An Outbreak of Leptospirosis among U. S. Army Troops in the Canal Zone

Abstract

Summary An outbreak of acute self-limited illness affected 9 of 365 infantry troops who took part in overnight jungle exercises in the Canal Zone in November 1961. Serological studies subsequently showed a leptospiral etiology with involvement of multiple serotypes. The illness was characterized by a “saddleback” fever curve, severe head and body pain, bone tenderness, and low to normal leukocyte counts. Epidemiologic evidence strongly suggested that infection had been incurred by wading in a 1000-meter segment of a jungle river. A month after the outbreak leptospiras were isolated from the river and four species of mammals along its banks were found harboring seven different serotypes. A serological survey was made of 167 non-hospitalized soldiers. Seven were found to have agglutinins but only one of the seven had had symptoms at the time of the outbreak and it is doubtful that any of the other six were infected at that time. Employing a genus-specific hemolytic test for leptospiral antibodies, reactions were elicited in 55 additional soldiers. These reactions could not be related exclusively to infections incurred in Panama.