Prevalence Of Lymphatic Filariasis Research Articles

Sero-antigen prevalence of lymphatic filariasis and risk factors of podoconiosis in Busiriba sub-county, Kamwenge district, Southwestern Uganda, August-September 2018.

Given the neglected nature of filariasis, especially in Uganda where data are scarce, this cross-sectional study aimed to determine the sero-antigen prevalence of lymphatic filariasis and risk factors associated with non-lymphatic filariasis (podoconiosis) in Busiriba Sub-county, Kamwenge District, Uganda, during August-September 2018, to inform targeted elimination efforts. We enrolled 101 participants, among whom 35 (34.7%) had podoconiosis. The sero-antigen prevalence of lymphatic filariasis was 1.0%. Older age and walking barefoot were associated with increased podoconiosis risk. Specifically, individuals aged 25-49 years with had 7.38 times higher odds of podoconiosis (adjusted odds ratio [aOR] = 7.38, 95% CI: 1.36-40.13) compared to those under 25 years, while those aged ≥ 50 years had even higher odds (aOR = 8.49, 95%CI: 1.44-50.15). Additionally, individuals who reported walking barefoot had 14 times higher odds of podoconiosis (aOR = 14.08; 95% CI: 2.49-79.50).

Towards Understanding the Microepidemiology of Lymphatic Filariasis at the Community Level in Ghana.

Studies on the distribution of lymphatic filariasis (LF) have mostly focused on reporting prevalence at the community level and distribution at the district levels. Understanding the distribution patterns at community levels may help in designing surveillance strategies. This study aimed to characterize the spatial distribution of LF infections in four hotspot communities in Ghana. The research, involving 252 participants, collected demographic data, mass drug administration (MDA) information, household GPS coordinates, and antigen detection test results. The LF prevalence varied significantly among the communities, with Asemda having the highest (33.33%) and Mempeasem having the lowest (4.44%). Females had lower odds of infection than males (OR = 2.67, p = 0.003 CI: 1.39-5.13). Spatial analysis using kernel density, Anselin Local Moran's, Getis-Ord Gi models, Ordinary Least Squares, and Geographic Weighted Regression revealed mixed patterns of spatial autocorrelation. This study identified LF hotspots, indicating clusters of high or low prevalence with some areas showing disparities between MDA coverage and LF positivity rates. Despite these hotspots, the overall distribution of LF appeared random, suggesting the importance of purposeful sampling in surveillance activities. These findings contribute valuable insights into the micro-epidemiology of LF, emphasizing the need for community-specific investigations to understand the factors influencing the effectiveness of MDA programs in controlling filarial infections. The study highlights the importance of refining surveillance strategies based on community-level distribution patterns.

Assessment of participants’ perception on the use of mass drug administration in communities endemic to <i>Wuchereria bancrofti</i> Cobbold, 1877 in Northern Nigeria

Lymphatic filariasis (LF) is one of the neglected tropical diseases that cause permanent long term disability inform of hydrocoele, lymphoedema and elephantiasis that develop as a result of inflammation of the lymphatic system. This study aimed to assess the prevalence of lymphatic filariasis and perception of participants towards Mass Drug Administration (MDA) programme. The study was a community-based cross-sectional study for screening microfilariae of Wuchereria bancrofti in consenting participants. A total of 1010 participants’ from selected communities on the MDA programme in 5 Local Government Areas (LGAs) of Bauchi, Plateau and Kaduna states were enlisted into to the study. The communities were chosen based on the presence of the people living with LF according to the signs and symptoms. A well-structured adapted questionnaire was administered to collect participants’ information and their perception of the MDA programme. Microflaria of Wuchereria bancrofti were identified based on the sheathed nuclear, caudal nuclei and bent tail in Parasitology and Entomology Research Laboratory, Ahmadu Bello University, Zaria. Data was analysed using descriptive statistics, chi-squared and odds ratio. Participants with knowledge (294/1010; 29.11%) of the MDA programme were less than those without knowledge (716/1010; 70.89%) of the MDA. Similar, the prevalence of LF was higher in participants with knowledge (26.87%) of the MDA than in those without knowledge (25.14%). The status of participation showed that, those that participated (380/1010; 37.62%) in the MDA were lower than those did not participants (630/1010; 62.38%); the infection in participants that did not partook in the MDA programme had higher prevalence (29.68%) of LF than those that participated. Participants gave various reasons for not being part of the MDA programme ranging from absent (177/1010; 17.53%) at the time of the campaign to side effect (2/1010; 0.20%) of the drugs after taking it. However, those that gave reasons for not participating because Community Drug Distributors (CDD) did not come, had highest prevalence (40.74%) of LF compared to those that gave reasons as side effect (0.00%) for not taking the drugs. Overall LF prevalence of 25.64% was found in this study. There is poor knowledge of MDA programme among the participants in the communities examined. Similarly, microfilaria was present in some participants despite the MDA campaign in the selected states. Intensive awareness campaign and drug distribution need to be carried out in most of the remote communities in the affected states. Furthermore, members of the communities must be part of the CDDs for acceptability and effectiveness of the campaign.

