Cost-effectiveness of vector control strategies for supplementing mass drug administration for eliminating lymphatic filariasis in India

Background/Methodology Despite progress using mass drug administration (MDA), lymphatic filariasis (LF) remains a major public health issue in India. Vector control (VC) is hypothesized as a potentially useful addition to MDA towards LF elimination. We conducted cost-effectiveness analysis of MDA alone and augmented by VC single (VCS) or integrated VC approaches (VCI). Data came from historical controls and a 3-arm cluster randomized trial of 36 villages at risk of LF transmission in Tamil Nadu, India. The arms were: MDA alone (the standard of care); VCS (MDA plus expanded polystyrene beads for covering the water surface in wells and cesspits to suppress the filariasis vector mosquito Culex quinquefasciatus ), and VCI (VCS plus insecticidal pyrethroid impregnated curtains over windows, doors, and eaves). Economic costs in 2010 US$ combined government and community inputs from household to state levels. Outcomes were controlled microfilaria prevalence (MfP) and antigen prevalence (AgP) to conventional elimination targets (MfP<1% and AgP<2%) from 2010 to 2013, and disability adjusted life years (DALYs) averted. Principal Findings The estimated annual economic cost per resident was US$0.53 for MDA alone, US$1.02 for VCS, and US$1.83 for VCI. With MDA offered in all arms, all reduced LF prevalence substantially and significantly from 2010 to 2013. MDA proved highly cost effective at $112 per DALY, a very small (8%) share of India’s then per capita GDP. Progress towards elimination was comparable across all three study arms. Conclusions The well-functioning MDA was effective and very cost-effective for eliminating LF, leaving little scope for further improvement. Supplementary VC demonstrated no statistically significant additional benefit in this trial. Authors’ Summary Lymphatic filariasis (LF) is one of the twenty neglected tropical diseases (NTDs) that affect more than one billion people worldwide. As part of the effort toward global elimination of LF, the Indian State of Tamil Nadu government has implemented mass drug administration (MDA) repeatedly since 1996. Despite their efforts, LF had not yet been eliminated. Although vector control (VC) is proposed to augment regular MDA to help eliminate LF, little is known about the increased impact or costs. Our study compares the costs of MDA alone to the combination of MDA with alternative VC interventions. We calculated both program operating costs and costs to communities. We found MDA to be very cost-effective for eliminating LF. Against low levels of LF endemicity (≤10%), the study had limited ability to detect further improvements and found no significant incremental improvements from VC. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement All authors received support from the Bill & Melinda Gates Foundation (gatesfoundation.org) through grant OPP 43922, Resolving the Critical Challenges Now Facing the Global Programme to Eliminate Lymphatic Filariasis, administered by the Task Force for Global Health, Decatur, Georgia, U.S.A. The funder had no role in the contents of this paper or the decision to submit for publication. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors or in the authors' prior publications. * AgP : Antigen prevalence BLPHC : Block level PHC CRME : Centre for Research in Medical Entomology DALY : disability adjusted life year DEC : diethylcarbamazine ELF : elimination of lymphatic filariasis EPB : expanded polystyrene beads EPS : expanded polystyrene FL : Florida (state, USA) HUD : Health unit district ICMR : Indian Council for Medical Research ICT : immunochromatography card test IRR : incident rate ratio IVM : Integrated vector management LF : Lymphatic filariasis M : mean MA : Massachusetts state, USA M.D. : Doctor of Medicine MDA : mass drug administration MDA-CAT : MDA cost analysis tool MfP : microfilaria prevalence M.S. : Master of Science NTD : neglected tropical disease NVBDCP : National Vector Borne Disease Control Program PHC : primary health center Ph.D. : Doctor of Philosophy PIC : pyrethroid impregnated curtain SC : suspension concentrate SD : standard deviation SHD : State health department TAS : transmission assessment survey TN : Tamil Nadu State, India TX : Texas State, USA US$ : United States dollar USA : United States of America USAID : United States Agency for International Development VC : vector control VC-CAT : MDA+ cost analysis tool VCI : Vector control integrated VCS : Vector control single WHO : World Health Organization