Leptospira spp., Brucella spp. e Toxoplasma gondii em peixes-boi amazônicos (Trichechus inunguis), botos-cor-de-rosa (Inia geoffrensis) e tucuxi (Sotalia fluviatilis) na Amazônia brasileira

Abstract

Leptospirosis, brucellosis and toxoplasmosis are common zoonotic diseases with global distribution that represent severe hazard to humans and animals. Although the occurrence of those diseases is broadly studied in marine mammals, very few information is available on their occurrence in Amazonian aquatic mammals. The present study aimed at investigating exposure to and infection by Leptospira spp., Brucella spp., and Toxoplasma gondii in samples from Amazonian manatees (Trichechus inunguis), Amazon river dolphins (Inia geoffrensis), and tucuxis (Sotalia fluviatilis), free-ranging or undergoing in-situ rehabilitation in the Mid-Solimões river region, Western Brazilian Amazon. Serum samples from Amazonian manatees were tested by microscopic agglutination test, Rose Bengal test and 2-Mercaptoethanol test, and indirect haemagglutination test for detection of anti-Leptospira spp., anti-Brucella spp. and anti-T. gondii antibody detection, respectively. Tissue and/or body fluid samples from Amazon river dolphins, a tucuxi, and Amazonian manatees, were subjected to a multiplex polymerase chain reaction (PCR) assay for Leptospira spp. and Brucella spp. and bacterial culture for attempted isolation. Samples of heart and brain from Amazon river dolphins and a tucuxi were tested by PCR for detection T. gondii DNA. A total of 63% of Amazonian manatee sera were reactive to Leptospira spp. and serovar Patoc was considered the infecting serovar in all positive samples. Titers were generally low, indicating chronic exposure, but active infection was suggested in three manatees with a four-fold in antibody titers. Anti-Brucella spp. antibodies were not detected. Anti-T. gondii antibodies were present in 35.3% of the samples and one manatee presented a 1:64 titer, considered as indicative of recent infection in humans. All river dolphin samples were negative for Leptospira spp. and Brucella spp. by PCR. T. gondii DNA was detected in heart and brain samples, which represents the first report of molecular identification of the protozoan parasite in river dolphins. Enterococcus faecalis and Bacillus spp. were isolated from tissue and body fluid samples, although the clinical significance of these opportunistic pathogens is not clear. The present study brings novel information on the occurrence of Leptospira spp. and T. gondii in Amazonian aquatic mammals in the Western Brazilian Amazon. Knowledge of the pathogens prevalent in Amazonian manatees, Amazon river dolphins, and tucuxis is of great relevance to species conservation and environmental health.