Angiostrongylus cantonensis is a nematode parasite that causes eosinophilic meningoencephalitis in humans. Disease presents following the ingestion of third-stage larvae residing in the intermediate mollusk host and disease manifests as an acute inflammation of the meninges characterized by eosinophil infiltrates which release a battery of proinflammatory and cytotoxic agents in response to the pathogen. As a mechanism of neutralizing these host defenses, A. cantonensis expresses different molecules with immunomodulatory properties that are excreted or secreted (ES). In this paper we discuss the role of ES proteins on disease exacerbation and their potential use as therapeutic targets. 1. Introduction Establishment of parasitic infections is dependent on a delicate and constant interaction between host and parasite, specifically, interactions between the host immune system and molecules released by the parasite or located at the parasite surface [1, 2]. Parasitic organisms have evolved the ability to survive in such hostile environments by evading or neutralizing host defense systems. This process is mediated in part by molecules released by parasites that consist of excretion and secretion (ES) products which may contain metabolites, enzymes, hormone-like factors, antioxidants, and proteinase inhibitors among others [3, 4]. Eosinophilic meningitis, also known as cerebral angiostrongyliasis, is an acute inflammation caused mainly due the presence of Angiostrongylus cantonensis young in the meninges, parenchyma of the medulla, pons, or cerebellum [5]. Humans get infected after ingestion of third-stage larvae residing in raw mollusks, vegetables, or contaminated water. To date, more than two thousand angiostrongyliasis cases have been reported, with most cases occurring in Southeast Asia and the Pacific Islands where the disease is endemic [6]. However, angiostrongyliasis cases have now been reported in regions of the world where this disease has not previously been reported, that is, Brazil, Caribe, Ecuador, Australia, and the USA. This change in the epidemiology of angiostrongyliasis should serve as a warning to authorities that this disease is an emerging public health problem [7–10]. The pathogenicity and pathophysiology of cerebral angiostrongyliasis, however, still remain poorly defined. The present paper discusses the potential role of excreted and secreted (ES) proteins in relation to Angiostrongylus infections in the context of developing novel diagnostic and treatment modalities. 2. Eosinophils and Meningoencephalitis Eosinophils play a critical
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