Lack of susceptibility of guinea pigs and gerbils to experimental infection with Ehrlichia chaffeensis

Guinea pigs and Mongolian gerbils were experimentally infected with Ehrlichia chaffeensis (St. Vincent strain, 10 passages in vitro). The infection was monitored by serial blood sampling for PCR and by xenodiagnosis with Amblyomma americanum larvae. Exposure to the pathogen was confirmed using serology. Neither guinea pigs nor gerbils were susceptible to infection with E. chaffeensis, and ticks fed upon these animals did not become infected with the pathogen.