The effects of selected neglected tropical diseases on economic performance at the macrolevel in Africa

BackgroundNeglected tropical diseases (NTDs) such as leprosy, lymphatic filariasis (LF), schistosomiasis and onchocerciasis are endemic in several African countries. These diseases can lead to severe pain and permanent disability, which can negatively affect the economic productivity of the affected person(s), and hence resulting into low economic performance at the macrolevel. Nonetheless, empirical evidence of the effects of these NTDs on economic performance at the macrolevel is sparse. This study therefore investigates the effects of the above-mentioned NTDs on economic performance at the macrolevel in Africa.MethodsThe study employs a panel design with data comprising 24 to 45 African countries depending on the NTD in question, over the period, 2002 to 2019. Gross domestic product (GDP) is used as the proxy for economic performance (Dependent variable) and the prevalence of the above-mentioned NTDs are used as the main independent variables. The random effects (RE), fixed effects (FE) and the instrumental variable fixed effects (IVFE) panel data regressions are used as estimation techniques.ResultsWe find that, an increase in the prevalence of the selected NTDs is associated with a fall in economic performance in the selected African countries, irrespective of the estimation technique used. Specifically, using the IVFE regression estimates, we find that a percentage increase in the prevalence of leprosy, LF, schistosomiasis and onchocerciasis is associated with a reduction in economic performance by 0.43%, 0.24%, 0.28% and 0.36% respectively, at either 1% or 5% level of significance.ConclusionThe findings highlight the need to increase attention and bolster integrated efforts or measures towards tackling these diseases in order to curb their deleterious effects on economic performance. Such measures can include effective mass drug administration (MDA), enhancing access to basic drinking water and sanitation among others.

An Ensemble Framework for Projecting the Impact of Lymphatic Filariasis Interventions Across Sub-Saharan Africa at a Fine Spatial Scale.

Lymphatic filariasis (LF) is a neglected tropical disease targeted for elimination as a public health problem by 2030. Although mass treatments have led to huge reductions in LF prevalence, some countries or regions may find it difficult to achieve elimination by 2030 owing to various factors, including local differences in transmission. Subnational projections of intervention impact are a useful tool in understanding these dynamics, but correctly characterizing their uncertainty is challenging. We developed a computationally feasible framework for providing subnational projections for LF across 44 sub-Saharan African countries using ensemble models, guided by historical control data, to allow assessment of the role of subnational heterogeneities in global goal achievement. Projected scenarios include ongoing annual treatment from 2018 to 2030, enhanced coverage, and biannual treatment. Our projections suggest that progress is likely to continue well. However, highly endemic locations currently deploying strategies with the lower World Health Organization recommended coverage (65%) and frequency (annual) are expected to have slow decreases in prevalence. Increasing intervention frequency or coverage can accelerate progress by up to 5 or 6 years, respectively. While projections based on baseline data have limitations, our methodological advancements provide assessments of potential bottlenecks for the global goals for LF arising from subnational heterogeneities. In particular, areas with high baseline prevalence may face challenges in achieving the 2030 goals, extending the "tail" of interventions. Enhancing intervention frequency and/or coverage will accelerate progress. Our approach facilitates preimplementation assessments of the impact of local interventions and is applicable to other regions and neglected tropical diseases.

