title: Presence of Wuchereria bancrofti microfilaremia despite 7 years of annual ivermectin monotherapy mass drug administration for onchocerciasis control: a study in north-west Ethiopia.
abstract: BACKGROUND
  There is considerable interest in determining whether mass drug administration (MDA) with ivermectin for onchocerciasis control will eliminate coendemic lymphatic filariasis (LF). The objective of this study was to determine the prevalence of LF microfilaremia in onchocerciasis endemic districts that had received 7 years of MDA with ivermectin.
  
  
  METHODS
  Three villages with a 2010 LF circulating antigenaemia prevalence (determined in a mapping exercise using immunochromatography tests) ranging from 23 to 56% were surveyed for the presence of Wuchereria bancrofti microfilaria (mf) in 2012. These villages had been treated with ivermectin MDA for onchocerciasis with reported total population coverage of ≥65%. A total of 774 residents aged 2 years and above, of both genders, provided 60 μl nocturnal blood samples between 10 pm and 2 am. Standard thick smears were prepared and examined microscopically after Giemsa staining for the presence of W. bancrofti mf.
  
  
  RESULTS
  The mean mf prevalence was 4.7% (village range 1.1-11.0%). The mean mf density was 9.8 mf/60 μl (village range 9-13.1) among the positive individuals. Children in the 2-4-year-old and 5-9-year-old age groups were infected suggesting transmission occurred during the MDA period. A village level review of MDA treatment coverage records showed an average total population coverage of 66.4% over a 7-year period, but with a considerable range of annual coverage (43.0-89.9%). In addition, village level treatment coverage data were missing from the village with the highest mf prevalence (11%) for 2 of the 7 years.
  
  
  CONCLUSIONS
  7 years of annual mass treatment with ivermectin monotherapy for onchocerciasis did not interrupt LF transmission. In expanding the onchocerciasis ivermectin MDA programme to include LF, albendazole should be added and treatment coverage improved.
authors.affiliation: 1 The Carter Center, Addis Ababa , Ethiopia.
authors.forename: Tekola
authors.initials: T
authors.lastname: Endeshaw
authors.forename: Aseged
authors.initials: A
authors.lastname: Taye
authors.forename: Zerihun
authors.initials: Z
authors.lastname: Tadesse
authors.forename: Moses N
authors.initials: MN
authors.lastname: Katabarwa
authors.forename: Oumer
authors.initials: O
authors.lastname: Shafi
authors.forename: Tewodros
authors.initials: T
authors.lastname: Seid
authors.forename: Frank O
authors.initials: FO
authors.lastname: Richards
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000818:Animals; D000977:Antiparasitic Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004334:Drug Administration Schedule; D004363:Drug Utilization / Q000706:statistics & numerical data; D004605:Elephantiasis, Filarial / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D019353:Endemic Diseases / Q000517:prevention & control; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D006801:Humans; D007559:Ivermectin / Q000008:administration & dosage* / Q000627:therapeutic use; D008297:Male; D008842:Microfilariae / Q000302:isolation & purification; D008875:Middle Aged; D009855:Onchocerciasis / Q000517:prevention & control*; D015995:Prevalence; D017678:Sex Distribution; D014958:Wuchereria bancrofti
chemical_list: D000977:Antiparasitic Agents; D007559:Ivermectin
keywords: Annual MDA; Elimination; Ivermectin; Lymphatic filariasis; Onchocerciasis