Surveys for Mansonella perstans Filariasis in Kalabo, Kazungula, Choma and Kafue Districts of Zambia

Abstract

Background: Past case reports have documented Mansonella perstans infections in Zambia. However, knowledge on the epidemiology and geographical distribution of this infection in the country is lacking. This paper reports on surveys for M. perstans in communities in four districts(Kalabo, Kazungula, Choma and Kafue) in the Southern and Western parts of Zambia.
Design: The study was cross sectional. In the Kalabo District surveys, individuals aged one year and above had thick blood smears prepared and examined for M. perstans microfilariae (mf). In the other three districts the study design was retrospective and prospective, i.e. previously examined archived malaria slides from health centres were re-examined for M. perstans mf and at the same time individuals aged 15years and above had thick blood spears prepared and examined for M. perstans mf.
Results: The retrospective study could only be undertaken in Choma District due to change in malaria examination method in the other districts from conventional preparation of Giemsa stained thick blood smears to use of rapid diagnostic tests. For the prospective surveys, out of the 1439 individuals recruited and examined, no M. perstans mf were seen in any of the blood smears.
Conclusions: The failure to find M. perstans mf was surprising considering previous case reports, even from some of surveyed areas. There is a need for more surveys to be carried in other parts of the country to ascertain the distribution of M. perstans. Health practitioners should moreover be informed about this infection, and trained to be able to accurately distinguish M. perstans infections from those of W. bancrofti, which are also endemic in Zambia.