An empirical analysis of the effects of schistosomiasis and lymphatic filariasis on macroeconomic output in Ghana

BackgroundSchistosomiasis and Lymphatic Filariasis (LF) are endemic in Ghana. These diseases cause significant morbidity and disability which can adversely affect the participation of affected persons and their caregivers in economic activities, resulting in reduced economic output at the macrolevel. This study, therefore aims to provide the first empirical evidence of the effects of these diseases on economic output at the macrolevel in Ghana. MethodsThe study uses annual time series data on Ghana collected from secondary sources over the period, 1990–2019. Gross Domestic Product (GDP) is used as the proxy for macroeconomic output (i.e., dependent variable) and the main independent variables are the point prevalence of schistosomiasis and LF (including their sex disaggregation). The Ordinary Least Square (OLS) and the Instrumental Variable Two-Stage Least Square (IV2SLS) regressions are employed as estimation techniques. ResultsUsing the OLS (IV2SLS) regressions, a percentage increase in the overall prevalence of schistosomiasis as well as the prevalence of schistosomiasis among males and females is found to be associated with a 1.37% (1.36%), 1.29% (1.30%) and 1.41% (1.39%) fall in macroeconomic output respectively, at the 1% level of significance. Similarly, a percentage increase in the overall prevalence of LF as well as the prevalence of LF among males and females is found to be associated with a 0.34% (0.37%), 0.34% (0.37%) and 0.34% (0.38%) fall in macroeconomic output respectively, at the 1% level of significance. ConclusionThere is the need to strengthen efforts towards fighting schistosomiasis and LF in Ghana in order to reduce their associated economic losses.

Heterogeneity in elimination efforts could increase the risk of resurgence of lymphatic filariasis in Madagascar

BackgroundProgress in lymphatic filariasis (LF) elimination is spatially heterogeneous in many endemic countries, which may lead to resurgence in areas that have achieved elimination. Understanding the drivers and consequences of such heterogeneity could help inform strategies to reach global LF elimination goals by 2030. This study assesses whether differences in age-specific compliance with mass drug administration (MDA) could explain LF prevalence patterns in southeastern Madagascar and explores how spatial heterogeneity in prevalence and age-specific MDA compliance may affect the risk of LF resurgence after transmission interruption. MethodologyWe used LYMFASIM model with parameters in line with the context of southeastern Madagascar and explored a wide range of scenarios with different MDA compliance for adults and children (40–100%) to estimate the proportion of elimination, non-elimination and resurgence events associated with each scenario. Finally, we evaluated the risk of resurgence associated with different levels of migration (2–6%) from surrounding districts combined with varying levels of LF microfilaria (mf) prevalence (0–24%) during that same study period. ResultsDifferences in MDA compliance between adults and children better explained the observed heterogeneity in LF prevalence for these age groups than differences in exposure alone. The risk of resurgence associated with differences in MDA compliance scenarios ranged from 0 to 19% and was highest when compliance was high for children (e.g. 90%) and low for adults (e.g. 50%). The risk of resurgence associated with migration was generally higher, exceeding 60% risk for all the migration levels explored (2–6% per year) when mf prevalence in the source districts was between 9% and 20%. ConclusionGaps in the implementation of LF elimination programme can increase the risk of resurgence and undermine elimination efforts. In Madagascar, districts that have not attained elimination pose a significant risk for those that have achieved it. More research is needed to help guide LF elimination programme on the optimal strategies for surveillance and control that maximize the chances to sustain elimination and avoid resurgence.

A dynamic game of lymphatic filariasis prevention by voluntary use of insecticide treated nets

Lymphatic filariasis (LF) has been targeted for elimination as a public health concern by 2030 with a goal to keep the prevalence of LF infections under the 1% threshold. While mass drug administration (MDA) is a primary strategy recommended by WHO, the use of insecticide treated nets (ITN) plays a crucial role as an alternative strategy when MDA cannot be used. In this paper, we use imitation dynamics to incorporate human behavior and voluntary use of ITN into the compartmental epidemiological model of LF transmission. We find the equilibrium states of the dynamics and the ITN usage as it depends on epidemiological parameters and the cost of ITNs. We investigate the conditions under which the voluntary use of ITNs can keep the LF prevalence under the 1% threshold. We found that when the cost of using the ITNs is about 105 smaller than the perceived cost of LF, then the voluntary use of ITNs will eliminate LF as a public health concern. Furthermore, when the ITNs are given away for free, our model predicts that over 80% of the population will use them which would eliminate LF completely in regions where Anopheles are the primary vectors.

