Paragonimus mexicanus

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Paragonimus mexicanus Miyazaki and Ishii, 1968

ETYMOLOGY:Para = side-by-side and gonimus = gonads along with mexicanus referring to the geographical location of this parasite.

SYNONYMS:Paragonimus peruvianus Miyazaki, Ibanez, and Miranda, 1968; Paragonimus ecuadorensis Voelker and Arzube, 1979.

HISTORY: This trematode was originally found in an opossum, Didelphis marsupialis, captured in Mexico. It has been found in other animals and in humans.

GEOGRAPHIC DISTRIBUTION: Mexico, Central America, and the western coast of South America, including Ecuador and Peru.

LOCATION IN HOST: In cysts in the lungs.

PARASITE IDENTIFICATION: Specimens of Paragonimus mexicanus are similar to the other species of Paragonimus possessing single cuticular spines (Tongu et al., 1995).

The eggs of the American species of Paragonimus, other than those of Paragonimus kellicotti, have eggshells that are undulated rather than smooth. The size of the eggs average 79 by 48 µm. In other aspects the eggs are quite similar morphologically to the other species.

LIFE CYCLE: The first intermediate hosts of this parasite are species of snails of the genus Aroapyrgus. The second intermediate hosts are fresh-water crabs of the genera Pseudothelphusa, Ptychophallus, Potamocarcinum, and Hypolobocerca. In the crab, the metacercaria has no cyst stage and it moves freely about in the liver tissue of the crab. This species has been shown to have metacercarial stages that persist in the tissues of rats as paratenic hosts and which are capable of developing to the adult stage upon the ingestion of the rats by cats. (Miyazaki, 1991).

CLINICAL PRESENTATION AND PATHOGENESIS: Clinical signs similar to those of Paragonimus kellicotti.

TREATMENT: Probably praziquantel.

EPIZOOTIOLOGY: Numerous mammals are capable of being infected with Paragonimus mexicanus; including: cats, jaguars, dogs, foxes, raccoon, coatimundis, skunks, and three species of opossums.

HAZARD TO OTHER ANIMALS: Other animals appear likely to develop infection and disease similar to that seen in the ct, but only if they ingest the infected crayfish. Thus, the infected cat is not a direct threat to other uninfected animals.

HAZARD TO HUMANS: Human infections with this parasite have been reported in Mexico, Central America, Ecuador, and Peru, where people are known to eat raw crabs (Brenes et al., 1983).

REFERENCES:

Brenes RR, Little MD, Raudales O, Múñoz G, Ponce C. 1983. Cutaneous paragonimiasis in man in Honduras. Am J Trop Med Hyg 32:376-378.

Tongu Y, Hata H, Orido Y, Pinto MR, Lamoth-Argumedo R, Yokogawa M, Tsuji M. 1995. Morphological observations of Paragonimusmexicanus from Guatemala. Jap[ J Parasitol 44:365-370.

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