Emergence of visceral leishmaniasis in Sri Lanka: a newly established health threat

Background: Sri Lanka is a new focus of human cutaneous leishmaniasis caused by a genetic variant of usually visceralizing parasite Leishmania donovani. Over 3000 cases have been reported to our institution alone, during the past two decades. Recent emergence of visceral leishmaniasis is of concern. Methods: Patients suspected of having visceral leishmaniasis (n = 120) fulfilling at least two of six criteria (fever > 2 weeks, weight loss, tiredness affecting daily functions, splenomegaly, hepatomegaly and anemia) were studied using clinic-epidemiological, immunological and haematological parameters. Seven cases (four progressive, treated (group A) and 3 non-progressive, potentially asymptomatic and observed (group B) were identified. Clinical cases were treated with systemic sodium stibogluconate or amphotericin B and all were followed up at the leishmaniasis clinic of University of Colombo for 3 years with one case followed up for 9 years. Results: All treated cases responded well to anti leishmanial treatment. Relapses were not noticed. Clinical features subsided in all non-progressive cases and did not develop suggestive clinical features or change of laboratory parameters. Visceral leishmaniasis cases have been originated from different districts within the country. Majority had a travel history to identified local foci of cutaneous leishmaniasis. Conclusion: Visceral leishmaniasis is recognized as an emerging health threat in Sri Lanka. At least a proportion of locally identified strains of L. donovani possess the ability to visceralize. Apparent anti leishmanial sensitivity is encouraging. Timely efforts in disease containment will be important in which accurate understanding of transmission characteristics, increased professional and community awareness, improved diagnostics and availability of appropriate treatment regimens.