"Prevalence of Lymphatic Filariasis in North and South Zones of Bangladesh"

"Prevalence of Lymphatic Filariasis in North and South Zones of Bangladesh"

Lymphatic Filariasis Elimination Status: Wuchereria bancrofti Infections in Human Populations after Five Effective Rounds of Mass Drug Administration in Zambia.

Lymphatic filariasis (LF), also commonly known as elephantiasis, is a neglected tropical disease (NTD) caused by filarial parasites. The disease is transmitted via a bite from infected mosquitoes. The bites of these infected mosquitoes deposit filarial parasites, Wuchereria or Brugia, whose predilection site is the lymphatic system. The damage to the lymph system causes swelling in the legs, arms, and genitalia. A mapping survey conducted between 2003 and 2011 determined LF as being endemic in Zambia in 96 out of 116 districts. Elimination of LF is known to be possible by stopping the spread of the infection through large-scale preventive chemotherapy. Therefore, mass drug administration (MDA) with diethylcarbamazine citrate (DEC) (6 mg/kg) and Albendazole (400 mg) for Zambia has been conducted and implemented in all endemic districts with five effective rounds. In order to determine whether LF prevalence has been sufficiently reduced to levels less than 2% antigenemia and less than 1% microfilaremia, a pre-transmission assessment survey (pre-TAS) was conducted. Therefore, post-MDA pre-TAS was conducted between 2021 and 2022 in 80 districts to determine the LF prevalence. We conducted a cross-sectional seroprevalence study involving 600 participants in each evaluation unit (EU) or each district. The study sites (sentinel and spot-check sites) were from districts that were the implementation units (IUs) of the LF MDA. These included 80 districts from the 9 provinces. A total of 47,235 people from sentinel and spot-check locations were tested. Of these, valid tests were 47,052, of which 27,762 (59%) were females and 19,290 (41%) were males. The survey revealed in the 79/80 endemic districts a prevalence of Wb antigens of 0.14% and 0.0% prevalence of microfilariae. All the surveyed districts had an optimum prevalence of less than 2% for antigenaemia, except for Chibombo district. The majority of participants that tested positive for Wuchereria bancrofti (Wb) Antigens (Ag) were those that had 2, 3, and 4 rounds of MDA. Surprisingly, individuals that had 1 round of MDA were not found to have circulating antigens of Wb. The study showed that all the surveyed districts, except for Chibombo, passed pre-TAS. This further implies that there is a need to conduct transmission assessment surveys (TASs) in these districts.

Assessing Geographic Overlap between Zero-Dose Diphtheria-Tetanus-Pertussis Vaccination Prevalence and Other Health Indicators.

The integration of immunization with other essential health services is among the strategic priorities of the Immunization Agenda 2030 and has the potential to improve the effectiveness, efficiency, and equity of health service delivery. This study aims to evaluate the degree of spatial overlap between the prevalence of children who have never received a dose of the diphtheria-tetanus-pertussis-containing vaccine (no-DTP) and other health-related indicators, to provide insight into the potential for joint geographic targeting of integrated service delivery efforts. Using geospatially modeled estimates of vaccine coverage and comparator indicators, we develop a framework to delineate and compare areas of high overlap across indicators, both within and between countries, and based upon both counts and prevalence. We derive summary metrics of spatial overlap to facilitate comparison between countries and indicators and over time. As an example, we apply this suite of analyses to five countries-Nigeria, Democratic Republic of the Congo (DRC), Indonesia, Ethiopia, and Angola-and five comparator indicators-children with stunting, under-5 mortality, children missing doses of oral rehydration therapy, prevalence of lymphatic filariasis, and insecticide-treated bed net coverage. Our results demonstrate substantial heterogeneity in the geographic overlap both within and between countries. These results provide a framework to assess the potential for joint geographic targeting of interventions, supporting efforts to ensure that all people, regardless of location, can benefit from vaccines and other essential health services.

