Leishmaniasis in Sri Lanka: atypical cutaneous disease by an unusual parasite species

Though clinical outcome of human leishmaniasis is multifactorial, it mainly depends on the causative species. Sri Lanka is now considered as a new focus of human cutaneous leishmaniasis.  Over 2500 cases have been investigated by us during past several years. Main clinical entity seen in the country is cutaneous leishmaniasis while it is caused by the usually visceralizing species L. donovani. Furthermore, the local L. donovani variant is genetically different from other members of L. donovani complex. Mismatch of a visceralizing parasite with a dermatological condition has led to several clinical and epidemiological concerns that need to be addressed without delay"

Visceralization or dissemination of primary skin infection and recurrence of treated lesions of L. donovani are dangerous possibilities. Clinical outcomes and treatment response patterns of the local parasite may be different from other known cutaneous variants of Leishmania parasites. Early case detection and management is the mainstay of L. donovani control as there are no known animal reservoirs. ln depth clinical and epidemiological characterization and scientifically defined treatment protocols that suit the local setting and availability of diagnostic services in the hospital settings are necessary in this regard. Few clinical trials carried out locally, under limited resources have shown encouraging results and need to be actively pursued. Phlebotomus argentipes, the vector of L. donovani is widely prevalent in the country. Regional differences in transmission characteristics and preliminary evidence showing a potential animal reservoir in Sri Lanka further complicate the decision making process in defining control strategies.

Parasite virulence is known to increase during an epidemic of leishmaniasis. Few cases of MCL and VL have already been reported locally. Preventive and control activities are required to be put in place urgently to minimize the spread of this potentially deadly species. Leishmaniasis was made a notifiable disease in Sri Lanka in 2008. Action plan for its control was drawn up in year 2008 with the involvement of all stake holders including the Ministry of health and the scientists in Universities. To achieve the defined objectives, a considerable amount of information is already available, and further research in all the fields is needed to fill in the essential gaps.