Leishmania donovani In Southwest of Sudan: Rapid assessment and Application of Geographic Information System

Abstract

Visceral leishmaniasis (VL) comprises a major health problem in several parts of the Sudan and it leads to severe morbidity and high mortality if uncontrolled. Western Upper Nile State and Southern Kordofan State were a scene of a huge outbreak that claimed hundreds of thousands of lives in the late eighties, which demonstrated the inability, and inadequacy of the health authorities, at that time, in dealing with such disasters that are more likely to occur from time to time. Control of VL is obstructing by the elusive nature of the vector and failure to identify a reservoir host. Case detection and treatment with antimonial drugs contribute to disease control. In this study we introduced the concept of rapid epidemiological assessment of patterns of L. donovani infection and visualized the data in a geographic information system (GIS) hoping to open new avenues into the question of VL control. Coupling this map with the map of vector distribution and climatic changes will provide valuable information that will help in disease control, despite our meagre health resources. This survey was based on simple in vivo and in vitro immunological techniques (leishmanin skin reactivity and the Direct Agglutination Tests), combined with clinical history to obtain data about the spectrum of L donovani infection in communities at risk of developing VL. The data was represented in map format to give an enhanced visual impact. Treatment and future control strategies can easily be formulated from such data. XI In this study clinical history and immunological tests were conducted on 1781 volunteers randomly selected from the mesairiya tribe who areliving in western Kordofan State. The mean age of the selected volunteers was 20.7 years with an equal male:female ratio. The overall leishmanin skin reactivity of ≥5 was 24.5%, where children below 15 years had higher (13.2%) leishmanin reactivity compared to 11.3% among adults above that age. The DAT results showed that 88% (1567/1781) of the study volunteers had DAT titres below the cut-off point of 3200, whereas 6% (112/1781) had a DAT titers = 3200, while the rest 5.7% (238/1781) had titres > 6400. DAT results were shown in Table (3.5) and Figure (3.7). Six L donvani and one L. major strains were in vitro tested in their amastigote forms against Pentostam and Amphotericin B using J774 murine macrophage-like cell line. The number of parasite in the infected cells decreased steadily at drug concentration 7.8μg/ml to 250μg/ml for Pentostam and 0.22μg/ml to 0.75μg/ml for Amphotericin B and the capacity of parasites to replicate inside the cells was also affected. In this system the parasite survival index (PSI) was similar for both tested drugs. L major showed the same response as other tested strains. Geographic information system (GIS) was applied in this study and the ArcGIS software was used to draw a map of the Sudan with different layers and themes. The maps included all the obtained information with coordinates of the studied area. In conclusion: the use of clinical interview combined with simple immunological tests can give valuable information about the pattern of L. donovani infection and predict future prevalence of VL in a short time. Leishmanin non-reactive individuals are a useful piece of data to plan for future vaccine efficacy studies. It is also clear that in vivo drug XII unresponsiveness does not correlate well with in vitro sensitivity for the same drugs. The interactive dynamic map that was produced in the ArcGIS can act as a nucleus for development of a Leishmania network in Sudan and the nearby countries that have the same belt of visceral leishmaniasis.