Dataset Information

Impact of three rounds of mass drug administration on lymphatic filariasis in areas previously treated for onchocerciasis in Sierra Leone.

ABSTRACT:

Background

1974-2005 studies across Sierra Leone showed onchocerciasis endemicity in 12 of 14 health districts (HDs) and baseline studies 2005-2008 showed lymphatic filariasis (LF) endemicity in all 14 HDs. Three integrated annual mass drug administration (MDA) were conducted in the 12 co-endemic districts 2008-2010 with good geographic, programme and drug coverage. Midterm assessment was conducted 2011 to determine impact of these MDAs on LF in these districts.

Methodology/principal findings

The mf prevalence and intensity in the 12 districts were determined using the thick blood film method and results compared with baseline data from 2007-2008. Overall mf prevalence fell from 2.6% (95% CI: 2.3%-3.0%) to 0.3% (95% CI: 0.19%-0.47%), a decrease of 88.5% (p?=?0.000); prevalence was 0.0% (100.0% decrease) in four districts: Bo, Moyamba, Kenema and Kono (p?=?0.001, 0.025, 0.085 and 0.000 respectively); and seven districts had reductions in mf prevalence of between 70.0% and 95.0% (p?=?0.000, 0.060, 0.001, 0.014, 0.000, 0.000 and 0.002 for Bombali, Bonthe, Kailahun, Kambia, Koinadugu, Port Loko and Tonkolili districts respectively). Pujehun had baseline mf prevalence of 0.0%, which was maintained. Only Bombali still had an mf prevalence ?1.0% (1.58%, 95% CI: 0.80%-3.09%)), and this is the district that had the highest baseline mf prevalence: 6.9% (95% CI: 5.3%-8.8%). Overall arithmetic mean mf density after three MDAs was 17.59 mf/ml (95% CI: 15.64 mf/ml-19.55 mf/ml) among mf positive individuals (65.4% decrease from baseline of 50.9 mf/ml (95% CI: 40.25 mf/ml-61.62 mf/ml; p?=?0.001) and 0.05 mf/ml (95% CI: 0.03 mf/ml-0.08 mf/ml) for the entire population examined (96.2% decrease from baseline of 1.32 mf/ml (95% CI: 1.00 mf/ml-1.65 mf/ml; p?=?0.000)).

Conclusions/significance

The results show that mf prevalence decreased to <1.0% in all but one of the 12 districts after three MDAs. Overall mf density reduced by 65.0% among mf-positive individuals, and 95.8% for the entire population.

SUBMITTER: Koroma JB

PROVIDER: S-EPMC3681681 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Impact of three rounds of mass drug administration on lymphatic filariasis in areas previously treated for onchocerciasis in Sierra Leone.

Koroma Joseph B JB Sesay Santigie S Sonnie Mustapha M Hodges Mary H MH Sahr Foday F Zhang Yaobi Y Bockarie Moses J MJ

PLoS neglected tropical diseases 20130613 6

<h4>Background</h4>1974-2005 studies across Sierra Leone showed onchocerciasis endemicity in 12 of 14 health districts (HDs) and baseline studies 2005-2008 showed lymphatic filariasis (LF) endemicity in all 14 HDs. Three integrated annual mass drug administration (MDA) were conducted in the 12 co-endemic districts 2008-2010 with good geographic, programme and drug coverage. Midterm assessment was conducted 2011 to determine impact of these MDAs on LF in these districts.<h4>Methodology/principal ...[more]

