Ultrastructural changes in the advanced third larval stage of Gnathostoma binucleatum Almeyda-Artigas, 1991 (Nematoda: Spirurida) following albendazole and albendazole sulfoxide in vitro exposure.

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.

Discovery of an endemic area of Gnathostoma turgidum infection among opossums, Didelphis virginiana, in Mexico.

Gnathostomosis, caused by Gnathostoma binucleatum, is a serious public health issue in Mexico. Although 2 other Gnathostoma spp., G. turgidum and G. lamothei, have been found in wild animals, their natural life cycle or their relation to human disease remains unclear. While we were conducting an epidemiological survey on Gnathostoma spp. in Sinaloa State, Mexico, we found an endemic area for G. turgidum in common opossums, Didelphis virginiana, located in Tecualilla, Sinaloa. The species identification was carried out by morphological and molecular biological methods. This is the first record of an endemic area for G. turgidum infection in opossums, D. virginiana, in the Americas.

Estuarine fish and turtles as intermediate and paratenic hosts of Gnathostoma binucleatum in Nayarit, Mexico.

Human gnathostomosis is a severe public health problem in the State of Nayarit, Mexico. Between 1995 and 2005, the registration of human cases numbered 6,328, which makes it one of the largest focal points of the disease in the country. The present study determined the presence of natural hosts of Gnathostoma binucleatum larvae at the Laguna de Agua Brava in Nayarit, Mexico. A total of 5,450 fish and 247 turtles were sampled. Muscular tissue was ground and observed against the light using a 100-W lamp to identify advanced third-stage larvae. The estuarine species Cathorops fuerthii, Pomadasys macracanthus, Mugil curema, and Dormitator latifrons were found positive for presence of larvae, and annual prevalence was 4.8, 1.83, 2.16, and 4.0%, respectively. The species Oreochromys aureus and Chanos chanos were negative. The species of estuarine turtles Kinosternum integrum and Trachemys scripta were positive with annual prevalence of 79.1 and 52.5%, respectively. The criteria of identification of the Gnathostoma species were: mean number of nuclei in intestinal larval cells (2.3), larval morphometry with optic microscopy, larval morphometry with scanning electron microscopy, and number and sequence of ribosomal deoxyribonucleic acid of adult parasites obtained from experimental infection in dogs. The estuarine fish Pomadasys macracanthus and Mugil curema are reported as intermediate hosts for the first time and likewise the estuarine turtle Kinosternon integrum as a paratenic host.

A new species of Gnathostoma (Nematoda: Gnathostomatidae) in Procyon lotor hernandezii from Mexico.

Gnathostoma lamothei n. sp., inhabiting the stomach of Procyon lotor hernandezii Wagler, 1831, in Tlacotalpan, Veracruz State, and Rio Sapo, Oaxaca, Mexico, is described. This new species differs from all other congeners by having the posterior half of the body surface covered by rows of tiny round bosses instead of spines, or lacking ornamentations. Sequences of the ITS2 of the ribosomal DNA of G. lamothei n. sp. are compared with sequences of other species of the genus recorded in Mexico; they show a wide divergence (<50%) with Gnathostoma binucleatum Almeyda-Artigas, 1991, and Gnathostoma turgidum Stossich, 1902, and high similarity with Gnathostoma sp. I sequence (99.2%). On the basis of morphometric traits and sequences, previous records of Gnathostoma sp. I (=Gnathostoma procyonis of Almeyda-Artigas et al., 1994, not Chandler, 1942, and Gnathostoma neoprocyonis nomen nudem) in Mexico are referred to as the new species.

Case report: Ocular gnathostomiasis in northwestern Mexico.

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.

Morphology of Gnathostoma spp. isolated from natural hosts in Sinaloa, Mexico.

Gnathostomosis is an emerging public health problem in Sinaloa, Mexico, where an increasing number of human cases have been diagnosed since 1989. The present study was carried out to determine the presence of the parasite in other natural hosts from the area. Birds, fish, opossums and raccoons were captured from local dams and lagoons. The flesh from bird and fish specimens was ground and examined under a 100 W light bulb. Larvae were processed for light and electron microscopy. A total of 368 advanced stage 3 (AL3) larvae were found in 300 ichthyophagous birds, with Egretta alba exhibiting the highest infection rate. A total of 4,156 fish were examined, of which six species were infected with AL3 larvae: Arius guatemalensis (blue sea catfish), Dormitator latifrons (Pacific fat sleeper), Gobiomorus sp. (fat sleeper), Oreochromis sp. (Nile tilapia), Cichlasoma beani (Sinaloan cichlid or green guapote) and Eleotris picta (spotted sleeper). Twenty larvae from birds were used to infect domestic cats and dogs. Young adult worms were recovered from the stomach of a cat with a 17 day infection and from a dog with a 35 day infection. Larvae exhibited four rows of hooklets on the head bulb, whereas the young adults had nine rows of hooklets. The cuticular spines of adult worms along the body evolved from single-pointed, bi- or trifurcated spines. Nuclei were counted in intestinal cells examined in serial sections of larvae recovered from a great heron and a fish, in which a mean of 1.6 nuclei/cell was found, corresponding to data published for Gnathostoma binucleatum. Although the external morphology of both larvae and adults are in agreement with previous descriptions of Gnathostoma spinigerum, the results indicate that natural host infections in Sinaloa may be caused by either G. spinigerum or G. binucleatum.

Echinocephalus scoliodonti n.sp (nematoda: Gnathostomidae) from an elasmobranch fish, scoliodon sorrakowah (Cuvier)

Echinocephalus scoliodonti n.sp de la valva espiral del pez elasmobranquio, scoliodon sorrakowah (Cuvier) recolectado en Bheemunipatnam (Bahía de Bengala) es descrito. Un examen detallado nos ha permitido constituir una nueva especie de Echinocephalus para incorporar al gusano. Muestra notables diferencias con otras especies conocidas de Echinocephalus en relación a medidas del cuerpo, número y disposición de las papilas caudales, número de filas de espinas cafálicas, ausencia de gubernaculum y presencia de valvas esófago-intestinales. La nueva especie es nominada como Echinocephalus scoliodonti