Integrated survey of helminthic neglected tropical diseases and comparison of two mosquito sampling methods for lymphatic filariasis molecular xenomonitoring in the River Galana area, Kilifi County, coastal Kenya.

A lymphatic filariasis (LF) endemic focus along the River Galana/ Sabaki in Kilifi County, coastal Kenya, provided a platform to conduct an integrated survey for three helminthic neglected tropical diseases (NTDs), namely soil-transmitted helminthiasis (STH), schistosomiasis (SCH) and LF. Additionally, the study compared the performance of two mosquito trapping methods for LF molecular xenomonitoring (MX). Cross-sectional surveys measuring STH, SCH and LF prevalence were conducted in four villages. Mosquitoes were trapped using the CDC light trap (CDC-LT) and the Ifakara A tent trap (Ifakara-TT) methods and stored in pools which were tested for Wuchereria bancrofti DNA using the real-time polymerase chain reaction assay. A total of 907 people (436 adults; 471 children) participated in the parasitological testing. Among the STH infections, Trichuris trichiura and hookworms were most prevalent among the children and adult populations, respectively. The schistosome worm eggs detected belonged to the species Schistosoma haematobium and the prevalence of the infection was generally higher among the children compared with the adult population. The prevalence of LF infection among the adult population ranged from 1.8% to 7.6% across all 4 villages (P < 0.05). A total of 3,652 mosquitoes, including Anopheles, Culex, Mansonia, and Aedes species were collected. One mosquito pool consisting of Anopheles mosquitoes tested positive for filarial DNA out of 1,055 pools that were tested. The CDC-LT caught significantly more mosquitoes compared with the Ifakara-TT (P < 0.001). This study demonstrated that integrated epidemiological surveys using standard parasitological and entomological methods can provide useful information on co-endemic parasitic diseases which could help direct interventions and surveillance activities.

Assessment of the progress toward elimination of lymphatic filariasis in the Federal Capital Territory- Abuja, Nigeria

Lymphatic filariasis (LF) is a neglected tropical disease caused by threadlike worms (nematodes) that live in the lymphatic vessels of humans. Although three species of filarial parasites (Wuchereria bancrofti, Brugia malayi and Brugia timori) infect humans; 90% of infection is caused by Wuchereria Bancrofti and humans are its exclusive host. Nigeria is one of over 70 countries endemic for Lymphatic filariasis with an estimated 134 million people at the risk of infection. The Federal Capital Territory (FCT), which is endemic for LF, commenced mass drug administration (MDA) using ivermectin (IVM) and albendazole (ALB) in 2011. While MDA is continuing in two Area Councils, in 2020, we assessed the impact of MDA on LF prevalence in two area councils that had achieved five effective annual rounds of MDA. In 2010, a baseline mapping exercise was conducted in all six area councils of FCT-Abuja. The results revealed that four out of the six area councils were endemic for LF, with prevalence ranging from 1.0%-4.0%. The number of persons treated with ivermectin and albendazole in the four Area Councils was documented during annual MDA and population-based cluster surveys were conducted at least once in each area council during the five years of treatment, to verify the reported geographic and programme MDA coverage. This is the number treated divided by the total population eligible to receive treatment (usually &amp;lt;5years). The survey results confirmed that in two area councils (Abaji and Kuje) the coverage exceeded the target of 65% the while two other Councils did not reach the recommended coverage. A pre-transmission assessment survey (pre-TAS) was conducted in one sentinel site and at least one spot check site in Abaji and Kuje in 2019 and were found to have LF antigenemia (LF Ag) &amp;lt; 2% (range 0.0% to 1.99%). In 2020, transmission assessment surveys (TAS) were conducted in the two area councils that previously passed the Pre-transmission assessment survey. The results showed that the two Evaluation units had achieved the LF Ag threshold required to stop MDA. FCT has made significant progress towards LF elimination with two Area Councils qualifying to stop treatment. However, two other area councils still require a further two years of mass drug administration with effective MDA coverage before these area councils qualify for impact assessment.

