A significant part of the ‘concomitant immunity’ of mice to Schistosoma mansoni is the consequence of a leaky hepatic portal system, not immune killing

Schistosomiasis is a parasitic infection that is highly prevalent worldwide, with a variety of species being responsible for causing the disease. In Brazil, however, the only identified species isSchistosoma mansoni. The adult parasites inhabit the blood vessels of the hepatic portal system of the main host. The disease may range from being asymptomatic to provoking liver damage or portal hypertension. Furthermore, ectopic schistosomiasis may develop, and several hypotheses have been raised to explain the occurrence of the disease. This paper describes two cases, one in a 39-year-old woman and the other in a 47-year-old woman. Both had similar symptoms of pain and abdominal distension caused by a large abdominal/pelvic mass. Histopathology of the ovary showed a mucinous cystadenocarcinoma of the intestinal type in the first patient and a papillary serous carcinoma in the second, with both tumors containing viable eggs ofSchistosoma mansoni. The neoplasms probably serve as a migratory route for the adult parasites and the embolization of eggs. Nevertheless, there is insufficient evidence to confirm the malignization of a benign lesion due to the presence ofSchistosoma mansoni. Few cases have been reported in the international literature on the association between ovarian schistosomiasis and neoplasms.

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Phenotypic plasticity of male Schistosoma mansoni from the peritoneal cavity and hepatic portal system of laboratory mice and hamsters

Journal of Helminthology ◽

10.1017/s0022149x14000066 ◽

2014 ◽

Vol 89 (3) ◽

pp. 294-301 ◽

Cited By ~ 2

Author(s):

V.L.T Mati ◽

R.M. Freitas ◽

R.S. Bicalho ◽

A.L. Melo

Keyword(s):

Schistosoma Mansoni ◽

Body Length ◽

Peritoneal Cavity ◽

Total Body Length ◽

Portal System ◽

Swiss Mice ◽

Plastic Potential ◽

Hepatic Portal System ◽

Total Body ◽

Hepatic Portal

AbstractMorphometric analysis of Schistosoma mansoni male worms obtained from AKR/J and Swiss mice was carried out. Rodents infected by the intraperitoneal route with 80 cercariae of the schistosome (LE strain) were killed by cervical dislocation at 45 and 60 days post-infection and both peritoneal lavage and perfusion of the portal system were performed for the recovery of adult worms. Characteristics including total body length, the distance between oral and ventral suckers, extension of testicular mass and the number of testes were considered in the morphological analysis. Changes that occurred in S. mansoni recovered from the peritoneal cavity or from the portal system of AKR/J and Swiss mice included total body length and reproductive characteristics. Significant morphometric alterations were also observed when worms recovered from the portal system of both strains of mice were compared with the schistosomes obtained from hamsters (Mesocricetus auratus), the vertebrate host in which the LE strain had been adapted and maintained by successive passages for more than four decades. The present results reinforce the idea that S. mansoni has high plastic potential and adaptive capacity.

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Portal shunting and resistance to Schistosoma mansoni in 129 strain mice

Parasitology ◽

10.1017/s0031182000059102 ◽

1989 ◽

Vol 99 (3) ◽

pp. 383-389 ◽

Cited By ~ 24

Author(s):

P. S. Coulson ◽

R. A. Wilson

Keyword(s):

