Tuberculosis serosurveillance and management practices of captive African elephants (Loxodonta africana) in the Kavango-Zambezi Transfrontier Conservation Area

Abstract

Transfrontier conservation areas represent an international effort to encourage conservation and sustainable development. Their success faces a number of challenges, including disease management in wildlife, livestock and humans. Tuberculosis (TB) affects humans and a multitude of non-human animal species and is of particular concern in sub-Saharan Africa. The Kavango-Zambezi Transfrontier Conservation Area encompasses five countries, including Zimbabwe, and is home to the largest contiguous population of free-ranging elephants in Africa. Elephants are known to be susceptible to TB; thus, understanding TB status, exposure and transmission risks to and from elephants in this area is of interest for both conservation and human health. To assess risk factors for TB seroprevalence, a questionnaire was used to collect data regarding elephant management at four ecotourism facilities offering elephant-back tourist rides in the Victoria Falls area of Zimbabwe. Thirty-five working African elephants were screened for Mycobacterium tuberculosis complex antibodies using the ElephantTB Stat-Pak and the DPP VetTB Assay for elephants. Six of 35 elephants (17.1%) were seropositive. The risk factor most important for seropositive status was time in captivity. This is the first study to assess TB seroprevalence and risk factors in working African elephants in their home range. Our findings will provide a foundation to develop guidelines to protect the health of captive and free-ranging elephants in the southern African context, as well as elephant handlers through simple interventions. Minimizing exposure through shared feed with other wildlife, routine TB testing of elephant handlers and regular serological screening of elephants are recommended as preventive measures.

Understanding Mycobacterium tuberculosis complex in elephants through a One Health approach: a systematic review

“…The seroprevalence of TB in elephants varied from 0 to 23.33%, however, there is a variation of seroprevalence between wild and captive elephants, African and Asian elephants. The TB seroprevalence among captive Asian elephant’s ranges from 15.2 to 23.33% [ 32 – 36 ]), while in captive African elephants is approximately 17% [ 10 ]). The point prevalence of M. tuberculosis infection in Asian elephants was 5.1% for the time period of 1997 to 2011, while it remained 0 in African Elephants for the same time period [ 37 ].…”

“… Malaysia Asian elephant Captive 23.30% Univariate analysis showed that elephants with assigned mahouts have significantly higher risk of TB OR = 3.8 The risk of seroconversion was significantly higher among elephants with assigned mahouts [OR = 4.9] 10 Magnuson et al (2017) [ 41 ] Clinical research Culture and Molecular Culture, PCR USA Asian elephant Captive 8.40% Molecular test results can be used to support current diagnostic procedures applied by veterinarians for treatment decisions to prevent the spread of tuberculosis in elephants. 11 Rosen et al (2018) [ 10 ] Cross sectional study Serology Elephant TB Stat-Pak and DPP VetTB Assay Zimbabwe African elephant Captive 17.10% Strong correlations were noted between contact with wild elephants and facilities ( p = 0.86) 12 Jeewan et al (2021) [ 35 ] Cross sectional study Serology Elephant TB Stat-Pak Nepal Asian elephant Captive 21.56% The occurrence of TB seropositive cases in other more remote national parks suggest TB may be wide spread among the captive elephant population of Nepal PCR Polymerase chain reaction, ELISA Enzyme-linked immunosorbent assay, TB Tuberculosis …”

“…Studies of TB in captive elephants from Thailand, Malaysia, Switzerland, USA, Nepal, India, and some African countries revealed possible transmission of M. tuberculosis between elephants and humans [ 1 , 10 , 12 , 20 , 34 , 38 ]. One of the studies carried out in Southern India among wild elephants indicated that TB might be spilling over from humans (reverse zoonosis) and emerging in wild elephants [ 16 ].…”

“… 7 Feldman et al (2013) [ 37 ] Asian and African elephant Captive USA The difference in species susceptibility Mandatory annual tuberculosis screening for all the elephants. 8 Rosen et al (2018) [ 10 ] African elephant Captive Zimbabwe Source of infection is unclear Routine TB testing of elephant handlers and regular serological screening of elephants are recommended as preventive measures. 9 Michalak et al (1998) [ 1 ] Asian and African elephants Free-ranging USA Between human and elephant Veterinary practices should be initiated to reduce the risks of exposure to animals infected with MTB.…”

“…Among the Asian countries, India has the greatest number of elephants and the highest number of human TB cases [ 9 ]. Among the African nations, Botswana has the greatest number of wild elephants and South Africa has the highest number of human TB cases [ 10 ]. Countries that have a high prevalence of TB in humans such as Nepal and Thailand also have TB in elephants [ 11 , 12 ].…”