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Letter
Angiostrongyliasis, Mainland
China
Xiao-Guang Chen,*
Hua Li,* and Zhao-Rong Lun†
*Southern Medical University, Guangzhou, People's Republic of China; and
†Zhongshan (Sun Yat-Sen) University, Guangzhou, People's Republic of China
Suggested
citation for this article
To the Editor: The first case of angiostrongyliasis caused by
Angiostrongylus cantonensis in mainland China was reported in 1984;
only 3 cases were reported between then and 1996 (1).
Recently, however, cases of angiostrongyliasis have increased rapidly
because of its natural focus and a change in human dietary patterns. For
example, snails have become a popular food in many regions of this country.
Nearly 100 cases of angiostrongyliasis have been reported in mainland
China, including 2 outbreaks (2,3).
From 1994 to 2003, 84 cases of angiostrongyliasis were documented in
mainland China. Of all the cases, 29 were reported individually, and 55
were reported from the 2 outbreaks that occurred in Zhejiang and Fujian.
Sixty-three of the 84 patients had eaten raw or undercooked snails, 5
had eaten raw crabs, 1 swallowed tadpoles, and several pediatric patients
had close contact with snails. Some researchers believe that the larvae
of A. cantonensis can be released from mollusks into slime fluid
and contaminate produce and other objects as they crawl. However, Liang
et al. (4) reported finding no larvae in body fluid washed
from 23 Achatina fulica that were infected with A. cantonensis.
Therefore, whether slime fluid plays a role in human infection remains
unclear.
Eosinophilia is a typical characteristic of eosinophilic meningitis or
meningoencephalitis caused by A. cantonensis. In our study, eosinophilia
was detected in 79 of 84 patients. Therefore, clinical patients with eosinophilic
meningitis or meningoencephalitis with eosinophilia should be presumptively
considered to be infected with A. cantonensis and parasitologic
or serologic tests should be performed. The parasitologic detection rate
of A. cantonensis infection in humans is low; because this parasite
is found in the human central nervous system (CNS) and the tiny larvae
often stick to meninges or nerve root, a false-negative result is often
shown when cerebrospinal fluid is examined. In the 84 cases reported in
this article, worms were isolated from only 8 patients (9.5%), whereas
64 cases were diagnosed as angiostrongyliasis by immunologic methods.
The most common immunologic methods used to diagnosis angiostrongyliasis
in this country are indirect fluorescent antibody test, immunoenzymatic
staining technique, and enzyme-linked immunosorbent assay. All antigens
used in these methods were prepared from whole adult worms. Reports indicated
that serologic cross-reaction occurred between trichinosis and angiostrongyliasis
when whole-worm lysate was used as the antigen (5). In
addition, whole-worm antigens cannot discriminate between new and previous
infection, or monitor the efficacy of the treatment. Therefore, finding
potential diagnostic antigens will be essential to solving this problem
and applying recombinant antigens may achieve this goal. A cDNA library
from the larvae of A. cantonensis was constructed and screened
with acute infection sera, and a diagnostic antigen that can detect early
infection of A. cantonensis (3 weeks) was identified (6).
Some researchers considered that anthelminthics, such as albendazole,
ivermectin, mebendazole, and pyrantel, did not affect A. cantonensis
but noted that the death of worms in the CNS might exacerbate neurologic
symptoms (7). However, many studies in mainland China
showed that anthelminthics can relieve symptoms and reduce the duration
of disease. For example, Wang et al. (8) reported that
albendazole could relieve the symptoms of angiostrongyliasis and suggested
that it can be used to treat the disease. Lin et al. (3)
also reported that in 8 patients who were treated with 20 mg/kg albendazole
for 9 days, the symptoms and signs of acute angiostrongyliasis were rapidly
relieved in 3–6 days. All of these patients had recovered by 10 days after
treatment, and no side effects were observed.
Angiostrongyliasis is an emerging foodborne public health problem in
mainland China. However, most clinicians are not familiar with this disease
and little is known about the prevalence of A. cantonensis in China.
