Filarial antigenemia and Loa loa night blood microfilaremia in an area without bancroftian filariasis in the Democratic Republic of Congo.

Didier K Bakajika,Gary J Weil,Kerstin Fischer,Peter U Fischer,Jean Pierre Lotsima,Melanie M Lloyd,Maurice M Nigo,Germain A Masikini

doi:10.4269/ajtmh.14-0358

Abstract

Implementation of mass drug administration for lymphatic filariasis (LF) has been delayed in central Africa because of incomplete mapping and coendemic loiasis. We mapped two regions in eastern Democratic Republic of Congo that were suspected to have LF. Night blood samples were collected from 2,724 subjects in 30 villages. Filarial antigenemia rates by card test exceeded 1% in 28 villages (range = 0–14%). Prevalence rates for large sheathed microfilariae (Mf) ranged from 4% to 40%; Mansonella perstans rates ranged from 22% to 98%. Large Mf were exclusively Loa loa by microscopy, and only 1 of 337 samples tested by quantitative polymerase chain reaction (qPCR) was positive for Wuchereria bancrofti DNA. Filarial antigen positivity was strongly associated with high L. loa Mf counts. Periodicity studies revealed atypical patterns, with no significant diurnal periodicity in some individuals. Thus, methods routinely used for LF mapping may not be reliable in areas in central Africa that are highly endemic for loiasis.

Highlights

Lymphatic filariasis (LF) affects some 120 million people in countries, and approximately 1.3 billion people are at risk of becoming infected with the nematode parasites (Wuchereria bancrofti and Brugia species) that cause this disease.[1]
This is especially important for regions with loiasis, because ivermectin used in LF elimination programs can cause serious adverse events in persons with heavy Loa loa infections
Two tests that are widely used for mapping LF are microfilaria (Mf) detection and detection of filarial antigenemia by immunochromatographic card test (ICT)

Summary

Introduction

Lymphatic filariasis (LF) affects some 120 million people in countries, and approximately 1.3 billion people are at risk of becoming infected with the nematode parasites (Wuchereria bancrofti and Brugia species) that cause this disease.[1] The. Global Program to Eliminate Lymphatic Filariasis (GPELF). Accurate mapping of the distribution of LF is a crucial first step for LF elimination programs. This is especially important for regions with loiasis, because ivermectin used in LF elimination programs can cause serious adverse events (including death) in persons with heavy Loa loa infections. Mansonella perstans is a third filarial species that infects humans in many areas of Africa, but M. perstans Mf can be distinguished from those of L. loa and W. bancrofti based on their smaller size and lack of a sheath

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