[Prevalence of Clonorchis sinensis infection and effect of albendazole treatment among residents in two communities of Zhongshan City].

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 clonorchiasis prevention and control. METHODS: The stool specimens were collected from the residents of two comprehensive demonstration 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 investigated 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. CONCLUSIONS: 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 survey and treatment should be strengthened in order to lower the infection rate.

[Investigation on sanitation of freshwater aquaculture environments and Clonorchis sinensis intermediate host infection in a city of Pearl River Delta region, China].

OBJECTIVE: To understand the current status of the sanitation of freshwater aquaculture environments, and Clonorchis sinensis infection of freshwater fish in the aquaculture and market in a city of Pearl River Delta region, so as to provide the evidence for formulating the prevention and control strategy of clonorchiasis sinensis. METHODS: In 2016, based on the distribution of freshwater aquaculture, 36 freshwater fish ponds among 14 towns were selected for sampling and investigation, and 10-20 pieces were collected from each pond. Besides, 3 aquatic product wholesale markets were included, among which 3-6 stalls were selected from each market, and 20-30 pieces were collected from each stall. The metacercaria in the fish was examined by the digestion method. RESULTS: In the 36 fish ponds, there were no toilets with the stool being drained into fish ponds directly, and there was only one pond with duck sheds with the stool being drained into fish ponds directly. Totally 437 pieces of freshwater fish from ponds were detected, with a metacercaria positive rate of 4.35% (19/437). The metacercaria positive fish were distributed in 50% (7/14) of towns and 25% (9/36) ponds. The positive rates of crucian carp, grass carp, dace, aristichthysnobilis, and tilapia were 13.95% (6/43), 4.76% (9/189), 4.44 (2/45), 1.55% (2/129), and 0 (0/31) respectively, with statistically significant difference (χ2 = 13.46, P = 0.01). Totally 307 pieces of freshwater fish were collected from the wholesale markets, with a total positive rate of 1.95% (6/307). The positive rate of grass carp and aristichthysnobilis were 3.20% (4/125) and 2.78% (2/72) respectively, and no positive samples were found in crucian carp, dace and tilapia, with no statistically significant difference among the different fish in the infection rate (Fisher exact P = 0.75). CONCLUSIONS: The sanitation of freshwater aquaculture environments in a city of Pearl River Delta region is relative good. However, there are different degrees of Clonorchis sinensis infection of freshwater fish in some aquaculture environments and markets.

[Epidemic situation and prevention and control strategy of clonorchiasis in Guangdong Province, China].

Clonorchiasis is one of the food-borne parasitic diseases. Adult parasites live in the human liver and gallbladder tube system, causing serious complications, such as gallstones, cholecystitis and cholangitis, and even bile duct cancer. The disease is very popular in our country, and the population infection rate is high. It is an important public health problem. Guangdong Province is the earliest province being found of clonorchiasis and with serious epidemic. In the second national human parasitic diseases distribution survey, the results showed that the average infection rate of Clonorchis sinensis in the epidemic areas in Guangdong was 16.42%. It is estimated that the population of C. sinensis infection is over 6 million. The prevention and control of clonorchiasis in China is still in the initial stage currently and we face many challenges such as unclear epidemic characteristics and transmission mode, and lack of long-term prevention and control mechanism. This article introduces the epidemic situation of clonorchiasis and prevention and control strategies and measures in Guangdong.

[Effect of comprehensive control in demonstration plot of clonorchiasis in Yangshan County, 2006-2009].

OBJECTIVE: To evaluate the effect of comprehensive control of clonorchiasis in demonstration plot in Yangshan County so as to popularize it. METHODS: Five areas in the east, south, west, north and center of Yangshan County were randomly sampled as the investigation spots, where the comprehensive control measures centered on health education and infectious source control were carried out. The baseline data were collected and the control effect was evaluated in the final term in 2009. RESULTS: The infection rate of Clonorchis sinensis decreased from 14.01% in 2006 to 6.87% in 2009, with the reduction rate of 50.96% (Chi2 = 36.37, P < 0.01), and the decline rates in the 5 investigation areas were 33.15%, 37.86%, 55.74%, 45.91% and 71.38%, respectively. CONCLUSIONS: The effect of comprehensive control measures in demonstration plot of in Yangshan County is significant, and it has achieved the goal of the national demonstration county of parasitic disease control, which requests for 40% decline in the infection rate.