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Human Angiostrongyliasis

Zhao-Rong Lun, Ph.D. School of Life SciencesSunYat-Sen University

Guangzhou 510275, ChinaEmail:lsslzr@mail.sysu.edu.cn

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Angiostrongyliasis caused byAngiostrongylus cantonensis•An important food-borne parasitic disease;

•Cases reported globally;

•Mainly outbreak in tropical regions with the exception of imported cases (Beijing in 2006, more than 160 cases reported, snails were imported from one of the endemic regions: Guangxi);

•Main clinical manifestation: eosinophilic meningoencephalitis and meningitis. Fetal occurred.

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Founder of A. cantonensis• Prof. Xin-Tao Chen (=H.T. Chen), 1935. (Chen,

HT., A new pulmonary nematode of rats, Pulmonema cantonensis ng, nsp from Canton. Ann Parasitol 1935; 13:312-317)

Dr. Chen discovered the rat lungworm (A. cantonensis) from a rat collected from Guangzhou in 1935. He also made a great contribution to the control of schistosomiasis in China.

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It is still a mysterious why this rat lungworm was mostly found in the brain and cerebral fluid although it could also be found from the lung of human? It may be one of the most important reasons which causing death in the non-natural hosts. More studies should be done on the pathogenesis.

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Brain and lung are the most organs where the rat lungworm was found from the patients. However, optical angiostrongyliasis was also found in some cases.

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The life cycle of AngiostrongyluscantonensisThe adult worms develop to sexual maturity and lay eggs at the pulmonary arteries (A). The eggs are hatched into first-stage larvae (the juveniles), which are swallowed and are excreted out with the feces (B). The larvae in feces are swallowed by intermediate host mollusks (snails or slugs) and develop into third-stage (infective) larvae (C). The third-stage larvae are then transmitted to the paratenic hosts such as shrimps, land crabs, predacious land planarians and monitor lizards (D). Humans occasionally acquire A. cantonensis when they eat snails, slugs and sometimes, land crabs, frogs, freshwater shrimps, monitor lizards, or vegetables, which contain the infective larvae (E). The larvae are digested from tissues and enter the bloodstream in intestine (F). The larvae finally reach the central nervous system (CNS) and cause eosinophilic meningitis (G) or move to the eye chamber and cause ocular angiostrongyliasis. (Adapted from Wang et al., 2008)

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Cases of angiostrongyliasis globally

• Human A. cantonensis infection has attracted increasingpublic attention worldwide due to outbreaks, and alsobecause more and more sporadic cases are being reported in Western travelers in recent years.

• By 2008, over 2,800 cases of human angiostrongyliasis had been documented in more than 30 countries.

• However, there are, no doubt, many more cases, unreported due to lack of awareness of this parasite within the medical community. During the period

• 2008–2010, an additional 77 cases were reported (next slide).

• (from Wang QP et al., The Lancet Inf Dis., 2008, 8:621-630)

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Map of A. cantonensis distribution globallyDistribution of A cantonensis and human A cantonensis infections or outbreaks worldwide.Endemic regions are those countries in which human cases of angiostrongyliasis or animal reservoirs of A cantonensis have been identifi ed. This is not intended toimply that A cantonensis is endemic throughout these entire countries. Conversely, those areas marked as non-endemic regions may well be countries where noinvestigation has taken place and so cannot be considered free from A cantonensis infection. (from Wang QP et al., The Lancet Inf Dis., 2008)

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Cases of human angiostrongyliasis reported worldwide since 2008 (Wang et al., 2011, Eur J Clin MicrobiolInfect Dis, DOI 10.1007/s10096-011-1328-5)

Regions Cases ReferencesChina 65 [17, 18]Thailand 8 [19, 20]India 1 [21]French 1 [22]Germany 1 [23]Jamaica 1 [24]

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The outbreaks of human angiostrongliasis have been reported in mainland China since 1997(Wang et al., 2011, Eur J Clin Microbiol Infect Dis, DOI 10.1007/s10096-011-1328-5)

Years Regions Cases References1997 Zhejiang 65 [25]1999 Heilongjiang 2 [26] 1999 Liaoning 3 [26]2002 Fujian 29 [27-29]2004 Zhejiang 3 [31]2006 Beijing 160 [33]2006-2008 Guangdong 38 [17,34]2003-2008 Yunnan 92 [18,30,31]

2011/8/23 11From Wang et al., 2011

The endemic regions of A. cantonensis are marked as purple and the outbreaks of human A. cantonensis are marked as green triangle.Patients were infected with the rat lungworm by digested uncooked infected snails (from Wang QP et al., 2011)

The distribution of A. cantonensis and its outbreaks in China.

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Mammalian Hosts

• Rattus norvegicus• Rattus rattus• Rattus exulans

From Wang et al., The Lancet Inf Dis., 2008

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Mammalian HostsRattus rattus

Rattus exulans

Rattus norvegicus

Rattus exulansdistribution

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Snails

• Achatina fulica,(African giant snail)

• Pomaceacanaliculata, (Apple snail), 1980’s, South China

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Acknowledgments• Dr. Qiao-Ping Wang (SYSU, Guangzhou)• DR. De-Hua Lai (SYSU, Guangzhou)• Prof. Zhong-Dao Wu (SYSU, Guangzhou)• Prof. Xiao-Guang Chen (SCMU，Guangzhou）• Dr. Xing-Quan Zhu, Lanzhou Vet Med Inst,

China• Supported by the National Basic Research

Program of China (973 program) (No#2010CB530000)

2011/8/23 16Lungworm workshop, Hawaii, August 16-19, 2011