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Abstract.A 42-year-old woman from Culiacan in the Sinaloa State of Mexico presented with a four-year history of migratory, pruritic, painful swellings of the face. Palpebral edema with conjunctival erythema developed when lesions developed near the eye. Routine eye examination showed a mobile worm in the anterior chamber. Following surgical removal, the parasite was identified by light and electron microscopy as an advanced third-stage larva of Gnathostoma sp. This prevalence of this helminthiasis may be increasing in areas where eating freshwater raw fish ("cebiche") is customary.

Porrorchis nickoli n. sp. is described from the intestine of the gray four-eyed opossum Philander opossum (type host), the Virginia opossum Didelphis virginiana, the common opossum Didelphis marsupialis, and the white-nosed coati Nasua narica. Hosts were collected in southeastern Mexico in the Los Tuxtlas region of the state of Veracruz (type locality) and in the states of Tabasco and Chiapas. This new species is distinguished from other Porrorchis species by its small proboscis (0.286-0.428 mm long x 0.273-0.438 mm wide), a proboscis armature consisting of 22-24 vertical rows of 7 or 8 hooks per row, and the male reproductive system extending postequatorially and occupying only half of the trunk. This is the first known occurrence of a Porrorchis species in the Western Hemisphere.

Porrorchis nickoli n. sp. is described from the intestine of the gray four-eyed opossum Philander opossum (type host), the Virginia opossum Didelphis virginiana, the common opossum Didelphis marsupialis, and the white-nosed coati Nasua narica. Hosts were collected in southeastern Mexico in the Los Tuxtlas region of the state of Veracruz (type locality) and in the states of Tabasco and Chiapas. This new species is distinguished from other Porrorchis species by its small proboscis (0.286-0.428 mm long x 0.273-0.438 mm wide), a proboscis armature consisting of 22-24 vertical rows of 7 or 8 hooks per row, and the male reproductive system extending postequatorially and occupying only half of the trunk. This is the first known occurrence of a Porrorchis species in the Western Hemisphere.

We report here the ultrastructural changes in the third advanced larval stage (AL3) of Gnathostoma binucleatum Almeyda-Artigas, 1991, induced by in vitro treatment with albendazole and the metabolite albendazole sulfoxide. During the whole period of the experiment, the controls remained active and vital throughout the 108-h exposure period. The primary site of action of both drugs appears to be the mitochondria and myofibrils of the polymyarian musculature. Degenerative changes in the secretory portion of the esophagus and somatic musculature were clearly observed. These degenerative changes, leading to complete muscular and glandular necrosis, were interpreted as the consequence of drug-induced blockade of metabolic energy production. Cuticular disruption had also been observed in the experimental groups. We observed a dramatic reduction in the number of mitochondria and muscle fibers, as well as the formation of large autophagic vesicles as result of an irreversible degenerative phenomenon. The passive cutaneous elimination of larvae in human infections is probably a consequence of parasite immobility, due to the effects of this antihelminthic drug.

Isolation of a specific Ancylostoma species typically requires death of the source animal, or holding an animal long enough to collect feces after treatment, for worm recovery and identification. The reason for collecting worms is that the eggs are not easy to distinguish morphologically. In keeping with the 3 Rs of laboratory animal research (reduction, refinement, replacement), the objective of this study was to obtain an isolate of Ancylostoma braziliense from 1-time field-collected samples of canine feces without the need for killing the host. During a collection trip to Florida, fecal samples (n  =  148) were collected and identified as containing eggs of Ancylostoma species (n  =  64) using centrifugal sugar flotation. Eggs from hookworm-positive slides were washed into tubes, DNA was extracted, and 2 samples were identified as A. braziliense using restriction fragment length polymorphism (RFLP) with Hinf1. Larval cultures were initiated from these samples, and larvae from the cultures were returned to New York and used to inoculate a purpose-bred kitten with the goal of inhibiting the growth of any contaminating Ancylostoma caninum that might be present in the culture. The infection was patent at 15 days, and eggs were identified as A. braziliense by RFLP and DNA sequencing. Using forceps during endoscopy, 2 adult worms (1 male, 1 female) were recovered from the cat and identified morphologically as A. braziliense . Larvae were cultured from the feces of this cat and used to infect a laboratory-reared beagle dog. Additionally, worms recovered from the feces of the cat post-treatment were confirmed to be A. braziliense , except for 1 female A. caninum containing infertile eggs. The dog (patent 14 days post-infection) was also infected with A. braziliense as determined by RFLP and DNA sequencing of eggs and cultured larvae. Both the cat and dog were treated, verified to be no longer shedding eggs, and then placed into adoptive homes.