Aspectos actuales de la esquistosomiasis

La esquistosomiasis es una parasitosis endémica en diversos países tropicales producida por seis especies diferentes de Schistosoma, especialmente por S. mansoni. El hospedador intermediario es el caracol y el definitivo el hombre y otros vertebrados. La clínica de la enfermedad depende de la especie de Schistosoma y viene definida, inicialmente, por la presencia de dermatitis, diarrea, fiebre, vómitos y esplenomegalia; la fase crónica se caracteriza por la aparición de hematuria, hematemesis, melena, adelgazamiento e hipertensión pulmonar. El diagnóstico se realiza con el estudio parasitológico de heces y pruebas serológicas y el tratamiento a base de oxamniquina y prazicuantel. La prevención se lleva a cabo aplicando la quimioterapia a las personas enfermas y mejorando el nivel de vida de las zonas endémicas (AU)

Formation of promutagenic methylation damage in tissue-DNA of mice treated with antischistosomal agents.

The existence of the promutagenic methylation damage O6-MedG has been measured at various time intervals in different tissue DNAs of mice received a single therapeutic dose of various antischistosomal agents (hycanthone, oxaminiquine and metrifonate). Liver-DNA exhibited the highest levels of O6-MedG in all treated animals while, spleen DNA contained the lowest. The three antischistosomal agents tested seemed to exert the peak concentrations of their alkylating metabolites over a period of several hours following the administration. In mice which had received hycanthone, liver-DNA contained readily detectable amounts of O6-MedG by 6 h post-treatment (0.089 mol O6-MedG/mol dG) and by the end of 48 h, this was decreased by about 3-fold to reach a level of 0.026 mumol/mol dG. In intestinal-DNA, however, O6-MedG was formed more slowly and contained about half the level of that found in the liver-DNA. In the tissue-DNA of animals which had received oxaminiquine, the highest level of O6-MedG was observed at 6 h after administration and at a 24-h time point, the adduct dramatically decreased in the liver and intestine-DNA to undetectable values. In neither tissues was there any evidence for O6-MedG accumulation in the DNA at the end of a 48-h post-treatment. A pattern of O6-MedG, almost similar to that of oxaminiquine, was also observed in tissue-DNA of mice pretreated with metrifonate. These results demonstrate that treatment with antischistosomal agents leads to the formation of highly promutagenic alkylated lesions in the tissue-DNA. The implication of such existence for antischistosomal-induced toxicity and carcinogenicity are discussed.

Arritmia cardiaca com uso de oxamniquine oral no tratamento de esquistossomose mansonica / Cardiac arrhytmia with oral oxamniquine in the treatment of schistosomiasis mansoni

Os autores relatam caso clinico de paciente com esquistossomose mansonica, tratado com oxamniquine oral em dose unica de 15mg/Kg, que apresenta como efeito colateral um bloqueio atrio-ventricular incompleto tipo Mobitz I, com parada sinusal e escape ventricular. Concluem que, apesar de a oxamniquine ser eficaz e segura, pode ser determinante de cardiotoxicidade.

[Cardiac arrhythmia with oral oxamniquine use in the schistosomiasis mansoni treatment]. / Arritmia cardíaca com uso de oxamniquine oral no tratamento de esquistossomose mansônica.

The authors report a case of a patient with schistosomiasis (S. mansoni) treated with one single dose (15 mg/kg/BWT) of oral oxamniquine who presented Mobitz type I second-degree AV block and sinus arrest with ventricular escape as a side-effect. They conclude that in spite of the safety and good activity of oxamniquine it may be a determinant of cardiotoxicity.

Comparison between the efficacy of oxamniquine and praziquantel in the treatment of Schistosoma mansoni infections on a sugar estate in Ethiopia.

The efficacy of the antischistosomal drugs praziquantel and oxamniquine was tested on four groups of Ethiopian sugar estate workers. The cure rates, determined by the absence of eggs in stools, were 96, 93 and 74% at one, three and six months post-treatment for patients receiving a single dose (40 mg kg-1 body weight) of praziquantel, and 82, 78 and 78% for patients on a single dose (15 mg kg-1 body weight) of oxamniquine. When split doses of these drugs were used, praziquantel achieved cure rates of 96, 95 and 89%, while the corresponding cure rates for oxamniquine were 98, 96 and 88% at one, three and six months post-treatment. In general, there were no statistically significant differences within the single and split doses of each drug, nor between the two drugs except that single doses of praziquantel had significantly higher cure rates than oxamniquine at one and three months post-treatment. Although both drugs produced mild and transient side-effects such as dizziness, abdominal discomfort and diarrhoea, serious side-effects such as seizures were seen only among patients on oxamniquine. As praziquantel is also effective against other forms of schistosomiasis as well as against cestodes, we recommended the use of this drug in mass chemotherapy and in the ambulatory treatment of schistosomiasis in Ethiopia.

