Biomedical subjects
Publications and source records attributed to M D Little.
A worm found in histopathologic sections of the skin of a 31-year-old man in Honduras was identified as Paragonimus sp. The worm was immature, and specific identification was not possible. This is the second human case of paragonimiasis in Honduras.
The life cycle of Lagochilascaris sprenti, a species which occurs in the stomach of opossums (Didelphis virginiana) in Louisiana, was determined. The larva in the egg developed to the infective stage after eggs from the feces of infected animals were in culture about 30 days. When eggs containing infective larvae were fed to mice, the larvae hatched, penetrated the intestinal mucosa, migrated through the liver and lungs, and eventually reached the skeletal muscles where they became encapsulated. Larvae were also found encapsulated in the skeletal muscles of rats, gerbils, hamsters, monkeys, and a rabbit fed infective eggs. No larvae were found in the muscles of opossums fed infective eggs. However, when opossums were fed mice with 39- to 204-day-old Lagochilascaris infections, larvae developed in the gastric mucosa to the adult stage within 21 days. Adult worms inhabited cavities in the submucosa of the stomach from which they could migrate through openings into the lumen. One to three abscesses, each containing a single adult worm, were found in the musculature of 16.4% of the mice fed infective eggs.
Sixty-eight specimens of Lagochilascaris from the stomach of seven naturally-infected opossums from Louisiana were described as Lagochilascaris sprenti sp. n. Observations were also made on adult worms of both sexes recovered from experimentally-infected opossums and mice. The new species differs from the four previously described species of Lagochilascaris in the length of the spicules, number of pits on the circumference of the egg, and position of the vulva. The spicules are shorter in L. sprenti than in L. turgida and L. buckleyi. The number of surface pits in the eggshell at the circumference of the egg is 24 to 31 in L. sprenti, less in L. minor (15-26), and more in L. major (33-45). In worms of equal length, the vulva is consistently about 1 mm further anteriad in L. sprenti than it is in L. minor or L. major.
Helminths similar to Strongyloides stercoralis were recovered from the jejunum and ileum of a 6-month-old Boston Terrier that was shedding unusually large eggs, both unembryonated and embryonated, as well as first-stage larvae in fresh feces. Clinical signs included stunting, mucoid and blood-flecked feces, radiographic evidence of diffuse interstitial pulmonary infiltrate, focal dermatitis, and anemia. Decreased intestinal absorption of carbohydrate was found by means of the oral glucose and oral lactose tolerance tests. Serum protein and calcium values were decreased. At necropsy, histopathologic findings included uneven crypt hyperplasia and mild inflammation in the ileum and jejunum, diffuse interstitial pulmonary inflammation, Kupffer's cell hyperplasia in the liver, and generalized lymph node hyperplasia.
Worms conforming to the description of Synhimantus longigutturata Chandler 1942 were recovered from the stomachs of raccoons, Procyon lotor, in Louisiana. The male is described for the first time. The worm has short, delicate, recurrent and anastomosing cephalic cordons; a long pharynx; and a pair of double, lateral alae, each arising behind a tricuspid cervical papilla. These features differ significantly from those of other species within the genus Synhimantus and, consequently, the worm is transferred to a new genus, Chandleronema.
Two areas of intradermal swelling removed from the upper thigh and iliac crest of a 43-year-old man in Louisiana were each found to contain a larval trematode about 0.5 mm in length. Based on morphology reconstructed from serial sections, the two worms were identified as a mesocercaria of an undescribed species belonging to the subfamily Alariinae.
Surgical repair of an inguinal hernia in a 19-year-old man in Honduras revealed massive numbers of small granulomata containing trematode eggs on the omentum and other peritoneal surfaces. The eggs resembled those of Achillurbainia recondita Travassos, 1942, a species found in the maxillary sinuses of the opossum, Didelphis marsupialis. Species of Achillurbainis (syn. Poikilorchis Fain and Vandepitte, 1957) have been reported in retroauricular cysts or abscesses in residents of West Africa and Southeast Asia.
During the course of a survey of intestinal parasites among the inhabitants of villages along the Fly River in the Kiunga region of Papua New Guinea, eggs of a Strongyloides species were found in the feces of several persons. In subsequent studies, 93 (17.8%) of 520 persons examined from five villages were found to be infected with this parasite. The examination of parasitic and free-living stages of the worm revealed that it is very similar to S. fulleborni, a parasite of monkeys, baboons and apes in Africa and Asia, although a definitive identification could not be made with the material available. Since non-human primates have apparently never inhabited New Guinea, the origin of these S. fulleborni-like infections is unknown.
The first case of intestinal anisakiasis in North America is described. This parasitic disease is recognized as a public health hazard in Japan and Europe. Man becomes infected with a larval form of the nematode Anisakis by consuming raw or undercooked fish containing the parasite. Typically, patients present with acute abdominal syndromes. Clinical and reontgenographic features may cause confusion with regional enteritis. Histologically, a striking oesinophilic granulomatous reaction occurs. Anisakiasis is most effectively prevented by discouraging the consumption of raw fish.
The persistence and precise location of Ancylostoma caninum larvae in tissues of vertebrate paratenic hosts and the nature of host responses were studied in mouse, cat, and monkey. Mice were infected percutaneously and examined at various intervals up to 260 days after exposure. Long-persisting larvae were found only in the muscles. Histologic sections revealed that within 4 hr after exposure some larvae had migrated through the skin and had entered individual fibers of the underlying muscles. After the 1st day nearly all larvae found in muscles were within fibers. Granuloma formation and encapsulation were not observed, suggesting that inside the fibers the larvae produced no direct inflammatory reaction. Only diffuse infiltration of inflammatory cells was observed in muscles and this appeared to be in response to destruction of muscle fibers. Larvae were similarly located in muscles of a cat and a rhesus monkey examined 16 and 17 days, respectively, after cutaneous exposure. The histologic changes observed in muscle fibers invaded by A. caninum larvae are similar to those observed in early Trichinella spiralis infections. The larvae of A. canninum lying coiled within the muscle fibers also bear superficial resemblance to the larvae of T. spiralis. A. caninum larvae were also recovered by tissue digestion from muscles of naturally infected dogs, which suggests that larvae reside in this location in the bitch prior to transfer to the neonate via the milk.
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