Focusing nucleic acid-based molecular diagnostics and xenomonitoring approaches for human helminthiases amenable to preventive chemotherapy

Abstract

SUMMARY The current mainstay for control of the four major helminth diseases in humans (lymphatic filariasis, onchocerciasis, soil-transmitted helminthiases and schistosomiasis) is with preventive chemotherapy by mass administration of key anthelminthics. Following the London Declaration on Neglected Tropical Diseases in 2012, a roadmap for the elimination and control of these helminthiases by 2020 has been devised. With expected declines in prevalence and intensity of these infections, there is urgent need for implementing more sensitive, high-throughput and cost-effective diagnostic tools. Currently available diagnostic approaches for surveying, monitoring and evaluating helminth control programmes are based on microscopical observation of eggs/larvae, and/or detection of antibodies or parasite antigens in stool, urine or blood; all relatively low-throughput and of limited sensitivity and specificity. Newly proposed approaches for helminthiases diagnosis include the nucleic acid-based methods of (multiplex) real-time polymerase chain reaction assays, loop-mediated isothermal amplification and recombinase polymerase amplification. However, as well as sensitivity/specificity evaluation, their comparison to current ‘gold standard’ diagnostics and future application in individual-/community-based diagnosis, or in xenomonitoring requires consideration of relative costs, agreement of standard methods and strategic interpretation of resulting data before control/elimination programmes might best utilize molecular diagnostics to inform decision making. We review current nucleic-acid-based molecular diagnostic methods and highlight the needs and future research required to refine these tools for monitoring and evaluation of control and elimination programmes for four major human helminthiases.