Bangladesh eradicates kala-azar, India on track too but challenges remain

Dec 05,2023

New Delhi: Bangladesh recently achieved a major public health goal when it eradicated visceral leishmaniasis, commonly known as kala-azar, raising the question of when India would wipe out the debilitating, often fatal, parasitic disease - the fight very much on but far from complete. Challenges in sustaining the momentum of the fight persist, particularly in tackling post-disease symptoms and HIV co-infections, experts said as the 'LV spotlight' swivelled to India.

"Disease incidence has gone down to approximately 463 in 2023 from the previous 44,533 in 2014, a 99 per cent decrease in case numbers," said Shyam Sundar, programme director of the Kala-Azar Medical Research Centre in Bihar, one of the four states most affected by the disease.

"The spotlight is currently on India as we eagerly await its announcement," Kavita Singh, director, South Asia, Drug for Neglected Diseases Initiative (DNDi), told a news agency.

Visceral leishmaniasis (VL) is caused by protozoan parasites transmitted by the bite of an infected female phlebotomine sand fly. It is characterised by irregular bouts of fever, weight loss, enlargement of the spleen and liver, and anaemia. In over 95 per cent of cases, the disease is fatal if left untreated.

There are three main forms of leishmaniasis: visceral (the most serious form because it is almost always fatal without treatment), cutaneous (the most common, usually causing skin ulcers), and mucocutaneous (affecting mouth, nose and throat).

Globally, most cases occur in Brazil, east Africa and India. An estimated 50,000 to 90,000 new cases of VL occur worldwide annually, with only 25-45 per cent reported to WHO.

Confident that India is on course to eliminating the disease, experts emphasise that efforts and continued vigilance are essential to overcome the hurdles in the way of lasting victory.

And amongst the most formidable is post kala-azar dermal leishmaniasis (PKDL), which occurs in individuals who have apparently been cured of VL. Such patients develop skin lesions that are variable in location and intensity.

However, as they appear on the skin, the sand fly vector can comfortably sit on a skin lesion, take a juicy blood meal and thereafter bite uninfected individuals who will then develop VL, and so the vicious cycle will continue.

While the country looks on course to eliminate the disease, experts emphasise the importance of addressing PKDL in tandem with VL to sustain elimination.

"This is the cycle we need to interrupt by diagnosing and treating VL and PKDL and also insecticidal spraying in endemic areas. So PKDL cases are considered as the disease reservoir, and are strong disease transmitters," said Dr Mitali Chatterjee, professor of Pharmacology at Kolkata's Institute of Postgraduate Medical Education & Research (IPGMER).

She said the reservoir continued to expand because PKDL was initially not accorded the same priority as LV.

"However, now there is active surveillance for both VL and PKDL and the scenario in another two-three years will change dramatically for the better, as both PKDL and VL cases are being detected and treated. Also, there is very good vector management and the sand fly density will also see a decline," she added. 

Source: Healthworld