OP 6 - Intestinal nematode infections in children: Molecular and microscopy evidence from contrasting endemic settingsettings
Jayakody NK1,4, Gordon CA2, Ranasinghe JC3, Silva NKA4, Wickramasinghe ND5, Wickramasinghe WDSJ6, Collinson N2, Wijayasekara AE1, Karunarathne CB7, de Silva NR8, Weerakoon KG4 , 1Department of Parasitology, Faculty of Medicine, Wayamba University of Sri Lanka, 2QIMR Berghofer Medical Research Institute, Infection and Inflammation Program, Applied Tropical and Molecular Parasitology Laboratory, Brisbane, Queensland, Australia, 3District General Hospital, Nuwara Eliya, Sri Lanka, 4Department of Parasitology, Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka, 5Department of Community Medicine, Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka, 6Department of Parasitology, Faculty of Medicine, University of Peradeniya, Sri Lanka, 7Department of Physiology, Faculty of Medicine, Wayamba University of Sri Lanka, 8Department of Parasitology, Faculty of Medicine, University of Kelaniya, Sri Lanka
Abstract
Introduction
As global focus shifts from control to elimination, accurate estimation of human intestinal nematode infection (HINIs) burden is essential for surveillance. In Sri Lanka, prolonged deworming has reduced infection prevalence among children to 0.97% islandwide (0.21%-9.08% across regions). Microscopy-based estimates guiding deworming scale-down may miss low-intensity infections and focal transmission.
Objective
To compare the prevalence and species distribution of HINIs among children in contrasting endemic settings using combined microscopic and molecular diagnostics.
Design, setting, and methods
Two cross-sectional studies conducted in 2023 were analysed. In Nuwara Eliya (high-prevalent district), 100 children aged 1-12 years admitted for non-helminth-related conditions were included with convenience sampling. In Anuradhapura (low-prevalent district), where routine deworming was discontinued, 967 primary schoolchildren were recruited through multistage stratified cluster sampling, of whom 688 provided samples. Stool and perianal samples were examined using wet-smears, Kato-Katz, formalin-ether concentration, agar plate culture, Scotch tape, and real-time quantitative PCR (qPCR) with multiplex assays (targeting Ascaris lumbricoides, Trichuris trichiura, Necator americanus, Ancylostoma duodenale, A. ceylanicum and Strongyloides spp.)
Results
In Nuwara Eliya, 36% (30%,qPCR; 18%,microscopy) of participants had HINIs. A. lumbricoides predominated at 25% (25%, qPCR; 5%, microscopy), followed by T. trichiura 5% (4%, qPCR; 2%, microscopy), hookworms 4% (3%, qPCR; all N. americanus; 1%, microscopy), and S. stercoralis 1%(1%, qPCR; 0%, microscopy). E. vermicularis prevalence was 10% by Scotch-tape. In Anuradhapura, overall 54.2% had HINIs; A. lumbricoides 18.9% (15.7%, qPCR; 5.7%, microscopy), T. trichiura 7.2% (5.4%, qPCR; 2.3%, microscopy), hookworms 6.9% (qPCR - N. americanus,5.6% and A. ceylanicum,1.3%; 0.3%, microscopy), S. stercoralis 19.2% (16.1%, qPCR; 5.2%, microscopy), and E. vermicularis 24.5% by Scotch-tape. qPCR detected between two- and twenty-fold more infections than microscopy. All microscopy-detected infections were of low intensity (WHO;Kato-Katz classification), with polyparasitism in 17.4% in Anuradhapura and 3% in Nuwara Eliya.
Conclusions
A predominantly low-intensity burden of HINIs persists among children across both high- and low-prevalent settings. Direct comparisons between settings are limited by differing study populations and sampling approaches. Detection among hospitalised children, likely good healthcare access, indicates ongoing transmission despite presumed treatment exposure. Molecular diagnostics reveal ongoing transmission missed by microscopy, with important implications for deworming policy and surveillance.
Financial assistance by the NRC - Grant NRC 20-118 is acknowledged.
Downloads
