Altered response of strain of Schistosoma mansoni to oxamniquine and praziquantel.
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The susceptibility of a fourth generation Ouh strain (Paranapanema Valley, Sao Paulo, Brazil) of Schistosoma mansoni to oxamniquine (OXA) and praziquantel (PZQ) was studied. Ten groups of 13 female albino mice each were infected with 70 cercariae per animal. These mice were medicated orally on the 50th day after infection. Five groups were given OXA doses of 0, 100, 200, 300 and 400 mg/kg (single doses) and the rest were treated with PZQ doses of 0, 100, 200, and 250 mg/kg/5 days. Each group was sub-divided: 8 animals underwent perfusion after 15 days treatment, 5 mice followed up for oviposition and their feces were tested every 15 days for miracidia hatching. The efficacy of the OXA doses of 100 and 200 mg/kg was 66% and 91.4%, respectively and for the 100 mg/kg PZQ dose it was 90.1%. The follow-up groups with 100 and 200 mg/kg of OXA and PZQ, 100 and 150 mg/kg, showed that they re-established the oviposition after a period of 60 to 75 days of treatment. The ED50 was 69.6 mg/kg OXA and 39.4 mg/kg PZQ. The results show the tolerance of the Ouh strain to a dose of 100 mg with both drugs and they appoint the need for a dose review during the follow up of the oviposition and in monitoring phenomena in the field. (+info)
Spinal cord schistosomiasis in children: analysis of seven cases.
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We describe seven cases of children (ages 2 to 14 years) with myeloradiculopathy caused by infection with S. mansoni. None of them presented hepatosplenic involvement and one presented an intestinal picture. The myeloradicular and pseudotumoral forms were observed in four and three patients, respectively. Comparing the reports in the literature, we found that the pseudotumoral form is more similarly frequent among children than in adults, while the myelitic and myeloradicular forms are the most frequent and distributed across all age groups. Diagnosis is based on clinical and epidemiological findings in association with laboratory tests. The diagnosis was confirmed by the presence of S. mansoni eggs in feces (5 cases) and / or the positivity in specific immunological tests (5 cases) associated with a cerebrospinal fluid inflammatory pattern with presence of eosinophils (between 1 and 24%). Magnetic resonance image, although it does not enable an etiological diagnosis, helped to confirm the form and spinal cord level of the lesion. (+info)
Longitudinal Study on the Natural Infection of Biomphalaria straminea and B. glabrata by Schistosoma mansoni in an Endemic Area of Schistosomiasis in Pernambuco, Brazil.
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The abundance of snail hosts and the rates of infection with Schistosoma mansoni were monitored monthly for four years in two representative localities subjected to repeated chemotherapy of infected persons. Snail abundance varied from 1.0 to 4.4 collected per person/minute/station for Biomphalaria straminea and from 0.1 to 7.0 for B. glabrata. Infection rates of snails in nature varied from 0% to 15% for the former and from 0% to 70% for the latter species. Human infection increased from 35.5% to 61.9% in the locality occupied by B. straminea, and decreased from 40.3% to 20.8% in that occupied by B. glabrata. No relationship could be detected between human infection and the snail variables. Despite seasonal variations, natural infection persisted throughout the monitoring period in both snail species. It reached remarkably high levels in B. straminea when compared to those obtained by other authors probably because of differences in methodology. It is recommended that longitudinal studies should be carried out focally and periodically to avoid underestimating the prevalence of schistosome infection in snails. (+info)
Ultrastructural alterations in adult Schistosoma mansoni caused by artemether.
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Progress has been made over the last decade with the development and clinical use of artemether as an agent against major human schistosome parasites. The tegument has been identified as a key target of artemether, implying detailed studies on ultrastructural damage induced by this compound. We performed a temporal examination, employing a transmission electron microscope to assess the pattern and extent of ultrastructural alterations in adult Schistosoma mansoni harboured in mice treated with a single dose of 400 mg/kg artemether. Eight hours post-treatment, damage to the tegument and subtegumental structures was seen. Tegumental alterations reached a peak 3 days after treatment and were characterized by swelling, fusion of distal cytoplasma, focal lysis of the tegumental matrix and vacuolisation. Tubercles and sensory organelles frequently degenerated or collapsed. Typical features of subtegumental alterations, including muscle fibres, syncytium and parenchyma tissues, were focal or extensive lysis, vacuolisation and degeneration of mitochondria. Severe alterations were also observed in gut epithelial cells and vitelline cells of female worms. Our findings of artemether-induced ultrastructural alterations in adult S. mansoni confirm previous results obtained with juvenile S. mansoni and S. japonicum of different ages. (+info)
Influence of specific treatment on the morbidity of Schistosomiasis mansoni in an endemic area of Minas Gerais, Brazil.
