Along with the transportation of dairy products infected with Brucella melitensis and Brucella abortus, the international dog trade and the lower veterinary control have led to the occurrence of Brucella canis infected dogs in Europe.
Brucella canis (B. canis) infections are spread across many regions in the world (South America, Mexico, South Africa), predominantly in countries with a large population of stray dogs. This ensures high levels of distribution and retention of the pathogen in the dog generations. B. canis can cause abortions in females. However, many cases showed chronically infected puppies were born, survived and became a dangerous source for spread of the disease. Breeding colonies are also exposed on a higher risk for canine brucellosis infection. Most studies report canine brucellosis is indicated in young dogs diagnosed with discospondylitis. B. canis can be transmitted from infected dogs to humans who have close contact like pet owners, vets, laboratory workers. An increase of cases with humans infected with B. canis has been reported, predominantly in patients and children with lower immunity. Symptoms described in B. canis-positive people are weakness, fever, fatigue, spleen enlargement. The epidemiological potential of B. canis is low in comparison with B. melitensis, B. suis and B. abortus, which are usually the pathogens that cause human brucellosis.
PCR is reported to be the more sensitive and reliable method for diagnosis of B. canis infection even in its early stage. It shows the occurrence of Brucella spp. DNA in clinical samples. The PCR method is also used for rapid detection of Brucella infection in dogs with discospondylitis. Serological analyses for detection of antibodies against B. canis often can give false-positive results. Due to this, specialists advise to use a combination of serological tests to obtain accurate results. Most vet clinics use rapid tests for extremely fast qualitative detection (in 20 minutes) of the presence of antibodies against Brucella spp.
Veterinarians recommend combined therapy with tetracyclines and aminoglycosides against Brucella canis. Brucella suis-positive dogs may be successfully cured with a complexed use of doxycycline and rifampicin. Additional treatment with hydroxychloroquine at early stage has reduced the risk of chronical brucellosis disease in human patients. Despite all schemes for antibiotic treatment, no therapy can eliminate completely Brucella canis from infected kennels and the disease can relapse. The spread of B. canis infections can be stopped by strict veterinary control on breeding and dog trafficking in the European countries.
According to the latest reports, travelling, migration and lower control on dairy products’ import may result in a spread of Brucellosis infection in Western Europe region. The consumption of raw milk and dairy products contaminated with Brucella spp. represents a major risk for human health.
The pathogens that cause the disease in humans are Brucella melitensis and Brucella abortus. Those can be transmitted from infected animals from the family Bovidae or their tissues to humans via inhalation or through skin lesions. The symptoms of this infection are like a flu disease, but brucellosis can become chronical and progress with additional complications as spondylitis and endocarditis.
Most of the countries, members of the European Union, have a status of officially free of bovine brucellosis caused by B. abortus and officially free of ovine and caprine brucellosis caused by B. melitensis in 2003. By the end of 2016, the countries on Iberian Peninsula and countries in Eastern Europe have not reached the level of officially free of B. melitensis animal infection.
Since the Brucella basically contaminates the food, quantitative PCR is recommended as the most reliable, rapid and sensitive method for detection of this pathogen. The validated PCR techniques are designed for detection of 16S/23S rRNA genes, bcsp31 gene that encodes a 31-kDa cell surface membrane protein with molecular mass 31 kDa. Also, the insertion sequence IS711 is used for screening in order to increase the sensitivity of PCR since IS711 is presented in several copies in the Brucella genome. Serological methods are another option for detection of brucellosis in humans. ELISA tests for determination of the presence and/or concentration of IgG, IgM or total Ig find wide application for detection of this disease and helps for the differentiation of the different phases (acute and chronical brucellosis) in patients.
The raw milk, cheese and meat products imported from endemic countries (Turkey, South Africa, China) and sold in the supermarkets or illegally passed through the borders can become a domestic source of Brucella in the European countries. The best way to avoid brucellosis is to consume pasteurized or sterilized dairy products that have detailed information about origin and treatment on the label and passed the food safety standards.