Human leptospirosis in Detroit and the role of rats as chronic carriers.

Human leptospirosis was diagnosed in three patients from Detroit General Hospital. Epidemiological studies of these cases revealed heavy rat infestations in the residences of two of the patients. Leptospires serotype icterohaemorrhagiae were isolated from the rats and one of the patients. Cultural isolation was attempted from numerous blood and urine samples from each patient. Media containing different selective contaminant inhibitor substances was also utilized. Only two samples were culturally positive. It appears that very few viable cells are shed by human patients intermittently. Clinical reports and leptospirosis diagnosis are reported for each of the cases. The agglutinin-absortion test proved to be helpful in elucidating the true etiologic agent in the absence of cultural isolation. A serological survey for leptospirosis was conducted among swine slaughterhouse workers in Detroit. Significant titres to Leptospira pomona were observed.