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Table 2 Advantages and disadvantages of currently available tools for monitoring and evaluation of onchocerciasis control and elimination programmes

From: From river blindness control to elimination: bridge over troubled water

Monitoring tools Advantages Disadvantages
Skin snip surveys during the treatment implementation phase Detection of skin microfilariae is the gold-standard diagnostic of active infection. PCR can be used on skin snips Need ethical approval*; painful; require sterilisation of punches between individuals being sampled; decreasing acceptance by communities
Ivermectin coverage surveys Relatively easy and affordable; can provide information about treatment uptake May lead to overestimation of coverage and/or provide incomplete information about treatment adherence
Ov16 rapid diagnostic test (RDT) surveys in children aged up to 10 years Relatively affordable, immediate answer on site Need ethical approval*, sensitivity and specificity of RDTs not yet well established
Ov16 ELISA surveys in children aged up to 10 years Sensitivity of up to 80% and specificity of up to 97% [72] Need ethical approval*; more expensive than RDTs; samples need to be sent to a lab, often located abroad. Variability in diagnostic performance according to lab and presence of other filarial infections [92]
PCR pool screening of simuliid vectors No ethical approval needed?*; many flies can be sampled; in principle, separate analysis of flies’ heads and bodies can provide information on infectivity to and from human populations Lack of trained entomologists and labs, as samples often shipped to reference labs for PCR analysis; increasing number of flies needed as infection levels decrease; sampling protocols need to be refined
  1. *Some ministries of health have given blanket ethical approval for all monitoring and evaluation activities (including skin snips, blood tests and catching flies by human vector collectors), as part of the control programme activities. Others seem to require approval for specific instances