Volume 94, Issue 4
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



Microscopic evaluation of skin biopsies is the monitoring and evaluation (M and E) method currently used by multiple onchocerciasis elimination programs in Africa. However, as repeated mass drug administration suppresses microfilarial loads, the sensitivity and programmatic utility of skin snip microscopy is expected to decrease. Using a pan-filarial real-time polymerase chain reaction with melt curve analysis (qPCR-MCA), we evaluated 1) the use of a single-step molecular assay for detecting and identifying microfilariae in residual skin snips and 2) the sensitivity of skin snip microscopy relative to qPCR-MCA. Skin snips were collected and examined with routine microscopy in hyperendemic regions of Uganda and Ethiopia ( = 500 each) and “residual” skin snips (tissue remaining after induced microfilarial emergence) were tested with qPCR-MCA. qPCR-MCA detected DNA in 223 residual snips: 139 of 147 microscopy(+) and 84 among microscopy(−) snips, suggesting overall sensitivity of microscopy was 62.3% (139/223) relative to qPCR-MCA (75.6% in Uganda and 28.6% in Ethiopia). These findings demonstrate the insufficient sensitivity of skin snip microscopy for reliable programmatic monitoring. Molecular tools such as qPCR-MCA can augment sensitivity and provide diagnostic confirmation of skin biopsies and will be useful for evaluation or validation of new onchocerciasis M and E tools.


Article metrics loading...

The graphs shown below represent data from March 2017
Loading full text...

Full text loading...