The Spatial-Temporal Distribution of Chronic Lymphatic Filariasis in Indonesia: A 18-Year Registry-Based Analysis

Lymphatic filariasis (LF) is a vector-borne disease caused by parasitic helminths and constitutes a serious public health issue in tropical regions. According to the World Health Organization (WHO), infected cases in Southeast Asia constitute 50% of the estimated 120 million infections globally. In Indonesia, LF is caused by all filarial species, and in 2018, 236 districts of a total of 514 districts in the entire country were declared as endemic areas. The global program to eliminate filariasis has been running for the last 19 years and has been conducted as a full national initiative for the last eight years in Indonesia. The study describes the surveillance of LF cases and prevalence in Indonesia for the past 17 years (2001–2017)—during the global and national LF elimination programs—using national registry-based data. The data demonstrate that the national program has been largely effective in the areas it has been active the longest, while there are provinces lagging behind in the successful suppression of LF. The high geographical fragmentation of the country, with the associated ecological parameters relating to LF incidence, likely play an important role in maintaining the highly varied incidence rate across Indonesia.

Step towards elimination of Wuchereria bancrofti in Southwest Tanzania 10 years after mass drug administration with Albendazole and Ivermectin.

BackgroundLymphatic filariasis is a mosquito transmitted parasitic infection in tropical regions. Annual mass treatment with ivermectin and albendazole is used for transmission control of Wuchereria bancrofti, the infective agent of lymphatic filariasis in many African countries, including Tanzania.MethodologyIn a general population study in Southwest Tanzania, individuals were tested for circulating filarial antigen, an indicator of W. bancrofti adult worm burden in 2009 before mass drug administration commenced in that area. Seven annual rounds with ivermectin and albendazole were given between 2009 and 2015 with a population coverage of over 70%. Participants of the previous study took part in a follow-up activity in 2019 to measure the effect of this governmental activity.FindingsOne thousand two hundred and ninety nine inhabitants of Kyela district in Southwest Tanzania aged 14 to 65 years who had participated in the study activities in 2009 were revisited in 2010/11 and 2019. Among this group, the prevalence of lymphatic filariasis of the 14–65 years olds in 2009 was 35.1%. A follow-up evaluation in 2010/11 had shown a reduction to 27.7%. In 2019, after 7 years of annual treatment and an additional three years of surveillance, the prevalence had dropped to 1.7%, demonstrating successful treatment by the national control programme. Risk factors for W. bancrofti-infection were the occupation as farmer, male sex, and older age. Most infected individuals in the 2019 follow-up study already had a positive test for filarial antigen in 2009 and/or 2010/11.ConclusionsThis data supports the findings of the Tanzanian Neglected Tropical Disease Control Programme (NTDCP), who conducted Transmission Assessment Surveys and found an impressive reduction in the prevalence of LF in children. Our results complement this data by showing a similar decrease in prevalence of LF in the adult population in the same area. The elimination of LF seems achievable in the near future.

Integrated transmission assessment surveys (iTAS) of lymphatic filariasis and onchocerciasis in Cross River, Taraba and Yobe States, Nigeria

