Study: Canine bacteria could cause problem pregnancies in humans

A new study on Brucellosis in dogs by researchers at Texas A&M University has troubling implications for people, particularly children, seniors, the immunosuppressed, and pregnant women.

Maybe especially for pregnant women.

Brucella canis is one of twelve recognized species of the genus Brucella and the only one that’s dog specific. Other species, such as Brucella melitensis, Brucella abortus, and Brucella suis, are well-known examples of zoonotic infections that can jump to humans, causing undulant fever and flu-like symptoms. 100 to 200 cases of Brucellosis are reported in humans each year in the United States, but most of those are transmitted through livestock.

The impact of B. canis on humans is much less clear.

B. canis is transmitted among dogs primarily through ingestion, inhalation, or contact with aborted canine fetuses or placenta, vaginal secretions, or semen. Reproductive problems are the primary way Brucellosis manifests in dogs.

Researchers aren’t certain exactly how the bacteria is spread to humans, but say it’s most likely the result of direct contact with dogs’ reproductive organs or urine. Intact males are known to have higher concentrations of the bacteria than neutered males or females, so neutering is recommended for dogs diagnosed with brucellosis.

The researchers say people who regularly handle infected dogs are most at risk for contracting brucellosis, so veterinary hospital staff, dog shelter employees, and breeders need to take special care.

Pet ownership is also a high risk factor: Documented cases of Brucellosis in humans include a three-year-old New York City girl who came down with the disease in 2012 after exposure to an infected puppy purchased from a pet store. Additionally, there are at least two reports of people with HIV developing Brucellosis that were linked to their ownership of intact dogs diagnosed with B. canis infection.

But how serious is the danger? That’s hard to say.

“We don’t really know how prevalent this disease is in the United States,” the study’s corresponding author, Martha Hensel, DVM, told HealthDay, an online consumer health blog. “The information we have to draw conclusions on the public health risk is outdated, to say the least—something like 30 to 40 years old.”

But, Hensel added, “An average healthy adult would probably not contract this disease unless they were exposed to a really high concentration of bacteria.”

The Centers for Disease Control and Prevention (CDC) warns that pregnant women who may have been exposed to Brucellosis should talk to their doctor, noting that “Prompt diagnosis and treatment of brucellosis during pregnancy can be lifesaving for the fetus.”

The CDC also cautions that, while such cases are rare, lactating mothers have been known to transmit the disease to their breastfed infants.

Meanwhile, Hensel and her colleagues hope that their study will promote the development of better diagnostic tools to test for the presence of B. canis bacteria in dogs and humans, and, even better, the development of a B. canis vaccine, which does not currently exist.

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