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The significant scale up and success of Transmission Assessment Surveys 'TAS' for endgame surveillance of lymphatic filariasis in Bangladesh: One step closer to the elimination goal of 2020.

ABSTRACT:

Background

Bangladesh had one of the highest burdens of lymphatic filariasis (LF) at the start of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) with an estimated 70 million people at risk of infection across 34 districts. In total 19 districts required mass drug administration (MDA) to interrupt transmission, and 15 districts were considered low endemic. Since 2001, the National LF Programme has implemented MDA, reduced prevalence, and been able to scale up the WHO standard Transmission Assessment Survey (TAS) across all endemic districts as part of its endgame surveillance strategy. This paper presents TAS results, highlighting the momentous geographical reduction in risk of LF and its contribution to the global elimination target of 2020.

Methodology/principal findings

The TAS assessed primary school children for the presence of LF antigenaemia in each district (known as an evaluation unit-EU), using a defined critical cut-off threshold (or 'pass') that indicates interruption of transmission. Since 2011, a total of 59 TAS have been conducted in 26 EUs across the 19 endemic MDA districts (99,148 students tested from 1,801 schools), and 22 TAS in the 15 low endemic non-MDA districts (36,932 students tested from 663 schools). All endemic MDA districts passed TAS, except in Rangpur which required two further rounds of MDA. In total 112 students (male n = 59; female n = 53), predominately from the northern region of the country were found to be antigenaemia positive, indicating a recent or current infection. However, the distribution was geographically sparse, with only two small focal areas showing potential evidence of persistent transmission.

Conclusions/significance

This is the largest scale up of TAS surveillance activities reported in any of the 73 LF endemic countries in the world. Bangladesh is now considered to have very low or no risk of LF infection after 15 years of programmatic activities, and is on track to meet elimination targets. However, it will be essential that the LF Programme continues to develop and maintain a comprehensive surveillance strategy that is integrated into the health infrastructure and ongoing programmes to ensure cost-effectiveness and sustainability.

SUBMITTER: Shamsuzzaman AK

PROVIDER: S-EPMC5302837 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature

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The significant scale up and success of Transmission Assessment Surveys 'TAS' for endgame surveillance of lymphatic filariasis in Bangladesh: One step closer to the elimination goal of 2020.

Shamsuzzaman A K M AK Haq Rouseli R Karim Mohammad J MJ Azad Motasim B MB Mahmood A S M Sultan AS Khair Abul A Rahman Muhammad Mujibur MM Hafiz Israt I Ramaiah K D KD Mackenzie Charles D CD Mableson Hayley E HE Kelly-Hope Louise A LA

PLoS neglected tropical diseases 20170131 1

<h4>Background</h4>Bangladesh had one of the highest burdens of lymphatic filariasis (LF) at the start of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) with an estimated 70 million people at risk of infection across 34 districts. In total 19 districts required mass drug administration (MDA) to interrupt transmission, and 15 districts were considered low endemic. Since 2001, the National LF Programme has implemented MDA, reduced prevalence, and been able to scale up the WHO stand ...[more]

PMID: 28141812

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Project description:BackgroundThe Bangladesh Lymphatic Filariasis (LF) Elimination Programme has made significant progress in interrupting transmission through mass drug administration (MDA) and has now focussed its efforts on scaling up managing morbidity and preventing disability (MMDP) activities to deliver the minimum package of care to people affected by LF clinical conditions. This paper highlights the Bangladesh LF Programme's success in conducting a large-scale cross-sectional survey to determine the number of people affected by lymphoedema and hydrocoele, which enabled clinical risk maps to be developed for targeted interventions across the 34 endemic districts (19 high endemic; 15 low endemic).Methodology/principal findingsIn the 19 high endemic districts, 8,145 community clinic staff were trained to identify and report patients in their catchment area. In the 15 low endemic districts, a team of 10 trained field assistants conducted active case finding with cases reported via a SMS mHealth tool. Disease burden and prevalence maps were developed, with morbidity hotspots identified at sub-district level based on a combination of the highest prevalence rates per 100,000 and case-density rates per square kilometre (km2). The relationship between morbidity and baseline microfilaria (mf) prevalence was also examined. In total 43,678 cases were identified in the 19 high endemic districts; 30,616 limb lymphoedema (70.1%; female 55.3%), 12,824 hydrocoele (29.4%), and 238 breast/female genital swelling (0.5%). Rangpur Division reported the highest cases numbers and prevalence of lymphoedema (26,781 cases, 195 per 100,000) and hydrocoele (11661 cases, 169.6 per 100,000), with lymphoedema predominately affecting females (n = 21,652). Rangpur and Lalmonirhat Districts reported the highest case numbers (n = 11,199), and prevalence (569 per 100,000) respectively, with five overlapping lymphoedema and hydrocoele sub-district hotspots. In the 15 low endemic districts, 732 cases were identified; 661 lymphoedema (90.2%; female 39.6%), 56 hydrocoele (7.8%), and 15 both conditions (2.0%). Spearman's correlation analysis found morbidity and mf prevalence significantly positively correlated (r = 0.904; p<0.01).Conclusions/significanceThe Bangladesh LF Programme has developed one of the largest, most comprehensive country databases on LF clinical conditions in the world. It provides an essential database for health workers to identify local morbidity hotspots, deliver the minimum package of care, and address the dossier elimination requirements.

Project description:BACKGROUND: The Global Programme to Eliminate Lymphatic Filariasis, launched following World Health Assembly Resolution 50.29 (WHA 50.29), has been facilitated in its progress by new research findings, drug donations, the availability of diagnostic tools, disability management strategies to help those already suffering and the development of partnerships. The strategy recommended by the World Health Organization of annual treatment with a two-drug combination has proved safe. DISCUSSION: Using different approaches in several countries the elimination of lymphatic filariasis (LF) has been demonstrated to be feasible during earlier decades. These successes have been largely overlooked. However, the programme progress since 2000 has been remarkable - upscaling rapidly from 2 million treatments in 2000 to approximately 60 million in 2002. Around 34 countries had active programmes at the end of 2002. It is anticipated that there will be further expansion - but this will be dependent on additional resources becoming available. The programme also provides significant opportunities for other disease control programmes to deliver public health benefits on a large scale. Few public health programmes have upscaled so rapidly and so cost-effectively (<$0.03/treatment in some Asian settings) - one country treating 9-10 million people in a day (Sri Lanka). The LF programme is arguably the most effective pro-poor public health programme currently operating which is based on country commitment and partnerships supported by a global programme and alliance. Tables are provided to summarize programme characteristics, the benefits of LF elimination, opportunities for integration with other programmes and relevance to the Millennium Development Goals. SUMMARY: Lymphatic filariasis elimination is an "easy-to-do" inexpensive health intervention that provides considerable "beyond filariasis" benefits, exemplifies partnership and is easily evaluated. The success in global health action documented in this paper requires and deserves further support to bring to fruition elimination of lymphatic filariasis as a public health problem and health benefits to poor people. A future free of lymphatic filariasis will reduce poverty and bring better health to poor people, prevent disability, strengthen health systems and build partnerships.

