Epidemiology of a cluster of Henoch-Schonlein purpura
T. A. Farley, S. Gillespie, M. Rasoulpour, N. Tolentino, J. L. Hadler and E. Hurwitz
Division of Field Services, Centers for Disease Control, Atlanta, GA.
We investigated a case cluster of Henoch-Schonlein purpura that occurred in
Connecticut during the fall and winter of 1987-1988. In Hartford County,
where the case finding was most complete, 16 children were identified with
disease onset during the 7-month cluster period (incidence, 1.7 cases per
10,000 children per year) compared with only 3 children with disease onset
during the preceding 7 months. The incidence in Hartford County was higher
among urban (4.8/10,000) and Hispanic (8.6/10,000) children and children in
lower socioeconomic groups (6.9/10,000) than among suburban children or
children in higher socioeconomic or different racial groups (0.9 to 1.1 per
10,000). We performed a case-control study involving 14 of the 16 case
children from Hartford County, 10 case children from nearby areas, and 47
control children matched to the case children by age and race. Case
children were more likely than control children to have had a sore throat
during the month before the onset of Henoch-Schonlein purpura (52% vs 22%;
odds ratio, 3.8; 95% confidence interval, 1.1 to 13). This difference and
other smaller differences between case and control children suggest that
the cluster may have been caused by person-to-person spread of an
infectious agent of the respiratory tract to susceptible hosts. To our
knowledge this is the first report of a cluster of Henoch-Schonlein
purpura, and it provides clues for a better understanding of the etiology
and epidemiology of the disease.
