In a retrospective review of Wisconsin Salmonella surveillance data, we found that 73 (39%) of 187 families with infant index patients had at least one family member with prior diarrheal illness, compared with only 20 (13%) of 158 families with 5- to 9-year-old index patients (P < .0001). Prior diarrheal illness was also more commonly identified in families with an infant index patient 0 to 2 months of age (28 of 52 families) than in families with an index patient 3 to 11 months (45 of 135 families) (P < .02); this difference was found largely in families of infant index patients with siblings. Intrafamilial transmission of Salmonella may explain a large proportion of cases of infant salmonellosis. Older children and adults with salmonellosis may be the most important exposures for infants 0 to 2 months of age.
- Received May 26, 1981.
- Accepted June 24, 1981.
- Copyright © 1982 by the American Academy of Pediatrics