Efetividade da vacina antiamarílica 17D: uma avaliaçäo epidemiológica em serviços de saúde / Efficacy of the 17D yellow fever vaccine: an epidemiologic evaluation in health services

O objetivo do presente estudo foi avaliar a efetividade da vacina antiamarílica 17D nas condições de sua utilização pelos serviços de saúde pública. Em 1989, um estudo prospectivo nãoconcorrente foi desenvolvido em Bocaiúva, Estado de Minas Gerais, Brasil, 6 meses após vacinação em massa da população. A = população-alvo do estudo foi constituída por estudantes matriculados no primeiro grau em todas as escolas situadas em Bocaiúva. O grupo exposto foi constituído por uma amostra probabilística simples de estudantes vacinados (n = 173) e o grupo não-exposto foi constituído por todos aqueles não submetidos à vacinação (n = 55). Os soros foram examinados pelo teste da neutralização em camundongos; estes exames foram realizados às cegas, ou seja, o examinador desconhecia a situação vacinal do paciente. Os resultados da sorologia foram os seguintes: entre os vacinados, 75% eram soropositivos, 17% soronegativos e 7% apresentaram exame inconclusivo; entre os não-vacinados estes resultados foram de 9, 87 e 4%, respectivamente. A razão de soropositividades entre vacinados e não-vacinados, ajustada pela idade, foi 7,6 (IC95%: 3,4 a 16,7). A fração da soropositividade atribuível à vacinação, ajustada pela idade, foi 86,8% (IC95%: 70,6 a 94,0). Os resultados mostram que a efetividade da vacinação, definida através da soropositividade para o vírus, ficou abaixo dos níveis esperados para a vacina 17D. Isto pode ter sido conseqüência de falhas operacionais na conservação ou aplicação da vacina. Nossos resultados apontam para a necessidade de avaliações sistemáticas na rotina dos serviços de saúde após a utilização em massa da vacina

The purpose of this study was to evaluate the efficacy of the 17D yellow fever vaccine in the conditions under which it is used in public health services. In 1989, a nonconcurrent prospective study was carried out in Bocaiúva, Minas Gerais State, Brazil, 6 months after mass vaccination of the population. The study population was made up of first-grade students from all the schools in Bocaiúva. The exposed group consisted of a simple random sample of vaccinated students (n = 173) and the unexposed group consisted of all those who had not been vaccinated (n = 55). Serum samples were examined with the neutralization test in mice; these tests were conducted blind, that is, the examiner did not know the vaccination status of the subject. The serology results were as follows: of those vaccinated, 75% were seropositive, 17% were seronegative, and 7% showed an inconclusive result; in the unvaccinated children, these results were 9%, 87%, and 4%, respectively. The age-adjusted seropositivity ratio between vaccinated and unvaccinated children was 7.6 (95%CI: 3.4 to 16.7). The proportion of seropositivity attributable to vaccination, adjusted for age, was 86.8% (95%CI: 70.6 to 94.0). The results showed that the efficacy of the vaccine, defined by means of seropositivity for the virus, was below the levels expected for the 17D vaccine. This may have been due to operational failures in the conservation or application of the vaccine. The results point to the need for routine systematic evaluations by the health services after mass utilization of the vaccine.

Avaliaçäo do programa de controle da esquistossomose (pce/pcden) em municípios situados na Bacia do Rio Säo Francisco, Minas Gerais, Brasil / Evaluation of the control on schistosomiasis (PCE/PCDEN) in the municipalities of the region of Säo Francisco river, Minas Gerais, Brazil

An evaluation of the control program on schistosomiasis (PCE/PCDEN) was performed in the region of Säo Francisco river in MInas Gerais. The study area comprises six municipalities, with 130,000 inhabitants and 916 localities situated in an area with 10,722 km2. The activities initiated in 1983-85 in four municipalities and in 1987 in the other two. The main measures of control were repeated treatment with oxamniquine and use of niclosamide. The prevalence of infection by Schistosoma mansoni in the first four municipalities, that was initially around 18 and 32 per cent, dropped abruptly after the first intervention (1983/85) and remained in levels below the initial ones until the last assessment (1990-94); similar trends were observed for the proportion of infected snails. In these municipalities, the proportion of localities without infection or with prevalence below 5 per cent increased in relation to those with higher prevalence. In the other two municipalities, with initial prevalence below 5 per cent, there were no substantial changes in S. mansoni prevalence or proportion of infected snails; the cost benefit of the program in these municipalities need to be assessed and the priorities redirected to eradicate focal areas and prevent spread to non infected localities. The authors call attention to the difficulties in the long term of a control program based on repeated treatments. Information on factors associated with S. mansoni infection in each locality, or in groups of similar localities, would allow to develop additional measures to treatment that could last longer and be less dependent on the continuous use of chemotherapy.