title: Conventional parasitology and DNA-based diagnostic methods for onchocerciasis elimination programmes.
abstract: Commonly used methods for diagnosing Onchocerca volvulus infections (microscopic detection of microfilariae in skin snips and nodule palpation) are insensitive. Improved methods are needed for monitoring and evaluation of onchocerciasis elimination programmes and for clinical diagnosis of individual patients. A sensitive probe-based qPCR assay was developed for detecting O. volvulus DNA, and this was tested with samples collected from an endemic area in eastern Côte d'Ivoire. The new test was evaluated with dried skin snip pairs from 369 subjects and compared to routine skin snip microscopy and nodule palpation results from the same individuals. Onchocerciasis prevalence for these samples by qPCR, skin snip microscopy, and nodule palpation were 56.9%, 26.0%, and 37.9%, respectively. Furthermore, the combination of all three tests produced an infection prevalence of 72.9%, which was significantly higher than 53.1% detected by microscopy plus nodule palpation without qPCR. However, the qPCR assay was negative for 54 of 229 individuals with palpable nodules. qPCR could be a useful tool for detecting residual O. volvulus infections in human populations as prevalence decreases in areas following community-directed treatment with ivermectin.
authors.affiliation: Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA. Electronic address: mlloyd@dom.wustl.edu.
authors.forename: Melanie M
authors.initials: MM
authors.lastname: Lloyd
authors.affiliation: Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Gilbert
authors.affiliation: Ministry of Health and Social Welfare of Côte d'Ivoire, Abidjan, Cote d'Ivoire.
authors.forename: Nathalie Tebao
authors.initials: NT
authors.lastname: Taha
authors.affiliation: Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Weil
authors.affiliation: Ministry of Health and Social Welfare of Côte d'Ivoire, Abidjan, Cote d'Ivoire.
authors.forename: Aboulaye
authors.initials: A
authors.lastname: Meite
authors.affiliation: Ministry of Health and Social Welfare of Côte d'Ivoire, Abidjan, Cote d'Ivoire.
authors.forename: Ilunga M M
authors.initials: IM
authors.lastname: Kouakou
authors.affiliation: Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: Peter U
authors.initials: PU
authors.lastname: Fischer
mesh_terms: D000328:Adult; D000818:Animals; D007560:Cote d'Ivoire; D005260:Female; D006801:Humans; D007559:Ivermectin / Q000627:therapeutic use*; D008297:Male; D008842:Microfilariae / Q000187:drug effects*; D008875:Middle Aged; D009854:Onchocerca / Q000187:drug effects; D009855:Onchocerciasis / Q000175:diagnosis* / Q000517:prevention & control*; D015995:Prevalence; D060888:Real-Time Polymerase Chain Reaction; D012867:Skin / Q000469:parasitology*
chemical_list: D007559:Ivermectin
keywords: Diagnosis; Molecular diagnostics; Onchocerciasis; qPCR