Genetic diversity of Leishmania donovani isolates from cutaneous lesions of military personnel in the Mullaitivu and Kilinochchi districts of the Northern Province, Sri Lanka

Objective: To compare the DNA sequences of Leishmania (L.)donovani isolated from individuals in two districts of the Northern Province with other parts of Sri Lanka and neighboring countries. Methods: Samples were collected from military personnel at the Army Hospital, Narahenpita, Sri Lanka from November 2018 to March 2020. A portion of the samples was fixed, stained with Giemsa and observed under the light microscope. The genomic The DNA was extracted from the remaining portion of the samples using DNEasy blood tissue kit (Qiagen, Germany) and amplified using Leishmania genus-specific primers for molecular diagnosis initially. DNA was amplified using L. donovani species-specific primers by PCR and the amplified product was sequenced for comparison of nucleotide sequences. Results: Out of 76 suspected patients, at least one biological sample of 45 (59.2%) was positive for L. amastigotes upon microscopy. Overall, 33 (43.4%) were positive in Leishmania genus-specific PCR, but only 23 (30.3%) were positive in L. donovani specific PCR. The dendrogram indicates that the current sequences clustered together with those from Nepal and Gampaha districts (Western Province), Sri Lanka, while the Indian and Eastern African sequences clustered separately. Conclusions: The genetic diversity was low among the isolates, indicating a single and possibly a local point of origin. However, the similarity of Sri Lankan and Nepal strains indicate a possibility of a shared point of origin, which needs more extensive evidence to confirm.

Scrub typhus: pathophysiology, clinical manifestations and prognosis

Scrub typhus is a zoonosis caused by the pathogen Orientia tsutsugamushi (O. tsutsugamushi). The disease has significant prevalence in eastern and Southeast Asia. Usually presenting as an acute febrile illness, the diagnosis is often missed because of similarities with other tropical febrile infections. Many unusual manifestations are present, and these are described in this review, together with an outline of current knowledge of pathophysiology. Awareness of these unusual clinical manifestations will help the clinician to arrive at an early diagnosis, resulting in early administration of appropriate antibiotics. Prognostic indicators for severe disease have not yet been clearly established.

Chemoprophylaxis in malaria: drugs, evidence of efficacy and costs

This review concentrates on different aspects of malaria chemoprophylaxis, namely drug combinations, resistance, impact of malaria prevention in pregnancy and cost effectiveness. A MEDLINE search was performed for all articles with the key word 'Malaria' in the title field and 'Prophylaxis' in any field. The search was restricted to articles published in English within the last decade (1999-2009). Data sources included review articles published in core clinical journals, cohort studies, interventional studies, case control studies and cross sectional analyses. The mechanism of action, trial evidence of efficacy, side effects and geographical distribution of resistance is discussed for each prophylactic drug regimen. Impact of prophylaxis in pregnancy and the cost considerations are discussed under two separate sub topics.