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Volume 17, Number 7—July 2011

Letter

Enzootic Angiostrongyliasis, Guangdong, China, 2008–2009

Suggested citation for this article

To the Editor: The nematode Angiostrongylus cantonensis was discovered in pulmonary arteries and hearts of domestic rats in Guangzhou (Canton), China, by Chen in 1935 (1). This parasite has a complex life cycle (2) and causes cerebral angiostrongyliasis after ingestion of infective larvae found in freshwater and terrestrial snails and slugs, paratenic hosts (such as freshwater fish, shrimp, frogs, and crabs), and contaminated vegetables (3).

During 2000–2006, a total of 7 outbreaks of angiostrongyliasis were reported in the People’s Republic of China, including an outbreak in Zhaoqing, Guangdong Province (46). We conducted a survey of A. cantonensis nematodes in mollusks and rodents in Qingyuan, Guangong Province, during August 2008–October 2009.

Qingyuan is located in northern Guangdong Province (23°31′–25°12′N, 111°55′–113°55′E). It is the largest city in the province. Qingyuan borders Zhaoqing on the west and Guangzhou on the south. Its climate is subtropical monsoon, and it has an average annual temperature of 20.7°C. The city has an area of 19,152.89 km2 and a population of 3.87 million. Nematode hosts were obtained in 3 counties in Qingyuan: Qingxin, Fogang, and Lianzhou.

During August 2008–October 2009, we captured 288 rats of 7 species (257 Rattus norvegicus, 13 R. flavipectus, 7 R. losea; 6 R. rattus, 3 Bandicota indica, 1 R. rattus alexandrinus, and 1 Mus musculus). Rats were examined for adult A. cantonensis nematodes in pulmonary arteries and right heart cavities.

Among the 288 rats examined, 27 (9.4%) from 3 species were infected with A. cantonensis adults in their cardiopulmonary systems (Table). Infected rodents were found in all 3 counties. The 27 infected rats were 25 R. norvegicus, 1 R. losea, and 1 M. musculus. R. norvegicus rats were most frequently captured in the 3 counties, and this rodent had the highest prevalence of infection. Infected B. indica rats in Lianzhou and M. musculus rats in Qingxin were also found, but the total numbers of infected animals and the prevalences are lower than that for R. norvegicus rats. On the basis of these findings, we conclude that R. norvegicus rats are the major definitive host for A. cantonensis nematodes in Qingyuan.

Specimens from 510 snails (144 Pomacea canaliculata, 306 Achatina fulica, and 60 Bradybaena despecta) were digested with pepsin for isolation of A. cantonensis larvae (7). Metastrongylid larvae were found in 21 (4.1%) of 510 examined snails. Prevalence rates of A. cantonensis in P. canaliculata, A. fulica, and B. despecta were 8.3%, 2.0% and 5.0%, respectively. Differences between the 3 prevalence rates were significant (χ2 9.604, p<0.05). Prevalence rates in the 3 counties are shown in the Table.

All 3 species of infected snails were found in Qingxin and Fogan Counties. P. canaliculata and B. despecta snails were found infected in Qingxin County. However, only A. fulica snails were found infected in Fogang. These findings are similar to those of studies conducted in Guangdong Province (810).

Distributions of snail species among the 3 sites differed. Although all 3 species were found in Qingxin and Fogang Counties, only A. fulica snails were found in Lianzhou County. Lower temperatures in this county may contribute to this uneven distribution. Our failure to detect infected snail hosts in Lianzhou County was unexpected, and further surveys are needed to identify parasite hosts in this area. Our findings suggest that the 3 species may play a major role as intermediate hosts for A. cantonensis nematodes in human infections.

Qingyuan is a natural focus for A. cantonensis nematodes. Residents in the study area frequently eat raw or undercooked snails and slugs, unaware that these animals may contain infective larvae of A. cantonensis that can cause eosinophilic meningitis. Therefore, to protect local residents from parasite infections, inhabitants of this region must be given relevant information about A. cantonensis nematodes. Control measures to control spread of this parasite must also be implemented.

Zhen-Yu Qu, Xiao Yang, Mei Cheng, Yan-Feng Lin, Xiao-Ming Liu, Ai He, Zhong-Dao Wu, and Xi-Mei ZhanComments to Author 
Author affiliations: Author affiliations: Sun Yat-sen University, Guangzhou, People’s Republic of China (Z.-Y. Qu, X. Yang, M. Cheng, A. He, Z.D. Wu, X.-M. Zhan); Qingyuan Center for Disease Control and Prevention, Qingyuan, Guangdong, People’s Republic of China (Y.-F. Lin, X-M Liu)

Acknowledgments

We thank Wen Yang for assistance in improving the manuscript.

This study was supported by grants from National Basic Research Program of China (973 Program 2010CB530004 entitled Mechanisms of Immunoregulation in Angiostrongylus cantonensis) to Z.-D.W., the National Natural Science Foundation of China, and the Guangdong Provincial People’s Government of the Joint Natural Science Fund (U0632003) to X.-M.Z.

References

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  2. Wang QP, Lai DH, Zhu XQ, Chen XG, Lun ZR. Human angiostrongyliasis. Lancet Infect Dis. 2008;8:62130. DOIPubMed
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  7. Lindo JF, Waugh C, Hall J, Cunningham Myrie C, Ashley D, Eberhard ML, Enzootic Angiostrongylus cantonensis in rats and snails after an outbreak of human eosinophilic meningitis, Jamaica. Emerg Infect Dis. 2002;8:3246. DOIPubMed
  8. Deng ZH, Zhang QM, Lin RX, Huang SY, Zhang Y, Lv S, Survey on the focus of angiostrongyliasis in Guangdong Province [in Chinese]. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi. 2010;28:126.PubMed
  9. Zhang Y, Huang D, Ding X, Chen DX, Zhan X-M. Investigation on the source of angiostrongyliasis in Luoding City, Guangdong Province [in Chinese]. Chin J Zoonoses. 2009;1:8791.
  10. Meng J-X, Zhan X-M, Cheng M, Liang Y, Li S-L, Gan M, Analysis of a survey on the infection of Achatina fulica with Angiostrongylus cantonensis in Guangzhow, Guangdong Province [in Chinese]. Chin J Zoonoses. 2007;2:1914.

Table

Suggested citation for this article: Qu Z-Y, Yang X, Cheng M, Lin Y-F, Liu X-M, He A, et al. Enzootic angiostrongyliasis, Guangdong, China, 2008–2009 [letter]. Emerg Infect Dis [serial on the Internet]. 2011 Jul [date cited]. http://dx.doi.org/10.3201/eid1707.100714

DOI: 10.3201/eid1707.100714

1These authors contributed equally to this article.

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Table of Contents – Volume 17, Number 7—July 2011

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Xi-Mei Zhan, Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan Second Rd, Guangzhou, Guangdong Province 510080, People’s Republic of China





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