The humoral and cell-mediated immune responses of the large, frugivorus bat, Artibeus lituratus, were studied following intraperitoneal injection of 10 or 104 viable mycelial particles of Histoplasma capsulatum. Most bats had both cultural and histologic evidence of disease at autopsy. Utilizing a technique designed to measure the volume of footpad swelling in hypersensitive bats a significant degree of delayed hypersensitivity to histoplasmin was evident in both groups 4 to 6 wk after infection. Precipitating antibodies first appeared in the serum 3 wk after infection, but only in the animals infected with 104 viable organisms. Both the double diffusion and counterimmunoelectrophoresis techniques for antibody gave identical results. These findings suggest that A. lituratus is very susceptible to infection with H. capsulatum, and that a mild infection will stimulate delayed hypersensitivity to the organism but only low levels of antibody. The footpad test utilized in this study may be a sensitive and practical method for detecting natural infection in bats.
Present address: Department of Medical Microbiology and Immunology, College of Medicine, Texas A&M University, College Station, Texas 77843.
Present address: 6116 Jefferson Street, Hollywood, Florida 33023.
Present address: Departmento de Microbiologia, Universidad del Valle, Cali, Colombia.
Present address: School of Public Health, University of Hawaii, Honolulu, Hawaii 96822.