Preventive chemotherapy for the control of strongyloidiasis in school-age children: Estimating the ivermectin need.

BACKGROUND: Strongyloides stercoralis is a soil-transmitted helminth (STH) that affects approximately 600 million people worldwide. Interventions targeting S. stercoralis have not been implemented yet. Specific treatment (ivermectin) could be included in already ongoing preventive chemotherapy (PC) campaigns targeting other STHs. The aim of this study was to estimate the quantity of ivermectin needed for an integrated STH/S. stercoralis control program. METHODODOLOGY/PRINCIPAL FINDINGS: Our study estimates the number of school- age children (SAC) (the main focus of STH deworming campaigns) in need of PC with ivermectin. The normal approximation of the binomial distribution was adopted to calculate the hypothetical prevalence distribution in each endemic country. Considering prevalence thresholds for PC equal to 10%, 15%, and 20%, we estimated the number of SAC in need of treatment. We adjusted the estimates accounting for ivermectin distributed in lymphatic filariasis and onchocerciasis elimination programs and excluded from our calculation areas where Loa loa is endemic. The global number of SAC that should be targeted in PC campaigns was estimated at 283.9 M (95% CI: 163.4-368.8), 207.2 M (95% CI: 160.9-380.7), and 160.7 M (95% CI: 86.6-225.7) when the threshold for intervention was set to 10%, 15%, and 20%, respectively. India, China, Indonesia, Bangladesh, and Nigeria accounted for about 50% of the global SAC would have to be covered by PC intervention. CONCLUSIONS/SIGNIFICANCE: Our analysis may support endemic countries to evaluate the ivermectin quantity needed for integrating strongyloidiasis in the existing STH programs. These estimates might also show to generic drug manufacturers the size of the potential market for ivermectin and encourage its production.

Status and Risk Factors of Strongyloides stercoralis Infection in Rural Communities of Xayaburi Province, Lao PDR.

The present study was performed to reveal the current status and risk factors of Strongyloides stercoralis infections in the villages of Kenethao district, Xayaburi Province, Lao PDR. Fecal specimens were collected and examined for S. stercoralis using Koga-agar plate culture technique. Among 516 individuals, the prevalence of S. stercoralis and hookworm infection was 44.2% and 17.1%, respectively. Co-infection was detected in 13.2% of the cases. The prevalence did not significantly differ between males and females (P=0.193). However, the prevalence of S. stercoralis infection increased significantly with age (P=0.041). Of the risk factors examined, both performing farming activities (P=0.001) and walking barefoot when going outside of the house (P=0.003) showed significant correlations with S. stercoralis infections. Our results suggest that S. stercoralis is highly endemic in this area. The National Helminth Control Program of Lao PDR should take actions to control S. stercoralis infection. In addition, provision of health education about the benefits of wearing shoes would be important for reducing infection in the study area. Moreover, the application of high-sensitivity diagnostic approaches is needed to obtain the true impact of S. stercoralis infections in all rural communities in order to provide surveillance activities in Lao PDR.

Control of soil-transmitted helminthiasis in Yunnan province, People's Republic of China: experiences and lessons from a 5-year multi-intervention trial.

The current global strategy for the control of soil-transmitted helminthiasis emphasises periodic administration of anthelminthic drugs to at-risk populations. However, this approach fails to address the root social and ecological causes of soil-transmitted helminthiasis. For sustainable control, it has been suggested that improvements in water, sanitation and hygiene behaviour are required. We designed a 5-year multi-intervention trial in Menghai county, Yunnan province, People's Republic of China. Three different interventions were implemented, each covering a village inhabited by 200-350 people. The interventions consisted of (i) initial health education at study inception and systematic treatment of all individuals aged ≥2 years once every year with a single dose of albendazole; (ii) initial health education and bi-annual albendazole administration; and (iii) bi-annual treatment coupled with latrine construction at family level and regular health education. Interventions were rigorously implemented for 3 years, whilst the follow-up, which included annual albendazole distribution, lasted for 2 more years. Before the third round of treatment, the prevalence of Ascaris lumbricoides was reduced by only 2.8% in the annual treatment arm, whilst bi-annual deworming combined with latrine construction and health education resulted in a prevalence reduction of 53.3% (p<0.001). All three control approaches significantly reduced the prevalence of Trichuris trichiura and hookworm, with the highest reductions achieved when chemotherapy was combined with sanitation and health education. The prevalence of T. trichiura remained at 30% and above regardless of the intervention. Only bi-annual treatment combined with latrine construction and health education significantly impacted on the prevalence of Taenia spp., but none of the interventions significantly reduced the prevalence of Strongyloides stercoralis. Our findings support the notion that in high-endemicity areas, sustainable control of soil-transmitted helminth infections necessitates measures to reduce faecal environmental contamination to complement mass drug administration. However, elimination of soil-transmitted helminthiasis will not be achieved in the short run even with a package of interventions, and probably requires improvements in living conditions, changes in hygiene behaviour and more efficacious anthelminthic drugs and treatment regimens.

