Aspectos clínicos y de diagnóstico de la gnatostomosis experimental canina / Clinical and diagnostic aspects of experimental canine gnathostomosis

Stages of the parasite were detected in the gastric wall of four female dogs infected with Gnathostoma binucleatum larvae. One showed a nodule with adult worms inside, two had nodules with larvae and the other one had juvenile stages without nodules. Pre-patent period in the bitch with adult worms was 22 weeks and patent period was 14 weeks. Egg morphology and clinical profile were described. In the bitch with adult worms, a 57 x 24 mm cavernous mass was detected by ultrasonography in the stomach wall and by endoscopy the mass was detected projecting into the gastric lumen. Antibodies against larvae antigens increased (P < 0.05) after the second pi month; Western blot showed a sequential recognition of the antigens. Results provide useful data for canine gnathostomosis diagnosis.

En 4 perras infectadas con larvas de Gnathostoma binucleatum se detectaron fases del parásito en pared gástrica. Una presentó un nódulo con gusanos adultos en el interior, 2 presentaron nódulos con larvas y la otra presentó fases juveniles sin nódulos. El periodo de prepatencia en la perra con gusanos adultos fue de 22 semanas y el de patencia de 14 semanas. Se realizó la descripción de la morfología del huevo y del cuadro clínico. En la perra con gusanos adultos se detectó, por ultrasonografía, una masa cavernosa de 57 x 24 mm en la pared del estómago, y por endoscopia, se observó la proyección de esta masa hacia el lumen gástrico. Los niveles de anticuerpos contra antígenos de larvas aumentaron (P < 0.05) a partir del segundo mes pi, el Western blot mostró un reconocimiento secuencial de los antígenos. Los resultados obtenidos aportan datos útiles para el diagnóstico de la gnatostomosis canina.

Effect of some physical factors on the viability of third-stage Gnathostoma binucleatum larvae.

To diminish the risk of transmission to humans of advanced third-stage larvae (A3L) of Gnathostoma binucleatum in fish foods, we evaluated the effects of some physical factors on larval viability. A3L protected within fish meatballs were subjected to freezing, refrigeration, boiling, dry heat, and immersion in lemon juice. By freezing, larvae were killed in 48 h, by refrigeration after 30 days, by boiling in 4 min, and by broiling for 60 min. By lemon juice immersion (pH 2.5), encysted larvae were killed after 5 days and nonencysted larvae in 7 h. Results show that freezing fish at -10 to -20°C for 48 h, or cooking fish by frying, boiling, or broiling, will prevent transmission of G. binucleatum. Furthermore, results dispel the popular myth that lemon juice kills encysted larvae in fish.

Study of the ethiological agent of gnathostomosis in Nayarit, Mexico.

In order to clarify the specific identity of the etiological agent of human gnathostomosis in Nayarit State, Mexico, morphological and molecular studies were conducted on advanced third stage larvae obtained from human and fish tissue. Cathorops fuerthii from Agua Brava lagoons complex, was the only fish species found to be infected among four species surveyed. Morphological variability does not allow specific identification of the larvae. Internal transcribed spacer 2 of the ribosomal DNA was sequenced for six larvae (five from fish, one from human tissue). Low divergence in the sequences of Nayarit larvae and Gnathostoma binucleatum (0.24% or less) indicate that the larvae examined belong to this species.