  1. World Health Organization, 2011. African programme for onchocerciasis control: meeting of National Task Forces, September, 2011. Wkly Epidemiol Rec 86: 541549. [Google Scholar]
  2. Richards FO, Miri E, Meredith S, Guderian R, Sauerbrey M, Remme H, Packard R, Ndiaye JM, , 1998. Onchocerciasis. Bull World Health Organ 76: 147149. [Google Scholar]
  3. Roberts JMD, Neumann E, Göckel CW, Highton RB, , 1967. Onchocerciasis in Kenya 9, 11 and 18 years after elimination of the vector. Bull World Health Organ 37: 195212. [Google Scholar]
  4. Turner HC, Walker M, Churcher TS, Basáñez MG, , 2014. Modelling the impact of ivermectin on River Blindness and its burden of morbidity and mortality in African Savannah: EpiOncho projections. Parasit Vectors 7: 241.[Crossref] [Google Scholar]
  5. World Health Organization, 2001. Criteria for Certification of Interruption of Transmission/Elimination of Human Onchocerciasis. Document WHO/CDS/CEE/2001.18a. Geneva, Switzerland: WHO. [Google Scholar]
  6. Lindblade KA, Arana B, Zea-Flores G, Rizzo N, Porter CH, Dominguez A, Cruz-Ortiz N, Unnasch TR, Punkosdy GA, Richards J, Sauerbrey M, Castro J, Catú E, Oliva O, Richards FO, Jr, 2007. Elimination of Onchocercia volvulus transmission in the Santa Rosa focus of Guatemala. Am J Trop Med Hyg 77: 334341. [Google Scholar]
  7. Diawara L, Traoré MO, Badji A, Bissan Y, Doumbia K, Goita SF, Konaté L, Mounkoro K, Sarr MD, Seck AF, Toé L, Tourée S, Remme JH, , 2009. Feasibility of onchocerciasis elimination with ivermectin treatment in endemic foci in Africa: first evidence from studies in Mali and Senegal. PLoS Negl Trop Dis 3: e497.[Crossref] [Google Scholar]
  8. Taylor HR, Munoz B, Keyvan-Larijani E, Greene BM, , 1989. Reliability of detection of microfilariae in skin snips in the diagnosis of onchocerciasis. Am J Trop Med Hyg 41: 467471. [Google Scholar]
  9. Basáñez M-G, Pion SDS, Boakes E, Filipe JAN, Churcher TS, Boussinesq M, , 2008. Effect of single-dose ivermectin on Onchocerca volvulus: a systematic review and meta-analysis. Lancet Infect Dis 8: 310322.[Crossref] [Google Scholar]
  10. Boatin BA, Toe L, Alley ES, Nagelkerke NJ, Borsboom G, Habbema JD, , 2002. Detection of Onchocerca volvulus infection in low prevalence areas: a comparison of three diagnostic methods. Parasitology 125: 545552. [Google Scholar]
  11. Morales-Hojas R, Post RJ, Shelley AJ, Maia-Herzog M, Coscaron S, Cheke RA, , 2001. Characterisation of nuclear ribosomal DNA sequences from Onchocerca volvulus and Mansonella ozzardi (Nematoda: Filarioidea) and development of a PCR-based method for their detection in skin biopsies. Int J Parasitol 31: 169177.[Crossref] [Google Scholar]
  12. Rishniw M, Barr SC, Simpson KW, Frongillo MF, Franz M, Dominguez Alpizar JL, , 2006. Discrimination between six species of canine microfilariae by a single polymerase chain reaction. Vet Parasitol 135: 303314.[Crossref] [Google Scholar]
  13. Tang TH, Lopez-Velez R, Lanza M, Shelley AJ, Rubio JM, Luz SL, , 2010. Nested PCR to detect and distinguish the sympatric filarial species Onchocerca volvulus, Mansonella ozzardi and Mansonella perstans in the Amazon Region. Mem Inst Oswaldo Cruz 105: 823828.[Crossref] [Google Scholar]
  14. Collins RC, Brandling-Bennett AD, Holliman RB, Campbell CC, Darsie RF, , 1980. Parasitological diagnosis of onchocerciasis: comparisons of incubation media and incubation times for skin snips. Am J Trop Med Hyg 29: 3541. [Google Scholar]
  15. Unnasch TR, Meredith SE, Clapp JP, , 1996. The use of degenerate primers in conjunction with strain and species oligonucleotides to classify Onchocerca volvulus . , ed. Methods in Molecular Biology, Vol. 50. Totowa, NJ: Humana Press Inc., 293303. [Google Scholar]
  16. Fink DL, Fahle GA, Fischer S, Fedorko DF, Nutman TB, , 2011. Toward molecular parasitologic diagnosis: enhanced diagnostic sensitivity for filarial infections in mobile populations. J Clin Microbiol 49: 4247.[Crossref] [Google Scholar]
  17. Lloyd MM, Gilbert R, Taha NT, Weil GJ, Meite A, Kouakou IMM, Fischer PU, , 2015. Conventional parasitology and DNA-based diagnostic methods for onchocerciasis elimination programmes. Acta Trop 146: 114118.[Crossref] [Google Scholar]
  18. Fischer P, Buttner DW, Bamuhiiga J, Williams SA, , 1998. Detection of the filarial parasite Mansonella streptocerca in skin biopsies by a nested polymerase chain reaction-based assay. Am J Trop Med Hyg 58: 816820. [Google Scholar]
  19. Nuchprayoon S, Junpee A, Poovorawan Y, Scott AL, , 2005. Detection and differentiation of filarial parasites by universal primers and polymerase chain reaction-restriction fragment length polymorphism analysis. Am J Trop Med Hyg 73: 895900. [Google Scholar]
  20. Jiménez M, González LM, Carranza C, Bailo B, Pérez-Ayala A, Muro A, Pérez-Arellano JL, Gárate T, , 2011. Detection and discrimination of Loa loa, Mansonella perstans and Wuchereria bancrofti by PCR-RFLP and nested-PCR of ribosomal DNA ITS1 region. Exp Parasitol 127: 282286.[Crossref] [Google Scholar]
  21. Poole CB, Tanner NA, Zhang Y, Evans TC, Jr Carlow CK, , 2012. Diagnosis of brugian filariasis by loop-mediated isothermal amplification. PLoS Negl Trop Dis 6: e1948.[Crossref] [Google Scholar]
  22. Gopal H, Hassan HK, Rodriguez-Perez MA, Toe LD, Lustigman S, Unnasch TR, , 2012. Oligonucleotide based magnetic bead capture of Onchocerca volvulus DNA for PCR pool screening of vector black flies. PLoS Negl Trop Dis 6: e1712.[Crossref] [Google Scholar]
  23. Pilotte N, Torres M, Tomaino FR, Laney SJ, Williams SA, , 2013. A TaqMan-based multiplex real-time PCR assay for the simultaneous detection of Wuchereria bancrofti and Brugia malayi . Mol Biochem Parasitol 189: 3337.[Crossref] [Google Scholar]
  24. Zimmerman PA, Guderian RH, Aruajo E, Elson L, Phadke P, Kubofcik J, Nutman TB, , 1994. Polymerase chain reaction-based diagnosis of Onchocerca volvulus infection: improved detection of patients with onchocerciasis. J Infect Dis 169: 686689.[Crossref] [Google Scholar]
  25. Toé L, Boatin BA, Adjami A, Back C, Merriweather A, Unnasch TR, , 1998. Detection of Onchocerca volvulus infection by O-150 polymerase chain reaction analysis of skin scratches. J Infect Dis 178: 282285.[Crossref] [Google Scholar]

Data & Media loading...

Supplementary PDF

  • Received : 23 Sep 2015
  • Accepted : 18 Dec 2015
  • Published online : 06 Apr 2016

Most Cited This Month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error