title: Fifteen years of annual mass treatment of onchocerciasis with ivermectin have not interrupted transmission in the west region of cameroon.
abstract: We followed up the 1996 baseline parasitological and entomological studies on onchocerciasis transmission in eleven health districts in West Region, Cameroon. Annual mass ivermectin treatment had been provided for 15 years. Follow-up assessments which took place in 2005, 2006, and 2011 consisted of skin snips for microfilariae (mf) and palpation examinations for nodules. Follow-up Simulium vector dissections for larval infection rates were done from 2011 to 2012. mf prevalence in adults dropped from 68.7% to 11.4%, and nodule prevalence dropped from 65.9% to 12.1%. The decrease of mf prevalence in children from 29.2% to 8.9% was evidence that transmission was still continuing. mf rates in the follow-up assessments among adults and in children levelled out after a sharp reduction from baseline levels. Only three health districts out of 11 were close to interruption of transmission. Evidence of continuing transmission was also observed in two out of three fly collection sites that had infective rates of 0.19% and 0.18% and ATP of 70 (Foumbot) and 300 (Massangam), respectively. Therefore, halting of annual mass treatment with ivermectin cannot be done after 15 years as it might escalate the risk of transmission recrudescence.
authors.affiliation: The Carter Center, Atlanta, GA, USA.
authors.forename: Moses N
authors.initials: MN
authors.lastname: Katabarwa
authors.forename: Albert
authors.initials: A
authors.lastname: Eyamba
authors.forename: Philippe
authors.initials: P
authors.lastname: Nwane
authors.forename: Peter
authors.initials: P
authors.lastname: Enyong
authors.forename: Joseph
authors.initials: J
authors.lastname: Kamgno
authors.forename: Thomas
authors.initials: T
authors.lastname: Kueté
authors.forename: Souleymanou
authors.initials: S
authors.lastname: Yaya
authors.forename: Rosalie
authors.initials: R
authors.lastname: Aboutou
authors.forename: Léonard
authors.initials: L
authors.lastname: Mukenge
authors.forename: Claude
authors.initials: C
authors.lastname: Kafando
authors.forename: Coulibaly
authors.initials: C
authors.lastname: Siaka
authors.forename: Salifou
authors.initials: S
authors.lastname: Mkpouwoueiko
authors.forename: Demanga
authors.initials: D
authors.lastname: Ngangue
authors.forename: Benjamin Didier
authors.initials: BD
authors.lastname: Biholong
authors.forename: Gervais Ondobo
authors.initials: GO
authors.lastname: Andze