Neglected tropical diseases (NTDs) continue to pose a significant health burden on some of the most disadvantaged communities in India, according to an expert working on the spectrum of such conditions.

On World NTD Day observed on January 30 every year, Dr. Kavita Singh, Director, South Asia, Drugs for Neglected Diseases initiative (DNDi), said innovation in diagnostics, treatment, and prevention is needed to create solutions that are effective, relevant, locally feasible, and sustainable.

NTDs comprise 20 conditions that disproportionately affect one billion people in impoverished communities worldwide. Of these, lymphatic filariasis, kala-azar, and leprosy are of greatest concern in most tropical countries.

India has the world's largest absolute burden of at least 10 major NTDs, including hookworm, dengue, lymphatic filariasis, leprosy, visceral leishmaniasis or kala-azar and rabies.

"NTDs continue to pose significant health burdens on some of the most disadvantaged communities in India. In the country, over 670 million people are at risk of infection by Wuchereria bancrofti and Brugia malayi parasites in 272 districts which represent around 40 per cent of the global disease burden," Singh told PTI in an interview.

Both Wuchereria bancrofti and Brugia malayi are the major cause of lymphatic filariasis (LF) also known as elephantiasis, an NTD characterised by swelling of the lower limbs.

"Infection due to Wuchereria bancrofti is widespread in 21 States and Union Territories. India still has over 23 million people suffering from lifelong disability as a result of LF. The Government of India calls it a priority disease as it is in the focus of the government for elimination since 2002," she added.

It is difficult to estimate the actual burden of NTDs in India as there is no single organisation or government agency which has been given this mandate.

"Of the 12-13 NTDs existing in India only dengue, rabies, snakebite and leprosy are notifiable, therefore it is impossible to estimate the true burden," Singh explained.

"Some of the vector-borne diseases (mosquito and sandfly) have been targeted for elimination or prevention by the National Centre for Vector Borne Disease Control and Programme for Leprosy and Soil-Transmitted Helminths," she said.

Excluding NTDs that are spatially bound by their requirement for unique insect vectors -- such as schistosomiasis, human African trypanosomiasis, and Chagas disease -- India leads the world in terms of the total number of cases for each of the major NTDs, as defined by the World Health Organisation (WHO).

India, which has the largest population in south Asia, has been trying for two decades to eliminate these diseases. The country initially aimed for their elimination by 2015, then 2018, and then 2020. Post-pandemic the loose target is now 2030.

Earlier this month, the Union Health Minister reiterated India's commitment towards the target of eradicating lymphatic filariasis by the end of 2027.

"As per the latest publication, the delays in the elimination of NTDs have been because of poor community participation due to deep-rooted systemic mistrust issues that were not addressed in a timely manner, and low compliance. The programme has faced multiple implementation challenges at a higher level," Singh added.

"For example, LF elimination was not a major part of the national public health agenda for years, and few champions publicly voiced support for accelerating elimination efforts. Frequent leadership transitions and postponement of technical advisory committee meetings also contributed to delays," she added.

At the implementation level, Singh said, delays in scheduling mass drug administration rounds in endemic districts resulted in other management problems. These included delays in drug inventory projections, lack of availability of family registers for health staff, delays in the development of district micro plans, delays in training plans, and inaccurate counts of community members in urban and rural areas.

"Limited external partner support in funding and technical assistance to help the states and districts successfully implement MDA further contributed to implementation challenges and thus repeated pushback on elimination targets," Singh added.

Government interventions to treat neglected tropical diseases such as lymphatic filariasis and kala-azar were also cut back during 2020 and 2021 due to the COVID-19 pandemic.

According to the WHO, 44 per cent of 109 countries had seen disruptions to established interventions to manage NTDs, and 19 per cent reported severe disruption by early 2021.