title: Is Gnathostoma turgidum an annual parasite of opossums? Drastic seasonal changes of infection in Didelphis virginiana in Mexico.
abstract: Gnathostoma turgidum is a nematode that parasitizes the stomach of opossums, Didelphis virginiana. Despite its wide distribution in the Americas, its natural life cycle is poorly understood. Recently, we found an endemic area for G. turgidum infection in Sinaloa, Mexico (Diaz-Camacho et al., 2009). Based on sporadic surveys for several years, the prevalence was apparently high in summer and extremely low in winter. To confirm that this is really a seasonal variance, we conducted a longitudinal survey on G. turgidum infection in opossums from November 2007 to November 2008. The results showed amazing seasonal changes in the prevalence, with synchronized migration and maturation of worms in opossums. Between February and March, many juvenile worms, with occasional AL3, were found in the liver, but no worms were found in the stomach. Mature adult worms began to appear in the stomach around April and rapidly increased in number toward July, when all worms resided in the stomach. Then, the worms disappeared almost completely by November. These results suggest that G. turgidum is an annual parasite of the opossum, D. virginiana, in Mexico.
authors.affiliation: Facultad de Ciencias Químico Biológicas, Universidad Autónoma de Sinaloa, Culiacán, Sinaloa, Mexico.
authors.forename: Yukifumi
authors.initials: Y
authors.lastname: Nawa
authors.forename: María del Carmen
authors.initials: Mdel C
authors.lastname: de la Cruz-Otero
authors.forename: Magda Luz
authors.initials: ML
authors.lastname: Zazueta-Ramos
authors.forename: Angel
authors.initials: A
authors.lastname: Bojórquez-Contreras
authors.forename: Josefina
authors.initials: J
authors.lastname: Sicairos-Félix
authors.forename: Samuel
authors.initials: S
authors.lastname: Campista-León
authors.forename: Edith Hilario
authors.initials: EH
authors.lastname: Torres-Montoya
authors.forename: Sergio
authors.initials: S
authors.lastname: Sánchez-Gonzalest
authors.forename: Roberto
authors.initials: R
authors.lastname: Guzmán-Loreto
authors.forename: Francisco
authors.initials: F
authors.lastname: Delgado-Vargas
authors.forename: Sylvia Páz
authors.initials: SP
authors.lastname: Díaz-Camacho
mesh_terms: D000818:Animals; D003964:Diaphragm / Q000469:parasitology; D048293:Didelphis / Q000469:parasitology*; D005260:Female; D006039:Gnathostoma / Q000033:anatomy & histology / Q000502:physiology*; D007422:Intestines / Q000469:parasitology; D008099:Liver / Q000469:parasitology; D008297:Male; D008800:Mexico / Q000453:epidemiology; D010537:Peritoneum / Q000469:parasitology; D015995:Prevalence; D012621:Seasons; D017205:Spirurida Infections / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D013270:Stomach / Q000469:parasitology