Project description:BACKGROUND:Lymphatic filariasis (LF) is endemic in Ghana, and the country has implemented the GPELF strategy since 2000 with significant progress made in the control of the disease. However, after several years of mass drug administration (MDA) implementation, there is persistent transmission in 17 of the 98 endemic districts in the country. Current approaches to surveillance are clearly unable to target untreated individuals and new strategies are required to address the endgame challenges to enhance LF elimination as a public health problem in endemic countries. Community registers are used during MDAs to enumerate community members, their age, gender, house numbers, and records of their participation in MDAs. These MDA registers represent an untapped opportunity to identify and characterize non-compliance and inform appropriate programmatic actions. In this study, we analyzed the data presented in the registers to assess the coverage and individuals' compliance in MDA. METHODS:The information in the MDA registers were assessed to verify the reported coverages obtained from the district. The community registers were obtained from the district health offices and the data from each individual record was entered into a database. A simple questionnaire was used to cross-check the participation of study participants in the 2017 MDA. The questionnaire solicited data on: participation in the 2017 MDA, reasons for not taking part in the MDA, adverse events experienced, what was done for the adverse events, and willingness to participate in subsequent MDAs. RESULTS:We found that 40.1% of the population in the registers missed at least one MDA in 3 years (2016-2018) and the majority of them were between 10-30 years of age. The results of the questionnaire assessment indicated that 13.8% of the respondents did not receive treatment in 2017 for various reasons, the most prominent among them being "absence/travel" (37.1%). Data in the registers were used to verify the treatment coverage for the years 2017 and 2018, and reviewed against the reported coverage obtained from the district. Significant differences between the reported and verified coverages were only observed in four communities. However, the assessment also revealed that the reported coverage was only accurate in 33.3% of cases. CONCLUSIONS:The MDA registers allow for the identification of eligible individuals who were not reached during any MDA round. Thus, the MDA registers could be utilized at the community and programme levels to identify missing and untreated individuals, appropriately address their non-compliance to MDA, and thereby improve MDA coverage in each implementation unit and monitor the progress towards elimination of LF. The challenges observed through the review of the registers also offer opportunities to improve the training given to the community drug distributors.

Project description:The Global Programme to Eliminate Lymphatic Filariasis has made significant progress toward interrupting transmission of lymphatic filariasis (LF) through mass drug administration (MDA). Operational challenges in defining endpoints of elimination programs include the need to determine appropriate post-MDA surveillance strategies. As humans are the only reservoirs of LF parasites, one such strategy is molecular xenomonitoring (MX), the detection of filarial DNA in mosquitoes using molecular methods (PCR), to provide an indirect indicator of infected persons nearby. MX could potentially be used to evaluate program success, provide support for decisions to stop MDA, and conduct post-MDA surveillance. American Samoa has successfully completed MDA and passed WHO recommended Transmission Assessment Surveys in 2011 and 2015, but recent studies using spatial analysis of antigen (Ag) and antibody (Ab) prevalence in adults (aged ?18 years) and entomological surveys showed evidence of possible ongoing transmission. This study evaluated MX as a surveillance tool in American Samoa by linking village-level results of published human and mosquito studies. Of 32 villages, seropositive persons for Og4C3 Ag were identified in 11 (34.4%), for Wb123 Ab in 18 (56.3%) and for Bm14 Ab in 27 (84.4%) of villages. Village-level seroprevalence ranged from 0-33%, 0-67% and 0-100% for Og4C3 Ag, Wb123 Ab and Bm14 Ab respectively. PCR-positive Aedes polynesiensis mosquitoes were found in 15 (47%) villages, and their presence was significantly associated with seropositive persons for Og4C3 Ag (67% vs 6%, p<0.001) and Wb123 Ab (87% vs 29%, p = 0.001), but not Bm14 Ab. In villages with persons seropositive for Og4C3 Ag and Wb123 Ab, PCR-positive Ae. polynesiensis were found in 90.9% and 72.2% respectively. In villages without seropositive persons for Og4C3 Ag or Wb123 Ab, PCR-positive Ae. polynesiensis were also absent in 94.1% and 70.6% of villages respectively. Our study provides promising evidence to support the potential usefulness of MX in post-MDA surveillance in an Aedes transmission area in the Pacific Islands setting.

