[Distribution of food-borne parasitic diseases and dietary habits in human population in Guangxi].

OBJECTIVE: To investigate the distribution of common food-borne parasitic diseases and dietary habits in Guangxi. METHODS: In the survey from 2002 to 2005, questionnairing, fecal examination, ELISA or skin test were applied in the endemic areas of clonorchiasis, taeniasis, cysticercosis, trichinelliasis or paragonimiasis in Guangxi Zhuang Autonomous Region. 13 990 residents at 27 sites in 9 counties were examined for clonorchiasis, 22772 residents at 22 sites in 10 counties for taeniasis, 9 638 residents at 20 sites in 10 counties for trichinelliasis and 9 347 residents at 18 sites in 6 counties for paragonimiasis. RESULTS: Among 109 counties, residents in 64 counties (59.8%) were found with local habit of eating raw meat, covering Han and other 6 ethnic groups (Zhuang, Yao, Miao, Maonan, Dong and Buyi) . Various animal food such as fish, pork, pork liver, swine blood, beef, ox blood, chicken blood, goat blood, crab, shrimp, clamworm, snail, oyster, and duck meat were consumed in raw with or without seasonings, or by ways of hot-pot, pickle, dipping in boiling water or wine-soaked. Food-borne diseases such as clonorchiasis, taeniasis, cysticercosis, trichinelliasis and paragonimiasis were prevalent in the Region. The survey showed that clonorchiasis is prevalent mainly in the river basins of Yongjiang, Zuojiang and Youjiang in the middle-west and southern part of the Region with a prevalence of 9.8%, taeniasis and cysticercosis in the north and middle-north such as Rongshui prevalence of 43.3% and 2.1% respectively, Bingyang (2.1% and 1.0%) and Tianlin (1.6% and 1.1%) counties. Sporadical cases of trichinelliasis were found in the counties of Debao, Baise, Luzhai and Nandan with positive rate 9.8%, 6.4%, 5.3% and 3.1% by serological test. Skin test on paragonimiasis among residents in sampled areas revealed a positive rate of 2.6% and the cases mainly distributed in Rongshui, Longsheng and Quanzhou counties. CONCLUSION: Consumption of raw or undercooked meat is popular in the local residents especially the ethnics, which is an important factor in the prevalence of food-borne parasitic diseases.

[Discovery of a residual focus of bancroftian filariasis after declaration of its transmission interruption in Guangxi].

OBJECTIVE: To describe the discovery of a residual foci of bancroftian filariasis in Fuchuan County where the disease was announced to have been eliminated, and reveal its epidemiologic feature. METHODS: The investigation was carried out from August 2007 to March 2008 among residents in Changtang village where the first case of filariasis was found and the neighboring villages. They were screened with two thick blood smears. Immunochromatographic technology (ICT) was conducted for those going out but returned and those in surrounding areas. Vector mosquitoes were collected and dissected to find filaria larvae. Historical documents were reviewed and relevant people were interviewed. RESULTS: In Changtang administrative village, 1052 residents were screened and 19 cases with microfilaremia were found in 2 natural villages, with a Mf-positive rate of 1.8% (5.1% in Gangshang and 1.4% in Yinshan respectively). No Mf-positive case was found in 4119 residents screened in other 3 villages. The average microfilaria density in the 19 cases was 17.37/60 +/- 1 blood. All the 19 cases belonged to 12 families, and 13 cases were relatives to each other, which showed a feature of spatial clustering and family clustering. More patients were identified in the age groups of 20-29 and 50-59, and 57.9% of them were older than 50 years. No larvae were found in 54 Culex pipiens fatigans dissected. CONCLUSION: The Changtang village is identified as a residual focus of bancroftian filariasis with a low, limited endemicity. More cases have been among the elderly with a low average microfilaremia.

[Study on 5S rDNA sequence of two isolates of Trichinella from Guangxi].

OBJECTIVE: To analyze 5S ribosomal DNA (5S rDNA) sequences of two Trichinella isolates from Guangxi. METHODS: The fragments of 5S rDNA were obtained by PCR from the isolates of Debao and Nandan, and sequencing was made for the PCR products. Homogeneity, genetic distance matrix and phylogenetic tree were analyzed by related software. 5S rDNA sequences of the two isolates were compared separately with those of Trichinella species in GenBank. RESULTS: 5S rDNA sequences of three Trichinella isolates (Debao, Nandan and T. spiralis) showed the same length at 695 bp. There were 4 variable positions. The homogeneities of Debao and Nandan isolates with T. spiralis were 99.0% and 99.1% respectively. The homogeneities between Debao isolate and Nandan isolate was 98.8%. Compared with other Trichinella isolates in GenBank, they were all less than 94.2%. The evolutionary distance among isolates of Debao and Nandan and T. spiralis was 0.014. Meanwhile, the evolutionary distances between the Guangxi isolates and other Trichinella isolates in GenBank were more than 0.056. Phylogenetic tree analysis revealed that two isolates of Guangxi and T. spiralis located at the same node, revealing a close relationship. Bootstrap confidence values in two phylogenetic trees were 96 and 99, respectively. CONCLUSION: The two Trichinella isolates of Guangxi show a high homogeneity with T. spiralis, locate at the same nodes in phylogenetic tree,suggesting that the Debao and Nandan Trichinella isolates be identified as T. spiralis.