Epidemiology and control of lymphatic filariasis in Burkina Faso

This thesis presents the work divided in three main areas: 1) the distribution of Lymphatic Filariasis caused by Wuchereria bancrofti and the non-pathogenic filarial parasite Mansonella perstans; 2) the implementation of a public health programme to eliminate LF describing the activities and discussing the impact of the programme, and 3) the assessment of the cost of the NPELF. This study was the first to provide countrywide epidemiological data on W. bancrofti and M. perstans infections in Burkina Faso as well as in some other West African countries. All the 55 health districts were mapped using immunochromatographic card tests for filarial antigenaemia detection. All the 102 sampled villages were positive except one. The prevalence ranged from 2% to 74% and the overall prevalence was 29.2%. W. bancroft; microfilaraemia baseline in sentinel sites showed an overall prevalence of 8.2% and the average mean density was 1108mf/ml in positive subjects. Children under 5 years presented 0.6% W. bancrofti microfilaraemia prevalence. The urban distribution of W. bancrofti showed a lower prevalence for antigenaemia (2.3%) and microfilaraemia (0.7%). Hydrocoele prevalence in males 15 years and above was 7.2% while lymphoedema was found in 0.6% of the 13 492 surveyed individuals. M. perstans has also been found to be widely distributed in the country with an overall prevalence of 5.9%. The impact of the onchocerciasis control programme activities using the distribution of ivermectin alone for 6 and 14 years in two different sites in Burkina Faso was also studied. It was concluded that 6-year treatment with ivermectin alone might have significantly reduced the prevalence of W. bancrofti whilst it appears that up to 14 years annual or twice-annual treatment with ivermectin may have stopped W. bancrofti transmission. These findings have implications for many areas of Africa where onchocerciasis and LF are co-endemic and the APOC programme has created sustained ivermectin distribution programmes. This thesis documented the impact of 2 to 5 rounds of mass drug administration using albendazole and ivermectin following the implementation of the national programme to eliminate lymphatic filariasis. Although, yearly treatment coverage (69% to 77%) never reached the recommended 80% coverage of total population a significant decline in community microfilaraemia prevalence (up to 95%) and density (up to 98%) has been observed in all sentinel sites except one. In general, there were no significant changes in M. perstans prevalence and density after 2 to 5 annual treatments. Monitoring results showed that reported and checked coverage were largely consistent in the rural and semi-urban districts but not in the urban settings. In addition, there was relative low prevalence of side effects following treatments. Lymphatic filariasis transmission knowledge was poor and the main reason for not taking the drugs was absenteeism. The cost analysis of the programme demonstrated that the start-up financial cost per person treated was US$ 0.11 as the programme is using the existing health system including community volunteers. The studies carried out in this thesis suggest that the GPELF recommended strategy is effective; however, used by and within a national public health system of a "developing" country elimination may need more time than the anticipated four to six years. The required improvement of the social mobilisation component remains a challenge for the success of the programme, especially in urban settings

Determinants of Success in National Programs to Eliminate Lymphatic Filariasis: a Perspective Identifying Essential Elements and Research Needs

The Global Programme to Eliminate Lymphatic Filariasis (GPELF) was launched in 2000. To understand why some national programs have been more successful than others, a panel of individuals with expertise in LF elimination efforts met to assess available data from programs in 8 countries. The goal was to identify: 1) the factors determining success for national LF elimination programs (defined as the rapid, sustained reduction in microfilaremia/ antigenemia after repeated mass drug administration [MDA]); 2) the priorities for operational research to enhance LF elimination efforts. Of more than 40 factors identified, the most prominent were 1) initial level of LF endemicity; 2) effectiveness of vector mosquitoes; 3) MDA drug regimen; 4) population compliance. Research important for facilitating program success was identified as either biologic (i.e., [1] quantifying differences in vectorial capacity; [2] identifying seasonal variations affecting LF transmission) or programmatic (i.e., [1] identifying quantitative thresholds, especially the population compliance levels necessary for success, and the antigenemia or microfilaremia prevalence at which MDA programs can stop with minimal risk of resumption of transmission; [2] defining optimal drug distribution strategies and timing; [3] identifying those individuals who are “persistently non- compliant” during MDAs, the reasons for this non-compliance and approaches to overcoming it). While addressing these challenges is important, many key determinants of program success are already clearly understood; operationalizing these as soon as possible will greatly increase the potential for national program success

