Comparing antigenaemia- and microfilaraemia as criteria for stopping decisions in lymphatic filariasis elimination programmes in Africa
Wilma A. Stolk,Luc E. Coffeng,Fatorma K. Bolay,Obiora A. Eneanya,Peter Fischer,T. Déirdre Hollingsworth,Benjamin G. Koudou,Aboulaye Meite,Edwin Michael,Joaquin M. Prada,Rocio Caja Rivera,Swarn Lata Sharma,Panayiota Touloupou,Gary J. Weil,Sake J. de Vlas +14 more
TL;DR: In this paper , the authors used mathematical modelling to investigate the validity of different thresholds regarding testing method and age group for African MDA programs using ivermectin plus albendazole.
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Abstract: Background Mass drug administration (MDA) is the main strategy towards lymphatic filariasis (LF) elimination. Progress is monitored by assessing microfilaraemia (Mf) or circulating filarial antigenaemia (CFA) prevalence, the latter being more practical for field surveys. The current criterion for stopping MDA requires <2% CFA prevalence in 6- to 7-year olds, but this criterion is not evidence-based. We used mathematical modelling to investigate the validity of different thresholds regarding testing method and age group for African MDA programmes using ivermectin plus albendazole. Methodolgy/Principal findings We verified that our model captures observed patterns in Mf and CFA prevalence during annual MDA, assuming that CFA tests are positive if at least one adult worm is present. We then assessed how well elimination can be predicted from CFA prevalence in 6-7-year-old children or from Mf or CFA prevalence in the 5+ or 15+ population, and determined safe (>95% positive predictive value) thresholds for stopping MDA. The model captured trends in Mf and CFA prevalences reasonably well. Elimination cannot be predicted with sufficient certainty from CFA prevalence in 6-7-year olds. Resurgence may still occur if all children are antigen-negative, irrespective of the number tested. Mf-based criteria also show unfavourable results (PPV <95% or unpractically low threshold). CFA prevalences in the 5+ or 15+ population are the best predictors, and post-MDA threshold values for stopping MDA can be as high as 10% for 15+. These thresholds are robust for various alternative assumptions regarding baseline endemicity, biological parameters and sampling strategies. Conclusions/Significance For African areas with moderate to high pre-treatment Mf prevalence that have had 6 or more rounds of annual ivermectin/albendazole MDA with adequate coverage, we recommend to adopt a CFA threshold prevalence of 10% in adults (15+) for stopping MDA. This could be combined with Mf testing of CFA positives to ensure absence of a significant Mf reservoir for transmission.
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Citations
Heterogeneity in elimination efforts could increase the risk of resurgence of lymphatic filariasis in Madagascar
Elinambinina Rajaonarifara,Benjamín Roche,Cédric B. Chesnais,Holivololona Rabenantoandro,Michelle Evans,Andrés Garchitorena +5 more
TL;DR: Heterogeneity in elimination efforts could increase the risk of resurgence of lymphatic filariasis in Madagascar. Differences in age-specific compliance with mass drug administration (MDA) better explained the observed heterogeneity in LF prevalence than differences in exposure alone. The risk of resurgence associated with differences in MDA compliance scenarios ranged from 0 to 19%.
3
Reducing the Antigen Prevalence Target Threshold for Stopping and Restarting Mass Drug Administration for Lymphatic Filariasis Elimination: A Model-Based Cost-effectiveness Simulation in Tanzania, India and Haiti
Mary Chriselda,Antony Oliver,Matt Graham,K. Gass,Graham F Medley,Jessica Clark,E. Davis,Lisa J. Reimer,Jonathan D King,Koen B. Pouwels,T. D. Hollingsworth +10 more
TL;DR: Lower Ag thresholds for stopping MDAs generally mean a higher probability of local elimination, reducing long-term costs and health impacts, however, they may also lead to an increased number of MDA rounds required to reach the lower threshold and, therefore, increased short-term costs.
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Improving the Cost-efficiency of Preventive Chemotherapy: Impact of New Diagnostics on Stopping Decisions for Control of Schistosomiasis
Luc E. Coffeng,Matthew Graham,Raiha Browning,Klodeta Kura,Peter J. Diggle,Matthew Denwood,Graham F. Medley,Roy M. Anderson,Sake J. de Vlas +8 more
TL;DR: More sensitive diagnostics improve stopping decisions for control of schistosomiasis but come at a cost of continuing PC for longer.
2
Predictive Value of Microfilariae-Based Stop-MDA Thresholds After Triple Drug Therapy With IDA Against Lymphatic Filariasis in Treatment-Naive Indian Settings
Ananthu James,Luc E. Coffeng,David J. Blok,Jonathan King,Sake J. de Vlas,Wilma A. Stolk +5 more
TL;DR: The predictive value of microfilariae-based stop-MDA thresholds after triple drug therapy with IDA against lymphatic filariasis in treatment-naive Indian settings is high for high MDA coverage and increases with additional TAS-es.
2
The predictive value of microfilariae-based stop-MDA thresholds after triple drug therapy with IDA in treatment-naiÌve Indian settings
Ananthu James,Luc E. Coffeng,David J. Blok,Jonathan D. King,S. D. Vlas,Wilma A. Stolk +5 more
TL;DR: How the probability of eventually reaching elimination of transmission depends on the critical threshold used in transmission assessment surveys (TAS-es) to define whether transmission was successfully suppressed and triple-drug MDA can be stopped is assessed.
2
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TL;DR: The issues addressed below include what has driven the LF Elimination Programme to this point, what will be required to sustain its momentum, and what will its impact be.
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Morbidity management in the Global Programme to Eliminate Lymphatic Filariasis: a review of the scientific literature
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Laboratory and Field Evaluation of a New Rapid Test for Detecting Wuchereria bancrofti Antigen in Human Blood
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TL;DR: A new filarial antigen test with increased sensitivity and other practical advantages is compared with the reference BinaxNOW Filariasis card test, and it is believed that the test strip represents a major step forward that will be welcomed by the GPELF and the filariasis research community.
A Comprehensive Assessment of Lymphatic Filariasis in Sri Lanka Six Years after Cessation of Mass Drug Administration
Ramakrishna U. Rao,Kumara C. Nagodavithana,Sandhya D. Samarasekera,Asha D. Wijegunawardana,Welmillage D. Y. Premakumara,Samudrika N. Perera,Sunil Settinayake,J. Phillip Miller,Gary J. Weil +8 more
TL;DR: Comprehensive surveillance is feasible for some national filariasis elimination programs and use of antibody and MX testing as tools to complement TAS for post-MDA surveillance is recommended.
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Transmission Assessment Surveys (TAS) to Define Endpoints for Lymphatic Filariasis Mass Drug Administration: A Multicenter Evaluation
Brian K. Chu,Michael S. Deming,Nana-Kwadwo Biritwum,Windtaré R. Bougma,Ameyo M. Dorkenoo,Maged El-Setouhy,Peter Fischer,Katherine Gass,Manuel Gonzalez de Peña,Leda Mercado-Hernandez,Dominique Kyelem,Patrick J. Lammie,Rebecca M. Flueckiger,Upendo Mwingira,Rahmah Noordin,Irene Offei Owusu,Eric A. Ottesen,Alexandre L. Pavluck,Nils Pilotte,Ramakrishna U. Rao,Dilhani Samarasekera,Mark A. Schmaedick,Sunil Settinayake,Paul E. Simonsen,Taniawati Supali,Fasihah Taleo,Melissa Torres,Gary J. Weil,Kimberly Y. Won +28 more
TL;DR: 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.
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