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PubMedDate not supplied

[Histopathology of Kingiella chilenica (bivalvia, cyamiidae) parasitized by rediae and cercariae of the Gymnophallidae family].

Gonadal and digestive gland tissues of Kingiella chilenica specimens, which were infected with trematode larvae, were examined to determine the organs that are normally invaded by these parasites. Rediae containing cercariae of this digenetic trematod, appeared exclusively restricted to the tissues of the digestive gland. Consequently, no damage or alterations were observed in the gonad or other related tissues of the infected specimens. This, linked to the fact that parasitized females may also appear with brooded embryos, supports the conclusion that the reproductive activities of the bivalve mollusc are not affected by the presence of these infecting larvae.

Animals↗
PubMed1993

Treatment of fish parasites. 10. Effects of a new triazine derivative, HOE 092 V, on Monogenea: a light and transmission electron microscopy study.

For chemotherapy of fish parasitized by monogeneans, a novel triazine derivative, 2-[3,5-alpha-dichloro-4-(4-methyl-sulfonylphenoxy)-phenyl]-1-methy l- hexahydro-1,2,4-triazine-3,5-dion (HOE 092 V), was tested in vivo against the gill- and skin-parasitizing species Dactylogyrus extensus, D. vastator, and Gyrodactylus arcuatus. Naturally infected fish were incubated in aerated, separate tanks at 22 degrees C for 1, 2, 3, and 4 h in water containing 0, 1, 5, 10, or 15 micrograms HOE 092 V/ml, whereas Pseudodactylogyrus bini was tested in vitro at 10 micrograms HOE 092 V/ml for 2.25 h. As seen by means of transmission electron microscopy, in vivo treatment against D. extensus caused vacuolization and lysis of the parasite's tegument at a dose as low as 1 micrograms/ml over a 3-h exposure period. Higher doses, such as 5 and 10 micrograms/ml over the same exposure period, produced lesions in the circular and longitudinal musculature of D. extensus and differing degrees of damage to the ciliary cells of protonephridia and immature vitelline cells. There was 100% mortality in D. vastator when incubation was done with 10 micrograms HOE 092 V/ml for 4 h (G. arcuatus; 5 micrograms/ml for 4 h; 10 micrograms/ml for 1 h) and in P. bini after 2.25 h in vitro exposure. In all species tested, the anterior portion and the opisthaptor region were most sensitive to the drug action.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2000

Associations between epidermal thionin-positive cells and skin parasitic infections in brown trout Salmo trutta.

The dynamics of the densities of epidermal thionin-positive cells (putative mast cells) in the skin of brown trout fry were investigated during experimental infections with the skin parasites Ichthyophthirius multifiliis (Ciliophora) and Gyrodactylus derjavini (Monogenea). It was shown that the metachromatic thionin-stained cells were extremely sensitive to parasite exposure, as the density of cells in the skin of trout decreased markedly after exposure to the pathogens. As early as 7 d post infection the cell counts were significantly reduced and almost totally depleted following 9 d infection, which suggests that degranulation of the cells occurs following parasite exposure. No recruitment of new cells was seen during the study period. Some reduction in uninfected control groups indicates that the putative mast cells are sensitive to stress as well. A notable variation in densities of thionin-stained cells between different fins was found and the corneal surface was devoid of these cells. The possible implications of these cells in host-parasite interactions are suggested and discussed.

Animals↗
PubMed1993

Experimental infection of domestic ducks and rodents by Notocotylus attenuatus (Trematoda: Notocotylidae).

In order to study transmission patterns of Notocotylus attenuatus five 3-wk-old domestic ducks, five 8-wk-old rats and ten 4-wk-old mice were infected with the parasite. All ducks became infected and all flukes were recovered from the intestinal ceca. Worms moved down the length of the cecum during development and as the parasites grew they changed their method of attachment. Flukes became gravid by day 16 post-infection, after which growth ceased. Egg filaments appear to play a role in the formation and movement of worm egg clusters from the distal portion of the cecum to the lumen of small intestine. Rodents also became infected with the parasite producing granulomatous nodular lesions in the lower small intestine but all flukes in the granulomata were dead. It is unlikely that transmission of this trematode can depend on mice and rats.

