Ending TB is possible, and cost-effective

One in every three Nepalis carries the tuberculosis bacillus. There may be no active symptoms, but they can at any point progree into a full blown infection.

TB kills up to 47 Nepalis daily. If so many people died every day in road traffic accidents, it would make headlines every day. But they do not because tuberculosis afflicts the poorest people in the poorest parts of Nepal. 

The annual 17,000 fatalities from tuberculosis in Nepal are preventable with cost-effective treatment. A new pilot study in Chitwan and Piuthan in the past two years showed that 1,160 (out of 1,173 household contacts) completed the Tuberculin Skin Test (Mantoux Test) of whom 542 (45%) were positive. After doing a chest x-ray, 509 met the eligibility criteria for TB preventive therapy. 500 (97%) gave consent to the treatment. 

Researchers were pleasantly surprised. As in other countries in the region, they were expecting very few to agree to take preventive therapy medicines because they did not have TB symptoms, so a 95% agreeing to the treatment was exceptionally high.

“People in Chitwan and Piuthan who participated in the study were not sick, they were just carrying the TB bacteria, but they agreed to take the preventive drugs because they have all known of relatives who had died of TB,” explains Buddha Basnyat, a physician who advised the Birat Nepal Medical Trust (BNMT) that conducted the research.

BNMT is now extending the study to Nawalparasi and Rupandehi with the National Tuberculosis Control Centre. Latent TB is more prevalent in the Tarai districts because of their higher population density.

With Nepal suffering such an enormous disease burden from tuberculosis, one would have thought World TB Day on Sunday 25 March would have got more attention. But it was overshadowed by Holi celebrations. It would have been interesting to see how many in the crowds attending the concert at Darbar Marg would test positive.

Scientists worry that the World Health Organisation’s END TB strategy of reducing global tuberculosis incidence by 90% and deaths by 95% in the next ten years is too ambitious unless latent tuberculosis cases are also treated. 

What makes this failure all the more tragic is that tuberculosis is a completely preventable and treatable infection. Every $1 invested in TB gives a $39 return, yet there is little investment and advocacy to combat this biblical illness.

South Asia accounts for some 40% of all TB cases and 38% of all TB deaths — most of them occurring in the thickly-populated states across the Nepal border in India. The region also has a high burden of multi-drug resistant TB, one-third of global cases.

In the past, Directly Observed Therapy Short Course (DOTS) drug therapy in which patients were administered medicines at health posts was considered a cure-all for tuberculosis. Nepal had a high success rate for DOTS, but there were loopholes in the program: latent cases remained hidden and only the cases that came to the health system were treated.

DOTS also added to the pre-existing stigma so that patients travelling to the health posts would be identified as having tuberculosis. In one instance, a patient in Bardia chose to take a dangerous tiger-infested jungle route to reach the health post.  

Meanwhile, BNMT had been setting up a strong community network of health volunteers, and was tracking active TB cases. Unlike DOTS, it involved meeting family and friends of patients, allowing more case detection and treatment. Even so, they were not looking for latent infections.

Latent cases can progress to active tuberculosis especially when a patient's immune system is weak because of malnutrition, illnesses like HIV, or age. In fact, half of TB worldwide can be attributed to undernourishment.

Latent TB can be confirmed in two simple steps: a Mantoux test with an above 10 score and a clear chest x-ray. If positive, the patient is given the 3HP preventive therapy — a once-weekly treatment with isoniazid-rifapentine for 12 weeks. This treatment can prevent reinfection for as long as six years, and is not to be confused with the one for active cases which requires daily treatment for six months.

“On an individual level, you can still get reinfected if you are living in a house with active cases. But if you treat the community at large with preventive therapy, you drive down the prevalence of TB and in turn, people won't get reinfected,” explains Maxine Caws of BNMT.

She adds: “If we can use preventive therapy to push down the reservoirs of infection then we extend the amount of time people are protected as is the case in Europe for example where people don't get TB anymore because they are not exposed to the bacteria at all. We have to eradicate that reservoir.”

The traditional BCG vaccine given within 28 days of birth is effective against childhood tuberculous meningitis and miliary disease, but does not prevent TB in adults. Efforts are underway to develop a new effective vaccine but there are many challenges. 

TB vaccine development is difficult because exposure to the tuberculosis bacillus does not seem to induce sufficient protective immunity. A new viable vaccine could take a decade, but in that time 13 million more people would die. 

“We cannot wait and do nothing until a new effective vaccine is developed. Preventive therapy is a vaccine until we have one,” adds Basnyat. Indeed, the 3HP preventive therapy after diagnosis costs only $5 per regimen. So, Nepal’s strategy should be a simultaneous focus on 3HP preventive therapy and case finding. 

The problem has been a lack of priority for preventive therapy at national and international levels because it does not involve costly research and interventions, and the patients are poor.

Explains Caws: “On paper, we have very strong policies but the commitment in terms of funding from the governments has not materialised, essentially because it is not affecting the rich unlike with Covid when we threw everything at it to have a vaccine developed in a year.”

TB’s main problem, unlike Covid and HIV/AIDS is that it is a disease of the poor.