Outbreak of leptospirosis associated with swimming

Between July 7 and 18, 1991, five boys from a small town in rural Illinois experienced the onset of an acute febrile illness subsequently confirmed as leptospirosis by serologic tests. A cohort study found that swimming in a small swimming hole, Steel Tunnel Pond, was associated with disease (P<0.01), the attack rate being 28%. Leptospira interrogans serovar grippotyphosa was isolated from urine cultures from two of the case patients and from a culture of Steel Tunnel Pond water. A high seroprevalence for grippotyphosa was found in animals near the pond