Human angiostrongyliasis outbreak in Dali, China - PubMed (original) (raw)

Human angiostrongyliasis outbreak in Dali, China

Shan Lv et al. PLoS Negl Trop Dis. 2009.

Abstract

Background: Several angiostrongyliasis outbreaks have been reported in recent years but the disease continues to be neglected in public health circles. We describe an outbreak in Dali, southwest China in order to highlight some key problems for the control of this helminth infection.

Methodology/principal findings: All available medical records of suspected angiostrongyliasis patients visiting hospitals in Dali in the period 1 October 2007-31 March 2008 were reviewed, and tentative diagnoses of varying strengths were reached according to given sets of criteria. Snails collected from local markets, restaurants and natural habitats were also screened for the presence of Angiostrongylus cantonensis. A total of 33 patients met criteria for infection, and 11 among them were classified as clinically confirmed. An additional eight patients were identified through a surveillance system put in operation in response to the outbreak. The epidemic lasted for 8 months with its peak in February 2008. Of the 33 patients, 97.0% complained of severe headache. 84.8% patients had high eosinophil cell counts either in the peripheral blood or in cerebrospinal fluid (CSF). Three-quarters of the patients were treated with a combination of albendazole and corticosteroids, resulting in significantly improved overall conditions. Twenty-two patients reported the consumption of raw or undercooked snails prior to the onset of the symptoms, and approximately 1.0% of the Pomacea canaliculata snails on sale were found to be infected with A. cantonensis. The snails were also found in certain habitats around Dali but no parasites were detected in these populations.

Conclusions/significance: The import and sale of infected P. canaliculata is the likely trigger for this angiostrongyliasis outbreak. Awareness of angiostrongyliasis must be raised, and standardized diagnosis and treatment are needed in order to provide clinicians with a guide to address this disease. Health education campaigns could limit the risk, and a hospital-based surveillance system should be established in order to detect future outbreaks.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1

Figure 1. Course of the angiostrongyliasis epidemic in Dali from October 2007–May 2008.

“Attack” and “Admission” designate the onset of symptoms and admission to hospital, respectively. “Mass media” indicates propagation of information on angiostrongyliasis through mass media and was initially performed in mid-March 2008. “Snail banning” is the prohibition of snail sales on markets since 1 April 2008.

Figure 2

Figure 2. Eosinophil counts in peripheral blood and CSF before treatment, stratified by illness duration and age.

An increased level of eosinophil cell counts in blood is defined as a relative count of more than >500 cells/µL and an increased eosinophil level in CSF is defined as a count of more than >10 cells/µL. The data of the 18 patients were collected before treatment. The collection date of blood and CSF samples from the same patient may differ up to 3 days.

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