Rapid re-infection with soil-transmitted helminths after triple-dose albendazole treatment of school-aged children in Yunnan, People's Republic of China.

Post-treatment soil-transmitted helminth re-infection patterns were studied as part of a randomized controlled trial among school-aged children from an ethnic minority group in Yunnan province, People's Republic of China. Children with a soil-transmitted helminth infection (N = 194) were randomly assigned to triple-dose albendazole or placebo and their infection status monitored over a 6-month period using the Kato-Katz and Baermann techniques. Baseline prevalence of Trichuris trichiura, Ascaris lumbricoides, hookworm, and Strongyloides stercoralis were 94.5%, 93.3%, 61.3%, and 3.1%, respectively, with more than half of the participants harboring triple-species infections. For the intervention group (N = 99), the 1-month post-treatment cure rates were 96.7%, 91.5%, and 19.6% for hookworm, A. lumbricoides, and T. trichiura, respectively. Egg reduction rates were above 88% for all three species. Rapid re-infection with A. lumbricoides was observed: the prevalence 4 and 6 months post-treatment was 75.8% and 83.8%, respectively. Re-infection with hookworm and T. trichiura was considerably slower.

Weekly iron and folic acid supplementation as a tool to reduce anemia among primary school children in Cambodia.

The prevalence of anemia decreased from 62% to 12% and from 57% to 26% in children 5 to 11 years of age in two rural primary schools in Kampot Province, Cambodia, after oral weekly supplementation with iron-folic acid tablets for 20 weeks and with vitamin A and mebendazole twice per year. In 12- to 15-year-old children, success was less marked. The prevalence of hookworm infestation did not change, but the number of eggs in the stool decreased drastically. The intervention had no significant influence on stunting and wasting. An integrated community approach including mass deworming, health education, and multi-micronutrient supplementation was very effective in reducing anemia in Cambodian schoolchildren and should be adopted on a larger scale.

Strongyloidiasis in patients at a comprehensive cancer center in the United States.

BACKGROUND: The frequency of Strongyloides stercoralis infestation and complication in patients with cancer in the United States is unknown. METHODS: The authors performed a retrospective analysis of S. stercoralis infection in patients who were undergoing cancer treatment at The University of Texas M. D. Anderson Cancer Center (Houston, TX). RESULTS: The overall S. stercoralis infection frequency was approximately 1.0 per 10,000 new cancer cases between 1971 and 2003. Twenty-two of 25 patients (88%) were U.S. residents (19 from Texas; 1 each from Mississippi, Tennessee, and Puerto Rico), and the remaining 3 (13%) were from Latin America. Thirteen (52%) had solid-organ malignancies, whereas 12 (48%) had hematologic malignancies (lymphoma or multiple myeloma, n=8; leukemia, n=3; aplastic anemia, n=1). Twelve patients (48%) received systemic corticosteroids, 9 (36%) received antineoplastic therapy, and 2 underwent hematopoietic stem cell transplantation (HSCT). Diarrhea was reported in 13 patients (57%), and eosinophilia was observed in 11 patients (48%); 4 patients (16%) had probable hyperinfection syndrome (in 3 cases of polymicrobial gram-negative bacteremia, 1 patient had Klebsiella pneumoniae pneumonia, whereas 1 patient presented with K. pneumoniae lung infection alone). Evidence of definite pulmonary hyperinfection syndrome was observed in 2 HSCT recipients (8%). Fourteen (74%) of 19 patients responded to thiabendazole therapy. Two patients with definite pulmonary hyperinfection syndrome developed fatal S. stercoralis hemorrhagic alveolitis despite receiving high-dose thiabendazole plus ivermectin therapy. CONCLUSIONS: In the current study, strongyloidiasis was uncommon in patients with cancer and remained localized in individuals with solid-organ malignancies. Definite pulmonary accelerated autoinfections were observed only in HSCT recipients. Therefore, pre-HSCT S. stercoralis screening in individuals from endemic regions of the United States warrants further study.

Geophagy as a therapeutic mediator of endoparasitism in a free-ranging group of rhesus macaques (Macaca mulatta).

Parasite levels were determined for 141 members of a naturally formed social group of rhesus macaques living under free-ranging conditions. Results indicate that group members harbor Trichuris trichiura, Balantidium coli, and large numbers of Strongyloides fuelleborni. Parasite counts decrease significantly with age in this population. Females have significantly fewer parasites than males and a significantly lower prevalence of multiple infections. There were no rank effects regarding parasitosis. While 89% of the animals examined are infected with one or more species of enteric parasite, the prevalence of diarrhea is negligible (2%). The low prevalence of diarrhea in the presence of high parasite loads may be due to the practice of geophagy, which is engaged in by 76% of group members. Soil eaten by these monkeys contains large amounts of kaolinitic clays. Kaolin-based pharmaceuticals (i.e. Kaopectate) are commonly used in human populations to treat diarrhea and intestinal upsets. The mechanical and pharmaceutical properties of the natural kaolinite-based clays may counteract the effects of parasitosis in this free-ranging population.