title: Serodiagnosis of tuberculosis in Asian elephants (Elephas maximus) in Southern India: a latent class analysis.
abstract: BACKGROUND
  Mycobacterium tuberculosis, a causative agent of chronic tuberculosis disease, is widespread among some animal species too. There is paucity of information on the distribution, prevalence and true disease status of tuberculosis in Asian elephants (Elephas maximus). The aim of this study was to estimate the sensitivity and specificity of serological tests to diagnose M. tuberculosis infection in captive elephants in southern India while simultaneously estimating sero-prevalence.
  
  
  RESULTS
  Health assessment of 600 elephants was carried out and their sera screened with a commercially available rapid serum test. Trunk wash culture of select rapid serum test positive animals yielded no animal positive for M. tuberculosis isolation. Under Indian field conditions where the true disease status is unknown, we used a latent class model to estimate the diagnostic characteristics of an existing (rapid serum test) and new (four in-house ELISA) tests. One hundred and seventy nine sera were randomly selected for screening in the five tests. Diagnostic sensitivities of the four ELISAs were 91.3-97.6% (95% Credible Interval (CI): 74.8-99.9) and diagnostic specificity were 89.6-98.5% (95% CI: 79.4-99.9) based on the model we assumed. We estimate that 53.6% (95% CI: 44.6-62.8) of the samples tested were free from infection with M. tuberculosis and 15.9% (97.5% CI: 9.8 - to 24.0) tested positive on all five tests.
  
  
  CONCLUSIONS
  Our results provide evidence for high prevalence of asymptomatic M. tuberculosis infection in Asian elephants in a captive Indian setting. Further validation of these tests would be important in formulating area-specific effective surveillance and control measures.
authors.affiliation: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India.
authors.forename: Shalu
authors.initials: S
authors.lastname: Verma-Kumar
authors.forename: David
authors.initials: D
authors.lastname: Abraham
authors.forename: Nandini
authors.initials: N
authors.lastname: Dendukuri
authors.forename: Jacob Varghese
authors.initials: JV
authors.lastname: Cheeran
authors.forename: Raman
authors.initials: R
authors.lastname: Sukumar
authors.forename: Kithiganahalli Narayanaswamy
authors.initials: KN
authors.lastname: Balaji
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D004606:Elephants / Q000276:immunology* / Q000382:microbiology*; D056724:Immunity, Humoral; D007194:India / Q000453:epidemiology; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies; D012698:Serologic Tests; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial