A case control model was used in the study of an outbreak of Brazilian purpuric fever BPF which occurred in Serrana, S. Paulo State, Brazil, in 1986. Three hypotheses were raised: 1 - purulent conjunctivitis is associated with BPF; 2 - a cluster effect accurs in BPF; 3 - respiratory symptoms may be a variation of the clinical picture of the disease. Numerical values were attributed to different findings, as follows: fever = 5; diarrhea and/or vomiting = 1; haemorrhagic findings = 3; thrombocytopenia and/or leukopenia = 3; Haemophilus aegyptius positive hemoculture and/or Haemophilus aegyptius positive cerebrospinal fluid culture and/or H. a. oropharynx culture = 7; Waterhouse Friedrichsen syndrome = 7. Those cases for which the sum total of points reached or exceeded 13 were considered as confirmed and those obtaining between 8 and 12 were considered as suspect. Children with a score below 5 were taken as control cases. Cases and controls were matched according to sex, age and socioeconomic level. The total groups studied included 14 confirmed cases, 38 suspect cases and 78 controls. It was concluded that purpuric fever is strongly associated with previous and/or present purulent conjunctivities; a cluster effect seems to occur; respiratory symptoms such as coughing and/or coryza were not associated with BPF.
Waterhouse-Friederichsen syndrome; Disease outbreaks
