Epidemiology of Blastocystis infection from 1990 to 2019 in China.

BACKGROUND: Blastocystis is ubiquitous presence in animals and humans worldwide and has a high level genetic diversity. The aim of this study was to conduct a summary of Blastocystis prevalence, subtypes (STs) in humans and animals in China and depict their distribution. METHODS: We searched for the articles related to epidemiology of Blastocystis in humans and animals throughout China which published from January 1, 1990, to July 31, 2019 in the following databases: PubMed, China National Knowledge Infrastructure (CNKI) and Wanfang database. The keywords were Blastocystis and one of the following ones: STs, subtypes, distribution, epidemiology, prevalence, infection, molecular, geographic, intestinal parasites, genetic diversity and characterization. RESULTS: In recent years, various molecular epidemiological studies have been carried out in some provinces/regions of China to identify subtypes of Blastocystis. Infants and young children, school students, hospitalized diarrhea patients, HIV/AIDS patients, tuberculosis patients, and cancer patients as respondents had been included. ST1-ST7 and ST12 were the main subtypes in Chinese population. Moreover, surveys of Blastocystis infection in animal were also conducted in some provinces of China. A variety of animals were investigated including pigs, cattle, sheep, yak, giant panda, and crested ibis (Nipponia nippon) with the main subtypes of ST1-ST8, ST10, ST12-ST14. CONCLUSIONS: In recent years, some provinces/regions in China have conducted various molecular epidemiological studies to identify the Blastocystis subtypes. It is important to focus on new subtypes and mixed subtypes of infection, while increasing data on ribosomal alleles. We encourage the scientific community to start research on humans and surrounding animals (including domestic and wild animals) to better understand the possibility of Blastocystis transmission between humans and animals. We call for action among researchers studying intestinal parasitic diseases (Blastocystis), start drawing the subtype of Blastocystis and increase the subtype related to its clinical symptoms.

[Effect of calcium cyanamid synthetic drug on Schistosoma japonicum egg morphology].

OBJECTIVE: To study the morphological change of Schistosoma japonicum eggs processed by calcium cyanamide synthetic drug, so as to provide the basis for further study of the mechanism that calcium cyanamide synthetic drug to schistosome eggs. METHODS: The calcium cyanamide synthetic drug was added to the cattle feces containing schistosome eggs and mixed up, and then the cattle feces was stacked as original shape on the marshland. Blank controls were set at the same time. The cattle feces samples were collected and.the schistosome eggs were observed under a microscope on the 1st, 2nd, 3rd, 7th day after the experiment. RESULTS: By the effect of calcium cyanamide synthetic drug, the color of eggs was deepening gradually, the miracidia were atrophied, and the shells of eggs were thickened. The embryonic membrane of miracidia was no longer completed 3 days later, and the miracidia were deformed severely 7 days later. The atrophy of miracidia was not obvious in the blank controls. CONCLUSION: The schistosome miracidia and embryonic membrane can be damaged by the calcium cyanamide synthetic drug, and worse damaged with time extending.

[Effect of schistosomiasis control in towns reached criteria of infection controlled in Nanchang City].

OBJECTIVE: To evaluate the effect of schistosomiasis control in towns that had reached the criteria of infection controlled in Nanchang City. METHODS: The residents and livestock of 14 towns that had reached the criteria of infection controlled in Nanchang, Xinjian and Jinxian counties of Nanchang City were sampled to investigate the schistosomiasis endemic situation, Oncomelania hupensis snail status, and data of schistosomiasis control work. RESULTS: The positive rate of serum tests of the residents was 2.58%, and no positive stool samples were found. No cattle or sheep were positive in stool tests. Totally 1 635 snails were caught, and 1278 were alive with an average density of living snails of 0.051/0.1 M2, while no schistosome infected snails were found. All the surveyed administrative villages had the completed files of schistosomiasis control. Conclusion All the 14 towns that had reached the criteria of infection controlled of schistosomiasis have already reached the criteria of transmission controlled in Nanchang City.

[Epidemic situation of acute schistosomiasis in Nanchang City of Jiangxi Province from 2005 to 2012].

OBJECTIVE: To understand the endemic regulation of acute schistosomiasis in Nanchang City of Jiangxi Province from 2005 to 2012 so as to provide the reference for policy-making of schistosomiasis control. METHODS: The data of acute schistosomiasis were collected and analyzed with the descriptive epidemiology method in Nanchang City from 2005 to 2012. RESULTS: A total of 52 acute schistosomiasis cases were reported in Nanchang City from 2005 to 2012. The morbidity of acute schistosomiasis was 0.003 46% in 2005, and it was 0 in 2012. The morbidity of acute schistosomiasis in different years was significant different (chi2 = 61.077, P < 0.01). The duration of incidence was from May to November, but the peak of the incidence was July. The sex ratio between males and females was 4.78:1 (43:9, chi2 = 22.231, P < 0.01). The ages of cases showed double humps, namely the 6-15 years' group and 30-40 years' group. Most of the acute cases were farmers (65.38%), students (25.00%), and fishermen (3.85%). Fishing and swimming were the main infection ways, with the infection rates of 63.46% and 26.92%, respectively. CONCLUSION: The susceptible populations are peasants and young students; therefore, we should strengthen health education for these high-risk groups.

[Influencing factors of changes of Oncomelania snail densities in Poyang Lake region, Nanchang City, 2011].

OBJECTIVE: To explore the influencing factors of the significant decrease of snail densities in Poyang Lake region, Nanchang City, 2011. METHODS: According to the elevation of the environment, 5 grasslands where there were high snail densities and their elevations were from 14 to 17 m were selected as study areas. The data of snails in the past three years and the hydrological information in the past five years were collected and analyzed. The current snail status was surveyed and the fishermen were interviewed. RESULTS: The snail density of Poyang Lake region in Jinxian County decreased by 91.2% in 2011 compared with that in 2009 (P < 0.01). In 2010, the water levels were 13.90 m in April and 16.07 m in May respectively in Xingzi Station, and the rainfalls were 312 mm in April and 356 mm in May in Poyang Lake region; in 2011, the water levels were 8.73 m in April and 10.31 m in May respectively in Xingzi Station, and the rainfalls were 90 mm in April and 145 mm in May respectively in Poyang Lake region, which were lower than those during the past five years. There was no any other apparently unusual phenomenon. CONCLUSION: The significant decrease of snail densities in Poyang Lake region in 2011 may be related to the long soaking time of marshland in 2010 and low rainfall in the first half of 2011.

[Effect of niclosamide spreading oil on killing schistosome cercariae].

Dechlorinated water (100 ml, 30 degrees C) was put into a plate (diameter 15 cm), and 1% niclosamide spreading oil 5 microl was added, then a ring of Schistosoma japonicum cercariae were picked up to the plate. The time of killing all the cercariae was observed at three time points (immediately, 24, 48 h), and the dechlorinated water was used as control. The results showed that schistosome cercariae were all killed in three minutes by 1% niclosamide spreading oil at the three time points. The cercaria-killing effects of each time point were not significantly different (F = 0.062, P > 0.05). The cercariae were alive in the control in 48 h.