Household-acquisition of measles and illness severity in an urban community in the United States.

Studies from developing countries suggest that persons with household-acquired (HA) measles are at greater risk of severe illness than persons with community-acquired (CA) infection. Reported measles cases occurring among Milwaukee residents from May 1989 to June 1990 were used to assess whether household-acquisition was a risk factor for severe measles in the United States. A case was classified as HA if onset of rash occurred 7-18 days after onset of rash in another case in the same household. Hospitalization rates were similar for 128 patients with HA measles (27%) and for 1004 patients with CA measles (26%). Multiple logistic regression was used to evaluate the association between hospitalization and household-acquisition after controlling for socioeconomic status, measles vaccination history, age, race, and date of onset of rash. Patients with HA measles were no more likely to be hospitalized than patients with CA measles (odds ratio 0.9, 95% confidence interval 0.6, 1.5). HA measles cases were not more severe than CA measles cases during this urban outbreak in the United States.