Introduction

The canine distemper is an important viral disease caused by canine distemper virus (CDV), a Morbillivirus family Paramyxoviridae, which affects systems: respiratory, gastrointestinal and central nervous system (CNS) in dogs from around the world, and affect other carnivores such as foxes, ferrets, lions, leopards, tigers and guepardos (Norris et al. 2006). In Brazil the infection by this virus is endemic and can result in acute or subacute multisystem disease. The disease affects dogs of any age, race and gender, with greater predilection for young animals, and the dog is the main reservoir for the canine distemper virus and serves as a source of infection for wild animals (Green & Appel 2006). This research aims to determine the occurrence and distribution of canine distemper in the city of Belém, to meet needs of data on the disease in the country and in the Amazon region.

Materials and Methods

We used 101 dogs treated at a private clinic in the city from August 2007 to November 2008, which showed signs suggestive of canine distemper, including some dogs with nervous symptoms. Of the total, 63 samples were female and 38 male, belonged to various breeds and crossbreeds, with different age groups, ranging from zero to 12 years old, from 23 districts of the center or connected to center of Belém. To aid in the diagnosis of the disease was used Anigen® Rapid CDV Ag Test Kit (Bioeasy, Code: RG 11-03, produced by: Animal Genetics Inc.467-1, Korea) which has the capacity to detect the quality of canine Distemper virus antigens in the conjunctival mucosa, serum, plasma, urine, saliva, nasal secretions or cerebrospinal fluid, through the chromatographic immunoassay. The diagnostic kit is complete (the test device, containing thinner tube, swab and dropper (Solozabal et al., 2007). For samples of the mucosa eye, used a swab moistened with saline solution and pressed in the conjunctiva of the animal. In serum samples of blood, was performed at the venipuncture cephalic or saphenous vein in the volume of five milliliters, then dumped by around two to three drops of serum on the container containing buffer solution. To sample of cerebrospinal fluid (CSF) was a dilution of samples and instilled are four drops in the hole in the device to the test after five to 10 minutes, there was the reading of the result.

Results

Of the total samples collected (101) of animals with nervous symptoms, 31 (30.6%) were positive and 70 (69.4%) negative. With respect to gender, 10 (26.3%) samples belonged to reagents males and 21 (33.3%) were female. Of the 31 (30.6%) positive samples, nine were of mixed breed animals and 22 (70%) with specific breed, however, is the animals of the Poodle in which 10 (34%) samples were positive for this race to the virus. In terms of age, of all animals that had aged from zero to three years (65 / 32.3%) were positive, three to six years (17 / 29.4%) were positive, six to nine years (9 / 22.2%) were positive, 42% of animals that were aged from nine to 12 years were positive and no animals were positive at the age of equal or above 12 years. The canine distemper had a uniform distribution in the city, the 23 districts analyzed, 17 contained animals positive for the disease, characterizing a hegemony between neighborhoods of the city center, from 31 positive samples, an animal was positive (3.2%) in the districts of the Umarizal, Reduto and Campina, two animals (6.4%) in the Cidade Velha, Nazaré and Cremação; four (12.9%) in the districts of São Brás, the neighborhood of Marco presented five positive animals (16.1%). In the neighborhoods of the periphery, similar results were obtained: an animal (3.2%) positive in each of the districts of Pratinha, Val-de-Cães, Sacramenta, Pedreira, Canudos and Jurunas; two animals (6.4%) reagents in the neighborhoods of the Telégrafo and Guamá predominantly in the neighborhood of Marambaia with three animals (12.9%) positive.

Discussion and Conclusions

The frequency of 30.6% of positive animals obtained in this work was expected when compared to other regions of Brazil, in which data are reported more than 11.7%. Most of the positive samples, 20 (64.5%) was found in animals treated during more rainy, cold and humid in the Amazon region that prevails in December to March, where the rate of rainfall varies from 2700 to 3000 mm and humidity from 90 to 95% (INMET, 2008), although some aspects of the disease are not well informed coldest periods that can promote the survival of canine distemper virus for longer in the environment (Headley & Grace 2000). In this research, there was not considerable discrepancy between males (26.3%) and females (33.3%) positive and the total number of animals with specific breed, 32.3% were positive and 27.2% were of mixed breed animals, indicating that there is no predilection for sex or race, but all nine positive animals mixed breed, were of unknown origin, animals found abandoned on the streets, collected by associations protective of animals and transported to a private clinic in the city, justifying the higher susceptibility of dogs from street, because it is directly related to the fact that these animals generally have low titles of neutralizing antibodies against the virus, are not well care and have higher chance of coming into contact with viral particles from other dogs already contaminated (Alex & Dhanapalan 1994; Patronek et al. 1995; Gorham 1966; Headley & Grace 2000). The highest percentages of positive samples were from animals aged from zero to three years (32.3%) and nine to 12 years with 42%, the incidence is highest between 60 and 90 days old, when decreases the rate of maternal antibodies, however dogs up to two years of age are commonly affected, according to the non-vaccination, immunological failure or lack of contact with the virus. Dogs from 7-9 years also develop the disease (Correa & Correa, 1992). The canine distemper presented a broad and uniform distribution in the city, where the 23 districts that had samples, 17 had positive animals, with attention for the district of Marco that the 31 positive samples, five (16.1%) belonged to this district, all of mixed breed animals, collected from the street by a association with assistance to animals and transported to the shelter of the association, with more opportunities to spread occurring in environments where the dogs are kept in groups, as stores of animals, shelters, kennels, veterinary clinics and research colonies (Birchard & Sherding 2003). Was conclude that the canine distemper virus presents wide spread in animals from the areas examined, the high frequency coinciding with the period of increased rainfall in the region north, requiring more information about this and other aspects relevant to the spread of canine distemper virus in dogs belonging to the city of Belém.

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