Evaluation of Mass Drug Administration Impact on Transmission of Lymphatic Filariasis in 13 Sanitary Districts in Burkina Faso

Introduction: Lymphatic filariasis (LF) is one of the neglected tropical diseases targeted for elimination as a public health issue in the world by 2020. To achieve this goal, one of the strategies is interruption of transmission using chemotherapy (mass drug administration). Burkina Faso in west Africa, an endemic country, has endorsed this resolution. In 2000, all Sanitary Districts (SD) in the country were endemic, and then a national elimination program has made it possible to stop mass treatment in 45 out of 70 SD over 12 years. Sixteen years later, 13 other SD were reeligible for Transmission Assessment Surveys (TAS). This study aimed to determine the current level of the Mass drugs Administration (MDA) impact indicators in these 13 targeted SD in order to decide whether we need to continue MDA. Method: It was a descriptive study that took place from June to September 2017 in 13 SD regrouped into 7 Evaluation Units (EU). The population of the study was 6 to 7 years old children. The community-based cluster survey method was used. The diagnostic test used to detect Wuchereria bancrofti’s circulating antigen (W. bancrofti) is the Filariasis Test Strip (FTS). The critical threshold of positivity was set at 18 positive subjects per EU. Results: We sampled a total of 12,060 children, 48.9% were female and 51.1% male. In the 7 EU, 13 children were positive to W. bancrofti test. The average antigenic prevalence was 0.11% (13/12,060). In all EU, the number of positive subjects was below the critical threshold. Conclusion: At the end of this evaluation of the transmission of lymphatic filariasis in 13 SD of Burkina Faso, we can tell the MDA could be stopped in these areas without risk of resurgence of the disease, according to the current recommendations of WHO. This can be possible by setting up post-TMM surveillance, considering migratory flows, and including villages where positive cases were found to search possible residual transmission zones.

Lessons from lymphatic filariasis elimination and the challenges of post-elimination surveillance in China

Background:The Global Programme to Eliminate Lymphatic Filariasis(GPELF)was launched in response to the call proposed at the 50th World Health Assembly.The goal of the GPELF is to ensure that all the countries where the disease is endemic would have been transmission-free or would have entered post-intervention mass drug administration(MDA)surveillance by 2020.However,several countries are still not on track to discontinue MDA as planned.Thus,issues remain regarding the achievement of stated goals and how to effectively monitor the disease in the post-control and post-elimination phases.Main text:China was once a lymphatic filariasis(LF)endemic country with heavy disease burden.There were three milestones in the LF control phase of China,including:the proposal that the major focus of the control strategy should be on infectious sources;the three regimens of diethylcarbamazine(DEC)administration according to LF endemic extent;and the establishment of the threshold for LF transmission interruption.It has been ten years since China entered the post-elimination stage(declaration of LF elimination in China was in 2007).Two schemes and a diagnostic criterion were issued to guide all levels of disease control and prevention workers that conduct LF surveillance,as well as those caring for chronic filariasis patients.Regular training courses are held to maintain LF control skills in grass-root institutions.The Notifiable Diseases Reporting System,which included LF in 2004,plays an important role in LF post-elimination surveillance.Until now,no resurgence of LF cases has been detected,except for LF residue foci being found in Fuchuan County of the Guangxi Zhuang Autonomous Region.To confirm that transmission is no longer achievable after a decade since the declaration of LF elimination in China,it is expected within the next two years a transmission assessment survey,conducted in previous LF-endemic areas.Conclusions:DEC-fortified salt can help accelerate the progress of GPELF before the sprite phase.Sophisticated diagnostic criteria,systematic surveillance regimes,the Direct Network Report system,and regular trainings can effectively prevent the recrudescence of LF during surveillance phases.

Mapping and modelling the impact of mass drug adminstration on filariasis prevalence in Myanmar

Background:Lymphatic filariasis(LF)is endemic in Myanmar and targeted for elimination.To highlight the National Programme to Eliminate Lymphatic Filariasis(NPELF)progress between 2000 and 2014,this paper describes the geographical distribution of LF,the scale-up and impact of mass drug administration(MDA)implementation,and the first evidence of the decline in transmission in five districts.Methods:The LF distribution was determined by mapping historical and baseline prevalence data collected by NPELF.Data on the MDA implementation,reported coverage rates and sentinel site surveillance were summarized.A statistical model was developed from the available prevalence data to predict prevalence at township level by year of measurement.Transmission assessment survey(TAS)methods,measuring antigenemia(Ag)prevalence in children,were used to determine whether prevalence was below a level where recrudescence is unlikely to occur.Results:The highest baseline LF prevalence was found in the Central Valley region.The MDA implementation activities scaled up to cover 45 districts,representing the majority of the endemic population,with drug coverage rates ranging from 60.0%to 98.5%.Challenges related to drug supply and local conflict were reported,and interrupted MDA in some districts.Overall,significant reductions in LF prevalence were found,especially after the first 2 to 3 rounds of MDA,which was supported by the corresponding model.The TAS activities in five districts found only two Ag positive children,resulting in all districts passing the critical threshold.Conclusion:Overall,the Myanmar NPELF has made positive steps forward in the elimination of LF despite several challenges,however,it needs to maintain momentum,drawing on international stakeholder support,to aim towards the national and global goals of elimination.