title: Situation analysis of parasitological and entomological indices of onchocerciasis transmission in three drainage basins of the rain forest of South West Cameroon after a decade of ivermectin treatment.
abstract: BACKGROUND
  Community-Directed Treatment with Ivermectin (CDTI) is the main strategy adopted by the African Programme for Onchocerciasis control (APOC). Recent reports from onchocerciasis endemic areas of savannah zones have demonstrated the feasibility of disease elimination through CDTI. Such information is lacking in rain forest zones. In this study, we investigated the parasitological and entomological indices of onchocerciasis transmission in three drainage basins in the rain forest area of Cameroon [after over a decade of CDTI]. River basins differed in terms of river number and their flow rates; and were characterized by high pre-control prevalence rates (60-98%).
  
  
  METHODS
  Nodule palpation and skin snipping were carried out in the study communities to determine the nodule rates, microfilarial prevalences and intensity. Simulium flies were caught at capture points and dissected to determine the biting, parous, infection and infective rates and the transmission potential.
  
  
  RESULTS
  The highest mean microfilaria (mf) prevalence was recorded in the Meme (52.7%), followed by Mungo (41.0%) and Manyu drainage basin (33.0%). The same trend was seen with nodule prevalence between the drainage basins. Twenty-three (23/39) communities (among which 13 in the Meme) still had mf prevalence above 40%. All the communities surveyed had community microfilarial loads (CMFL) below 10 mf/skin snip (ss). The infection was more intense in the Mungo and Meme. The intensity of infection was still high in younger individuals and children less than 10 years of age. Transmission potentials as high as 1211.7 infective larvae/person/month were found in some of the study communities. Entomological indices followed the same trend as the parasitological indices in the three river basins with the Meme having the highest values.
  
  
  CONCLUSIONS
  When compared with pre-control data, results of the present study show that after over a decade of CDTI, the burden of onchocerciasis has reduced. However, transmission is still going on in this study site where loiasis and onchocerciasis are co-endemic and where ecological factors strongly favour the onchocerciasis transmission. The possible reasons for this persistent and differential transmission despite over a decade of control efforts using ivermectin are discussed.
authors.affiliation: Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon. swanji@yahoo.fr.|Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon. swanji@yahoo.fr.
authors.forename: Samuel
authors.initials: S
authors.lastname: Wanji
authors.affiliation: Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon. arnaudkengne@yahoo.com.|Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon. arnaudkengne@yahoo.com.
authors.forename: Jonas A
authors.initials: JA
authors.lastname: Kengne-Ouafo
authors.affiliation: Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon. mathias_mesum@yahoo.fr.|Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon. mathias_mesum@yahoo.fr.
authors.forename: Mathias E
authors.initials: ME
authors.lastname: Esum
authors.affiliation: Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon. ndongmopatrick@yahoo.com.|Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon. ndongmopatrick@yahoo.com.
authors.forename: Patrick W N
authors.initials: PW
authors.lastname: Chounna
authors.affiliation: Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon. ntendongfor@yahoo.com.|Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon. ntendongfor@yahoo.com.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Tendongfor
authors.affiliation: Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon. adzemye@gmail.com.|Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon. adzemye@gmail.com.
authors.forename: Bridget F
authors.initials: BF
authors.lastname: Adzemye
authors.affiliation: Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon. jeebanga@yahho.com.|Department of Biological Sciences, Faculty of Science, University of Bamenda, P.O. Box 39, Bambili, North West Region, Bamenda, Cameroon. jeebanga@yahho.com.
authors.forename: Joan E E
authors.initials: JE
authors.lastname: Eyong
authors.affiliation: Tropical Medicine Research station, P.O. Box 55, Kumba, Cameroon. jatojatoisaac@yahoo.com.
authors.forename: Isaac
authors.initials: I
authors.lastname: Jato
authors.affiliation: Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon. fabriceroberto@yahoo.fr.|Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon. fabriceroberto@yahoo.fr.
authors.forename: Fabrice R
authors.initials: FR
authors.lastname: Datchoua-Poutcheu
authors.affiliation: Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon. kah_elvis@yahoo.fr.|Department of Geography, University of Yaounde1, Yaounde, Cameroon. kah_elvis@yahoo.fr.
authors.forename: Elvis
authors.initials: E
authors.lastname: Kah
authors.affiliation: Parasite and Vectors Research Unit, Department of Microbiology and Parasitology, University of Buea, P.O. Box 63, Buea, Cameroon. enyongap@gmail.com.|Tropical Medicine Research station, P.O. Box 55, Kumba, Cameroon. enyongap@gmail.com.
authors.forename: Peter
authors.initials: P
authors.lastname: Enyong
authors.affiliation: Division of Pathway Medicine, School for Biomedical Studies, University of Edinburgh, 49 Little France Crescent, Edinburgh, EH16 4SB, UK. David.W.Taylor@ed.ac.uk.
authors.forename: David W
authors.initials: DW
authors.lastname: Taylor
mesh_terms: D000818:Animals; D002163:Cameroon / Q000453:epidemiology; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D005247:Feeding Behavior; D006801:Humans; D007306:Insecticides / Q000008:administration & dosage*; D007559:Ivermectin / Q000008:administration & dosage*; D009854:Onchocerca / Q000302:isolation & purification; D009855:Onchocerciasis / Q000453:epidemiology* / Q000517:prevention & control*; D015995:Prevalence; D065947:Rainforest; D012843:Simuliidae / Q000254:growth & development* / Q000469:parasitology*
chemical_list: D007306:Insecticides; D007559:Ivermectin