Experimental Infection of by the Group II Intermediate Pathogen, .

serovar Varillal, a group II intermediate pathogen species/serovar discovered in the Peruvian Amazon city of Iquitos, is commonly recognized in this region by sera from humans (at least 40% seroprevalence) without a known clinical history of leptospirosis. This high frequency of human seroreactivity remains unexplained. To test the hypothesis that the oral route of infection might explain the high rate of human seroreactivity against , an experimental infection model using was developed, given that rats were one of the original reservoir hosts identified as being colonized by this leptospire. Sprague-Dawley rats were experimentally exposed via mucosa, direct gastric gavage, or parenteral inoculation with nine different isolates of originally isolated from Peruvian humans, peridomiciliary rodents, and wildlife. As shown by quantitative polymerase chain reaction of kidney tissue, infection via these routes of infection was equally successful. Importantly, the data show that infects via the oral route, leading to renal colonization. Not only do these findings confirm the infectiousness of group II , but also they underscore the potential importance of oral as well as mucosal and transcutaneous routes of infection.