Soil-transmitted helminthiasis in Laos: a community-wide cross-sectional study of humans and dogs in a mass drug administration environment

Abstract

We conducted a community cross-sectional survey of soil-transmitted helminthiasis in humans and dogs in four provinces in northern Laos. We collected and tested human and dog fecal samples and analyzed results against sociodemographic data. The prevalence of Ascaris lumbricoides, Trichuris trichiura, hookworm, and Strongyloides stercoralis was 26.1% (95% confidence interval [CI] = 23.7-28.4%), 41.5% (95% CI = 38.8-44.1%), 46.3% (95% CI = 43.3-49.0%), and 8.9% (95% CI = 7.4-10.4%), respectively. We observed strong heterogeneity for helminthiasis by ethnicity, province, and wealth status, which coincided with a risk profile demonstrating that Mon-Khmer persons and the poorest households are highly vulnerable. Necator americanus was the dominant hookworm species infecting humans and Ancylostoma ceylanicum was the only Ancylostoma species detected. Hookworm prevalence in village dogs was 94%, and the dominant species was A. ceylanicum. Necator americanus was also detected in dogs. It appears that dogs have a role in human hookworm transmission and warrant further investigation.

Figure 1.

Study sites in northern Laos, 1 = Xay District, Oudomxay Province; 2 = Xiengngeun District, Luangprabang Province; 3 = Pek District, Xiengkhuang Province; 4 = Viengxay District, Huaphan Province.

Figure 2.

Prevalence of dual and triple infections of soil-transmitted helminthes at the community level (left column) and children 6–11 years of age (right column) by (A) province, (B) ethnicity, and (C) wealth status, Laos. Error bars represent 95% confidence intervals. As = Ascaris lumbicoides; Tr = Trichuris trichiura; Hkw = Hookworm; OUD = Oudomxay; LP = Luangprabang; HUA = Huaphan; XK = Xiengkhuang; LT = Lao-Tai; MK = Mon-Khmer; HM = Hmong-Mien.