Project description:BackgroundLymphatic filariasis (LF) is targeted for global elimination through treatment of entire at-risk populations with repeated annual mass drug administration (MDA). Essential for program success is defining and confirming the appropriate endpoint for MDA when transmission is presumed to have reached a level low enough that it cannot be sustained even in the absence of drug intervention. Guidelines advanced by WHO call for a transmission assessment survey (TAS) to determine if MDA can be stopped within an LF evaluation unit (EU) after at least five effective rounds of annual treatment. To test the value and practicality of these guidelines, a multicenter operational research trial was undertaken in 11 countries covering various geographic and epidemiological settings.MethodologyThe TAS was conducted twice in each EU with TAS-1 and TAS-2 approximately 24 months apart. Lot quality assurance sampling (LQAS) formed the basis of the TAS survey design but specific EU characteristics defined the survey site (school or community), eligible population (6-7 year olds or 1(st)-2(nd) graders), survey type (systematic or cluster-sampling), target sample size, and critical cutoff (a statistically powered threshold below which transmission is expected to be no longer sustainable). The primary diagnostic tools were the immunochromatographic (ICT) test for W. bancrofti EUs and the BmR1 test (Brugia Rapid or PanLF) for Brugia spp. EUs.Principal findings/conclusionsIn 10 of 11 EUs, the number of TAS-1 positive cases was below the critical cutoff, indicating that MDA could be stopped. The same results were found in the follow-up TAS-2, therefore, confirming the previous decision outcome. Sample sizes were highly sex and age-representative and closely matched the target value after factoring in estimates of non-participation. The TAS was determined to be a practical and effective evaluation tool for stopping MDA although its validity for longer-term post-MDA surveillance requires further investigation.

Project description:BackgroundTo secure the gains of lymphatic filariasis (LF) elimination programs, attention is needed to the 'residual microfilaremia phase', in which high-risk populations may be crucial. The present study documents the impact of mass drug administration (MDA) in the urban Indian setting of Surat City, with high rates of in-migration.MethodsEpidemiological assessment included National Filaria Control Program (NFCP) and World Health Organization recommended routine and pre-MDA microfilaremia surveys respectively. Routine filaria surveys were conducted around the year in approximately 2000-4000 people per month, while pre-MDA surveys were carried out annually among approximately 4000 people from four fixed and four random sites. In 2016, Transmission Assessment Survey (TAS) was done in primary school children. The outcomes were microfilaremia (Mf) and antigen prevalence; more specifically, microfilaremia according to place of birth, in pre-MDA and routine night blood smears (NBS) collected from 2008 to 2015. Prevalence ratios and confidence intervals were calculated.ResultsA total of 25 480 pre-MDA and 306 198 routine NBS were examined during the study. In 2008, the Mf prevalence in the routine survey was 63/18 814 (0.33%), declining to 23/39 717 (0.06%) in 2016. Pre-MDA surveys showed a similar decrease from 47/4184 (1.1%) in 2008 to 12/4042 (0.3%) in 2015. In those born outside Surat, microfilaremia decreased below transmission thresholds, but remained more than treble that of the remainder of the population, in both the pre-MDA surveys [prevalence ratio: 3.17, 95% confidence interval (CI): 1.15-8.72], and the routine surveys (3.31, 95% CI: 1.47-7.48). Though the TAS results indicated that MDA endpoints had been reached, sub-group analysis identified that 90% of antigenemic children were from families of high-risk groups.ConclusionsExtensive long-term epidemiological monitoring suggests that all the urban population, including high-risk groups, have benefitted from the ELF program. To prevent re-establishment of infection in large urban areas with unsanitary conditions conducive to filarial vector breeding, there is need to identify residual microfilaremia by customized surveys in addition to pre-MDA monitoring and TAS. The present findings can be used to develop strategies to prioritize screening, surveillance and plan treatment of high-risk groups after achieving MDA endpoints.

