title: Mapping the geographical distribution of lymphatic filariasis in Zambia.
abstract: BACKGROUND
  Past case reports have indicated that lymphatic filariasis (LF) occurs in Zambia, but knowledge about its geographical distribution and prevalence pattern, and the underlying potential environmental drivers, has been limited. As a background for planning and implementation of control, a country-wide mapping survey was undertaken between 2003 and 2011. Here the mapping activities are outlined, the findings across the numerous survey sites are presented, and the ecological requirements of the LF distribution are explored.
  
  
  RESULTS
  Approximately 10,000 adult volunteers from 108 geo-referenced survey sites across Zambia were examined for circulating filarial antigens (CFA) with rapid format ICT cards, and a map indicating the distribution of CFA prevalences in Zambia was prepared. 78% of survey sites had CFA positive cases, with prevalences ranging between 1% and 54%. Most positive survey sites had low prevalence, but six foci with more than 15% prevalence were identified. The observed geographical variation in prevalence pattern was examined in more detail using a species distribution modeling approach to explore environmental requirements for parasite presence, and to predict potential suitable habitats over unsurveyed areas. Of note, areas associated with human modification of the landscape appeared to play an important role for the general presence of LF, whereas temperature (measured as averaged seasonal land surface temperature) seemed to be an important determinant of medium-high prevalence levels.
  
  
  CONCLUSIONS
  LF was found to be surprisingly widespread in Zambia, although in most places with low prevalence. The produced maps and the identified environmental correlates of LF infection will provide useful guidance for planning and start-up of geographically targeted and cost-effective LF control in Zambia.
authors.affiliation: School of Veterinary Medicine, University of Zambia, Lusaka, Zambia.
authors.forename: Enala T
authors.initials: ET
authors.lastname: Mwase
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark ; Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Anna-Sofie
authors.initials: AS
authors.lastname: Stensgaard
authors.affiliation: Ministry of Health, Lusaka, Zambia.
authors.forename: Mutale
authors.initials: M
authors.lastname: Nsakashalo-Senkwe
authors.affiliation: World Health Organization, Regional Office for Africa, Harare, Zimbabwe.
authors.forename: Likezo
authors.initials: L
authors.lastname: Mubila
authors.affiliation: University Teaching Hospital, University of Zambia, Lusaka, Zambia.
authors.forename: James
authors.initials: J
authors.lastname: Mwansa
authors.affiliation: World Health Organization, Lusaka, Zambia.
authors.forename: Peter
authors.initials: P
authors.lastname: Songolo
authors.affiliation: School of Veterinary Medicine, University of Zambia, Lusaka, Zambia.
authors.forename: Sheila T
authors.initials: ST
authors.lastname: Shawa
authors.affiliation: Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Paul E
authors.initials: PE
authors.lastname: Simonsen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000947:Antigens, Helminth / Q000097:blood; D002648:Child; D004605:Elephantiasis, Filarial / Q000453:epidemiology*; D005260:Female; D062306:Geography, Medical; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D055815:Young Adult; D015024:Zambia / Q000453:epidemiology
chemical_list: D000947:Antigens, Helminth