A review of clinical experience with oxamniquine.

Oxamniquine has now been in general use for 11 years for the treatment of schistosomiasis mansoni. Dosage varies with the geographical origin of the parasites due to different susceptibilities of local strains, and the appropriate regimen can be expected to cure over 80% of patients and reduce egg excretion in others by over 90%. The drug has been used safely in all stages of the disease. Some late-stage and complicated forms have shown clinical improvement, and prognosis has been improved in all by the removal of the causative organisms. Toleration is usually good with side effects limited to a mild, transient dizziness. Neuropsychiatric disturbances have been recorded in a small number of patients, and care should be taken in treating subjects with a history of such disorders. Nevertheless, these effects have not limited use of the drug which has been used widely for the field treatment of several million people in rural communities. These schemes have led to reductions in incidence, prevalence and the occurrence of hepatosplenic involvement.

Seizures associated with oxamniquine therapy.

Three patients who were treated for schistosomiasis mansoni with oxamniquine suffered generalized seizures. We suggest that this side effect may be more common than previously reported. Specific ethnic groups may be particularly at risk.

Treatment of Schistosoma mansoni infection with oxamniquine in Riyadh, Saudi Arabia.

Single dose therapy with oral oxamniquine was given to 107 Saudi patients suffering from schistosomiasis due to Schistosoma mansoni and they were followed for a period of six months. Clinical cure judged by symptomatic improvement and negative stool counts for S. mansoni eggs was achieved in 88.8%. Side effects were minimal and reversible and it is concluded that this form of treatment is successful for the control of S. mansoni infection.

Neurotoxicidade do oxamniquine no tratamento da infecçäo humana pelo Schistosoma mansoni / Neurotoxicity of oxamniquine in the treatment of human infection by Schistosoma mansoni

Foram tratados com oxamniquine (dose oral única de 12,5 a 15 mg e 15 a 20 mg/kg de peso, para maiores e menores de 15 anos respectivamente) 180 indivíduos com esquistossomose mansoni, matriculados na Clínica de Doenças Infecciosas e Parasitárias do Hospital das Clínicas da Faculdade de Medicina da Universidade de Säo Paulo. As idades variam de 5 a 65 anos e as formas clínico-evolutivas prevalentes foram a intestinal e hepatointestinal. Os principais efeitos colaterais neuropsiquiátricos foram:sonolência (50,6%), tontura (41,1%), cefaléia (16,1%), amnésia transitória (2,2%), alteraçöes de comportamento (1,7%), tremores (1,1%) e convulsäo (1,1%). Em 20 indivíduos foi avaliada a neurotoxicidade da froga através de eletroencefalografia, antes e após o tratamento. Em 3 (15%), foram detectados alteraçöes no traçado, sem contudo apresentarem manifestaçöes clínicas neuropsiquiátricas. Os resultados demonstraram ser o oxamniquine determinante de efeitos tóxico-colaterais na esfera neuropsiquiátrica

Eficácia terapêutica da oxamniquine oral no tratamento da salmonelose septicêmica prolongada / Therapeutic efficacy of oral oxamniquine in the treatment of prolonged septicemic salmonellosis

Trinta e cinco pacientes com salmonelose septicêmica prolongada (SSP) foram selecionados para o estudo. Vinte (Grupo 1), foram tratados com a oxamniquine oral (15-20mg/Kg de peso, dose única) e 15 (Grupo 2) com o cloranfenicol (50mg%Kg de peso/15-20 dias). Realizaram-se exames clínico, laboratorial e radiológico antes e após o tratamento. Oito pacientes do Grupo 1 (40%) exibiram uma ou mais queixas após o tratamento. Exceçäo feita a um paciente que apresentou crise convulsiva, uma hora após a ingestäo do medicamento, os demais efeitos colaterais foram de pouco importância. Näo se observou efeito tóxico da oxamniquine à luz dos exames complementares realizados após o tratamento. Os pacientes do Grupo 2, näo apresentaram qualquer manifestaçäo que pudesse ser imputada ao cloranfenicol. No Grupo 1, 90% dos pacientes foram considerados curados e no Grupo 2, 93% também o foram. Os Autores concluem pela boa eficácia e baixa toxicidade da oxamniquine no tratamento da SSP

Safety and toxicity of oxamniquine in the treatment of Schistosoma mansoni infections, with particular reference to electroencephalographic abnormalities.

Thirty-seven patients infected with Schistosoma mansoni were treated with oxamniquine. All were cured. The only significant adverse reaction was the development of abnormal electroencephalographic (EEG) findings in 6 (17.6%) of 34 patients whose pretreatment EEG was normal. Management of patients, with particular reference to the EEG abnormalities, is discussed.