Prevalência de Brucella Canis

Brucella canis: Frequency of antibodies present in dogs in a brazilian capital

Brucella canis: Frequência de anticorpos presentes em cães em uma capital brasileira

Resumo

A brucelose é uma doença infecciosa e cosmopolita que afeta animais domésticos, animais selvagens e humanos, por isso é considerada uma zoonose. Portanto, um estudo foi realizado com animais em idade reprodutiva em uma capital brasileira. Um total de 591 amostras de soro foram utilizadas de 1 a 7 anos de cães não castrados, sem distinção de sexo ou raça. As amostras foram submetidas a um teste de imunodifusão em gel de ágar usando o antígeno Brucella ovis, a técnica mais utilizada no Brasil nestes casos. Entre os animais selecionados, 44 animais apresentaram positividade para Brucella canis. Concluiu-se que a brucelose está presente na população canina da cidade, mas ainda não veem ser diagnosticados corretamente pelas clínicas veterinárias, o que representa um risco para a saúde pública, uma vez que é uma zoonose.

Palavras-chave: Brucelose, caninos, aborto, orquite, zoonoses.

Abstract

Brucellosis is an infectious, cosmopolitan disease that affects domestic animals, wild animals and humans, so it is considered a zoonoses.  Therefore, a study was carried out with of animals in reproductive age in a Brazilian capital. A total of  591 serum samples were used from 1 to 7 years of age non-castrate dogs, without distinction of sex or race. The samples were submitted to an agar gel immunodiffusion test using Brucella ovis antigen, the most used technique in Brazil in these cases. Among the selected animals, 44 animals showed positivity for Brucella canis. It was concluded that brucellosis is present in the canine population of city, but they still do not see it being properly diagnosed by the Veterinary Clinics, which poses a risk to public health, since it is a zoonoses.

Keywords: Brucellosis, canine, abortion, orchitis, zoonoses.

Introduction

        Canine brucellosis is an infectious, systemic disease of a global distribution characterized by presenting a prolonged bacterium of zoonotic character. Dogs affected by Brucella canis infections have several reproductive disorders, with or without obvious clinical signs. In recent decades, social changes and urbanization of the human population have favored an increase in the canine population in developing countries (1). This increase, associated with the sentimental and emotional relations of the man with the dog, has implications in public health, since the animal can be responsible for the transmission of several zoonoses, among them, the brucellosis (2).

The disease is caused by bacteria belonging to the genus Brucella, they are obligate intracellular organisms. There are different Brucella species, which exhibit preferences by hosts and differ in severity of disease caused (3).

        For dogs, there are two serotypes that are the most pathogenic, being Brucella abortus and Brucella canis, causing chronic or subclinical disorders difficult to diagnose by similarity to several other diseases (4). Brucella canis is the etiological agent considered important epidemiologically for establishing inter-relations of the canine population with humans, mainly, the contact between dogs and children in the family environment (4).

        Serological tests for the detection of antibodies to Brucella are the best means of detecting infection. Among the most widely used serological tests in the diagnosis of Brucella canis in dogs, the most used technique in Brazil is the AGID (agar gel immunodiffusion), in which a lipopolysaccharide antigen extracted from Brucella ovis is used. The sharing of antigens among Brucella canis and Brucella ovis makes it possible to use indistinct reactives produced from these two microorganisms for the diagnosis of brucellosis in canines and sheeps. As this represents a finding of great relevance in public health, since it is a zoonoses, companion animals should be tested, after all, canine brucellosis assumes growing importance in large urban centers (6).

                In the studied capital, canine brucellosis has not yet been diagnosed and there is no case report of this zoonoses in dogs. Therefore, the objective of this study was to detect if the disease occurs in dogs of this city with clinical signs of the disease or not. This research was carried out using anti-Brucella canis antibodies in serological tests, thus contributing to a better knowledge of this zoonoses in the metropolitan regions.

        The epidemiological study was carried out in a Brazilian capital to detect a situation in zoonoses in the Metropolitan Region, dogs of the medical clinic of the of Veterinary Teaching Hospital, as well as private clinics in the city, from January 2013 to March 2013.

Materials and methods

        The dogs were randomly selected, without regard to complaint or clinical signs. Were used 591 animals between the age of 1 to 7 years, non-castrate, without distinction of sex or race, with the consent of the person responsible and approval of the Bioethics Committee, in accordance with current rules. Information on age, gender and racial pattern were recorded on an individual file and the clinical examination was conducted by Veterinarians. For serological analysis, blood samples were collected by venipuncture of the jugular vein after antisepsis with 2% iodinated alcohol, with the use of a vacuum system in tubes without anticoagulant which were identified with data concerning the owner and the animal. The tubes were held for 1 to 2 hours to coagulate at room temperature, then stored at 4 ° C overnight and then subjected to centrifugation at 2500 rpm for 10 minutes to obtain serum that were stored at -20 ° C.

        Agar gel immunodiffusion (AGID) was performed with antigen extracted from the Brucella ovis cell wall (Tecpar, Paraná, Brazil) according to a method described in the literature (7), in the Laboratory of Pathophysiology of Female Reproduction on Veterinary Teaching Hospital. The agar gel was prepared using 1.2 g of Noble agar, 5 ml of Borate buffer pH 8.3, and 93 ml of 10% NaCl. Then, 4.5% of the gel was distributed in Petri dishes. After solidification, the gel was drilled with six-hole peripheral rosettes and a central one, with holes 6 mm in diameter and 2.5 mm between the edges. The orifices were then filled with the antigen, positive control serum, serum to be tested and the plates kept in a humid chamber at room temperature.