Diagnosis, Treatment and Risk Factors of Strongyloides stercoralis in Schoolchildren in Cambodia

Abstract

BackgroundWorldwide, an estimated 30 to 100 million people are infected with Strongyloides stercoralis, a soil-transmitted helminth. Information on the parasite is scarce in most settings. In semi-rural Cambodia, we determined infection rates and risk factors; compared two diagnostic methods (Koga agar plate [KAP] culture and Baermann technique) for detecting S. stercoralis infections, using a multiple stool examination approach; and assessed efficacy of ivermectin treatment.Methods/Principal FindingsWe performed a cross-sectional study in 458 children from four primary schools in semi-rural villages in Kandal province, using three diagnostic procedures (Kato-Katz, KAP culture and Baermann technique) on three stool samples. Infected children were treated with ivermectin (100 µg/kg/day for two days) and re-examined three weeks after treatment. Hookworm, S. stercoralis, Trichuris trichiura, and small trematode eggs were most prevalent, with 24.4% of children being infected with S. stercoralis. The sensitivity of KAP culture and Baermann technique was 88.4% and 75.0%, respectively and their negative predictive values were 96.4% and 92.5%, respectively. The cumulative prevalence of S. stercoralis increased from 18.6% to 24.4%, after analyzing three stool samples, which was close to the modeled ‘true’ prevalence of 24.8%. Children who reported defecating in latrines were significantly less infected with S. stercoralis than those who did not use latrines (p<0.001). Itchy skin and diarrhea were significantly associated with S. stercoralis infection. The cure rate of ivermectin was 98.3%.Conclusions/Significance S. stercoralis infection is highly prevalent among semi-rural Cambodian schoolchildren. The sensitivity of KAP culture is higher than that of the Baermann technique. In the absence of a “gold standard”, analysis of multiple stool samples by different diagnostic methods is required to achieve a satisfactory level of sensitivity. Almost three-quarters of the infections could have been avoided by proper sanitation. Ivermectin is highly efficacious against S. stercoralis but prohibitive costs render the drug inaccessible to most Cambodians.

Prevalence and Risk Factors for Intestinal Parasitic Infection in Schoolchildren in Battambang, Cambodia

“…Almost all these studies have focused on Ascaris lumbricoides (2-40%), Hook worm (3.4-65%), Trichuris trichiura (0.4-17.3%), and Strongyloides stercoralis (0.4-31.5%) in communities and hospitals. [6][7][8][9][10][11][12][13] The Cambodian Ministry of Health has implemented national deworming programs. However, mass treatment has only focused on the most common parasites, such as A. lumbricoides, Hook worm, and T. trichiura.…”

High prevalence of large trematode eggs in schoolchildren in Cambodia

“…In 2009, LTE were observed in the stools of 27/150 schoolchildren (18.0%) in the Damrei Chhlang village primary school, Kandal province, Cambodia, during a standard parasitological survey using the Kato-Katz technique (Khieu et al, 2013). Given the high prevalence of Fasciola spp.…”

The laboratory diagnosis of Strongyloides stercoralis

“…Results are available within two days, although extended incubation up to four days increases yield 8,11,12 .…”

“…Two studies comparing 48 h APC with Baermann culture found an improved recovery of S. stercoralis larvae in APC 11,12 . Recovery rates improve markedly with multiple stool cultures 6,11,13 …”