Animals↗
PubMed2004

Oviposition by Aedes aegypti (Diptera: Culicidae) in relation to conspecific larvae infected with internal symbiotes.

Female mosquitoes use abiotic and biotic factors, such as the presence of heavy metals or parasites, to determine the acceptability of oviposition sites. Some biotic factors can originate from mosquito larvae. When mosquito larvae are starved or infected with trematode metacercaria, they render associated water unacceptable to ovipositioning females. Internal symbiotes are common in wild mosquito populations, and I tested whether or not larvae of Aedes aegypti infected with a gregarine (Ascogregarina taiwanensis), a yeast (Candida near pseudoglaebosa), or a trichomycete (Smittium morbosum) rendered their rearing water unacceptable to oviposting mosquitoes. Infections with S. morbosum had no effect on the acceptability of the associated rearing water when compared to rearing water from uninfected larvae. However, the rearing water from larvae infected with A. taiwanensis or C. near pseudoglaebosa was more acceptable to ovipositing females than was distilled water or rearing water from uninfected larvae. Ovipositing female mosquitoes either preferred or were neutral to rearing water from larvae with gut symbiotes.

Aedes↗
PubMed1995

Effect of exposure to malachite green solution on common carp fry with Dactylogyrus vastator (monogenea) infection.

In five experiments, common carp (Cyprinus carpio) fry with Dactylogyrus vastator (Monogenea) infection of different severity, as well as parasite-free fry, were placed into aquaria containing malachite green solution of 0.5-10 mg/l concentration. Most of the fish died within 6 hours. The correlation between the time of death and helminth infection was studied. The experiments demonstrated that in malachite green solution the carp with the heaviest helminth infection died first while the less severely infected specimens survived for the longest time.

Animals↗
PubMed1995

Experiments on second intermediate fish host related cercarial transmission of the eyefluke Diplostomum spathaceum into rainbow trout (Oncorhynchus mykiss).

The effect of host variables such as size and density, on the transmission of cercariae of Diplostomum spathaceum (Rudolphi, 1819) into a second intermediate fish host, rainbow trout, Oncorhynchus mykiss (Walbaum), was studied quantitatively in laboratory experiments under varying exposure conditions. Differences in the number of established metacercariae were noted in differently sized fish exposed singly to the same number of cercariae and in water volumes related to the body surface area of the host. When exposed (1) singly in an equal water volume or, (2) simultaneously in the same tank, no differences in recovery of metacercariae per fish were found between "small" and "large" hosts. The latter observation is valid for three water volumes tested using the same number of cercariae per host. No significant difference in metacercarial infection was revealed in similar sized fish exposed at different host densities. It appears that transmission is more influenced by cercarial density (number of cercariae per water volume) and fish size than by fish density. These experimental findings support the view that cercarial infection of fish occurs by chance, presumably mainly in the gill region. Accordingly, in the field, individual fish size and cercarial density rather than fish population density, prevail in parasite transmission from snail to fish. This is of interest in coastal areas heated by cooling water, where fish growth and fish population density are enhanced.

Animals↗
PubMed2004

Use of rDNA polymorphism for identification of Heterophyidae infecting freshwater fishes.

Infections by trematodes are among the most common fish-borne zoonoses. Metacercariae of the Family Heterophyidae in marine and freshwater fishes are nonfastidious in their choice of definitive hosts, and therefore, cause infections in human and domestic animals. In the present study, species-specific polymerase chain reaction (PCR) assays were developed for identifying and differentiating the various species examined. Sequencing and aligning the 18S (SSU) rDNA revealed interspecific variation for which species-specific DNA oligonucleotides were designed and used for the identification of 6 heterophyid species recovered from piscivorous birds. The oligonucleotides were further used to evaluate the various stages (cercariae recovered from snails, metacercariae recovered from fish and adult trematodes) of the digeneans. By applying this method we elucidated for the first time the life cycle of Pygidiopsis genata. The phylogenetic interrelationship among the newly sequenced species of Heterophyidae is outlined.

