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Flea/tick study examines maternal transfer of Bartonella
Bartonella species is a new and emerging bacterial pathogen for veterinarians.
RALEIGH, N.C. — The bacteria Bartonella vinsonii subsp. berkhoffii and Bartonella henselae, normally transmitted by fleas and/or ticks, may be transferred to human babies via the mother, increasing the risk of chronic infection and bacterially triggered birth defects, according to research published in the June 2010 Journal of Clinical Microbiology. But this is just one of a number of emerging findings impacting humans and animals alike, one expert notes.
Edward B. Breitschwerdt, DVM, Dipl. ACVIM, professor of internal medicine at North Carolina State University and an internationally recognized expert on the Bartonella genus, was lead author of this and other similar case studies. Bartonella species, sustained in nature through ticks, fleas and other insects that bite, also can be passed through infected dogs and cats.
"One of the more important messages behind this research is that Bartonella is a new and emerging bacterial pathogen," Breitschwerdt says. "As a result, there is an increasing amount of information that is being generated and published that most veterinarians are not going to be readily familiar with. Much of the material is being published in microbiology, parasitology and vector journals, not in the veterinary literature."
The importance of the Bartonella species research and findings is twofold.
1. Bartonella species have been identified in the blood of numerous animal species. Historically, 10 to 15 years ago, researchers were not aware that these bacteria were in the blood of healthy animals and in animal patients.
2. "What complicates matters is that there are a very large number of proven and perhaps even larger number of suspected arthropod vectors that may be responsible for transmission in nature," Breitschwerdt notes.
For instance, the gray squirrel has one type of Bartonella species that it carries in its blood, and the groundhog has yet another Bartonella species, and so on.
A common Bartonella species-associated illness is cat-scratch disease, triggered by B. henselae, which can be active in a cat's blood for years. Previously, the disease was thought to be a one-time infection, but Breitschwerdt's work has disproven that, showing cases of adults and children with chronic, blood-borne Bartonella species infections.
Through Bartonella species-research, Breitschwerdt and colleagues have discovered that reservoir-adapted animals can carry the bacterial organisms in their blood without carrying obvious signs of disease. Using the cat as an example, the flea would be responsible for being its transmission source.
"The cat and flea are happy with each other and in a so-called state of peace for the most part. But when the same Bartonella species ends up in a horse, these animals are not reservoir-adapted, and the same is true for dogs and humans, all of which may be then exposed to disease," he explains.
In the current case study, which occurred over several years, Breitschwerdt's research team analyzed tissue and blood samples from a mother, father and son who had chronic illnesses for 10-plus years. An autopsy of the son's twin sister who died soon after birth revealed DNA proof of B. henselae and B. vinsonii subsp. berkhoffii bacteria also present in the other family members.
The parents had ongoing neurologic conditions, such as headaches and memory loss, along with muscle weakness, difficulty breathing and fatigue before the children's births. Their son had chronic illnesses since birth. Microbiologic test results showed the parents were exposed to Bartonella species before the twins' births. Because the bacteria was found in both twins, there is the possibility, according to researchers, that the children were infected during the mother's pregnancy.
Funding, not findings, lacking
Given the abundance of findings related to Bartonella species organisms to date, Breitschwerdt hopes the funding catches up to the study results.
"What I've learned is that it takes a lot of time and work by a number of research groups before any emerging bacteria is appreciated for its importance," he says. "With the exception of one NIH-funded Bartonella study that I'm aware of, there is no federally funded work going on relative to the importance of this bacteria as a cause of disease. It is virtually impossible to get federal funding.
"We are doing research relative to human illness and telling human colleagues, 'Hey folks, there's a problem out there,'" he adds. "We've done this with limited resources in terms of funding, equipment, time and space. I don't understand why there is not more attention being paid to this newly discovered species of bacteria. Yet as we understand it, it will never cause a huge outbreak of cases in relation to the flu epidemic."
Yet, he says, it has the potential to cause chronic, very insidious illness.
"Any of these organisms are capable of causing complex disease presentations, which are difficult to nail down on basis of evidence-based medicine," he says.
Who's at risk
Researchers to date have discovered that immunocompromised people are at increased risk of Bartonella species-related infection.
"Yet, it's reasonably clear from the research that you don't have to be immunocompromised to develop bacteremia with many members of the genus Bartonella. As a veterinary internist, I am even more concerned about pets harboring Bartonella species that could be transmitted to people with immunocompromised systems — if they're exposed to organisms," Breitschwerdt says.
"Using a novel diagnostic testing approach we've developed at NCSU, we've been able to determine that dogs, horses and people can have chronic infections within their blood. And, by the way, they're not immunocompromised," he adds. "Although we've come a long way and have the most sensitive diagnostic modality currently for protecting these bacteria, there's still much work to be done regarding diagnosis."
A veterinarian's most important response to the research findings should be to help keep ticks and fleas off dogs and cats so that the vectors known to transmit Bartonella species aren't transmitting. Breitschwerdt recommends using any safe, effective products to kill fleas and ticks.
He cautions, however, "Despite how good the products are, vectors and organisms are pretty talented. Don't create expectations that the products can offer 100 percent guarantee of removal of the potential for infection. Vaccination would get us a lot closer to our goal."
The second most important step for veterinarians is to continue to follow the literature relative to the importance of the bacteria and how they cause disease in cats, dogs and people.
Third, advise clients to avoid bites and scratches from cats and dogs.
On the horizon
Major pharmaceutical companies are becoming aware that there is a need to vaccinate dogs and cats against these bacterial organisms.
"If these animals are being vaccinated, then one mode of transmission to humans would be cut off," Breitschwerdt says.
"The question is why there is not more recognition in veterinary and human medicine about the importance of the Bartonella species bacteria now," he notes. "Much of what is being published are case reports and series. There's good reason for that — the type of funding it takes to do large clinical trials is not available.
"Until we can elevate the biomedical importance of this genus to the level that others really think it's important enough to fund, we're in a tough place."
The way Breitschwerdt and his team of researchers began focusing on Bartonella species in research relative to humans is that they were trying to devise a better way of diagnosing bartonellosis in dogs. He and other researchers began to develop a diagnostic enrichment culture approach because of queries by veterinarians and veterinary technicians with disease manifestations similar to dogs. They wanted to know if they could be affected by exposure to these dogs.
Currently, Breitschwerdt and other researchers are collaborating with Duke University Medical Center, with physicians at UNC Chapel Hill, with researchers in Brazil and with some researchers Germany.
"It is possible that there will be a tipping point, which, based on our work, will result in improved funding for this genus. My fear is that, until then, basic science researchers around the world will not be able to keep labs open and do research if there isn't funding. Many researchers have given up on Bartonella in the United States and internationally because they've struggled to get funding. But this is the worst time in history to give up. We are getting close to a point where it may not be quite so hard to convince those with influence that this genus is important enough for studies," he explains.
Breitschwerdt has spent the last two years getting his own company, Galaxy Diagnostics, which employs eight, launched. There's an animal-health division and a human-health division, both of which offer testing for Bartonella species. Visit www.galaxydx.com for more information.
"Given everything we have learned to date about Bartonella, I want to be cautious not to overstate what we know about the genus. It is so much more important than any of us currently realize, including me. The place where we're in trouble is in proving how the bacteria is causing chronic illness. The issue is what is Bartonella causing, how does it do it and how long does it take to do it?" he says.
Ms. Skernivitz is a freelance writer in Cleveland, Ohio. She is formerly a senior associate editor of DVM Newsmagazine.