Abstract:

Objective To understand the status of key parasitic infections of humans in Heilongjiang Province, and provide scientific basis for formulating the prevention and control measures for key parasites in the province. Methods The study was performed from April to June 2015, in accordance with the National Survey Program and Implementation Rules for the status of human key parasites. A stratified cluster random sampling method was used to extract 104 rural survey sites and 15 town survey points from 40 counties (cities and districts) in the Province. The number of persons examined at each survey point was no less than 250. Fecal samples were collected from subjects, and worm eggs of nematode, Taenia tapeworm and Clonorchis sinensis were examined by a modified thick smear method and counted. The direct smear method was used to detect intestinal protozoan cysts and trophozoites, while the cellophane and swab method was used to detect pinworm eggs and the eggs of Taenia solium. Results A total of 30 280 people were examined, of whom the total intestinal parasite infection rate was 2.5% (751/30 280), while no intestinal protozoa were found. Three kinds of intestinal worms were detected: Ascaris lumbricoides, Trichuris trichiura and C. sinensis, with infection person of 3, 1 and 747, respectively. The infected population was predominated by C. sinensis infection (99.5%, 747/751). Both A. lumbricoides and T. trichura showed mild infection. The proportion with light, medium or heavy infections of C. sinensis was 82.3% (615/747), 16.9%(126/747), and 0.8%(6/747), respectively. The infection rate in rural areas was 2.8%(737/26 456), significantly higher than that in urban areas (0.4%, 14/3 824) (χ² = 80.875, P < 0.05). There were also significant differences in infection rate between males and females [3.1% (464/15 171) versus 1.9% (287/15 109), χ² = 42.037, P < 0.05), among different age groups (χ² = 121.628, P < 0.05) [being highest in the 30-39 group which was 3.3% (148/4 430)], among different occupations (χ² = 165.864, P < 0.05) [being highest in the famers (herdsmen and fishermen) which was 3.2% (695/21 914)], among different ethnic groups (χ² = 8.482, P < 0.05)[being highest in the Han population which was 2.5% (743/29 487)], and among different educational levels (χ² = 123.031, P < 0.05) [being highest in those with a middle high school level which was 3.5% (500/14 425)]. Conclusion Three species of key parasites in humans are found in Heilongjiang Province, predominated by Clonorchis sinensis infection (99.5%), most of which showed a light degree of infection. The infection rate varied by factors of gender, age, occupation, ethnicity and education level.

Key words: Parasitic disease, Epidemiology, Heilongjiang Province