PMID: 23785535

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Project description:BackgroundOnchocerciasis is endemic in 12 of the 14 health districts of Sierra Leone. Good treatment coverage of community-directed treatment with ivermectin was achieved between 2005 and 2009 after the 11-year civil conflict. Sentinel site surveys were conducted in 2010 to evaluate the impact of five annual rounds of ivermectin distribution.MethodsIn total, 39 sentinel villages from hyper- and meso-endemic areas across the 12 endemic districts were surveyed using skin snips in 2010. Results were analyzed and compared with the baseline data from the same 39 villages.ResultsThe average microfilaridermia (MF) prevalence across 39 sentinel villages was 53.10% at baseline. The MF prevalence was higher in older age groups, with the lowest in the age group of 1-9 years (11.00%) and the highest in the age group of 40-49 years (82.31%). Overall mean MF density among the positives was 28.87 microfilariae (mf)/snip, increasing with age with the lowest in the age group of 1-9 years and the highest in the age group of 40-49 years. Males had higher MF prevalence and density than females. In 2010 after five rounds of mass drug administration, the overall MF prevalence decreased by 60.26% from 53.10% to 21.10%; the overall mean MF density among the positives decreased by 71.29% from 28.87 mf/snip to 8.29 mf/snip; and the overall mean MF density among all persons examined decreased by 88.58% from 15.33 mf/snip to 1.75 mf/snip. Ten of 12 endemic districts had > 50% reduction in MF prevalence. Eleven of 12 districts had ≥50% reduction in mean MF density among the positives.ConclusionsA significant reduction of onchocerciasis MF prevalence and mean density was recorded in all 12 districts of Sierra Leone after five annual MDAs with effective treatment coverage. The results suggested that the onchocerciasis elimination programme in Sierra Leone was on course to reach the objective of eliminating onchocerciasis in the country by the year 2025. Annual MDA with ivermectin should continue in all 12 districts and further evaluations are needed across the country to assist the NTDP with programme decision making.

Project description:BackgroundPreventive chemotherapy was administered to 3.2 million Sierra Leoneans in 13 health districts for lymphatic filariasis, onchocerciasis, and soil transmitted helminthes from October 2008 to February 2009. This paper aims to report the findings of a coverage survey conducted in 2009, compare the coverage survey findings with two reported rates for lymphatic filariasis coverage obtained using pre-mass drug administration (MDA) registration and national census projections, and use the comparison to understand the best source of population estimates in calculating coverage for NTD programming in Sierra Leone.Methodology/principal findingsCommunity drug distributors (CDDs) conducted a pre- MDA registration of the population. Two coverage rates for MDA for lymphatic filariasis were subsequently calculated using the reported number treated divided by the total population from: 1) the pre-MDA register and 2) national census projections. A survey was conducted to validate reported coverage data. 11,602 persons participated (response rate of 76.8%). Overall, reported coverage data aggregated to the national level were not significantly different from surveyed coverage (z-test >0.05). However, estimates based on pre-MDA registration have higher agreement with surveyed coverage (mean Kendall's W = 0.68) than coverage calculated with census data (mean Kendall's = 0.59), especially in districts with known large-scale migration, except in a highly urban district where it was more challenging to conduct a pre-MDA registration appropriately. There was no significant difference between coverage among males versus females when the analyses were performed excluding those women who were pregnant at the time of MDA. The surveyed coverage estimate was near or below the minimum 65% epidemiological coverage target for lymphatic filariasis MDA in all districts.Conclusion/significanceThese results from Sierra Leone illustrate the importance of choosing the right denominator for calculating treatment coverage for NTD programs. While routinely reported coverage results using national census data are often good enough for programmatic decision making, census projections can quickly become outdated where there is substantial migration, e.g. due to the impact of civil war, with changing economic opportunities, in urban settings, and where there are large migratory populations. In districts where this is known to be the case, well implemented pre-MDA registration can provide better population estimates. Pre-MDA registration should, however, be implemented correctly to reduce the risk of missing pockets of the population, especially in urban settings.

