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NADALow Microfilaremia Levels in Three Districts in Coastal Ghana with at Least 16 Years of Mass Drug Administration and Persistent Transmission of Lymphatic FilariasisNMIMR_LYMPHATIC_FILARIASIS_2018Dziedzom K. de Souza
Regional and district health management teams
NTDP
Noguchi Memorial Institute for Medical ResearchNADAEDCTP2 programme supported by the European UnionDziedzom K. de Souzav1Ghana18 LF endemic villages in the AhantaWest, Nzema East and Ellembele Districts in the Western Region of Ghanasample survey data[ssd]Ghana has been implementing mass drug administration (MDA) of ivermectin and
albendazole for the elimination of lymphatic filariasis (LF) since the year 2000, as part of the Global
Programme to Eliminate Lymphatic Filariasis (GPELF). It was estimated that 5–6 years of treatment
would be sufficient to eliminate the disease. Tremendous progress has been made over the years,
and treatment has stopped in many disease endemic districts. However, despite the successful
implementation of MDA, there are districts with persistent transmission. In this study we assessed
the epidemiology of LF in three adjoining districts that have received at least 16 years of MDA.
The assessments were undertaken one year after the last MDA. 1234 adults and 182 children below
the age of 10 years were assessed. The overall prevalence of circulating filarial antigen in the
study participants was 8.3% (95% CI: 6.9–9.9), with an estimated microfilaria prevalence of 1.2%.
The microfilarial intensity in positive individuals ranged from 1 to 57 microfilariae/mL of blood.
Higher antigen prevalence was detected in males (13.0%; 95% CI: 10.3–16.2) compared to females
(5.5%; 95% CI: 4.1–7.2). The presence of infection was also highest in individuals involved in outdoor
commercial activities, with the risks of infection being four- to five-fold higher among farmers,
fishermen, drivers and artisans, compared to all other occupations. Using bednets or participating in
MDA did not significantly influence the risk of infection. No children below the age of 10 years were
found with infection. Detection of Wb123 antibodies for current infections indicated a prevalence of
14.4% (95% CI: 8.1–23.0) in antigen-positive individuals above 10 years of age. No antibodies were
detected in children 10 years or below. Assessment of infection within the An. gambiae vectors of
LF indicated an infection rate of 0.9% (95% CI: 0.3–2.1) and infectivity rate of 0.5% (95% CI: 0.1–1.6).
These results indicate low-level transmission within the districts, and suggest that it will require
targeted interventions in order to eliminate the infection.
Study sites were selected following a review of the Neglected Tropical Disease Programme
(NTDP) sentinel and spot check site monitoring data, as well as recommendation from the District
Health Management Team (DHMT). The sample size determination took into consideration the null
hypothesis that an additional MDA is not more effective than the standard single dose per annum
treatment, and the alternate hypothesis that an additional MDA is more effective than the standard
single dose. With prevalence between sites ranging from 1% to 18%, the sample size was determined
assuming an effect size of 0.4, power of 0.80, 37% non-response rate (determined from a previous
study). Thus, 80 participants were targeted from each community, with a total of 1440 participants for
the entire study.A computer-assisted personal interviewing (CAPI) A computer-assisted personal interviewing (CAPI) using Census and Survey Processing System
(CSPro) was employed to obtain data on age, sex, occupation, place of residence, use of treated bednet,
and participation in MDA.Dziedzom K. de Souza