Abstract:

Objective To understand the endemic status of human common parasite infections in Qinghai Province, so as to provide scientific basis for developing prevention and control measures. Methods The survey was performed in accordance with the National Survey Program and Implementation Rules to understand the status of human key parasite infections from May to September 2015. Total 51 survey sites were selected in 16 counties or cities based on a stratified cluster sampling method. Each site included no less than 250 permanent residents with age over 3 years old. The fecal samples were collected from each participant and the geohelminth eggs were examined under microscope using modified Kato-Katz method in triplicate. The intestinal protozoan trophozoites and cysts were examined using direct saline/iodine wet mount. The species of hookworm was identified by observing the larvae cultured from hookworm egg positive feces. The anal adhesive tape test was used to examine Enterobius vermicularis eggs for children with 3-6 years old. The collected data were statistically analyzed using SPSS 17.0 software. Results Totally 12 859 people were examined and overall prevalence of intestinal parasite infections was 2.0% (249/12 859), specifically 1.1%(138/12 859) for Ascaris lumbricoides, 0.9% (8/857) for E. vermicularis, and 0.8% (103/12 859) for intestinal protozoan infections (Entamoeba coli and Giardia lamblia), only one case was found with Taenia infection. The people living in Qilian mountain ecological region had the highest prevalence of soil-transmitted helminth (STH) (1.5%, 65/4 292) with statistical significance compared to that in other ecological regions (P < 0.01). For intestinal protozoan infection, people living in River source/Gannan ecological regions had the highest prevalence of 1.3% (56/4 302) with statistical significance compared to people living in other regions (P < 0.01). The infection rates of soil-transmitted nematodes for male and female people were 0.9% (59/6 435) and 1.2% (79/6 424), respectively. The infection rates of protozoan infections for male and female were 0.9% (56/6 435) and 0.7% （47/6 424）. There was no significant difference in the prevalence of intestinal parasite (STH or protozoan) between males and females (P > 0.05). People with age of 0-9 years old had the highest prevalence of STH (2.5%, 37/1 512) and people with 70-79 years old had the lowest STH infection rate (0.3%, 1/371), with statistical difference compared to other age groups (P < 0.01). People with age over 80 or between 10-19 had the highest prevalence of intestinal protozoan infections (1.3%, 1/78 and 1.2%, 20/1 673, respectively), however, the difference is not statistical significant compared to other age groups（P > 0.05）. For the prevalence in different nationality, Han and Tu had the highest prevalence for STH (2.1%, 99/4 707 and 1.0%, 5/486), and Mongol and Tibetan had the highest prevalence of intestinal protozoan infections (1.4%, 15/1 056 and 1.1%, 59/5 231), with statistical significance compared to people with other nationality (P < 0.01). The prevalence of STH was high in pre-school children (2.4%, 24/1 014), students (1.7%, 29/1 666) and farmers (1.4%, 72/5 336） with statistical significance compared with other occupations（P < 0.01）. The unemployed people had significantly higher infection rate of intestinal protozoan infections (4.8%, 1/21） than other people (P < 0.01). Conclusion A. lumbricoides infection is a major concern for the control of parasitic diseases in Qinghai, which are mostly distributed in agricultural-oriented areas and low-age populations. Intestinal protozoal infections are mostly distributed in animal husbandry areas with poor natural environment and poor living conditions.

Key words: Human intestinal parasite, Endemic status, Qinghai Province