High prevalence of taeniasis and Taenia solium cysticercosis in children in western Sichuan, China.

Data in China on human Taenia infections, including Taenia solium cysticercosis, is largely lacking. We aimed to determine the prevalence of taeniasis with all three human Taenia species as well as T. solium cysticercosis in primary school-aged children in minority areas of western Sichuan, China. During April 2016 to December 2017, we did a cross-sectional study in five western Sichuan Province primary schools in Liangshan (3 schools), Ganzi (1 school) and Aba (1 school) prefectures. Diagnosis of taeniasis was made by stool microscopy for presence of Taenia eggs, as well as recovery of taeniid tapeworms or proglottids by medicinal treatment followed by species identification using multiplex PCR. Diagnosis of T. solium cysticercosis was made serologically using an ELISA with low-molecular-weight antigens purified from T. solium cyst fluid to detect specific IgG antibodies. A total of 1672 children were screened for taeniasis and 1639 were evaluated for cysticercosis antibodies. Overall prevalence of taeniasis was 7.5% but was as high as 15.6% at one school site (e.g., Shuiluo). Of the three known human Taenia species, adult T. solium tapeworms were detected in 42 children from four of the five schools (all three schools in Liangshan and one in Aba), giving a prevalence of T. solium taeniasis of 2.5% (95% confidence interval 0-6.7%). Cysticercosis antibody seropositivity by school varied from 2.3% to 15.6% (overall 7.5%). T. solium taeniasis carriers were more likely to have cysticercosis antibodies than children without T. solium taeniasis (43.6% vs 6.6%). Schools with higher prevalences of T. solium taeniasis were more likely to have children with human cysticercosis IgG antibodies. This study shows a high prevalence of taeniasis and T. solium cysticercosis in primary school-aged children in minority areas of western Sichuan, suggesting an urgent necessity for school-based disease control.

Structural Equation Modeling (SEM) of Cysticercosis in School-Aged Children in Tibetan Rural Farming Areas of Western China: Implications for Intervention Planning.

Neurocysticercosis (NCC) significantly contributes to morbidity in developing countries. We recently published a study of prevalence and risk factors in school-aged children in three mountainous areas in Sichuan province of western China. Using structural equation modeling (SEM) on data from that study to guide intervention planning, here we examine risk factors grouped into three broad interventional categories: sociodemographics, human behavior, and sources of pork and pig husbandry. Because neuroimaging is not easily available, using SEM allows for the use of multiple observed variables (serological tests and symptoms) to represent probable NCC cases. Data collected from 2608 students was included in this analysis. Within this group, seroprevalence of cysticercosis IgG antibodies was 5.4%. SEM results showed that sociodemographic factors (ß = 0.33, p < 0.05), sources of pork and pig husbandry (ß = 0.26, p < 0.001), and behavioral factors (ß = 0.33, p < 0.05) were all directly related to probable NCC in school-aged children. Sociodemographic factors affected probable NCC indirectly via sources of pork and pig husbandry factors (ß = 0.07, p < 0.001) and behavioral variables (ß = 0.07, p < 0.001). Both sociodemographic factors (ß = 0.07, p < 0.05) and sources of pork and pig husbandry factors (ß = 0.10, p < 0.01) affected probable NCC indirectly via behavioral variables. Because behavioral variables not only had a large direct effect but also served as a critical bridge to strengthen the effect of sociodemographics and sources of pork and pig husbandry on probable NCC, our findings suggest that interventions targeting behavioral factors may be the most effective in reducing disease.

Prevalence and risk factors for Taenia solium cysticercosis in school-aged children: A school based study in western Sichuan, People's Republic of China.

BACKGROUND: Taenia solium cysticercosis affects millions of impoverished people worldwide and can cause neurocysticercosis, an infection of the central nervous system which is potentially fatal. Children may represent an especially vulnerable population to neurocysticercosis, due to the risk of cognitive impairment during formative school years. While previous epidemiologic studies have suggested high prevalence in rural China, the prevalence in children as well as risk factors and impact of disease in low-resource areas remain poorly characterized. METHODOLOGY/PRINCIPAL FINDINGS: Utilizing school based sampling, we conducted a cross-sectional study, administering a questionnaire and collecting blood for T. solium cysticercosis antibodies in 2867 fifth and sixth grade students across 27 schools in west Sichuan. We used mixed-effects logistic regression models controlling for school-level clustering to study associations between risk factors and to characterize factors influencing the administration of deworming medication. Overall prevalence of cysticercosis antibodies was 6%, but prevalence was significantly higher in three schools which all had prevalences of 15% or higher. Students from households owning pigs (adjusted odds ratio [OR] 1.81, 95% CI 1.08-3.03), from households reporting feeding their pigs human feces (adjusted OR 1.49, 95% CI 1.03-2.16), and self-reporting worms in their feces (adjusted OR 1.85, 95% CI 1.18-2.91) were more likely to have cysticercosis IgG antibodies. Students attending high prevalence schools were more likely to come from households allowing pigs to freely forage for food (OR 2.26, 95% CI 1.72-2.98) and lacking a toilet (OR 1.84, 95% CI 1.38-2.46). Children who were boarding at school were less likely to have received treatment for gastrointestinal worms (adjusted OR 0.58, 95% CI 0.42-0.80). CONCLUSIONS/SIGNIFICANCE: Our study indicates high prevalences of cysticercosis antibodies in young school aged children in rural China. While further studies to assess potential for school-based transmission are needed, school-based disease control may be an important intervention to ensure the health of vulnerable pediatric populations in T. solium endemic areas.