title: Programmatic Use of Molecular Xenomonitoring at the Level of Evaluation Units to Assess Persistence of Lymphatic Filariasis in Sri Lanka.
abstract: Sri Lanka's Anti Filariasis Campaign distributed 5 rounds of mass drug administration (MDA with DEC plus albendazole) to all endemic regions in the country from 2002-2006. Post-MDA surveillance results have generally been encouraging. However, recent studies have documented low level persistence of Wuchereria bancrofti in Galle district based on comprehensive surveys that include molecular xenomonitoring (MX, detection of filarial DNA in mosquitoes) results. The purposes of this study were to demonstrate the use of MX in large evaluation units (EUs) and to field test different mosquito sampling schemes.
  
  
  
  Galle district (population 1.1 million) was divided into two EUs. These included a coastal EU with known persistent LF and an inland EU with little persistent LF. Mosquitoes were systematically sampled from ~300 trap locations in 30 randomly selected clusters (health administrative units) per EU. Approximately 28,000 Culex quinquefasciatus were collected with gravid traps and tested for filarial DNA by qPCR. 92/625 pools (14.7%) from the coastal EU and 8/583 pools (1.4%) from the inland EU were positive for filarial DNA. Maximum likelihood estimates (MLE) for filarial DNA rates were essentially the same when the same number of mosquito pools were collected and tested from 75, 150, or 300 trap sites (range 0.61-0.78% for the coastal EU and 0.04-0.07% for the inland EU). The ability to use a smaller number of trap sites reduces the cost and time required for mosquito sampling.
  
  
  
  These results suggest there is widespread persistence of W. bancrofti infection in the coastal Galle EU 8 years after the last round of MDA in 2006, and this is consistent with other data from the district. This study has shown that MX can be used by national programs to assess and map the persistence of W. bancrofti at the level of large EUs in areas with Culex transmission.
authors.affiliation: Department of Internal Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, Missouri, United States of America.
authors.forename: Ramakrishna U
authors.initials: RU
authors.lastname: Rao
authors.affiliation: Anti Filariasis Campaign, Sri Lanka Ministry of Health, Colombo, Sri Lanka.
authors.forename: Sandhya D
authors.initials: SD
authors.lastname: Samarasekera
authors.affiliation: Anti Filariasis Campaign, Sri Lanka Ministry of Health, Colombo, Sri Lanka.
authors.forename: Kumara C
authors.initials: KC
authors.lastname: Nagodavithana
authors.affiliation: Regional Anti Filariasis Unit, Galle, Sri Lanka.
authors.forename: Manjula W
authors.initials: MW
authors.lastname: Punchihewa
authors.affiliation: Anti Filariasis Campaign, Sri Lanka Ministry of Health, Colombo, Sri Lanka.
authors.forename: Tharanga D M
authors.initials: TD
authors.lastname: Dassanayaka
authors.affiliation: Anti Filariasis Campaign, Sri Lanka Ministry of Health, Colombo, Sri Lanka.
authors.forename: Gamini
authors.initials: G
authors.lastname: P K D
authors.affiliation: Department of Internal Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, Missouri, United States of America.
authors.forename: Ethan
authors.initials: E
authors.lastname: Ford
authors.affiliation: Anti Filariasis Campaign, Sri Lanka Ministry of Health, Colombo, Sri Lanka.
authors.forename: Udaya S B
authors.initials: US
authors.lastname: Ranasinghe
authors.affiliation: Task Force for Global Heath and NTD Support Center, Atlanta, Georgia, United States of America.
authors.forename: Ralph H
authors.initials: RH
authors.lastname: Henderson
authors.affiliation: Department of Internal Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, Missouri, United States of America.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Weil
mesh_terms: D000818:Animals; D001769:Blood / Q000469:parasitology; D003465:Culex / Q000469:parasitology / Q000502:physiology; D016054:DNA, Protozoan / Q000032:analysis* / Q000235:genetics; D004605:Elephantiasis, Filarial / Q000453:epidemiology* / Q000469:parasitology / Q000635:transmission; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D000072138:Mosquito Vectors / Q000469:parasitology* / Q000502:physiology; D015995:Prevalence; D060888:Real-Time Polymerase Chain Reaction; D013188:Sri Lanka / Q000453:epidemiology; D014958:Wuchereria bancrofti / Q000235:genetics* / Q000302:isolation & purification*
chemical_list: D016054:DNA, Protozoan