Immunization against Schistosoma mansoni in rhesus monkeys and the requirement of activation of both cell-mediated and humoral mechanisms.
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When groups of rhesus monkeys were pretreated with BCG plus hyperimmune serum from monkeys with chronic schistosomiasis or with dialyzable transfer factor from uninfected monkeys plus hyperimmune serum and were challenged with 1,500 cercariae of Schistosoma mansoni, the mean worm burdens were significantly lower than that of untreated controls. Pretreatment with neither BCG alone nor Corynebacterium parvum plus a membrane antigen of adult worms of S. mansoni affected susceptibility. Neither lymphocyte proliferation in the presence of mitogens or schistosome antigen nor serological responsiveness (as measured by gel diffusion, Cercarienhullenreaktion, circumoval precipitation, or enzyme-linked immunoabsorbent assay) correlated with the degree of resistance of the animals to S. mansoni. The pretreatment procedures used did not cause any abnormal histopathological responses and did not alter the characteristic host response to schistosome eggs in the lungs, liver, mesenteric lymph nodes, and colon. (+info)
Immune responses to Schistosoma mansoni in rhesus monkeys with multiple chronic and early primary infections.
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Immunological reactivity in 10 rhesus monkeys was monitored over a 22-week period. Cellular and humoral responses of three animals were studied after primary infection with Schistosoma mansoni. Two uninfected animals served as controls. Increased lymphocyte proliferative responsiveness to mitogens and adult worm antigen was evident during the prepatent period of the infection. Marked suppression of these responses occurred during the acute phase of the disease, but by weeks 9 and 11 the animals were again responsive to mitogens and antigen, respectively, and remained so throughout the remainder of the observation period. No antibody response to various cercarial, adult worm, and egg antigens could be detected until weeks 5 to 7, after which these responses also persisted. Comparison of the immunological reactivities of these animals with primary infection and those of five chronically infected immune animals indicated possible correlations between protective immunity and (i) strong Cercarienhullenreaktion reactivity, and (ii) lymphocyte proliferative responsiveness to adult worm antigen. (+info)
Pyogenic abscesses and parasitic diseases.
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Parasitic diseases which during their course in the host switch the immune system from a T helper 1 to a T helper 2 response may be detrimental to the host, contributing to granuloma formation, eosinophilia, hyper-IgE, and increased susceptibility to bacterial and fungal infections. Patients and animals with acute schistosomiasis and hyper-IgE in their serum develop pyogenic liver abscess in the presence of bacteremia caused by Staphylococcus aureus. The Salmonella-S. mansoni association has also been well documented. The association of tropical pyomyositis (pyogenic muscle abscess) and pyogenic liver abscess with Toxocara infection has recently been described in the same context. In tropical countries that may be an interesting explanation for the great morbidity of bacterial diseases. If the association of parasitic infections and pyogenic abscesses and/or fungal diseases are confirmed, there will be a strong case in favor of universal treatment for parasitic diseases to prevent or decrease the morbidity of superinfection with bacteria and fungi. (+info)
Biochemical changes in patients with combined chronic schistosomiasis and viral hepatitis C infections.
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This study was undertaken to assess the biochemical changes induced in chronic schistosomiasis and/or chronic HCV, as well as to pinpoint the most significant parameters which could be used as dependable indices for the differentiation of single and coupled infections with or without liver cirrhosis. The selected patients were allocated into 2 broad groups: GrII (Schistosomiasis) which was subdivided into 3 subgroups: GrII(a) schistosomal patients with hepatosplenomegaly; GrII(b) hepatosplenic schistosomal patients with decompensated liver cirrhosis; GrII(c) schistosomal patients with no organomegaly. GrIII (Combined) comprised 2 subgroups: GrIII(a) schistosomal-HCV infection with decompensated liver cirrhosis; GrIII(b) schistosomal-HCV infection without liver cirrhosis. For statistical comparison normal healthy subjects were taken as a reference group (Gr I). Results showed that schistosomal patients without organomegaly manifested non significant changes in all studied parameters compared to normal controls. Highly significant elevations in serum ALT, AST, ALP and GGT activities were recorded in all other subgroups but the highest levels are reported in GrIIb. AST/ALT and direct/indirect bilirubin ratios were highest in GrIIIa (1.17+/-0.26, 1.54 +/- 0.37, respectively). Serum total protein and albumin levels showed the highest reduction (33 and 59%) concomitantly with the highest increase in gamma-globulin level (75%) in GrIII(a). Blood total iron was significantly reduced in GrII(a,b) (15.6 and 12%) (8.8%) bilirubin, GGT and AST in this order are good discriminators between the different subgroups in GrII. On the other hand, ALT, AST, albumin, ALP, GGT, protein and direct bilirubin are the most significant indices to differentiate chronic schistosomiasis and the combined group with/or without liver cirrhosis. (+info)
Hepatitis C in a community in Upper Egypt: I. Cross-sectional survey.
