Multi-parallel qPCR provides increased sensitivity and diagnostic breadth for gastrointestinal parasites of humans: field-based inferences on the impact of mass deworming. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Easton, Alice; Oliveira, Rita; O'Connell, Elise; Kepha, Stella; Mwandawiro, Charles; Njenga, Sammy; Kihara, Jimmy; Mwatele, Cassian; Odiere, Maurice; Brooker, Simon; Webster, Joanne; Anderson, Roy; Nutman, Thomas
• Is Part Of: Parasites & vectors. Volume 9:Issue 1(2016)
• Page Start: 1
• Page End: 12
• Publication Date: 2016-12
• Subjects: qPCR -- Diagnostics -- Soil-transmitted helminths -- Deworming -- Impact evaluation -- Gastrointestinal parasites -- Co-infection -- Ascaris lumbricoides; Parasitism -- Periodicals; Parasites -- Periodicals; Vector-pathogen relationships -- Periodicals; Animals as carriers of disease -- Periodicals; Insects as carriers of disease -- Periodicals; 616.96
• DOI: 10.1186/s13071-016-1314-y
• Languages: English
• ISSNs: 1756-3305

Abstract

Abstract Background Although chronic morbidity in humans from soil transmitted helminth (STH) infections can be reduced by anthelmintic treatment, inconsistent diagnostic tools make it difficult to reliably measure the impact of deworming programs and often miss light helminth infections. Methods Cryopreserved stool samples from 796 people (aged 2–81 years) in four villages in Bungoma County, western Kenya, were assessed using multi-parallel qPCR for 8 parasites and compared to point-of-contact assessments of the same stools by the 2-stool 2-slide Kato-Katz (KK) method. All subjects were treated with albendazole and allAscaris lumbricoides expelled post-treatment were collected. Three months later, samples from 633 of these people were re-assessed by both qPCR and KK, re-treated with albendazole and the expelled worms collected. Results Baseline prevalence by qPCR (n = 796) was 17 % forA. lumbricoides, 18 % forNecator americanus, 41 % forGiardia lamblia and 15 % forEntamoeba histolytica . The prevalence was <1 % forTrichuris trichiura, Ancylostoma duodenale, Strongyloides stercoralis andCryptosporidium parvum . The sensitivity of qPCR was 98 % forA. lumbricoides andN. americanus, whereas KK sensitivity was 70 % and 32 %, respectively. Furthermore, qPCR detected infections withT. trichiura andS. stercoralis that were missed by KK, and infections withG. lamblia andE. histolytica that cannot be detected by KK. Infection intensities measured by qPCR and by KK were correlated forA. lumbricoides (r = 0.83, p < 0.0001) andN. americanus (r = 0.55, p < 0.0001). The number ofA. lumbricoides worms expelled was correlated (p < 0.0001) with both the KK (r = 0.63) and qPCR intensity measurements (r = 0.60). Conclusions KK may be an inadequate tool for stool-based surveillance in areas where hookworm orStrongyloides are common or where intensity of helminth infection is low after repeated rounds of chemotherapy. Because deworming programs need to distinguish between populations where parasitic infection is controlled and those where further treatment is required, multi-parallel qPCR (or similar high throughput molecular diagnostics) may provide new and important diagnostic information.