Dynamics of antigenemia and transmission intensity of Wuchereria bancrofti following cessation of mass drug administration in a formerly highly endemic region of Mali

Background After seven annual rounds of mass drug administration (MDA) in six Malian villages highly endemic for Wuchereria bancrofti (overall prevalence rate of 42.7%), treatment was discontinued in 2008. Surveillance was performed over the ensuing 5 years to detect recrudescence. Methods Circulating filarial antigen (CFA) was measured using immunochromatographic card tests (ICT) and Og4C3 ELISA in 6–7 year-olds. Antibody to the W. bancrofti infective larval stage (L3) antigen, Wb123, was tested in the same population in 2012. Microfilaraemia was assessed in ICT-positive subjects. Anopheles gambiae complex specimens were collected monthly using human landing catch (HLC) and pyrethrum spray catch (PSC). Anopheles gambiae complex infection with W. bancrofti was determined by dissection and reverse transcriptase polymerase chain reaction (RT-PCR) of mosquito pools. Results Annual CFA prevalence rates using ICT in children increased over time from 0% (0/289) in 2009 to 2.7% (8/301) in 2011, 3.9% (11/285) in 2012 and 4.5% (14/309) in 2013 (trend χ 2  = 11.85, df =3, P = 0.0006). Wb123 antibody positivity rates in 2013 were similar to the CFA prevalence by ELISA (5/285). Although two W. bancrofti-infected Anopheles were observed by dissection among 12,951 mosquitoes collected by HLC, none had L3 larvae when tested by L3-specific RT-PCR. No positive pools were detected among the mosquitoes collected by pyrethrum spray catch. Whereas ICT in 6–7 year-olds was the major surveillance tool, ICT positivity was also assessed in older children and adults (8–65 years old). CFA prevalence decreased in this group from 4.9% (39/800) to 3.5% (28/795) and 2.8% (50/1,812) in 2009, 2011 and 2012, respectively (trend χ 2  = 7.361, df =2, P = 0.0067). Some ICT-positive individuals were microfilaraemic in 2009 [2.6% (1/39)] and 2011 [8.3% (3/36)], but none were positive in 2012 or 2013. Conclusion Although ICT rates in children increased over the 5-year surveillance period, the decrease in ICT prevalence in the older group suggests a reduction in transmission intensity. This was consistent with the failure to detect infective mosquitoes or microfilaraemia. The threshold of ICT positivity in children may need to be re-assessed and other adjunct surveillance tools considered

A Multicenter Evaluation of Diagnostic Tools to Define Endpoints for Programs to Eliminate Bancroftian Filariasis

Successful mass drug administration (MDA) campaigns have brought several countries near the point of Lymphatic Filariasis (LF) elimination. A diagnostic tool is needed to determine when the prevalence levels have decreased to a point that MDA campaigns can be discontinued without the threat of recrudescence. A six-country study was conducted assessing the performance of seven diagnostic tests, including tests for microfilariae (blood smear, PCR), parasite antigen (ICT, Og4C3) and antifilarial antibody (Bm14, PanLF, Urine SXP). One community survey and one school survey were performed in each country. A total of 8,513 people from the six countries participated in the study, 6,443 through community surveys and 2,070 through school surveys. Specimens from these participants were used to conduct 49,585 diagnostic tests. Each test was seen to have both positive and negative attributes, but overall, the ICT test was found to be 76% sensitive at detecting microfilaremia and 93% specific at identifying individuals negative for both microfilariae and antifilarial antibody; the Og4C3 test was 87% sensitive and 95% specific. We conclude, however, that the ICT should be the primary tool recommended for decision-making about stopping MDAs. As a point-of-care diagnostic, the ICT is relatively inexpensive, requires no laboratory equipment, has satisfactory sensitivity and specificity and can be processed in 10 minutes—qualities consistent with programmatic use. Og4C3 provides a satisfactory laboratory-based diagnostic alternative

