8%) few AFB-smear positive (only 1 cell) but no
confirmed TB case by culture-positive sputum. In crude and adjusted analysis, risk behaviors of mycobacterium infection
between elephant keepers and their elephants were not associated with detected TB disease. Of 190 elephants surveyed,
38 (20.0%) showed evidence of mycobacterium infection by rapid serological screening (STAT-PAK), no laboratory
confirmation for TB by trunk-wash culture. Three infected captive elephants died with undiagnosed cause after autopsy;
therefore TB as a cause of death could not be ruled out. Four clusters of TB-positive elephants were observed and the
elephants lived together in close proximity. In conclusion, high percentage of TST of M. tuberculosis infections was
detected among people who were in close contact with elephants. No significant associations between studied factors and
TB disease in the elephant keepers. Mycobacterium-infected elephants living closely with other elephants might increase
risk of TB transmission. Development of TB surveillance in the Elephant Village and proper management of TB in
elephants and associated humans was recommended.
Key words: Mycobacterium tuberculosis, elephant keeper, captive elephant, prevalence, Thailand