title: The impact of a filariasis control program on Lihir Island, Papua New Guinea.
abstract: BACKGROUND
  Annual mass drug administration (MDA) over five years is the WHO's recommended strategy to eliminate lymphatic filariasis (LF). Some experts, however, consider that longer periods of treatment might be necessary in certain high prevalence and transmission environments based upon past unsuccessful field experience and modelling.
  
  
  RESULTS
  To evaluate predictors of success in a LF control program we conducted an ecological study during a pre-existing MDA program. We studied 27 villages in Lihir Island, Papua New Guinea, from two areas with different infection rates before MDA. We undertook surveys to collect information on variables potentially having an influence on the outcome of the program, including epidemiological (baseline prevalence of infection, immigration rate), entomological (vector density) and operational (treatment coverage, vector control strategies) variables. The success in a village was defined using variables related to the infection (circulating filarial antigenemia prevalence < 1%) and transmission (antigenemia prevalence < 1 in 1000 children born since start of MDA). 8709 people were involved in the MDA program and average coverage rates were around 70%. The overall prevalence of filariasis fell from an initial 17.91% to 3.76% at round 5 (p < 0.001). Viewed on a village by village basis, 12/27 (44%) villages achieved success. In multivariate analysis, low baseline prevalence was the only factor predicting both success in reducing infection rates (OR 19,26; CI 95% 1,12 to 331,82) and success in preventing new infections (OR 27,44; CI 95% 1,05 to 719,6). Low vector density and the use of an optimal vector control strategy were also associated with success in reducing infection rates, but this did not reach statistical significance.
  
  
  CONCLUSIONS
  Our results provide the data that supports the recommendation that high endemic areas may require longer duration MDA programs, or alternative control strategies.
authors: Department of Medicine, Lihir Medical Centre, International SOS, Lihir Island, New Ireland Province, Papua New Guinea. oriolmitja@hotmail.com
authors: Oriol
authors: O
authors: Mitjà
authors: Raymond
authors: R
authors: Paru
authors: Russell
authors: R
authors: Hays
authors: Lysaght
authors: L
authors: Griffin
authors: Nedley
authors: N
authors: Laban
authors: Mellie
authors: M
authors: Samson
authors: Quique
authors: Q
authors: Bassat
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D003140:Communicable Disease Control / Q000379:methods*; D004605:Elephantiasis, Filarial / Q000188:drug therapy* / Q000453:epidemiology* / Q000517:prevention & control; D005260:Female; D005369:Filaricides / Q000008:administration & dosage*; D006302:Health Services Research; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010219:Papua New Guinea / Q000453:epidemiology; D011247:Pregnancy; D015995:Prevalence; D012424:Rural Population; D013997:Time Factors; D055815:Young Adult
chemical_list: D005369:Filaricides