Epidemiology of visceral leishmaniasis in India

Kala-azar has re-emerged from near eradication. The annual estimate for the incidence and prevalence of 'kala-azar cases worldwide is 0.5 million and 2.5 million, respectively. Of these, 90% of the confirmed cases occur in In dia, Nepal, Bangladesh and Sudan. In India, it is a serious problem in Biha r, West Bengal and eastern Utter Pradesh where there is under-reporting of kala-azar and post kala-azar dermal leishmaniasis In women and children 0-9 years of age. Untreated cases of kala-azar are associated with up to 90% m ortality, which with treatment reduces to 15% and is 3.4% even in specializ ed hospitals. It is also associated with up to 20% subclinical infection. Spraying of DDT helped control kala-azar; however, there are reports of the vector Phlebotomus argentipes developing resistance, Also lymphadenopathy, a major presenting feature in India mises the possibility of a new vector or a variant of the disease. The widespread co-existence of malaria and kal a-azar in Bihar may lead to a difficulty in diagnosis and inappropriate tre atment, In addition, reports of the organism developing resistance to sodiu m antimony gluconate-the main drug for treatment-would make its eradication difficult. Clinical trials in India have reported encouraging results with amphoterici n B (recommended as a third-line drug by the National Malaria Eradication P rogramme). Phase III Trials with a first-generation vaccine (killed Leishma nia organism mixed with a low concentration of BCC as an adjuvant) have als o yielded promising results. Preliminary studies using autoclaved Leishmani a major mixed with BCG have been successful In preventing infection with Le ishmania donovani. Until a safe and effective vaccine is developed, a combi nation of sandfly control, detection and treatment of patients and preventi on of drug drug resistance is the best approach for controlling kala-azar.