Schistosoma Mansoni ◽

Post Infection ◽

Superior Mesenteric Vein ◽

Negative Association ◽

Portal System ◽

Hepatic Veins ◽

Mesenteric Vein ◽

Hepatic Portal System ◽

Hepatic Portal

SummaryThe integrity of the hepatic portal vasculature was examined, relative to the resistance to Schistosoma mansoni observed in 68°0 of 129/Ola mice. The passage of microspheres to the lungs, following their injection via the superior mesenteric vein, indicated the presence of shunts in the majority of both naive and infected mice. There was a negative association between shunting of microspheres to the lungs and paucity of liver worms at 28/35 days post-infection. Schistosomula accumulated in the livers of resistant mice at a slower rate than in susceptible animals, and after day 21 relocated to the lungs. Many lung schistosomula injected via the superior mesenteric passed immediately to the lungs; the shunts thus greatly reduce the probability of trapping in the liver. Some parasites migrated back from the lungs, successfully lodged in the liver and began to feed on blood. Latex infusion demonstrated the location of large intrahepatic connections between the portal and hepatic veins. We suggest that as these liver worms grow, migrating upstream into progressively larger vessels, they reach the connections, pass out of the hepatic portal system, and relocate to the lungs. The presence of the natural shunts thus accounts for the resistant status of the mice.

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Recovery of Schistosoma mansoni from the skin, lungs and hepatic portal system of naive mice and mice previously exposed to S. mansoni: evidence for two phases of parasite attrition in immune mice

Parasitology ◽

10.1017/s0031182000000755 ◽

1980 ◽

Vol 80 (2) ◽

pp. 289-300 ◽

Cited By ~ 87

Author(s):

S. R. Smithers ◽

K. Gammage

Keyword(s):

Schistosoma Mansoni ◽

Early Phase ◽

Late Phase ◽

Significant Loss ◽

Challenge Infection ◽

Egg Laying ◽

Portal System ◽

Hepatic Portal System ◽

Two Phases ◽

Hepatic Portal

SummaryNew or improved techniques for recovering Schistosoma mansoni from the skin, lungs and liver have enabled us to trace the attrition of a challenge infection in naive (i.e. previously uninfected) and chronically infected mice. Within each experiment, the numbers of schistosomes recovered from the skin of naive mice on day 2 after challenge or from the skin and lungs on days 3, 4 or 5, did not differ significantly from the numbers recovered from the liver on days 14, 21, 28 or 35. Approximately 65% of cercariae which penetrated the skin failed to be recovered from naive mice by any of the assays and it appeared that these schistosomes had already died in the skin in the first 24 h. No further significant loss of the infection was detected in naive mice. In chronically infected mice a further attrition of the challenge infection was demonstrated in two distinct phases. An ‘early phase’ occurred within the first 3 days of exposure and accounted for the death of 30% of the remaining parasites. A ‘late phase’ occurred between days 6 and 14 and accounted for an additional 43% of deaths. Thus, the two phases of attrition accounted for a loss of approximately 73% of the infection that would have survived in naive mice. The late phase of attrition could be demonstrated before the primary infection had matured, in contrast to the early phase of attrition which was seen only after egg laying had commenced. We believe that the early phase of attrition takes place in the skin and the late phase occurs after the schistosomes have left the lungs, either en route for the liver or as soon as they arrive in that organ. The results suggest that there are two distinct mechanisms of immunity against re-infection with S. mansoni in mice.

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Schistosoma mansoni: Mechanism of Attrition and Routes of Migration from Lungs to Hepatic Portal System in the Laboratory Mouse

Journal of Parasitology ◽

10.2307/3282399 ◽

1987 ◽

Vol 73 (4) ◽

pp. 706 ◽

Cited By ~ 8

Author(s):

Jay R. Georgi ◽

Susan E. Wade ◽

David A. Dean

Keyword(s):

Schistosoma Mansoni ◽

Laboratory Mouse ◽

Portal System ◽

Hepatic Portal System ◽

Hepatic Portal

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Attrition and temporal distribution of Schistosoma mansoni and S. haematobium schistosomula in laboratory mice

Parasitology ◽

10.1017/s0031182000049829 ◽

1986 ◽

Vol 93 (1) ◽

pp. 55-70 ◽

Cited By ~ 19

Author(s):

J. R. Georgi ◽

S. E. Wade ◽

D. A. Dean

Keyword(s):

