Hiroshige Akahane

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.

Case report: eosinophilic colitis with high antibody titre against Ascaris suum.

Eosinophilic gastroenteritis (EGE) is an inflammatory disease characterized by eosinophilic infiltration of the gastrointestinal tract accompanied by varying abdominal symptoms and usually by peripheral blood eosinophilia. Although the precise aetiology of EGE remains to be determined, contribution of allergic process to certain allergens, such as foods, drugs and parasites, has been repeatedly proposed as the pathogenesis of the disease. Here we report on a rare case of a woman who had extensive eosinophilic infiltration in the descending and rectal colon with a high titre of IgG antibody against Ascaris suum. The patient was successfully treated with prednisolone.

Surface Ultrastructure of Adults and Eggs of Gnathostoma spinigerum (Nematoda: Gnathostomatidae)

Adult specimens Gnathostoma spinigerum were examined by scanning electron microscopy (SEM). Worms had an anterior head-bulb with one pair of lateral lips. The head-bulb was armed with 7-10 transverse rows of hooks. On the anterior one-half of the worms, multidigitate cuticular spines are spaced unevenly on the outer edge of transverse striations. Small unidentate cuticular spines also are located on the posterior one-half of the body. Other structures included labial papillae, amphids, cervical papillae, an excretory pore, caudal papillae, small flat papillae, and phasmids. Eggs from the uteri of female worms are covered with pits of irregular size, shape, and depth. Gnathostoma spinigerum Owen, 1836 is widely distributed in Southeast Asia and South America and is one of the etiological agents of human gnathostomiasis. Adult worms are normally found in nodules of the stomach wall of feline and canine hosts. Man is an unnatural host for this helminth. When accidental infections do occur, the worms often undergo extensive larval migrations and usually do not reach maturity. Morphology of adult stages of G. spinigerum have been studied in detail by light microscopy (Daengsvang, 1981; Lin & Chen, 1986; Miyazaki, 1954; Takeichi, 1956). Scanning electron microscopical (SEM) studies are few; there are only two brief descriptions of the surface morphology of eggs of this helminth (Ishii & Tokunaga, 1970; Ratanarapee, 1982; Ratanarapee & Jesadapatarakul, 1982; Ratanarapee et al., 1988; Scholz & Ditrich, 1990; Zaman, 1987). We report detailed observations of the external surface of the adult stages and eggs of G. spinigerum using SEM. MATERIALS AND METHODS Six adult specimens of Gnathostoma spinigerum were obtained from dogs that were infected experimentally with advanced third-stage larvae obtained in Thailand. Eggs were removed from the uteri of gravid female worms. Viable adult male and female worms were washed in several changes of tap water and soaked in physiological saline. The worms were fixed in 10% formalin for at least one week, washed in running tap water overnight to remove the fixative, and transferred to distilled water. Specimens were rinsed twice in Millonigs phosphate buffer and postfixed in 1% Os04 for 3 h. During postfixation, worms were cut transversely into seven pieces to facilitate observations by SEM. These pieces were dehydrated in an ascending series of ethanol, transferred into amyl acetate, and critical-point dried with a Hitachi HCP-2 critical-point dryer. 1 The authors express their gratitude to Dr. C. T. Atkinson, Institute of Pathology, Case Western Reserve University, for his critical reading of the manuscript. TRANS. AM. MICROSC. SOC., 110(4): 315-320. 1991. ? Copyright, 1991, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.127 on Tue, 28 Jun 2016 06:58:21 UTC All use subject to http://about.jstor.org/terms TRANS. AM. MICROSC. SOC.