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PubMed1994

A follow-up examination of intestinal parasitic infections of the Army soldiers in Whachon-gun, Korea.

A follow-up stool examination was done to know the status of intestinal parasitic infections in Army soldiers who were stationing in Whachon-gun, Kangwon-do, Korea in 1993. Of 233 examined soldiers, Infections with Clonorchis sinensis (0.4%), Metagonimus spp. (0.9%), Echinostoma hortense (0.4%), Neodiplostomum seoulensis (0.4) and Giardia lamblia (3/233) were found. E. hortense and N. seoulensis infections were each 75th, and 27th cases in Korea. Regular control program of intestinal parasitic infections might be able to contribute to diminish the prevalence rate in young Army soldiers in Korea.

Adult↗
PubMed1998

Microhabitat distribution and coexistence of Microcotylidae (Monogenea) on the gills of the striped mullet Mugil cephalus: chance or competition?

The two monogenean species Metamicrocotyla cephalus and Microcotyle mugilis have specific microhabitats on the gills of Mugil cephalus on which they may or may not coexist. M. cephalus is found in sector 1 of the posterior hemibranch of arch I. M. mugilis is found on the filaments of sector 5 of the posterior hemibranch of arch I. The coexistence of these two monogenean species on the same fish does not induce a change in their respective distribution, except for a marked preference of M. cephalus for the left side and of M. mugilis for the right. This 15-month-long study shows that when the two species of monogeneans coexist the infection prevalence and intensity are higher than in cases of monospecific infection. The specific character of the microhabitat, the apparent absence of interspecific competition, and the existence of positive species interactions are discussed.

Animals↗
PubMed1986

Clinical and pathological effects of Echinostoma revolutum (Digenea: Echinostomatidae) in the golden hamster, Mesocricetus auratus.

Laboratory hamsters (Mesocricetus auratus) were infected with Echinostoma revolutum (Trematoda). Hamsters developed marked and sometimes fatal echinostomiasis. Clinical signs included progressive unthriftiness, watery diarrhoea and weight loss. Packed cell volume, haemoglobin and red blood cell counts increased in those animals with severe diarrhoea. No increase in eosinophils was noted in peripheral blood smears. Examination of tissues of infected animals showed wide individual variations related to the intensity of infection. The histopathological responses of hamsters to the parasite showed erosion of intestinal villi with lymphocytic infiltration being the primary response. Periportal lymphocytic infiltration and focal hepatic necrosis were observed in livers from some infected animals. The findings of this study are discussed in terms of variations in pathogenicity of E. revolutum and as a model for the study of echinostomiasis.

Animals↗
PubMed1994

[Chronological observation on intestinal histopathology and intraepithelial lymphocytes in the intestine of rats infected with Metagonimus yokogawai].

The relationship between the intestinal histopathology and number and position of intraepithelial lymphocytes (IEL) was observed chronologically in the small intestine of rats experimentally infected with Metagonimus yokogawai. Fifteen Sprague-Dawley rats were orally infected each with 3,000 metacecariae, and 3 were kept uninfected for controls. Three rats each were sacrificed on the day 5, 10, 15, 24 and 70 post-infection (PI) and samples of the small intestine, 5 cm, 10 cm, 20 cm and 70 cm posterior to the pylorus were taken. The samples were processed routinely and stained with Giemsa. The intestinal histopathology was severe during the day 5-15 PI and characterized by villous atrophy, crypt hyperplasia, and decrease of villus/crypt height ratio. After the day 24 PI, the intestinal lesions showed some tendency of recovery. The number of IEL increased at the early stage of infection, but decreased thereafter to a lower level than that of controls, with progression of the pathological changes. Then, the IEL number began to increase again after the day 24 PI. In control rats, the great majority of the IEL were located at the basal region of the epithelium. During the early stage of infection, however, a considerable proportion of IEL was found to have moved to the intermediate or apical region of the epithelium. From the above results, it is suggested that the change of IEL number and position during the course of M. yokogawai infection should be closely related to the progression and recovery of the intestinal histopathology.

Animals↗
PubMed2000

Persistent endemicity of Gymnophalloides seoi infection in a southwestern coastal village of Korea with special reference to its egg laying capacity in the human host.

