Abstract:

Objective To analyze the infection status of soil-transmitted nematodes among the population in coastal areas of Shandong Province for scientific evidences in formulation of parasite prevention and control strategies or measures. Methods From 2016 to 2023, a survey was conducted at the monitoring sites in 40 counties (cities and districts) along the coastal areas of Shandong Province. Each survey site was divided into 5 geographical zones (east, south, west, north, and central), from which one administrative village (community) was selected for monitoring, and at least 200 permanent residents aged 3 years and above were sampled from each administrative village (community). The modified Kato-Katz thick smear method (one stool sample tested twice) was used to detect soil-transmitted helminth infections, analyze the differences in infection rates among different regions and populations. Results From 2016 to 2023, a total of 43 217 people in the coastal areas of Shandong Province underwent survey, which revealed nematode infection in 558 people, with a total infection rate being 1.29% (558/43 217). The infection rates of the population over the years were 2.43%, 2.84%, 1.05%, 1.74%, 0.26%, 1.56%, 0.68% and 0.02%, respectively. The infection rate generally showed a downward trend (χ²_trend=194.132, P<0.01). By regional distribution, the infection rate of soil-transmitted nematodes exceeded 5.00% in three counties (cities and districts), which were Rongcheng City (8.76%), Lanshan District (7.83%), and Haiyang City (5.96%). No infections were detected in the remaining 18 counties (cities and districts). Trichuris trichura was the major species for the infection, accounting for 94.80% (529/558), with an infection rate of 1.22% (529/43 217), and the infection rates of Ascaris lumbricoides and Ancylostoma duodenale were 0.07% (31/43 217) and 0.03% (11/43 217), respectively. There were 13 cases of mixed infection, with an infection rate of 0.03%. The infection rates were the highest among people aged 60 and above (2.01%), farmers and herdsmen (1.72%), and illiterates or semi-illiterates (4.91%). The infection rates of soil-transmitted nematodes showed significant differences among people of different ages, occupations, and educational levels (χ²=141.018, 106.445, 297.168, all P<0.01). Conclusion The infection rate of soil-transmitted nematodes in the coastal areas of Shandong Province has generally shown a downward trend, yet it is higher than the provincial average level, the prevalence varies greatly among different regions and populations. Trichuris trichura are the dominant species. It is recommended to continue the monitoring work and strengthen the prevention and control of the infection in key regions and populations.

Key words: Soil-transmitted nematode, Infection rate, Monitoring, Coastal area, Shandong Province