RESUMO
Objective To evaluate the impact of water pollutants, water levels and meteorological factors on the Oncomelania hupensis density in Eastern Dongting Lake regions, so as to provide insights into schistosomiasis control. Methods O. hupensis snails were surveyed using a systematic sampling method in snail-infested marshlands in Eastern Dongting Lake regions from 2007 to 2014, and data pertaining to water pollutants, water levels and meteorological factors were collected. The duration of submergence and the date of the start of submergence were calculated. The snail density and its influencing factors were descriptively analyzed, and a linear mixed model was generated to examine the impacts of variables on the snail density. In addition, smooth curves were fitted to investigate the relationship between snail density and variables. Results The snail density appeared a fluctuation in Eastern Dongting Lake regions during the period from 2007 to 2014, with the highest density on October, 2010 (52.79 snails/0.1 m2) and the lowest density on January 2009 (2.15 snails/0.1 m2). Linear mixed-model analysis showed that permanganate index, total phosphorus and the date of the start of submergence affected the snail density (t = 6.386, −2.920 and −3.892, all P values < 0.01). Smooth curve analysis revealed that the associations of the snail density with the permanganate index and total phosphorus appeared an approximately quadratic curve. After the end of April, the earlier date of the start of submergence resulted in a higher snail density. Conclusion Permenganate index, total phosphorus and the date of the start of submergence affect the O. hupensis snail density in Eastern Dongting Lake regions.
RESUMO
Objective To understand the prevalence of Clonorchis sinensis infection among residents in two communities of Zhongshan City,and evaluate the effect of albendazole treatment,so as to offer the evidence for formulating the strategy of clo-norchiasis prevention and control.Methods The stool specimens were collected from the residents of two comprehensive dem-onstration areas,and the eggs of C.sinensis were detected by Kato-Katz technique.Those who were tested positive were treated with albendazole(0.4,twice a day for 4 days in adults,and half dosage for children aged 16 years or below).Three weeks after the treatment,the stool specimens were recollected and retested to evaluate the effect. Results A total of 532 people were in-vestigated and 96 were tested positive,with an infection rate of 18.05%.The infection rate was 28.63%(69/241)in the males and 9.28%(27/291)in the females,and there was a significant difference between them(Χ2=334.99,P<0.01).The infection rate increased with the increase of the age(Χ2=63.84,P<0.01).Among the 96 positive residents,94 received the albendazole treatment,and 86 were retested after the treatment with a negative conversion rate of 91.86%(79/86).Of the 7 residents without the conversion,5 had irregular medication.No severe adverse reactions were reported during the period of treatment. Conclu-sions The infection rate of C.sinensis among residents in the two communities of Zhongshan City is high,especially among the males and aged people.The effect of albendazole is good in the treatment of C.sinensis infection.In the future,the general sur-vey and treatment should be strengthened in order to lower the infection rate.