key: cord-0714519-j2o2daub authors: Mendoza-Roldan, Jairo; Modry, David; Otranto, Domenico title: Zoonotic parasites of reptiles: a crawling threat date: 2020-05-07 journal: Trends Parasitol DOI: 10.1016/j.pt.2020.04.014 sha: b1b8ca268fabb16a871fc927474b9cb39743927a doc_id: 714519 cord_uid: j2o2daub Abstract Reptiles are reservoirs of a wide range of pathogens including many protozoa, helminths, pentastomids and arthropod parasitic species, some of which may be of public health concern. In this review we discuss the zoonotic risks associated with human-reptile interactions. Increased urbanization and introduction of exotic species of reptiles may act as drivers for the transmission of zoonotic parasites through the environment. In addition, being a part of human diet, reptiles can be a source of life-threatening parasitoses, such as pentastomiasis or sparganosis. Finally, reptiles kept as pets may represent a risk to owners given the possibility of parasites transmitted by direct contact or faecal contamination. Awareness of reptile-borne zoonotic parasitoses is important to advocate control, prevention and surveillance of these neglected diseases. J o u r n a l P r e -p r o o f 6 this habit persists until nowadays. Beside consumption of wild caught reptiles, reptile farming was developed in past decades in order to cover growing demand and to replace the animals from diminished wild populations [45] . Among the farmed reptiles, crocodiles probably form the largest proportion, however, snake and turtle farming are fast developing in South Eastern (SE) Asia and iguanas are locally farmed in South America [46] . This farming system is in urgent need for defined food inspection protocols as well as trained professionals, through updating animal science curricula. In addition, reptiles are used as part of the traditional medicine, mainly in Asia (Box 2). Cases of zoonotic helminthic infections are reported throughout the world being associated with reptile consumption or with reptile meat used in medicinal practices [47] . In all food-borne parasitoses associated with reptile consumption (e.g., Anisakis spp., Gnathostoma spp., Spirometra spp., Alaria, Angiostrongylus cantonensis, Trichinella spp. and several pentastomids, Table 1) humans represent aberrant or dead-end hosts. Pseudophyllidean tapeworms of the genus Spirometra (Diphyllobothriidae) are the most frequent reptile-borne zoonotic helminths being Spirometra erinaceieuropaei, Spirometra mansonoides, and Spirometra proliferum, among the most commonly reported species. Life cycle of Spirometra spp. typically involves carnivorous mammals as definitive hosts and freshwater crustaceans (i.e., cyclops) and poikilothermic vertebrates as first and second intermediate hosts, respectively. The infective larval stages (i.e., the plerocercoids, commonly referred to as sparganum or spargana in plural) are typically found in subcutaneous tissue ( Figure 2C ) and/or muscles of reptiles and may become infective to humans by eating uncooked meat. After the infection plerocercoids migrate to various organs and tissues in human body, including subcutaneous tissue, muscles, lungs, pleural cavity, urogenital and abdominal viscera, and, importantly, to central nervous system [48, 49] . Therefore, depending on invaded organs, disease is usually classified as subcutaneous, ocular, cerebral or visceral sparganosis [50] . It may occur that plerocercoids asexually multiply within the human host causing a severe clinical condition known as proliferative sparganosis [51] . Most of the cases of human sparganosis are confined to SE Asia, apparently due to locally common consumption of raw or inadequately cooked J o u r n a l P r e -p r o o f snakes, frogs and tadpoles infected with the plerocercoid. Cases recently reported from Europe were foreigners that probably acquired infection in other continents [49] . Drinking untreated water with infected copepods (i.e., first intermediate hosts) or applying the meat of infected snake or frog as a poultice to a wound, are alternative routes of human infection [52] . As the disease in humans is difficult to identify at preoperative stage, the anamnesis is pivotal for an expedite diagnosis and treatment. Angiostrongylus cantonensis is a metastrongyloid nematode of emerging concern causing eosinophilic meningitis in humans [53] . This parasite exploits various species of rats as definitive hosts and a broad range of molluscs as intermediate hosts [54] . Amphibians and reptiles represent paratenic hosts that are able to cumulate infective L3 larvae in liver and other tissues. Although the major source of infections by A. cantonensis in SE Asia is through the consumption of molluscs, prawns and shrimps, eating raw meat of varanids was documented as an alternative infection route [55, 56] . Nonetheless, the importance of poikilothermic hosts in the circulation of A. cantonensis in food-chain is not fully understood. Trichinella spp. are nematodes with high potential for zoonotic infections. While the majority of species (the encapsulated ones) are infective only for mammals, two non-encapsulated species -Trichinella zimbabwensis and Trichinella papuae -are found also in large carnivorous reptiles, namely in crocodiles and monitor lizards [57] . Completion of Trichinella spp. life cycle in these hosts was confirmed also experimentally [58] . Trichinellosis cases associated with consumption of meat of monitor lizards and turtles have been documented in Thailand, even though the Trichinella species involved was not identified. Even though they occur frequently in some areas of West and Central Africa, human infections are usually asymptomatic, diagnosed incidentally as liver calcifications by X-ray or ultrasonography, or, at autopsy [61] [62] [63] . Human cases of pentastomiasis are associated with consumption of snake meat, though infection by eggs in the contaminated environment represents a risk in endemic areas [64] , as well as from captive reptiles (see further). Massive infections leading to rare lethal cases are tentatively associated with incidental ingestion of entire gravid female of Armillifer spp. [65] . Historically, postmortem prevalence in humans has been recorded up to 23% in Central (Congo) and southern Africa (Zimbabwe) and 40% in SA Asia (i.e., Malaysia, [66]). 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