Abstract:

Objective To understand the endemic status of human intestinal parasitic infections in the eastern part of Henan Province, in order to facilitate control of the disease in this region. Methods According to the economic level and geographical location, stratified cluster sampling was made to randomly select 26 survey spots in 9 counties including Linying, Puyang, Taiqian, Taikang, Xiping, Xixian, Xiangcheng, Xinzheng and Yucheng, from November 2014 to June 2015. Human fecal samples were collected and examined for intestinal worm infection using Kato-Katz thick smear method. For the hookworm egg-positive samples, larvae were cultured on the filter paper to identify the species of Ancylostoma. The adhesive tape method was used to detect pinworm eggs in children aged 3 to 6, and iodine staining was used to detect protozoan infection in fecal samples. Information on the source of drinking water and the annual per capita net income of farmers was collected. The infection rate was normalized and compared among different regions. The parasitic infection rate was also analyzed in aspects of species, sex, age, and occupation using the Chi-square test. Results A total of 6 696 fecal samples were collected, from which 6 species of intestinal worms and 4 species of intestinal protozoans were found. The overall infection rate of intestinal parasites was 1.57% (105/6 696), comprising 0.91% (61/6 696) for worms and 0.66% (44/6 696) for protozoans. Concerning the infection rate, the top three intestinal parasites were the pinworms(0.36%, 24/6 696), Blastocystis hominis (0.30%, 20/6 696), and Ascaris lumbricoides (0.19%, 13/6 696). The pinworm infection rate was 2.23% (15/674) among children aged 3-6 and that revealed by the adhesive tape method was 1.93% (13/674). The hookworm larvae detected in 7 samples were all identified to be Ancylostoma duodenale. The top three counties with highest intestinal parasite infection rate were Xiangcheng (4.24%), Xinzheng (3.51%) and Taikang (3.34%). There was no significant difference in the intestinal parasite infection rate between males (1.71%, 55/3 214) and females (1.44%, 50/3 482) (χ² = 0.82, P > 0.05). Among populations with different educational levels, the infection rate was higher in those at a high school or secondary high school level (2.11%, 10/473) (χ² = 2.41, P > 0.05 vs. other groups). Among different age groups, the infection rate of intestinal parasite was highest in the 15-29 age group (2.38%, 21/884) (χ² = 9.39, P < 0.01). Among different occupations, the infection rate of intestinal parasite was significantly higher in preschool children (2.5%, 24/720) and students (2.09%, 24/1 148) (χ² = 9.93, P < 0.05). The infection rate of intestinal parasite was higher in populations in the well water-based spots (1.21%, 31/2 562) than in the tap water-based spots (0.65%, 27/4 134) (χ² = 5.71, P < 0.05). The average annual per capita net income of farmers in the survey spots was 1 200-11 600 yuan (median, 5 604.5 yuan). The intestinal parasite infection rate decreased with increasing annual per capita net income of farmers (χ² = 11.08, P < 0.01). Conclusion The intestinal parasite infection in the eastern part of Henan Province has significantly decreased than the previous two surveys. Preschool children and students are the main population targets for surveillance in the future.

Key words: Epidemiological investigation, Intestinal parasite, Eastern Henan