Project description:BackgroundThe prevalence of Wuchereria bancrofti, which causes lymphatic filariasis (LF) in The Gambia was among the highest in Africa in the 1950s. However, surveys conducted in 1975 and 1976 revealed a dramatic decline in LF endemicity in the absence of mass drug administration (MDA). The decline in prevalence was partly attributed to a significant reduction in mosquito density through the widespread use of insecticidal nets. Based on findings elsewhere that vector control alone can interrupt LF, we asked the question in 2013 whether the rapid scale up in the use of insecticidal nets in The Gambia had interrupted LF transmission.Methodology/principal findingWe present here the results of three independently designed filariasis surveys conducted over a period of 17 years (1997-2013), and involving over 6000 subjects in 21 districts across all administrative divisions in The Gambia. An immunochromatographic (ICT) test was used to detect W. bancrofti antigen during all three surveys. In 2001, tests performed on stored samples collected between 1997 and 2000, in three divisions, failed to show positive individuals from two divisions that were previously highly endemic for LF, suggesting a decline towards extinction in some areas. Results of the second survey conducted in 2003 showed that LF was no longer endemic in 16 of 21 districts surveyed. The 2013 survey used a WHO recommended LF transmission verification tool involving 3180 6-7 year-olds attending 60 schools across the country. We demonstrated that transmission of W. bancrofti has been interrupted in all 21 districts.ConclusionsWe conclude that LF transmission may have been interrupted in The Gambia through the extensive use of insecticidal nets for malaria control for decades. The growing evidence for the impact of malaria vector control activities on parasite transmission has been endorsed by WHO through a position statement in 2011 on integrated vector management to control malaria and LF.

Project description:BackgroundFollowing the World Health Assembly resolution on Elimination of lymphatic filariasis (ELF) as a public health problem by the year 2020, a Global Program (GPELF) was launched in 1997 to help endemic countries to initiate national programs. The current strategy to interrupt transmission of LF, is administration of once-yearly, single-dose, two-drug regimen (Albendazole with Diethylcarbamazine (DEC) to be used in endemic areas with the goal of reaching 65% epidemiological coverage for 4-6 years. We report findings of independent assessment from year 2010 to 2015 for last six rounds, after initial five rounds of Mass Drug Administration (MDA) since 2005 for ELF in endemic area of Gujarat.MethodsIndependent assessment of MDA was performed to find coverage and compliance indicators, reasons for non-coverage and non-compliance in five Implementation Units (IUs). Pre, during and post MDA evaluations were done in three phases. The impact of MDA was measured by microfilaraemia survey. A total of eight sites, four random and four fixed sentinel sites were selected to calculate microfilaria rate (MF) per IUs per year. In years 2010 to 2015, we report results from 125,936 nocturnal blood smears and 17551 population in 120 selected clusters. Four clusters were selected per year in each of the five IUs for assessment of MDA round.ResultPost MDA survey showed drug coverage between 81%-88% and epidemiological coverage 77%-89% across years. Main reasons for non-coverage were drug administrator related (the team did not visit or missed people) while non-compliance was population related (fear of side effects, sickness, people forgot or absent). During MDA findings show that the directly observed consumption is considerably improved from 58% in 2010 to 82% in 2015. The knowledge about benefits of drug provided also increased from 59% to 90% over the years. The current MF rate is less than one in all IUs with an overall 68% percent decrease from baseline year 2005 to year 2015. The average MF rate of Gujarat is 0.44 for year 2015.ConclusionsThe findings show that achieving adequate epidemiological and drug coverage is possible by actual field level operation of the program in large endemic areas. The results and feedback from independent assessment, performed regularly, could guide the policymakers and program managers for mid-term corrections and to frame strategies to enhance program. Monitoring of coverage and impact indicator together informs decisions for reaching end-point of MDA. The impact indicator- microfilaria rate in all IUs of South Gujarat Region has reached and remained less than one percent signaling end-points of MDA. Post MDA stringent monitoring in form of TAS is recommended to keep vigil on maintenance of elimination achieved.

Dataset Information

The significant scale up and success of Transmission Assessment Surveys 'TAS' for endgame surveillance of lymphatic filariasis in Bangladesh: One step closer to the elimination goal of 2020.

Background

Methodology/principal findings

Conclusions/significance

Publications

The significant scale up and success of Transmission Assessment Surveys 'TAS' for endgame surveillance of lymphatic filariasis in Bangladesh: One step closer to the elimination goal of 2020.

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