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 India, Nepal, Bangladesh and Sudan. In India, it is a serious problem in Bihar, West Bengal and eastern Uttar 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% mortality, which with treatment reduces to 15% and is 3.4% even in specialized 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 raises the possibility of a new vector or a variant of the disease. The widespread co-existence of
malaria and
kala-azar in Bihar may lead to a difficulty in diagnosis and inappropriate treatment. In addition, reports of the organism developing resistance to
sodium antimony gluconate--the main
drug for treatment--would make its eradication difficult. Clinical trials in India have reported encouraging results with
amphotericin B (recommended as a third-line
drug by the National
Malaria Eradication Programme). Phase III Trials with a first-generation
vaccine (killed Leishmania organism mixed with a low concentration of BCG as an adjuvant) have also yielded promising results. Preliminary studies using autoclaved Leishmania major mixed with BCG have been successful in preventing
infection with Leishmania donovani. Until a safe and effective
vaccine is developed, a combination of sandfly control, detection and treatment of patients and prevention of drug resistance is the best approach for controlling
kala-azar.