National Centre for Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia.
PLoS Negl Trop Dis. 2013;7(2):e2035. doi: 10.1371/journal.pntd.0002035. Epub 2013 Feb 7.
Worldwide, 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 FINDINGS: We 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.
全世界估计有 3000 万至 1 亿人感染粪类圆线虫，这是一种土壤传播的蠕虫。在大多数情况下，关于这种寄生虫的信息都很匮乏。在柬埔寨半农村地区，我们确定了感染率和风险因素；比较了两种诊断方法（加藤琼脂平板[KAP]培养和贝曼氏技术）检测粪类圆线虫感染的效果，采用多次粪便检查方法；并评估了伊维菌素治疗的效果。
方法/主要发现：我们在干丹省四个半农村村庄的四所小学的 458 名儿童中进行了一项横断面研究，使用三种诊断程序（加藤氏法、KAP 培养和贝曼氏技术）对三份粪便样本进行了检测。感染儿童用伊维菌素（100μg/kg/天，连用两天）治疗，并在治疗后三周进行复查。钩虫、粪类圆线虫、鞭虫和小吸虫卵最为常见，有 24.4%的儿童感染了粪类圆线虫。KAP 培养和贝曼氏技术的灵敏度分别为 88.4%和 75.0%，阴性预测值分别为 96.4%和 92.5%。分析三份粪便样本后，粪类圆线虫的累计患病率从 18.6%上升到 24.4%，接近模型预测的“真实”患病率 24.8%。报告在厕所排便的儿童感染粪类圆线虫的比例明显低于未使用厕所的儿童（p<0.001）。皮肤瘙痒和腹泻与粪类圆线虫感染显著相关。伊维菌素的治愈率为 98.3%。
结论/意义：粪类圆线虫感染在柬埔寨半农村地区的学童中高度流行。KAP 培养的灵敏度高于贝曼氏技术。在缺乏“金标准”的情况下，需要使用不同的诊断方法分析多次粪便样本，以达到满意的灵敏度水平。通过适当的卫生措施，近四分之三的感染是可以避免的。伊维菌素对粪类圆线虫非常有效，但高昂的成本使大多数柬埔寨人无法获得这种药物。
