Mapping of Bancroftian Filariasis in Cameroon: Prospects for Elimination

PLoS Negl Trop Dis. 2015 Sep 9;9(9):e0004001. doi: 10.1371/journal.pntd.0004001. eCollection 2015.

Abstract

Background: Lymphatic filariasis (LF) is one of the most debilitating neglected tropical diseases (NTDs). It still presents as an important public health problem in many countries in the tropics. In Cameroon, where many NTDs are endemic, only scant data describing the situation regarding LF epidemiology was available. The aim of this study was to describe the current situation regarding LF infection in Cameroon, and to map this infection and accurately delineate areas where mass drug administration (MDA) was required.

Methodology: The endemicity status and distribution of LF was assessed in eight of the ten Regions of Cameroon by a rapid-format card test for detection of W. bancrofti antigen (immunochromatographic test, ICT). The baseline data required to monitor the effectiveness of MDA was collected by assessing microfilariaemia in nocturnal calibrated thick blood smears in sentinel sites selected in the health districts where ICT positivity rate was ≥ 1%.

Principal findings: Among the 120 health districts visited in the eight Regions during ICT survey, 106 (88.3%) were found to be endemic for LF (i.e. had ICT positivity rate ≥ 1%), with infection rate from 1.0% (95% CI: 0.2-5.5) to 20.0% (95% CI: 10-30). The overall infection rate during the night blood survey was 0.11% (95% CI: 0.08-0.16) in 11 health districts out of the 106 surveyed; the arithmetic mean for microfilaria density was 1.19 mf/ml (95% CI: 0.13-2.26) for the total population examined.

Conclusion/significance: ICT card test results showed that LF was endemic in all the Regions and in about 90% of the health districts surveyed. All of these health districts qualified for MDA (i.e. ICT positivity rate ≥ 1%). Microfilariaemia data collected as part of this study provided the national program with baseline data (sentinel sites) necessary to measure the impact of MDA on the endemicity level and transmission of LF important for the 2020 deadline for global elimination.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Cameroon / epidemiology
  • Child
  • Child, Preschool
  • Chromatography, Affinity
  • Elephantiasis, Filarial / epidemiology*
  • Endemic Diseases*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Topography, Medical
  • Young Adult

Grants and funding

These surveys were funded by the United States Agency for International Development (USAID) ENVISION Project through Helen Keller International. ENVISION is a global project led by RTI International in partnership with CBM International, The Carter Center, Helen Keller International, IMA World Health, Light for the World, Sightsavers, and World Vision. ENVISION is funded by the US Agency for International Development project under cooperative agreement number AID-OAA-A-11-00048. The period of performance for ENVISION is September 30, 2011 through September 29, 2016. The Center for Research on Filariasis and other Tropical Diseases (CRFilMT), the platform where biological tests were performed for this study, is funded by Mectizan Donation Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.