Follow-up studies have been conducted every three years on the endemicity of Gymnophalloides seoi infection in a small coastal village of Chollanam-do (Province), Korea, since it was first known as an endemic area in 1994. Special attention was given to its egg laying capacity in the human host. In fecal examinations, the overall helminth egg and/or cyst positive rate was 78.7% (74/94) in 1997 and 76.6% (82/107) in 2000. Among them G. seoi eggs showed the highest rate; 71.3% (67/94) in 1997 and 72.0% (77/107) in 2000. The average number of eggs per gram of feces (EPG) was 1,015 in 1997, while a reduced rate of 353 was observed in 2000. In 1997, total of 320,677 adult flukes of G. seoi (av. 10,344/person, 94-69,125 in range) were collected from the diarrheic stools of 31 treated patients. The EPG/worm obtained from 21 cases ranged from 0.04 to 0.77 (av. 0.23), suggesting density-dependent constraints on the worm fecundity. The relationship between the worm burden (X) and EPG/worm (Y) can be expressed as Y = 0.42.e-1.2 chi (r = 0.49). The results showed that G. seoi infection is persistently endemic in this village.

Adult↗
PubMed1988

Helminths of stocked rainbow trout (Salmo gairdneri) with special reference to Clinostomum complanatum.

Rainbow trout (Salmo gairdneri) stocked into a small prairie dug-out were examined for helminths at harvest time. Five species of helminths were found (Diplostomum sp., Diplostomulum scheuringi, Clinostomum complanatum, Crepidostomum farionis and Pomphorhynchus bulbocolli); C. farionis and P. bulbocolli mature in fish while the remaining species utilize fish-eating birds as definitive hosts. Examination of stomach contents indicated that all invertebrate hosts required for the life-cycles of these helminths were present in the dug-out. The most conspicuous and prevalent helminth was C. complanatum as fish were "wormy" and unmarketable due to the presence of high numbers of metacercariae. Metacercariae of C. complanatum were recovered from most organs of rainbow trout. The low survival of stocked fish suggests that C. complanatum may cause some host mortality, but the condition of infected and uninfected fish was similar. It appears that a community of ichthyoparasites can become established in a population of stocked fish in a single growing season in north temperate regions.

Animals↗
PubMed1991

Experimental observations on the specificity of Strigea falconispalumbi (Trematoda: Strigeidae) toward planorbid first intermediate hosts.

Planorbis planorbis, Planorbarius corneus and Biomphalaria alexandrina (Egyptian strain) were ascertained as new experimental first intermediate hosts, thus bringing the total number of planorbid experimental first intermediate hosts to eight. The highest degree of compatibility was exhibited with P. planorbis (infection prevalence 80%) followed by P. corneus (46.6%), whereas B. alexandrina (as snail species not occurring in the geographical range of S. falconispalumbi) showed the lowest degree of compatibility (23.3%).

Animals↗
PubMedDate not supplied

[Tetraonchus alaskensis Price, 1937 and its epizootic role].

Mortality of pelyad (Coregonus peled) caused by Tetraonchus alaskensis took place in winter 1973 in the Voikara and Syn rivers (the Ural tributaries of the Lower Ob) during anadromous and catadromous migrations. The highest infection rate was observed in older fished. Up to 2330 specimens of the parasite were recorded from the gills of one pelyad. A low infection rate with T. alaskensis was recorded from Coregonus nasus, C. lavaretus pidgian and Stenodu. The mortality coincided with the period of the greatest abundance of the Ob pelyard stock.

Animals↗
PubMed1994

Infrapopulation dynamics of Gyrdicotylus gallieni (Monogenea: Gyrodactylidae).

