A three year follow-up of chemotherapy with oxamniquine in a Brazilian community with endemic schistosomiasis mansoni

Abstract

Oral oxamniquine was tested as a control strategy for endemic schistosomiasis in a rural area of Bahia, Brazil. Adults were treated with a single dose (12.5 to 15 mg per kg) and children (less than 12 years old) with a total of 20 mg per kg in two doses. The 191 (infected) persons treated represented 69% of the infected population in the study area. Follow-up stool examinations (Kato-Katz method) at one, 3, 6, 13, 25 and 33 months showed the cure rate declining from 80% at three months to 46% at 33 months. Over one half of those not cured showed a decrease in egg counts throughout the follow-up which, after 33 months, remained 66% below the pre-treatment levels. Stool examinations conducted on all study area residents during three years before chemotherapy showed the prevalence and intensity of Schistosoma mansoni infection to be high and stable. 33 months after the chemotherapy the prevalence was 41% and for infected individuals the geometric mean egg count was 121 epg, a decline of respectively 35% and 40% from pre-treatment levels for each index. Chemotherapy of infected persons with oxamniquine protected the community as a whole from high worm burdens for almost three years, although at this point the prevalence began to rise towards pretreatment levels.

Schistosomiasis control based on repeated chemotherapy in a rural village of the sugar-cane zone in Northeast Brazil

“…In contrast with the findings from other endemic areas (Sleigh et al 1981, Barakat et al 1995, Homeida et al 1996, it is unlikely that repeated chemotherapy alone would keep infection down at satisfactory levels among children in the present study area. Since continuing cycles of bi-annual treatment would be unfeasible, the best strategy here might be to combine targeted chemotherapy with other measures, such as small-scale environmental interventions (Kloetzel et al 1994, Pieri 1995 and focal mollusciciding (Sturrock 1995).…”

Esquistossomose mansônica no estado da Bahia, Brasil: tendências históricas e medidas de controle

“…Interessante notar que outras medidas de controle haviam sido adotadas na área, como a utilização de moluscicidas, melhoria nas condições sanitárias e ações educativas. Posteriormente, seguiu-se uma série de estudos verificando também redução da prevalência de infecção em áreas submetidas à quimioterapia nos estados da Paraíba (Coura et al, 1987), Minas Gerais (Coura-Filho, 1990;Santos & Coura, 1986) e Bahia (Sleigh et al, 1981), tendo sido observada em alguns deles redução na ocorrência de formas graves.…”

“…O primeiro deles diz respeito ao período em que persiste a redução na prevalência. Em estudo realizado no município de Castro Alves, Bahia, Sleigh et al (1981) verificaram que a proporção de indivíduos que foram tratados e voltaram a eliminar ovos de S. mansoni nas fezes aumentou significativamente no terceiro ano após a quimioterapia. Santos & Coura (1986), em estudo realizado em Padre Paraíso, Minas Gerais, observaram que a prevalência e a intensidade de infecção (medida pelo número de ovos eliminados nas fezes) retornaram aos níveis pré-tratamento no período de seis anos.…”

HTLV-1 modifies the clinical and immunological response to schistosomiasis

“…TNF‐ α , IL‐1 and IFN‐ γ are increased in perivascular infiltrating cells of HAM/TSP patients [20] and high levels of IFN‐ γ in serum and in cerebrospinal fluid are observed in HAM/TSP patients [21]. Similarly, in schistosomiasis high expression of type‐2 cytokines are found in the liver [22] and in peripheral blood cells [5]. Reported values represent the difference between the stimulated cultures minus unstimulated cultures.…”