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Why Is It a Problem?

Image by Ian Macharia
Fresh Cow Milk
Image by Rachel Lees

In 2018, WHO estimated that there were 143,000 new cases of ZTB in people and 12,300 deaths due to the disease. However, estimates of the global burden of zoonotic TB are imprecise. This is due to the lack of routine surveillance data from human and animal populations from most countries – in particular, countries where bovine TB is endemic and where laboratory capacity is limited. Cases of ZTB in people are uncommon in countries where bovine TB in cattle is controlled and where standards of food

safety are high.*


The implications of ZTB extend beyond human health. During 2017 to 2018, 188 countries and territories reported their status with regards to bovine TB to the World Organisation for Animal Health (WOAH). Of these, more than half reported the presence of the disease in livestock and/or wildlife, demonstrating its wide geographical spread. Bovine TB threatens the well-being of communities that rely on livestock for their livelihoods. The disease has an important economic impact through reduced meat and milk production, as well as condemnation of carcasses or affected parts that are unfit for human consumption. Bovine TB also creates barriers to the international trade of animals and animal products. When it becomes endemic in wildlife populations, this threatens conservation efforts and can serve as a reservoir of infection for livestock and people.


ZTB also poses challenges for effective antimicrobial treatment and recovery. M. bovis is naturally resistant to pyrazinamide, one of the four essential medications used in the current standard first-line anti-TB treatment regimen. As most healthcare providers initiate treatment without drug susceptibility testing results, people affected by ZTB may receive inadequate treatment. This may lead to poorer treatment outcomes and the development of further resistance to other anti-TB drugs. Resistance to additional drugs has also been detected in some M. bovis isolates, including rifampicin and isoniazid. Resistance to these two essential first-line medications is defined as multidrug-resistant TB (MDR-TB), which poses a major threat to human health globally. **

*   Global Tuberculosis Report 2019, World Health Organization (WHO), 2019

**  Roadmap for Zoonotic Tuberculosis, World Health Organization (WHO), Food and Agriculture Organization of the United Nations (FAO) and World Organisation for Animal Health (OIE), 2017

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