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The prevalence of antibody to hepatitis C virus (anti-HCV) was determined in a cross-sectional survey in a village in Upper Egypt. Exposure and demographic characteristics were obtained through a questionnaire. Antibody to hepatitis C virus was assessed using a second generation enzyme immunoassay, and the presence of HCV RNA was tested using a reverse transcriptase-polymerase chain reaction. Collection of blood samples was targeted at those > or = 5 years old, and obtained from 62.8%. This report describes the community, the HCV infection characteristics of the subjects, and evaluates some factors associated with presence of anti-HCV. Of the 6,031 participants, 522 (8.7%) were anti-HCV positive. Prevalence was higher among males than females (11.3% versus 6.5%; P < 0.001). It was greater among those > 30 years of age than among those < or = 30 years of age (20.0% versus 3.6%; P < 0.001). Those who were less educated, farmed, provided health care, and were currently married had a significantly higher anti-HCV prevalence than those who were not; however, these associations were not significant after adjusting for age. Although active infections with Schistosoma haematobium were not associated with anti-HCV, a history of past infection was (age-adjusted risk ratio [RR] = 2.1, 95% confidence interval [CI] = 1.8, 2.4); 134 persons who had a history of receiving parenteral anti-schistosomal therapy had a higher age-adjusted RR (3.0; 95% CI = 2.5, 3.7) for anti-HCV than those who did not. Hepatitis C virus RNA was detected in 62.8% of the anti-HCV positive subjects, without significant variation by age, gender, education, or marital status. The prevalence of anti-HCV in Upper Egypt is high, albeit lower than in Lower Egypt, with continuing but limited transmission indicated by the lower prevalence in residents < or = 30 years old. (+info)
A protocol for geographically randomized snail surveys in schistosomiasis fieldwork using the global positioning system.
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A protocol was created for performing geographically randomized snail surveys for schistosomiasis research using the global positioning system (GPS). This protocol differs from traditional surveys in its ability to accurately map and measure the spatial distribution of snail habitat. The protocol was used to map irrigation ditches, the primary habitat for Oncomelania hupensis, in two residence areas in Sichuan Province, China. From the 7,450 meters of mapped ditches, snail surveys were performed at 203 random sites along the ditch network. Of these, 116 (57.1%) sites had snails. The total number of living snails captured was 2,014, resulting in an average snail density of 0.27 snails per linear meter of potential habitat. (+info)
Pathogenic aspects of pyogenic liver abscess associated with experimental schistosomiasis.
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Schistosomiasis mansoni infection that occurs concurrently with Staphylococcus aureus bacteremia favors the formation of pyogenic liver abscess. The present experimental study in mice evaluated the following aspects of the relationship between infection with Schistosoma mansoni and liver abscess caused by S. aureus: a) the role of the eggs of S. mansoni in the genesis of the abscesses; b) the influence of different phases of schistosomiasis in the development of liver abscesses; and c) the effect of the treatment of schistosomiasis on the development of the abscesses. Macroscopic and histopathological study showed multiple liver abscesses around granulomas of S. mansoni in the acute and chronic phases of schistosomiasis. Treatment of acute schistosomiasis before experimentally-induced bacteremia did not prevent the formation of liver abscess. The study findings indicate that granulomas around S. mansoni eggs and worms lodged in the liver provide a focus and substrate for pyogenic abscesses caused by S. aureus. (+info)
Dynamics of egg counts and circulating antigen levels in a recent Schistosoma mansoni focus in northern Senegal.
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Serum circulating anodic antigen (CAA) levels were compared with faecal egg counts in four subsequent population samples, randomly selected at 8-month intervals, in a recent Schistosoma mansoni focus in northern Senegal. In all four samples, antigen levels showed the same age-intensity profiles as egg counts, with a strong decline in adults. Also across population samples, a consistent relationship was found between egg counts and antigen levels. Assuming the level of CAA to be a direct reflection of worm burden, these findings support the idea that the observed egg count patterns and levels indeed reflect dynamics of worm burdens, and not of egg excretion or worm fecundity. Remarkably similar levels of both egg counts and CAA were observed in the first and last sample, collected in the same season (August--September), but 2 years apart. This suggests that a steady state of S. mansoni infection had already been reached shortly after the onset of the epidemic in this focus (3 years). Significantly lower infection levels were found in the intermediate population samples collected in January and April. The differences in infection levels across the four population samples may be because of seasonal transmission patterns. They would indicate a substantial turnover of worm populations, with an estimated average life span of only 7 months, probably less, in this recently emerged, intense S. mansoni focus. (+info)