Abstract:

Objective To understand the current status and trends of human important parasitic diseases (HIPD) as a basis for their better control, a survey was carried out in Hainan Province in 2015. Methods According to the Protocol of the 3rd National Survey on the Status of Human Key Parasitic Infections. Total 18 survey sites (10 villages, 8 townships) were selected from 8 cities (counties) using a stratified random sampling method. The prevalence of soil-transmitted helminth and taenia infections was surveyed in all sites. The prevalence of intestinal protozoa infections was surveyed only in 10 village sites. In each survey site, no less than 250 permanent residents with age above 3 years old were recruited. Fecal sample was collected from each participant and the eggs of intestinal helminthes were examined in duplicate under microscope using Kato-Katz technique. Tube filter paper culture method was applied to culture the larvae and identify the species of hookworm. The Enterobius eggs were detected in children aged 3 to 6 years old by using adhesive tape. The cysts and trophozoites of intestinal protozoans were examined using saline direct smear and iodine staining. SPSS 21.0 software was used for statistical analysis. Results A total of 4 773 individuals were surveyed for HIPD from 18 selected sites with an overall infection rate of 13.3% (633/4 773) for HIPD infections. The prevalence of intestinal protozoa infections was 2.8% (76/2 698) with 5 species of protozoans identified. The prevalence of helminth infection was 12.1% (576/4 773) with 7 species of helminths including whipworm (5.6%) and hookworm (4.3%) as main species. Using adhesive tape method, 252 children of 3-6 years old were examined for the infection of E. vermicularis, and an infection rate of 31.4% (79/252) was found among the children examined. No Taenia infection was found. A total of 143 fecal samples with hookworm egg positive were cultured for identifying the species of hookworm, 120 of them were Necator ameicanus only, while other 23 were mixed with N. ameicanus and Ancylostoma duodenale. There was a significant difference (P < 0.01) in helminth prevalence between villages (18.1%, 488/2 698) and townships (4.2%, 88/2 075). A significant difference (P < 0.05) in helminth prevalence between male (10.9%, 247/2 273) and female (13.2%, 329/2 500) was observed. Among different age groups, people with age between 60-69 years old had the highest helminth prevalence (17.58%, 77/438), while group with age 15-19 years old had the lowest helminth prevalence (6.19%, 12/194) with statistical difference (P < 0.01). The Miao nationality had the highest helminth prevalence (19.1%, 97/508; P < 0.01) among different nationality people. Among different occupations, farmers had the highest helminth prevalence (14.1%, 384/2 717), while merchant had the lowest (3.5%, 8/228) with statistical difference (P < 0.01). Among different education levels, the illiterates had the highest helminth prevalence (20.8%, 33/159), while people with college and above education with the lowest helminth prevalence (5.8%, 34/591) with significant difference among different education levels (P < 0.01). The prevalence of intestinal protozoa infections was surveyed in Dongfang, Qionghai, Qiongzhong and Lingao counties only with 2.0% (16/790), 1.7% (14/829), 3.8% (20/527), and 4.7% (26/552), respectively. There was a significant difference in protozoa prevalence among different areas (P < 0.01). The protozoa prevalence in male and female were 2.8% (37/1 316) and 2.8 (39/1 382) respectively. The highest prevalence of intestinal protozoa infections was distributed in people with 20-29 years old (4.7%, 15/320) and Miao nationality (4.6%, 12/263). Among different occupations, preschoolers had the highest intestinal protozoa infections (4.6%, 12/260) with significant difference compared to other occupations (P < 0.01). Conclusion Although the overall infection rate of important human parasites has been showing a trend of significant reduction in Hainan province during past years, it still remains higher in context of nationwide level, particularly the infection rate of E. vermicularis in children appears notably high, thus it should be the prior target of intestinal parasitic disease control in Hainan in future.

Key words: Hainan Province, Human important parasitic diseases, Endemic status