Body Weight ◽

Schistosoma Mansoni ◽

Temporal Distribution ◽

Distribution Patterns ◽

Systemic Circulation ◽

The Body ◽

Portal System ◽

Hepatic Portal System ◽

Total Body ◽

Hepatic Portal

SUMMARYThe total number and distribution of schistosomula of Schistosoma mansoni and S. haematobium in all tissues and organs of mice from infection to 14–27 days was determined by compressed tissue autoradiography. Attrition of schistosomula, manifested as a decrease in the number of autoradiographic foci, was observed in organs other than the liver. Attrition commenced about 2 days after cercariae entered the skin, and conformed to a single exponential function with a rate constant (± standard error) of 7·0±0·5%/day for S. mansoni and 3·2±0·7%/day for S. haematobium. The temporal distribution of schistosomula of S. mansoni and S. haematobium differed quantitatively. In the case of S. mansoni, concomittant with a decrease in skin counts, the lung curve rose rapidly to a peak centred on day 6 and thereafter decreased more or less parallel to the total body curve. Significant accumulation in the liver was not observed until day 7, whereupon liver counts rose steadily to a plateau that extended from about day 14 to the end of the experiment and approximated the number of adult worms recovered from the hepatic portal vessels on day 42. A maximum of 26% and mean of 12% of all foci in the body were counted on autoradiograms of tissues other than the skin, lung and liver. The pelt averaged 14% of the body weight yet schistosomula were detected only in the area initially exposed to cercariae. The eviscerated carcass averaged 54% of the body weight yet contained only 0·8% −3·4 % of the schistosomula during the period of accumulation in the liver. Between day 6 and day 14, the ratio of schistosomula in the pulmonary circulation to schistosomula in the systemic circulation did not remain constant, as would be the case if schistosomula circulated passively and randomly, but instead displayed a statistically significant decrease from 0·92 and 0·85. For these reasons, it was considered unlikely that schistosomula had circulated randomly and repeatedly through the pulmonary and systemic circulations and entered the hepatic portal system by chance, as hypothesized by Miller & Wilson (1980). Instead it was considered more probable that schistosomula migrating from lungs to liver had followed a directed path through intervening vessels (Kruger, Heitman, van Wyk & McCully, 1969) or tissues (Wilks, 1967). Schistosoma haematobium distribution patterns differed from those of S. mansoni in slower movement of schistosomula from skin, their peak accumulation in lungs at about day 8 followed by a low rate of decrease, and a very low liver plateau which approximated the number of adult worms recovered from the hepatic portal vessels on day 42.

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An examination of the skin phase of schistosome migration using a hamster cheek pouch preparation

Parasitology ◽

10.1017/s0031182000000731 ◽

1980 ◽

Vol 80 (2) ◽

pp. 257-266 ◽

Cited By ~ 20

Author(s):

R. A. Wilson ◽

J. Ruth Lawson

Keyword(s):

Cheek Pouch ◽

Surrounding Tissue ◽

Portal System ◽

Hamster Cheek Pouch ◽

Post Exposure ◽

Hepatic Portal System ◽

65 H ◽

The Mean ◽

Hepatic Portal ◽

Mean Time

SummaryA living hamster cheek pouch preparation has been used to study the skin phase of schistosomulum migration. Between 0 and 16 h post-exposure schistosomula become increasingly difficult to see and lateral movement in the skin ceases. Up to 50 h post-exposure they remain poorly visible. They lie in fluid-filled lacunae within the epidermis, external to the basement membrane. The first schistosomula enter the dermis from. 40 h post-exposure, approximately half having done so by 52·5 h. Coincidentally, they can be more easily distinguished from surrounding tissue. Up to 91% of original penetrants have been observed alive in. pouch tissue at 65 h post-exposure. Since only 26% eventually mature in the hepatic portal system there would appear to be considerable attrition subsequent to the skin phase of migration. The mean diameter of venules penetrated was 22·7 μm and the mean time taken to penetrate was 8·01 h. The majority of schistosomula left the pouch between 60 and 80 h post-exposure.

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