Resumen

CASAGRANDE, Silvana Tadeu et al. Laboratorial diagnosis of diphtheria and the practice of material collection from contacts as a strategy of epidemiological surveillance - metropolitan area of São Paulo, 1987 to 1996. Epidemiol. Serv. Saude [online]. 2005, vol.14, n.3, pp.181-190. ISSN 1679-4974.  http://dx.doi.org/10.5123/S1679-49742005000300006.

Diphtheria is an acute disease caused by Corynebacterium diphtheriae. In Brazil, diphtheria continues to be endemic despite information about its etiology and pathogenicity, clinical aspects, treatment, and prophylaxis. The wide utilization of the diphtheria-pertussis-tetanus vaccine (DPT) for more than 25 years, along with improved sanitary conditions of the population, is responsible for the change in the epidemiological situation of diphtheria, especially in São Paulo State, with a dramatic reduction in the number of cases and deaths from the disease. Although laboratory confirmation is not always required to validate clinical data, laboratory investigation is essencial for increasing the specificity of the clinical diagnosis and for the determination of frequency of infection, toxigenic strains, and other characteristics of the etiological agent. In the present study, laboratory data concerning patients with suspected diphtheria and their contacts were analyzed for the period from 1987 to 1996 for the Metropolitan Area of São Paulo to assess the practice of sample collection as a strategy of epidemiological surveillance for the control of the disease and the diagnosis of cases. Analysis of the number of suspected cases showed an important decrease in the number of diphtheria cases starting in 1992, and stability at still lower levels beginning in 1994. Analysis of toxigenicity showed that 91.2% of the strains isolated from suspected cases and 63.2% of the strains isolated from contacts were toxigenic. These results support the validity of current regulations concerning the collection of samples from contacts and the remaining measures for disease prevention, which should not be delayed until confirmation. Negative results should not interfere with the decision about the number of samples to be collected from contacts.

Palabras clave : Corynebacterium diphtheriae; diphtheria; contacts; suspected cases.

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