Epidemiology and control of lymphatic filariasis in Burkina Faso

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Baseline drivers of lymphatic filariasis in Burkina Faso

Lymphatic filariasis (LF) is a parasitic disease that is endemic throughout sub-Saharan Africa, infecting approximately 40 million people. In Burkina Faso, mass drug administration (MDA) for LF with ivermectin and albendazole has been ongoing since 2001, and by 2006 all endemic health districts were receiving MDA with a therapeutic coverage of at least 65%. As MDA activities scale down, the focus is now on targeting areas where LF transmission persists with alternative elimination strategies. This study explored the relationship between village-level, baseline LF prevalence data collected in 2000 with publicly available meteorological, environmental and demographic variables in order to determine the factors that influence the geographical distribution of the disease. A fitted multiple logistic regression model indicated that the length of the rainy season, variability in normalized difference vegetation index (NDVI) and population density were significantly positively associated with LF prevalence, whereas total annual rainfall, average June-September temperature, mean NDVI, elevation and the area of cotton crops were significantly negatively associated. This model was used to produce a baseline LF risk map for Burkina Faso. An extended model which incorporated potential socio-demographic risk factors also indicated a significant positive relationship between LF prevalence and wealth. In overlaying the baseline LF risk map with the number of MDA rounds, plus an insecticide-treated net (ITN) ownership measure, the central southern area of the country was highlighted as an area where baseline LF prevalence was high and ITN coverage relatively low (<50%), while at least 10 rounds of MDA had been undertaken, suggesting that more concentrated efforts will be needed to eliminate the disease in these areas

Improving drug delivery strategies for lymphatic filariasis elimination in urban areas in Ghana

<div><p>The Global Program to Eliminate Lymphatic Filariasis (GPELF) advocates for the treatment of entire endemic communities, in order to achieve its elimination targets. LF is predominantly a rural disease, and achieving the required treatment coverage in these areas is much easier compared to urban areas that are more complex. In Ghana, parts of the Greater Accra Region with Accra as the capital city are also endemic for LF. Mass Drug Administration (MDA) in Accra started in 2006. However, after four years of treatment, the coverage has always been far below the 65% epidemiologic coverage for interrupting transmission. As such, there was a need to identify the reasons for poor treatment coverage and design specific strategies to improve the delivery of MDA. This study therefore set out to identify the opportunities and barriers for implementing MDA in urban settings, and to develop appropriate strategies for MDA in these settings. An experimental, exploratory study was undertaken in three districts in the Greater Accra region. The study identified various types of non-rural settings, the social structures, stakeholders and resources that could be employed for MDA. Qualitative assessment such as in-depth interviews (IDIs) and focus group discussions (FGDs) with community leaders, community members, health providers, NGOs and other stakeholders in the community was undertaken. The study was carried out in three phases: pre-intervention, intervention and post-intervention phases, to assess the profile of the urban areas and identify reasons for poor treatment coverage using both qualitative and quantitative research methods. The outcomes from the study revealed that, knowledge, attitudes and practices of community members to MDA improved slightly from the pre-intervention phase to the post-intervention phase, in the districts where the interventions were readily implemented by health workers. Many factors such as adequate leadership, funding, planning and community involvement, were identified as being important in improving implementation and coverage of MDA in the study districts. Implementing MDA in urban areas therefore needs to be given significant consideration and planning, if the required coverage rates are to be achieved. This paper, presents the recommendations and strategies for undertaking MDA in urban areas.</p></div

Public education before distribution.

<p>Public education before distribution.</p

Demographic characteristics of respondents.

<p>Demographic characteristics of respondents.</p