Ação sinergística do praziquantel e resposta imune específica do hospedeiro ao Schistosoma mansoni em diferentes fases da infecção

A interação entre a resposta imune específica ao Schistosoma mansoni e praziquantel (PZQ) foi avaliada em modelo murino. Em camundongos portadores de imunidade concomitante, parasitos com 6 dias de idade e tratados com PZQ, foram eliminados mais eficazmente do que parasitos de apenas 24 h, apesar de ambos mostrarem uma redução significativa da carga parasitária quando comparados com os respectivos controles tratados. Estes resultados mostram que o PZQ pode ser eficaz nos estágios de pele e pulmão durante o desenvolvimento do parasita, agindo principalmente com uma resposta imune específica estabelecida e, particularmente, na fase pulmonar.The interaction between specific immune response to Schistosoma mansoni and praziquantel (PZQ) was studied in mice. In mice harboring concomitant immunity, 6-day-old parasites treated with PZQ were more effectively removed than 24h treated parasites despite both had a significant worm burden reduction when compared with respective treated controls. These results show that PZQ can be effective at the skin and lung stages of parasite's development mainly acting with a established specific immune response, and particularly at the lung phase

The circumovat precipitin test as a control of cure in children with chronic schistosomiasis mansoni

Seventy nine children in the 6-14 age group, with chronic schistosomiasis man- soni were selected for this stud,y. Sixty seven (850/o) with positive circumoval pre- cipitin test (COPT) were divided in two groups: 86 children (Group l) were treat_ ed with oxamniquine (20 mg/kg in a singre orar dose) and 31 children (Group 2) were given placebo under the same conditions. Follow-up was mantained for 1.0 months with monthly quantitative stool examinations and the absence of fecal eggs from the first month onwards was considered as a successful treatment. COPT was repeated on the tenth month. In Group L, 6gVo were cured. Group P showed no cures. rn the 28 Group I patients considered cured, copr was negative in20 (87%). Negative reactions were also found in BZo/o of the Group p children, after 10 months. These false negative reactions occurred in patients with a smaller stool egg count. The Authors conclude that copr shows a high positivity ratio in the diagnosis of chronic schistosomiasis mansoni, with negative reactions post cure in the majority of cases. However, a significant number of false negative results does rlot allow the isolated use of COPT in the control of cure of schistosomiasis mansoni

Schistosoma mansoni: avaliação da atividade da oxamniquina (Mansil*) em esquistossômulos com 24 horas após infecção

Mice transcutaneously infected with about 400 cercariae were submitted to treatment with oxamniquine (400 mg/kg), 24 hours after infection. The recovery of schistosomules, at 4, 24, 48 and 72 hours and 35 days after treatment, showed the activity of the drug on the parasites, thus practically preventing their migration from the skin to the lungs. Worm recovery performed in the lungs (96 hours after treatment) showed recovery means of 0.6 worms/mouse in the treated group and 53.8 in the control group (untreated). The perfusion of the portal system carried out at 35 days after treatment clearly showed the elimination of all the parasites in the treated group, whereas a recovery mean of 144.7 worms/mouse was detected in the control group (untreated). These findings confirm the efficacy of oxamniquine at the skin phase of infection, and also show similarity with the immunization method that uses irradiated cercariae. The practical application of these findings in the medical clinic is discussed tooCamundongos infectados transcutaneamente com cerca de 400 cercárias foram submetidos a tratamento com oxamniquina (400 mg/kg), 24 horas após a infecção. A recuperação dos esquistossômulos a nível da pele mostrou a atividade da droga nos parasitos e impediu praticamente sua migração para os pulmões. A recuperação a nível pulmonar (96 horas após tratamento) mostrou uma média de 0,6 vermes por camundongo no grupo tratado e 53,8 no grupo controle, não tratado. A perfusão do sistema porta, realizada aos 35 dias após infecção, mostrou claramente a eliminação de todos os parasitos no grupo tratado, enquanto foi recuperada uma média de 144,7 vermes no grupo controle, não tratado. Estes achados vem comprovar a eficácia da oxamniquina na fase cutânea da infecção e mostra analogia com o sistema de imunização que usa cercárias irradiadas. Também se discute a aplicação destes resultados na clínic

Antischistosomal activity of acridanone- hydrazones in Cebus monkeys experimentally infected with the SJ strain of Schistosoma mansoni

In this study, four compounds were utilized at the dose of 12.5mg/kg body weight, p.o., to treat Cebus monkeys experimentally infected with about 200 cercariae of Schistosoma mansoni (SJ strain), via transcutaneous route. The oograms performed with rectal snips, as well as stool examinations carried out periodically, showed no viable eggs of the parasite, from day 29 to 226post-treatment. The perfusion undertaken after killing the animals showed absence of worms in the treated monkeys, whereas 83 worms were recovered from the control, thus corroborating the results obtained by means of oograms and coproscopy. These results confirm the efficacy of 9-acridanone- hydrazones previously tested against the LE strain of S. mansoni. The low curative dose and apparent absence of toxicity render these dmgs an important therapeutic reserve, taking into consideration the reports on the resistance of S. mansoni to the modern drugs oxamniquine and praziquantel.<br>No presente trabalho, quatro compostos foram utilizados na dose de 12,5mg/kg de peso, por via oral, em macacos infectados transcutaneamente com cerca de 200 cercárias de Schistosoma mansoni. Os oogramas realizados com fragmentos de mucosa retal e os exames de fezes realizados, periodicamente, demonstraram a ausência de ovos viáveis do parasito a partir do 29- até o 226a dia pós-tratamento. A perfusão, apôs sacrifício dos animais tratados, não detectou vermes, enquanto que do macaco cotztrole 83 vermes foram recuperados, confirmando assim os resultados dos oogramas e da coproscopia. Estes resultados confirmam a eficácia das 9-acridanonas- hydrazonas já observada anteriormente contra a cepa LE de S. mansoni. A baixa dosagem curativa e aparente ausência de toxicidade colocam estas drogas como uma reserva terapêutica importante, tendo em vista o relato de resistência do S. mansoni às drogas modernas oxamniquína e praziquantel

Schistosoma mansoni in mice: modulation of granulomatous response after reinfection and chemotherapeutic treatment

Mice previously infected with Schistosoma mansoni, and cured by specific treatment (400mg/kg oxamniquine, p. o.) in the chronic phase of the disease, were reinfected 20 days after treatment to assess their capacityfor modulation ofthe granulomatous response. Histopathologic examination of the animals ' liver, at 60 days after reinfection, evidenced the presence of typical granulomas of the chronic phase in most animals. This infer that the capacity for modulation of the granulomatous response had been maintained, thus preventing a new acute phase of the disease. Conversely, a group of previously infected mice, untreated and submitted to reinfection, showed reactivation of the granulomatous response in 50% of the animals. The possible implications of these findings in human schistosomiasis mansoni are discussed