[Measles outbreaks: considerations apropos of the outbreaks investigated in Catalonia (1990-1995)].

OBJECTIVES

To determine the factors associated with outbreak size in Catalonia.

METHODS

Outbreaks over the period 1990-95 were investigated. A comparison was run between outbreaks of more than 6 cases with respect to outbreaks of 2-6 cases in function of the following variables: median age of cases, transmission setting and year of presentation. Multiple logistic regression was used to asses the independent effect of each variable, with the adjusted odds ratio (ORa) and their 95% confidence interval (CI) being obtained.

RESULTS

In all, 45 outbreaks were studied, with 595 cases of measles 39.5% of outbreaks occurred in the 6-10 age group. Outbreaks of more than 6 cases had a higher likelihood of appearing in a school setting (ORa = 4.3, CI 95% 1.0-17.6); but there were no association with age (ORa = 2.1, CI 95% 0.5-9.2) or occurring prior to 1994 (ORa = 0.9, CI 95% 0.2-3.6).

CONCLUSIONS

School setting determines the outbreak size of measles and demands to apply specific preventive strategies.