Feature Vector borne disease

# India’s ambition to eliminate visceral leishmaniasis

BMJ 2014; 349 (Published 07 November 2014) Cite this as: BMJ 2014;349:g6671
1. Talha Burki, journalist, London
1. talhakburki{at}gmail.com

With the introduction of a new drug, can the new government keep its promise to rid India of kala azar? Talha Burki reports

## Outstanding questions

Crucial scientific questions remain unanswered, Jorge Alvar, former head of WHO’s leishmaniasis programme and now at DNDi, told The BMJ. Foremost of these is the role that post kala azar dermal leishmaniasis (PKDL) plays in transmission of kala azar. Some 5% to 10% of patients are thought to develop PKDL in the form of skin lesions within a year or so of treatment for kala azar. Just how infective these lesions are has yet to be established. But these patients could conceivably form a reservoir from which the disease could resurge.

“There is no clear position on how to treat PKDL—there have not been any proper clinical trials,” said Alvar. Moreover, the lesions often do not bother the patient, raising ethical questions over the necessity for treatment.

Coinfection with HIV is a small but growing problem; such patients are highly infectious for visceral leishmaniasis and particularly difficult to treat.

Finally, there are asymptomatic patients who harbour infection—estimated to be somewhere between 10% and 30% of the population in endemic regions. Just how infectious are these individuals? Were they the reservoirs of infection that caused the sharp resurgence of kala azar in the 1970s, after the campaigns of indoor residual spraying ended?

Despite these unknowns, the fact that experts such as Alvar are turning their attention to such questions is testament to the progress of the past decade or so, which has seen the World Health Assembly issue its first resolution on visceral leishmaniasis; enormous advances in treatment; and estimates of disease burden established.

India will attain its elimination target sometime in the foreseeable future—though probably not by the end of 2015—but for now at least a neglected tropical disease is receiving welcome attention.

#### A history of kala azar in India

Through the ages, there have been dozens of different terms for visceral leishmaniasis. Dum-dum fever and Burdwan fever were named after Indian localities in which the disease was endemic. Cachexial fever referenced its characteristic wasting symptoms, and non-malarial remittent fever hinted at the mystery that surrounded the sickness.

One name, however, has stuck—kala azar. It is commonly taken to mean “black fever” in Hindi, so called because some patients experience a darkening of the skin. But kala has another meaning—deadly—as the British Army medical officer Ronald Ross suggested in 1899.6

The nature of visceral leishmaniasis certainly justifies the appellation: without treatment, the mortality rate is nearly 100%, and treatment did not arrive until the 1920s. By that time, the parasite responsible for transmitting the disease in India had been identified (Leishmania donovani) and a consensus was emerging that the sandfly was the vector.

## Notes

Cite this as: BMJ 2014;349:g6671

## Footnotes

• Competing interests: I have read and understood the BMJ policy on declaration of interests and have no relevant interests to declare.

• Provenance and peer review: Commissioned; not externally peer reviewed.

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