Project description:Mass Drug Administration (MDA) programs to eliminate Lymphatic Filariasis (LF) in western Africa use the anthelminthics ivermectin plus albendazole. These drugs have the potential to impact also Soil-Transmitted Helminth (STH) infections, since the drugs have a broad range of anthelminthic activity. Integration of preventive chemotherapy efforts for LF, onchocerciasis and STH is recommended by the World Health Organization (WHO) in order to avoid duplication of MDA and to reduce costs. The objective of the current study was to determine whether five semi-annual rounds of community-wide MDA to eliminate LF and onchocerciasis have a greater impact on STH than three annual rounds of MDA with similar compliance. The effects of MDA using ivermectin (IVM, 0.2 mg/kg) combined with albendazole (ALB, 400 mg) on the prevalence and intensity of hookworm infection were evaluated in the Abengourou (annual MDA) and Akoupé (semi-annual MDA) health Districts in eastern Côte d'Ivoire from 2014 to 2017. A cross-sectional approach was used together with mixed logistic regression, and mixed linear models. Subjects were tested for STH using the Kato-Katz technique before the first round of MDA and 12, 24, and 36 months after the first round of MDA. The mean self-reported MDA compliance assessed during the survey was 65%, and no difference was observed between treatment areas. These results were confirmed by an independent coverage survey as recommended by WHO. Hookworm was the most prevalent STH species in both areas (23.9% vs 12.4%) and the prevalence of other STH species was less than 1%. The crude prevalence of hookworm dropped significantly, from 23.9% to 5.5% (p <0.001, 77% reduction) in the annual MDA treatment area and from 12.4% to 1.9% (p <0.001, 85% reduction) in the semi-annual treatment area. The average intensity of hookworm infection decreased in the annual MDA area (406.2 epg to 118.3 epg), but not in the semi-annual MDA area (804.9 epg to 875.0 epg). Moderate and heavy infections (1% and 1.3% at baseline) were reduced to 0% and 0.4% in the annual and semi-annual treatment areas, respectively. Using a mixed logistic regression model, and after adjusting for baseline prevalence, only the year 2 re-examination showed a difference in prevalence between treatments (OR: 2.26 [95% CI: 1.03, 4.98], p = 0.043). Analysis of intensity of hookworm infection indicated also that treatment differences varied by follow-up visit. In conclusion twelve months after the last treatment cycle, three annual and five semi-annual rounds of community-wide MDA with the combination of IVM and ALB showed strong, but similar impact on hookworm prevalence and intensity in eastern Côte d'Ivoire. Therefore, an annual MDA regimen seems to be an efficient strategy to control hookworm infection in endemic areas with low and moderate infection prevalence. Trial registration: The study was registered at ClinicalTrial.gov under the number NTC02032043.

Project description:BackgroundLymphatic filariasis (LF) elimination program in Tanzania started in 2000 in response to the Global program for the elimination of LF by 2020. Evidence shows a persistent LF transmission despite more than a decade of mass drug administration (MDA). It is advocated that, regular monitoring should be conducted in endemic areas to evaluate the progress towards elimination and detect resurgence of the disease timely. This study was therefore designed to assess the status of Wuchereria bancrofti infection in Culex quinqefasciatus and Anopheles species after six rounds of MDA in Masasi District, South Eastern Tanzania.MethodsMosquitoes were collected between June and July 2019 using Center for Diseases Control (CDC) light traps and gravid traps for indoor and outdoor respectively. The collected mosquitoes were morphologically identified into respective species. Dissections and PCR were carried out to detect W. bancrofti infection. Questionnaire survey and checklist were used to assess vector control interventions and household environment respectively. A Poisson regression model was run to determine the effects of household environment on filarial vector density.ResultsOverall, 12 452 mosquitoes were collected of which 10 545 (84.7%) were filarial vectors. Of these, Anopheles gambiae complex, An. funestus group and Cx. quinquefasciatus accounted for 0.1%, 0.7% and 99.2% respectively. A total of 365 pools of Cx. quinquefasciatus (each with 20 mosquitoes) and 46 individual samples of Anopheles species were analyzed by PCR. For Cx. quinquefasciatus pools, 33 were positive for W. bancrofti, giving an infection rate of 0.5%, while the 46 samples of Anopheles species were all negative. All 1859 dissected mosquitoes analyzed by microscopy were also negative. Households with modern latrines had less mosquitoes than those with pit latrines [odds ratio (OR) = 0.407, P < 0.05]. Houses with unscreened windows had more mosquitoes as compared to those with screened windows (OR = 2.125, P < 0.05). More than 80% of the participants own bednets while 16.5% had no protection.ConclusionsLF low transmission is still ongoing in Masasi District after six rounds of MDA and vector control interventions. The findings also suggest that molecular tools may be essential for xenomonitoring LF transmission during elimination phase.

Dataset Information

Impact of three rounds of mass drug administration on lymphatic filariasis in areas previously treated for onchocerciasis in Sierra Leone.

Background

Methodology/principal findings

Conclusions/significance

Publications

Impact of three rounds of mass drug administration on lymphatic filariasis in areas previously treated for onchocerciasis in Sierra Leone.

Similar Datasets

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