BackgroundIntegrated transmission assessment surveys (iTAS) have been recommended for evaluation of the transmission of both lymphatic filariasis (LF) and onchocerciasis as the prevalence of both diseases moves toward their respective elimination targets in Nigeria. Therefore, we conducted an iTAS between May and December 2017 in five local government areas (LGAs), also known as implementation units (IUs), in states of Cross River, Taraba and Yobe in Nigeria.MethodsThe TAS comprised two phases: the Pre-iTAS and the iTAS itself. Three states (Cross River, Taraba and Yobe), comprising five LGAs and 20 communities that have completed five rounds of combined treatment with ivermectin and albendazole for LF and 12 total rounds of ivermectin, were selected for inclusion in the study. All participants were tested with the Filariasis Test Strip (FTS; Alere Inc.) and the Biplex rapid Diagnostic Test (RDT; identifying filaria antigens Ov16/Wb123; Abbott diagnosctics Korea Inc.). Pre iTAS included 100 children ages 5-9 in each 4 communities and 300 individuals ages 10 and older in a subset of two communities. For the iTAS, only LGAs where antigenemia prevalence in all sampled communities during the Pre-iTAS was < 2% for LF were selected.ResultsOf the five LGAs included in the study, four met the cutoff of the Pre-iTAS and were included in the iTAS; the Ikom LGA was excluded from the iTAS due to antigenemia prevalence. A total of 11,531 school-aged children from 148 schools were tested for LF and onchocerciasis across these four LGAs, including 2873 children in Bade, 2622 children in Bekwara, 3026 children in Gashaka and 3010 children in Karim Lamido. Using the FTS, all samples from Bade and Karim Lamido were negative, whereas 0.2% of the samples from Bekwara and Gashaka were positive. Using the Biplex RDT, LF prevalence in Bade, Bekwara, Gashaka and Karim Lamido was < 0.1%, 0.5%, 0.4% and < 0.1%, respectively. Moreover, all samples from Bade and Karim Lamido were negative for onchocerciasis, whereas 3.1% and 1.8% of the samples from Bekwara and Gashaka were positive, respectively.ConclusionThis study has provided additional information on the current burden of onchocerciasis and LF in the four IUs sampled where mass drug administration (MDA) for both infections has been ongoing for years. The study identifies that LF-MDA can be safely stopped in all four of the IUs studied, but that MDA for onchocerciasis needs to continue, even though this may pose a challenge for LF surveillance. Based on the preliminary results from all four sites, this study has fulfilled the primary objective of determining the programmatic feasibility of an iTAS as a tool to simultaneously assess onchocerciasis and LF prevalence in areas co-endemic for the two infections that have completed the recommended treatment for one or both infections, and to make decisions on how to proceed.Graphical

Mapping Spatial Variation and Impact of the National MDA Program on Lymphatic Filariasis Elimination in Ghana: An Initial Study

Lymphatic filariasis (LF) is a public health menace, especially in developing countries. A periodic review of mass drug administration (MDA) performance is critical to monitoring elimination progress. However, investigating the spatial pattern of LF with respect to MDA intervention is yet to be documented. This is essential to appreciating the transmission dynamics across LF-endemic communities and how it is spatially impacted by MDA programs. The aim of this study was to map and explore the spatial variation and hotspots of LF infection among endemic communities and evaluate the impact of the MDA intervention program on its spatial pattern in Ghana. Relative risks, clustering and clusters, prevalence odds ratios, and their confidence intervals were studied with community-level LF data prior to intervention and post intervention periods. The overall risk of LF infection was 0.12% and 0.02% before and after MDA, respectively, suggesting reduced transmission. Using empirical Bayesian smoothing to map the relative risk, a substantial variation in the spatial distribution of the relative risk of LF among endemic communities was observed. Most of the excess prevalence communities were unexpectedly visible even after years of MDA. The Empirical Bayesian Moran’s Index for global clustering showed a reduction in clustering of LF prevalence after MDA with IM = 0.455 and 0.119 for before and after MDA, respectively. Furthermore, examining risks associated with ecological zones, it was observed that the Guinea Savannah and the Transition Zone were the most vulnerable zones for LF infection with prevalence odds ratios 18.70- and 13.20-fold higher than in the reference Moist evergreen zone, respectively. We observed a drastic reduction in risk in the Wet evergreen zone after MDA, while the Guinea Savannah sustained high levels of risk even after MDA. These findings should prompt public health officials to adopt stratified cluster sampling in LF-endemic regions to monitor the rate and density of microfilaria.

Simulating the effect of evaluation unit size on eligibility to stop mass drug administration for lymphatic filariasis in Haiti.

The Transmission Assessment Survey (TAS) is a decision-making tool to determine when transmission of lymphatic filariasis is presumed to have reached a level low enough that it cannot be sustained even in the absence of mass drug administration. The survey is applied over geographic areas, called evaluation units (EUs); existing World Health Organization guidelines limit EU size to a population of no more than 2 million people. In 2015, TASs were conducted in 14 small EUs in Haiti. Simulations, using the observed TAS results, were performed to understand the potential programmatic impact had Haiti chosen to form larger EUs. Nine "combination-EUs" were formed by grouping adjacent EUs, and bootstrapping was used to simulate the expected TAS results. When the combination-EUs were comprised of at least one "passing" and one "failing" EU, the majority of these combination-EU would pass the TAS 79% - 100% of the time. Even in the case when both component EUs had failed, the combination-EU was expected to "pass" 11% of the time. Simulations of mini-TAS, a strategy with smaller power and hence smaller sample size than TAS, resulted in more conservative "passing" and "failing" when implemented in original EUs. Our results demonstrate the high potential for misclassification when the average prevalence of lymphatic filariasis in the combined areas differs with regards to the TAS threshold. Of particular concern is the risk of "passing" larger EUs that include focal areas where prevalence is high enough to be potentially self-sustaining. Our results reaffirm the approach that Haiti took in forming smaller EUs. Where baseline or monitoring data show a high or heterogeneous prevalence, programs should leverage alternative strategies like mini-TAS in smaller EUs, or consider gathering additional data through spot check sites to advise EU formation.