Animals↗
PubMed2002

Effects of environmental temperature on the susceptibility of Xenopus laevis and X. wittei (Anura) to Protopolystoma xenopodis(Monogenea).

Immune responses in ectothermic vertebrates and the life-processes of their parasites are profoundly linked to ambient temperature, but the functional effect of thermal environment on infectivity and host-specificity in helminths from ectotherms is poorly known. Primary infection establishment of Protopolystoma xenopodis (Monogenea) in compatible hosts ( Xenopus laevis: Anura) is strongly modulated by ambient temperature. Significantly fewer worms survived to the urinary bladder stage at 25 degrees C than at 15 degrees C (relatively high and low temperatures for this system in nature). Pre-infection exposure of X. laevis to cold (10 degrees C) did not significantly affect parasite establishment in the urinary bladder (at 15 or 25 degrees C p.i.), nor shorter-term postlarval survival in the kidneys (at 20 degrees C p.i.), suggesting that residual immunosuppressive effects on host susceptibility are not important. Low temperatures had no permissive effect on the establishment of P. xenopodis in incompatible hosts (Xenopus wittei). The link between thermal conditions and parasitic infection of ectotherms is discussed.

Animals↗
PubMed1978

Experimental studies of infection dynamics: infection of the definitive host by the cercariae of Transversotrema patialense.

The number of cercariae of Transversotrema patialense which attach to the fish host Brachydanio rerio, during a fixed exposure period, is shown to be directly proportional to cercarial density within an experimental infection arena. The distribution of successful infections/host is shown to change from a random pattern to an over-dispersed form as cercarial exposure density or duration of host exposure to infection increases. A stochastic simulation model is used to demonstrate that small differences in host susceptibility to infection, within a population of hosts, can generate patterns of dispersion in parasite numbers/host similar to those observed in the experimental studies. Differences in host behaviour, during the period of exposure to infection, are thought to generate variability in host susceptibility to cercarial infection.

Animals↗
PubMed1981

Clinical changes caused by the liver fluke Metorchis conjunctus in cats.

Cats infected with metacercariae of the fluke Metorchis conjunctus were followed clinically through their infection. Cats given 200 metacercariae showed few symptoms. All the cats passed ova on the 17th day. Three hundred metacercariae caused diarrhea, icterus, discolored urine, green feces and eosinophilia after 18 to 21 days. Eosinophilia, leucine aminopeptidase and alanine aminotransferase were elevated and remain the best indicators for metorchiasis. The hematological and serological abnormalities resolved rapidly and were absent from cats with chronic infection. Acute lesions (less than 32 days) were confined to the biliary trees with extensive epithelial exfoliation, fibrosis, and pus from necrosis, tissue feeding by the worms and pressure atrophy. Chronic infections (32 to 150 days) caused hyperplasia of the bile epithelium, proliferation of connective tissues, and fibrosis of the perilobular areas. Intense eosinophilic infiltrates were replaced by mononuclear cells. Granuloma formation around an ovum was seen in one cat 719 days after infection. Adult worms established preferentially in the left lateral lobe and never in the caudal lobe. No gall bladder involvement was found even in heavy infections.

Animals↗
PubMed1989

A human case of Stellantchasmus falcatus infection.

A human case infected with Stellantchasmus falcatus(Heterophyidae) is reported based on the adult worms collected after praziquantel treatment. The patient is a 33-year old male residing in Seoul. For several months he experienced vague abdominal discomfort and hunger pain. Praziquantel at a single dose of 600 mg was given followed by purgation with magnesium salt, and 17 adult S. falcatus specimens were collected from the diarrheal stools. He recalled he had eaten raw flesh of several kinds of brackish water fishes. This is the 4th human case of S. falcatus infection in Korea.

Adult↗