Gyrdicotylus gallieni is a viviparous gyrodactylid monogenean that infects the buccal cavity and pharynx of Xenopus laevis laevis. Offspring directly recolonize the same host as their parent and transmission is carried out exclusively by adult worms which are capable of leech-like stepping locomotion. The infrapopulation dynamics (at 20 degrees C) of this species were studied by experimental exposure to single worms of previously uninfected hosts (which were dissected at various time-intervals post-infection). Infrapopulations increased exponentially until 50 days post-infection (p.i.), during which time the intrinsic rate of increase was estimated by regression as 0.065/parasite/day. After this, infrapopulation sizes showed greater variability, with established infections becoming extinct 2-5 months p.i.: elimination was probably due to some form of host reaction, as parasite lineages were maintained for up to 10 months by transfers to successive uninfected hosts. The development of infrapopulations is similar to that reported for other viviparous gyrodactylids parasitic on the body surface of teleosts. However, the intrinsic rate of increase was comparatively slow in G. gallieni and the duration of infection in isolated hosts prolonged. Slow-growing infrapopulations may elicit a host response more slowly and extend the period during which dispersal to a new host or host population can occur. This might be important in G. gallieni for which the internal site of infection could limit the transmission rate, as worm migration from the oral cavity or accidental detachment and expulsion is necessary for host-host transfer to occur.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Description of the life-cycle stages of Brachylaima cribbi n. sp. (Digenea: Brachylaimidae) derived from eggs recovered from human faeces in Australia.

The life-cycle of Brachylaima cribbi n. sp. was established in the laboratory. Asymmetrical brachylaimid eggs, measuring 26-32 microm (29.1 microm) long and 16 -17.5 microm (16.6 microm) wide, were recovered from human faeces and fed to the helicid land snail Theba pisana as the first intermediate host. Sporocysts and cercariae were recovered from the T. pisana eight weeks after infection. The cercariae were used to infect the helicid land snails Cernuella virgata and Helix aspersa as second intermediate hosts. Metacercariae were recovered from the kidneys of these snails and used to infect mice. Adults of Brachylaima cribbi n. sp. were recovered from the small intestine of the mice. The differential features of B. cribbi n. sp. are the specificity for helicid snails as first and second intermediate hosts; characteristic ventral sucker and body cercarial chaetotaxy; and a long slender adult worm with equal size suckers in the first quarter of the worm, the ventral sucker occupying 41% of the body width, the uterus extending anterior to the ventral sucker and the vitelline follicles falling short of the posterior margin of the ventral sucker. No other known Brachylaima species exhibits all of these features. B. cribbi n. sp. is the first brachylaimid known to have infected humans and is probably of European origin, as the intermediate host snails were all introduced into Australia from Europe.

Aged↗
PubMed1997

Intestinal pathologic findings at early stage infection by Centrocestus armatus in albino rats.

This study was performed to observe intestinal pathology in early infection by Centrocestus armatus. The flukes were in the lowermost part of the intervillous space of the duodenum and jejunum from 1 day to 7 days postinfection (PI). The stroma of villi around the young fluke was edematous and infiltrated by inflammatory cells such as lymphocytes, plasma cells and eosinophils. The crypt became mildly hyperplastic and villi were moderately atrophied at 4 days PI. The intestinal lesion produced was confined to the areas around the fluke. The pathologic findings were not significantly different between 1,000 and 5,000 metacercariae infection groups. It is suggested that the lesion should be produced by mechanical destruction of the fluke on the enteroepithelial cells.

Animals↗
PubMed1998

A digenean metacercaria from the reef coral, Porites compressa, experimentally identified as Podocotyloides stenometra.

Feeding Porites compressa infected with a digenean metacercaria to the coral-feeding butterflyfish, Chaetodon multicinctus, established that the metacercaria was Podocotyloides stenometra. Those and field examinations finding a prevalence of 100% and an average intensity of infection of 6.5 worms/fish in 28 C. multicinctus off Kaneohe Bay, Oahu, Hawaii, established this fish as a definitive host. Plagioporus sp. of Cheng and Wong, 1974 is a synonym of P. stenometra.

Animals↗
PubMed2000

Prevalence of Paramphistomum daubneyi infection in cattle in central France.

Investigations at the slaughterhouse of Limoges (Central France) were performed in 1994-1996 to determine the prevalence of Paramphistomum daubneyi infection in cattle. In 1994/1995, higher prevalences of P. daubneyi were recorded in May, October, and January. In 1996, smaller variations were recorded, and prevalence in April and May was higher. The prevalence of P. daubneyi in summer was lower. Breed and age of cattle were not significantly associated to P. daubneyi infection, but females were significantly more infected than males. P daubneyi infection was related to that of Fasciola hepatica, but not to that of Dicrocoelium lanceolatum.

Abattoirs↗
PubMed1996

Effects of gamma-irradiation on the survival and development of Gymnophalloides seoi in C3H mice.