Prevalence of soil-transmitted helminth infections, schistosomiasis, and lymphatic filariasis before and after preventive chemotherapy initiation in the Philippines: A systematic review and meta-analysis

ObjectiveTo estimate the impact of preventive chemotherapy on the prevalence and intensity of soil-transmitted helminth (STH) infections, schistosomiasis, and lymphatic filariasis in the Philippines, using systematic review and meta-analysis.MethodsWe included reports reporting prevalence of STH infections, schistosomiasis, or lymphatic filariasis in the Philippines published until 31 March 2021. Peer-reviewed studies were identified in electronic databases. Grey literature reports by the University of the Philippines and the Department of Health were also included. Pooled infection prevalence, before and after the initiation of preventive chemotherapy, stratified by age group, was calculated using the inverse variance heterogeneity model.FindingsA total of 109 reports were included in the review and meta-analysis. Overall prevalence of moderate-heavy intensity Ascaris lumbricoides (6.6%) and Trichuris trichiura (2.7%) infection after initiation of preventive chemotherapy were significantly lower than the prevalence prior to initiation (23.6% for A. lumbricoides and 12.2% for T. trichiura). Prevalence reductions were also found in school and preschool-age children for A. lumbricoides and T. trichiura. Studies conducted after preventive chemotherapy initiation had significantly lower overall prevalence of moderate-heavy intensity schistosomiasis (3.1% vs 0.2%) and of schistosomiasis in school-age children (30.5% vs 1%). Pooled prevalence of lymphatic filariasis prior to preventive chemotherapy initiation was 3.2% across 12 provinces, while currently only two provinces still have prevalence of more than 1%. There were no published studies reporting prevalence of lymphatic filariasis after initiation of preventive chemotherapy. Heterogeneity was high with I2 mostly above 90%.ConclusionThe burden of STH infections and schistosomiasis in children were significantly lower in studies conducted following the initiation of preventive chemotherapy. Eliminating morbidity and interrupting transmission, however, may require expanded control initiatives including community-wide treatment, and improved water, sanitation, and hygiene. Lymphatic filariasis burden has decreased since the implementation of preventive chemotherapy, with all but two provinces having reached the elimination of lymphatic filariasis as a public health problem.

Progress towards control and elimination of neglected tropical diseases targeted by preventive chemotherapy in São Tomé e Príncipe.

The São Tomé e Príncipe government is committed to achieving neglected tropical disease (NTD) control and elimination as a public health problem by 2025. In 2014, the Ministry of Health led a national survey to determine the prevalence of soil-transmitted helminths (STHs) and schistosomiasis across the country. Following this survey, a preventive chemotherapy (PC) campaign with mebendazole and praziquantel reached 31 501 school-age children in 2015. A follow-up 2017 survey to determine the impact of the intervention showed success in controlling schistosomiasis, as no infections were found, but limited impact on STHs, with prevalence similar to pretreatment levels. The survey also investigated the prevalence of a third NTD, lymphatic filariasis (LF), which was found to be endemic in the country. Since then the Ministry of Health has developed the Strategic Plan for the Fight Against Neglected Tropical Diseases 2019–2025 and identified gaps to be addressed. This narrative review systematises the existing literature reporting on the epidemiology of NTDs for which there are PC programs in São Tomé e Príncipe. PubMed was searched for relevant papers that measured the prevalence of LF, schistosomiasis and STHs. Additionally, data provided by the Ministry of Health surveys were analysed. Finally, we discuss current NTD control, including the impact of the coronavirus disease 2019 pandemic and identify priorities for program strengthening and operational research.