[Investigation on serology, risk factor and awareness of angiostrongylus cantonensis in Hainan province].

Five survey sites were selected from Hainan Province and one village were randomly extracted in each site. A survey that covered knowledge and risk factor on angiostrongyliasis cantonensis was conducted and infection rate of Angiostrongylus cantonensis tested by ELISA. Among 393 sampled people, the sero-positive IgG rate was 20.6% and about 39.7% residents were found with a history of eating snails in recent half year, 12.5% from respondents had the habit of eating raw snails. Questionnairing showed that the ratio of awareness on A. cantonensis was 8.4%. All factors were analyzed by multi-logistic module and showed that the history of snail-eating and resident area may be the risk factors.

The control and surveillance of filariasis in Hainan Province, China.

Hainan is a single bancroftian filariasis endemic province where filariasis is prevalent in all 18 cities and counties. A program to control filariasis was started in 1953. The strategy of eliminating infection sources has been adopted as the principal intervention measure in filariasis control. Over 30 years, the sustained effort throughout the province reached the point of basic elimination of filariasis in 1987. After the basic elimination of filariasis, the patterns of filariasis transmission in residual microfilaremia cases in Hainan Province were studied so as to provide a scientific basis for formulating strategies to eliminate filariasis. According to the "Technical scheme for surveillance in areas where fialariasis has been basically eliminated" issued by the Ministry of Health, a longitudinal and cross-sectional and entomological surveillance of fialariasis was carried out using parasitological and entomological and serological methods in the whole province during 1983-2004. In the cross-sectional and entomological surveillances, the last microfilaremia case was found in 1999, no mosquitoes were found to be infected with filarial larvae. A total of 132 microfilaremia cases found in the longitudinal surveillance become negative by 10 years. Since 1997 no mosquitoes were found to be infected with filarial larvae in the longitudinal surveillance. Serological surveillance of the population showed the mean positive rate of IFAT dropped from 10.63% in 1990 to 0.28% in 2000, which being similar to that of nonendemic areas. The results show that residual sources of infection after basic elimination of filariasis were tending to be naturally eliminated and transmission of filariasis has been interrupted in Hainan Province.

[Study on the polymorphism in circumsporozoite protein of Plasmodium vivax before the completion on elimination program of malaria, in Hainan province].

OBJECTIVE: To explore the polymorphism in circumsporozoite protein of Plasmodium vivax before malaria was eliminated in Hainan island. METHODS: PCR amplification, sequencing, and alignment methodologies were conducted and phylogenetic tree constructed. RESULTS: From all the cases, 19 of them belonged to two types, with 18 as VK210 type and 1 as VK247 type. VK210 type could be divided into seven kinds of subtypes but VK247 had only one type. Ratio of tropical strain with temperate stain in VK210 type was explored between the two stages:control or elimination. Phylogenetic tree was constructed by amino acid sequencing which clearly manifested that VK210 type and VK247 type belonged to different clusters. CONCLUSION: Compared the proportion of two types in the control stage, there was no significant difference seen in the stage of elimination.

Epidemic status of Angiostrongylus cantonensis in Hainan island, China.

OBJECTIVE: To understand the current epidemiological status of Angiostrongylus cantonensis in Hainan island and provide the scientific evidences for prevention and control of the disease. METHODS: The investigation on nature infection condition of intermediate hosts and final hosts of Angiostrongylus cantonensis were carried out in five counties, Hainan Province, and enzyme linked immunosorbent assay (ELISA) was employed to detect antibodies of Angiostrongylus cantonensis in human hosts. RESULTS: A total of 1612 molluscs were examined, 21.3% of which harbored L3 of Angiostrongylus cantonensis. Among them, the infection rates of Pomacea canaliculata, Achatina fulica, Cepaea and Phlegm bilineatus were 12.36%(64/518), 22.66%(121/534), 20.93%(9/43), and 28.24%(146/517), respectively. Of the 118 rats trapped, 13 Rattus norvegicus were found to be infected with Angiostrongylus cantonensis. A total of 459 serum samples were collected and tested. 92 serum samples were Angiostrongylus cantonensis antibody-positive. CONCLUSIONS: The survey revealed a wide distribution of Angiostrongylus cantonensis in Hainan island. Pomacea canaliculata and Achatina fulica are main intermediate hosts of Angiostrongylus cantonensis. Rattus novegicus is a nature definitive host, indicating that a considerable number of people are at risk of angiostrongyliasis. Health education, rigorous food inspection and surveillance are all needed to prevent angiostrongyliasis outbreaks in future.