An experimental study was carried out to observe the effects of radiation on the infectivity of metacercariae of Gymnophalloides seoi to C3H mice. Oysters, the second intermediate host, were collected from an endemic area, and non-irradiated control, metacercaria-irradiation, and oyster-irradiation groups were prepared. One hundred metacercariae were infected orally to each mouse, and worm recovery rate was compared by groups at 7th day post-infection. In the metacercaria-irradiation group, the worm recovery rate was significantly reduced at radiation doses higher than 200 Gy, and the number of intrauterine eggs significantly reduced at doses over 50 Gy. In the oyster-irradiation group, 50 Gy significantly reduced both the worm recovery rate and number of uterine eggs. In the two groups, no worm was recovered at 1,000 Gy irradiation. Conclusively, irradiation of oysters with 200-1,000 Gy was effective to control infectivity of metacercariae to C3H mice, and could be adopted as a control measure for gymnophalloidiasis.

Animals↗
PubMed1989

Effects of concurrent infections on growth, development, distribution, and infectivity of adult Philophthalmus megalurus and Philophthalmus gralli.

Chickens were infected concurrently with 10 and 20 metacercariae/eye of Philophthalmus megalurus and Philophthalmus gralli. After 14 and 34 days of growth, the adults were removed and worm lengths, return rates, stage of development, and distribution within the host recorded. In a second experiment, chickens infected on day 1 with 10 metacercariae/eye of P. megalurus were concurrently infected with a similar dose of P. gralli on day 14. At day 34, the worms were removed and evaluated for the same parameters as in the first study. The effect of concurrent infections on worm length of P. gralli but not P. megalurus was significant when compared to single species control groups. In all cases recovery rates of P. megalurus in concurrent infections were significantly lower than controls, whereas P. gralli adults were recovered at lower rates only in 20-metacercariae--14-day infections. Maturation of eggs was delayed in both species in concurrent infections at the higher infection levels. Normal distribution was disrupted more for P. gralli at the higher infection levels and longer growth periods. Philophthalmus megalurus adults rarely left their normal habitat in the conjunctival sac. A delayed infective dose of P. gralli affected both species by disrupting normal distribution patterns, delaying egg development, and, in the case of P. megalurus, reducing the recovery rate. The possible role of crowding and antagonistic effects is discussed.

Animals↗
PubMed1995

Proterometra autraini n. sp. (Digenea: Azygiidae) from Michigan's upper peninsula and a key to species of Proterometra.

Life stages of Proterometra autraini n. sp. (Digenea: Azygiidae) from the Au Train River, Au Train, Michigan are described, with emphasis on the cercarial stage. Progenetic cercariae develop in rediae in the snail Elimia livescens and emerge seasonally from mid-summer to mid-autumn. Cercariae emerge naturally between 1000 and 2100 hr EDT. Adults were retrieved from several naturally infected fish species. Specimens of Cottus bairdi (n = 16) displayed the greatest prevalence (75%), mean intensity (7.1), and abundance (5.3) of infection. Experimental infections were successful in C. bairdi, Lepomis macrochirus, and Perca flavescens. The geographical range of this parasite is limited to the portion of the Au Train River between Au Train Lake and Lake Superior.

Animals↗
PubMed1994

Pathology of infection with Paramphistomum ichikawai in sheep.

Lambs were given 40,000 or 50,000 metacercariae of Paramphistomum ichikawai by injection into the rumen and necropsied at 21, 42 and 84 days after infection. Pathological changes were observed grossly and confirmed histologically in the small intestine and rumen. The numbers of flukes and their location in the gastrointestinal tract were recorded and the populations of eosinophils, mast cells and globule leucocytes estimated. Changes varied, according to the numbers of flukes present, from a localised enteritis and villous atrophy in the duodenum in light infections to severe destruction of the mucosa extending into most of the jejunum in heavy infections. As the infection progressed changes were characterised by extensive thickening and fibroplasia in the mucosa and submucosa. Severe damage to the mucosa of the rumen was also observed in heavy infections. Heavy infections were associated with increased infiltration with eosinophils. Mast cells were generally depleted and globule leucocytes only appeared after the flukes had left the small intestine. Migration of the flukes from the small intestine was delayed in heavy infections exacerbating the effect of the infection. It is suggested that the presence of 20,000 to 25,000 flukes would result in clinical disease; smaller numbers would cause significant subclinical disease.

Animals↗