Abstract

The objective of the present trial was to characterize the periods of seroconversion, leptospiremia and leptospiruria in capybaras (Hydrochaeris hydrochaeris). In order to achieve this aim, six animals were infected intravenously, using Leptospira interrogans serovar pomona. The capybaras were anesthetized using intramuscular injections of ketamine (Vetaset, Fort Dodge; 1.5 mg/kg) and xylazine (Rompum, Bayer; 0.5 mg/kg). After the experimental infection, blood and urine collections were performed for culture of Leptospira sp., as well as serologic testing and polymerase chain reaction (PCR). The animal sera were tested by microscopic agglutination test using a collection of 24 serovars. The samples for culture were inoculated in semi-solid modified EMJH medium with 5 fluorouracil (300 mg/l) and nalidixic acid (20 mg/l) and after 24 hours, transferred to both Fletcher and modified semi-solid EMJH media without antibiotics. These media were incubated at 28°C and examined weekly for 8 weeks. The capybaras were euthanatized after the experiment, and kidney and liver were collected for culture and PCR. Anti-Leptospira agglutinins started to be detected between day 2 and 10, and peak was reached between the 9th and the 27th day, coinciding with the 83rd day after infection (AI). Leptospiremia was detected until the period between days 12 and 14 AI. Leptospiruria was first detected between days 6 and 10 AI and was detected until the 43rd day AI. The culture of the tissues was negative. The control animal was negative to all diagnostics tests. Results of this study indicate that capybaras may have a role as Leptospira reservoirs and may contribute to the maintenance of this infection in rural and wild environments. This is the first description of experimental infection in capybaras with Leptospira.