Thus, more studies should be conducted on the biology, epidemiology, and
clinical characteristics of angiostrongyliasis, and more effective diagnostic
methods and treatments for A. cantonensis should be developed.
Acknowledgments
We thank Mark L.
Eberhard for his critical review of this manuscript.
Authors' laboratories
were supported by the National Key Project on Science and Technology
of China (No.2003BA712A03-07) and DPCKSCU (IRT0447).
References
- He JZ, Zhu SH, Yang SQ. First discovery and evidence
of Angiostrongylus cantonensis in the cerebrospinal fluid from
the case of population of mainland of China. J Guangzhou Med Coll. 1984;12:1–4.
- Xue DY, Ruan YZ, Lin BC. Epidemiological investigation on an outbreak
of angiostrongyliasis in Wenzhou. Chin J Parasit Dis. 2000;18:176–8.
- Lin JX, Li YS, Zhu K. Epidemiological study on group infection of
Angiostrongylus cantonensis in Changle City. Chin J Parasitol
Parasit Dis. 2003;21:110–2.
- Liang HK, Shen HX, Xu BK. Investigation on the definite, intermediate
and paratenic hosts of Angiostrongylus cantonensis in Guangzhou.
Chin J Epidemiol. 1984;5:245–8.
- Huang XQ, Zhong QC, He JZ. Investigation of Angiostrongylus cantonensis
infection in rat with IEST method. Journal of Guangdong Medical and
Drug College. 1993;9:22–3.
- Li H, Chen XG, Shen HX. Analysis on the antigens of Angiostrongylus
cantonensis and screen of the dominant diagnostic antigen. Chin
J Parasitol Parasit Dis. 2005;23:33–9.
- Slom TJ, Cortese MM, Gerber SI. An
outbreak of eosinophilic meningitis caused by Angiostrongylus cantonesis
in travelers returning from the Caribbean. N Engl J Med. 2002;346:668–75.
- Wang XT, Huang HJ, Dong QQ. A clinical research for eosinophilic meningoencephalitis
caused by angiostrongyliasis. Chin J Intern Med. 1999;38:326–8.
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Table. Clinical characteristics
of patients with angiostrongyliasis in 2 outbreaks in China*
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Characteristics
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Outbreak 1 (%)
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Outbreak 2 (%)
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No. of patients
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47
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8
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No. of male patients (%)
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24 (51)
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8 (100)
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Age, y
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Median
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32
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12
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Range
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6–58
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11–13
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Incubation (day)
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Median
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10.35
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6
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Range
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1–27
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5–7
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Symptoms†, no. (%)
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Headache
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44 (93.6)
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8 (100)
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Nuchal rigidity or neck pain
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0
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6 (75.0)
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Fatigue
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7 (14.9)
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7 (87.5)
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Vomiting
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9 (19.1)
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8 (100)
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Paresthesias
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30 (63.8)
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3 (37.5)
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Muscle pain
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43 (91.5)
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8 (100)
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Fever
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27 (57.4)
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3 (37.5)
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Cough
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4 (8.5)
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0
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Somnolence
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4 (8.5)
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7 (87.5)
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Skin eruption
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10 (21.3)
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0
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Skin itch
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13 (27.7)
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0
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Laboratory detection
No. positive/no. examined (%)
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Eosiniphils in cerebrospinal fluid
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23/25 (92)
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8/8 (100)
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Eosinophils in blood
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23/25 (92)
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8/8 (100)
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Serologic diagnosis
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21/25 (84)
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NT
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Pathogenic test
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ND
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1/8‡ (12.5)
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*NT, not tested; ND, not detected.
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†No patients had visual disturbance or photophobia,
hyperesthesias, muscle weakness, or diarrhea.
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‡Two larvae were found in cerebrospinal fluid.
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Suggested citation
for this article:
Chen X-G, Li H, Lun
Z-R. Angiostrongyliasis, mainland China [letter]. Emerg Infect Dis [serial
on the Internet]. 2005 Oct [date cited]. Available from http://www.cdc.gov/ncidod/EID/vol11no10/04-1338.htm
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