To permit improvements in the targeting of control activities, the geographical distribution of lymphatic filariasis in Uganda was assessed by using a rapid immunochromatographic card test to check school-aged children for Wuchereria bancrofti-specific circulating filarial antigens (CFA). Survey sites were selected to represent the various ecological and topographical diversities in the country. Overall, 17,533 children from 76 sites were examined. CFA-positive cases were detected at 31 of the sites, with prevalences ranging from 0.4% to 30.7%. There appeared to be strikingly more lymphatic filariasis in the north of the country than in the south. The main focus was north of the Victoria Nile, where 27 (66%) of 41 sites had CFA-positive cases, often at high prevalences. Only four (11.4%) of the 35 sites south of the Victoria Nile had CFA-positive cases, and all four were along the western rift valley and had relatively low CFA prevalences. Geostatistical interpolation was used to create a map showing the geographical distribution of CFA prevalences in Uganda (by ordinary kriging), and to assess the population exposed to W. bancrofti transmission. Estimates based on population data from 2002 indicated that approximately 8.7 million people (35.3% of the national population) lived in areas where > 1% of the school-aged children were CFA-positive. CFA prevalences generally decreased with increasing altitude, and no CFA-positive cases were found at sites that were > 1300 m above sea level. Although it gives an under-estimate of the overall community prevalence (a fact that should be taken into account when interpreting the present results and comparing them with the results of other surveys), the screening of schoolchildren for CFA was found to be a simple and useful approach for mapping the geographical distribution of lymphatic filariasis.

The geographical distribution of Mansonella perstans infections in Uganda was assessed by day-time examination of school-aged children for microfilariae. Overall, 12,207 children from 76 sites representing the various topographical and ecological zones in the country were examined. Children with M. perstans microfilaraemia were detected at 47 (61.8%) of the study sites, with prevalences ranging from 0.4% to 72.8%. A broad, east-west-oriented belt of high endemicity was identified, stretching across the central part of the country from the southern end of Lake Albert to the north-western shores of Lake Victoria. To the north and south of this belt prevalences generally decreased, although high-prevalence foci were also identified in the far north-western and south-eastern corners of the country. Geostatistical interpolation was used to create a map showing the geographical distribution of M. perstans prevalences in Uganda (by ordinary kriging), and to assess the population exposed to M. perstans transmission. Estimates based on population data from 2002 indicated that 20.4 million people (82.6% of the national population) and 6.8 million people (27.5% of the national population) lived in areas where, respectively, >1% and >10% of the school-aged children had M. perstans microfilaraemias. Since the prevalence of M. perstans microfilaraemia is known to increase with age, the overall population prevalences are likely to be even higher than the prevalences observed in the school-aged children. More attention needs to be paid to the public-health implications of this wide-spread but neglected infection.