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The authors describe the evolution of schistosomiasis mansoni in inhabitants of Capitao Andrade, Minas Gerais, Brazil, from 1973 to 1994. The prevalence of infection was 60.8% in 1973, 36.2% in 1984, and 27.3% in 1994. The evolution of the clinical forms of the disease in this group was as follows: unchanged in 76.7%, clinical progression in 8.4% and clinical regression in 14.9%. The reduction of the prevalence and severity of Schistosoma mansoni infection over the 21 years period, can be attributed to treatment of infected subjects performed in the area and to the installation of piped water in their dwellings. (+info)
Synthesis of a new antischistosomally active and toxicologically tolerant C-12 monothione surrogate of the universal antihelmintic praziquantel.
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A new C-12 monothione mimic (III) of the universal antihelmintic Praziquantel (I) namely, 2-cyclohexylthiocarbonyl( 1,2.3,6,7,11b)-hexahydro-4H-pyrazino[2-1a] isoquinoline-4-one was chemically synthesized and structurally elucidated (Elemental analysis. El-Mass, 13C-NMR and IR spectroscopy). Antischistosomal potency in the order of -76% comparable to that for our newly reported C-12 and C-4 dithion mimic II (-70%) and Praziquantel. Praziquantel (100%, mice infected with S. mansoni cercariae), was realized. Toxicological evaluation (mice liver and kidney functions) and biochemical parameters (cholesterol, triglycerides, albumin, total serum proteins and amino acid profile of liver protein homogenate) were also assayed. Comparable to the parent drug, general insignificant toxicological diferences could be attributed for III. Interestingly, III exhibited intermediate biological figures between I and II. An order of IIIII>I, for the other tested biochemical parameters was observed. A consideration of obtained results could indicate that, structurally, an intact glycine amide segment of the pyrazine moiety, as it is the case in both I and III, and not in II (glycine thioamide) seemed now more crucial for exhibiting an optimum antihelmintic potency as well as a more tolerant toxicity characteristics. Additionally, the obtained comparable amino acid profile of mice liver protein homogenate after the treatment by III, could suggest similar biochemical, lethal mechanistic and metabolic routes for II, III and I. The new lipophilic candidatee III seems to merit more profound chemical, biological, and pharmaceutical investigations. (+info)
Antibody isotype responses to egg antigens in human chronic Schistosomiasis mansoni before and after treatment.
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In the present communication we analyzed the levels of IgG1, IgG2, IgG3, IgG4 and IgE isotypes to soluble egg antigen of Schistosoma mansoni by ELISA in individuals from an endemic area for schistosomiasis in Northeast Brazil. The analysis was performed before and after treatment to evaluate the age-dependent pattern, and to identify differences in the reactivities to antigens. Our results suggest that schistosomiasis treatment would not interfere with this sort of immune response. (+info)
Schistosomiasis mansoni in Bananal (State of Sao Paulo, Brazil): I. Efficiency of diagnostic and treatment procedures.
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Bananal is an important focus of Schistosoma mansoni in the State of Sao Paulo. Accordingly, programmed active search for human cases, annual coproscopic surveys and treatment of infected cases were started in 1998, aiming at producing a sharp prevalence rate drop by the year 2000. S. mansoni eggs were searched for in two Kato-Katz slides per patient. Cases were followed up according to the routine of the local Family Health Program. In 1998, 130 samples out of 3,860 showed S. mansoni eggs; in 1999, 105 out of 3,550, and in 2000, 64 out of 3,528. Prevalence rates were 3.4%, 2.9%, and 1.8%, and average egg-counts 59, 64, and 79 eggs per gram of feces respectively. Prevalence rates decreased steadily after treatment, but persistently positive cases showed no significant decrease in parasite burdens. Egg count variation depended on sex and age bracket. Persistent residual cases admittedly preclude the eradication of this infection by only searching for and treating carriers. In addition, resistance to therapy and low sensitivity of fecal examinations, can not be ignored. Moderate to heavy worm burdens, frequently associated with hepatomegaly elsewhere, produced no serious cases in Bananal. (+info)