Abstract
BackgroundLeptospirosis is an endemic zoonosis in Brazil, with a great impact on human and animal health. Although dogs are frequently infected by pathogenic Leptospira, the current epidemiological understanding of canine leptospirosis is mainly based on serological tests that predict the infecting serogroup/serovar. Thus, the present study aimed at identifying the causative agent for severe cases of canine leptospirosis in a highly endemic area through the isolation and characterization of the isolated strains.ResultsUrine, serum and blood samples were collected from 31 dogs with suspected acute leptospirosis treated at the Veterinary Hospital Service of Santo Amaro University between 2018 and 2019. Acute infection was confirmed in 17 dogs (54.8%) by the associated use of Polymerase Chain Reaction (PCR), Microscopic Agglutination (MAT) and bacteriological culture. Eleven dogs (35.5%) had titers ≥800, with the most frequent serogroups being Autumnalis and Icterohaemorrhagiae (n = 4 each) and Canicola (n = 2). Leptospires were recovered from four dogs, and Multilocus Sequence Analysis (MLSA) revealed infection caused by L. interrogans, which were further characterized as serogroups Canicola (n = 1) and Icterohaemorrhagiae (n = 3).ConclusionThe identity of the isolates and serological pattern of MAT suggest that dogs are highly exposed to the serogroup Icterohaemorrhagiae and Canicola, also indicating possible circulation of serogroups not yet isolated in Brazil, notably serogroup Autumnalis. Our findings also reinforce the usefulness of using multiple diagnostic approaches to confirm acute canine leptospirosis.
Highlights
Leptospirosis is an endemic zoonosis in Brazil, with a great impact on human and animal health
By using an integrative approach, which included clinical/laboratorial evaluation and serological and molecular methods, the present study aims to provide characterization of the isolated leptospires from dogs with acute leptospirosis treated at the Veterinary Service of the University Santo Amaro (UNISA), a hospital service that provides animal care for low-income communities located at the most endemic region for human leptospirosis in São Paulo city, Brazil
One animal presented the highest titers against serogroups Australis and Autumnalis, but only titers against Australis persisted after serological reevaluation of the convalescent sample, reflecting a possible decrease in titers typically found during the late convalescent phase, or even a paradoxical titration found in the first evaluated sample
Summary
Leptospirosis is an endemic zoonosis in Brazil, with a great impact on human and animal health. Dogs are frequently infected by pathogenic Leptospira, the current epidemiological understanding of canine leptospirosis is mainly based on serological tests that predict the infecting serogroup/serovar. The present study aimed at identifying the causative agent for severe cases of canine leptospirosis in a highly endemic area through the isolation and characterization of the isolated strains. Leptospirosis is a bacterial zoonotic disease of worldwide distribution, potentially lethal and capable of causing epidemic outbreaks in human and domestic animal populations [1, 2]. Dogs can act as an important source of infection for humans and other mammals, as they are Canine leptospirosis has been widely reported, and infection in dogs can lead to a wide variety of clinical manifestations, ranging from asymptomatic infections or mild febrile illness to severe multisystem organ failure [4, 5]. The evaluation of a single sample may fail to detect antibodies during the initial phase of the disease, and it is often necessary to test sera obtained in the convalescent phase to reveal seroconversion, which is often not possible due to the high lethality of the disease
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