For Nepal, a game-changer in TB control

Tuberculosis killed 33 million people worldwide between 2000-2015, more than the entire population of Nepal. The infection still kills three people every minute all over the world, and 11 Nepalis a day. This perfectly curable medieval disease is the biggest infectious killer in the world today, more than HIV or malaria. In sharp contrast, Ebola, which receives far more media coverage, killed only four people in 2017.

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World Tuberculosis Day on 24 March is an opportunity for governments to renew efforts to control this devastating disease. More than 40% of the world’s TB cases occur in South Asia. While much research and funding focuses on HIV-associated TB and multi-drug resistant (MDR) TB in sub-Saharan Africa, HIV infected individuals make up only 9% of global TB cases and less than 1% had MDR TB in 2017. Despite a huge sample size, there is a lack of research on TB in South Asia, particularly India, and on cases not associated with HIV. If nothing is done, TB will cost another 28 million lives in the next 10 years.

These shocking figures may seem like numbing statistics, but at an emotional level in Nepal, we all know people, including many family members, who have suffered and died of TB. Many readers also may have suffered from TB, and fortunately have been cured. Tuberculosis is so rampant in South Asia that every working day, clinicians struggle with the question in any random patient: Is this TB? This is in sharp contrast to the western world where TB is essentially a biblical disease.

While Nepal is a role model in the community-based DOTS (directly observed treatment short course) treatment, which ensures index patients are taking their medicines, this alone will not suffice in the battle against TB, since a patient would often have already infected others in the household and workplace. Which is why active case finding and early treatment is the key. But tragically there is massive under-reporting -- Nepal gets over 40,000 new cases of TB a year with over 4,000 deaths, but many do not get diagnosis and treatment due to lack of resources for TB control.

The first ever prevalence survey for TB in Nepal is currently underway, and preliminary findings show a substantial increase in the estimate of total TB cases in the country. This would be consistent with the results of other prevalence surveys in the region, which have all demonstrated that the burden of TB has been substantially underestimated in South Asia. For example, evaluation of data from multiple sources in India showed an increase of more than 80% in the estimated incident TB cases from 1.6 million to 2.9 million in 2014. Although better than DOTS, just active case finding and treatment will not be enough to bring TB under control.

This is where George Comstock’s work becomes relevant in Nepal and South Asia. In the 1950-60s this epidemiologist worked with the largely Inuit population in the town of Bethel in Alaska. He determined that, although patients and their household contacts were being treated properly, the rates of TB in the community was not declining as predicted. He felt that unless latent TB infection was treated, the TB organism ‘pool’ would continue to perpetuate the disease. Many people who are exposed to the tuberculosis organism will just have an infection, that is latent TB, without any symptoms.

Comstock started treating latent TB infections with one drug (isoniazid) which, sure enough, brought down TB cases in Bethel. Since then, multiple studies all over the world have shown that treating latent TB infection this way helps substantially decrease the TB pool in the community and make a resounding impact in the control of TB. Indeed, this is how TB has been nearly removed from many poor communities in the West. For many reasons, including financial and perceived concerns of isoniazid’s liver toxicity, Comstock’s game plan has never been taken seriously in South Asia. It is time we change this and replicated the strategy.

In 2018, the World Health Organization (WHO) emphasised treatment of latent TB in high incidence countries. This will be a game-changer in Nepal, besides the highly efficient Gene Xpert machine used for active case finding. By decreasing the pool of tuberculosis patients, we have a chance to meet the lofty WHO END TB strategy of reducing global incidence by 90% and deaths from TB by 95% by 2035. But even these targets only represent a reduction in TB to the levels seen in developed western nations today, not elimination.

These targets are not achievable unless there is a dramatic escalation in TB control efforts and a significant paradigm shift in our approach. To attain the target, the annual decline in global TB incidence rates must accelerate from 2% per year in 2015 to approximately 17%  per year by 2025. This requires the deployment of George Comstock’s strategy to act now, and to observe this year’s TB Day slogan ‘It is time for action’.

Buddha Basnyat is a physician at Patan Hospital and Max Caws is with the Britain Nepal Medical Trust in Kathmandu.