Leading global experts in veterinary medicine, human medicine, and parasitology attending the “7th International Conference on Bartonella as Animal and Human Pathogens” are united in a desire to deepen their understanding of this bacterium and increase medical and public awareness of the “stealth pathogen” that plays an important role in a number of human ills.
The North Carolina State University College of Veterinary Medicine is the host institution for this year’s international conference, which has attracted 82 scientists from 14 nations to Raleigh. The four-day meeting involves some 33 presentations and 61 research abstract poster sessions.
Keynote speaker is Dr. Christoph Dehio, an associate professor in molecular microbiology at the Biozentrum of the University of Basel, Switzerland. Dr. Dehio will discuss his current research on bacterial pathogens associated with human tumors. In particular, he is studying the molecular and cellular mechanisms that lead to the formation of vascular tumors by Bartonella henselae.
Bartonella is a bacterium that is maintained in nature by fleas, ticks, and other biting insects. It can be transmitted to humans both by these parasites as well as by bites or scratches from infected cats and dogs. The most commonly known Bartonella-related illness is cat scratch disease, caused byB. henselae, a species of Bartonella that can be carried in a cat’s blood for years.
Those who work with animals–veterinarians, veterinary technicians, shelter and rescue staff, trainers, groomers–are at greater risk of Bartonella infection given frequent exposure to a large number of animals and their parasites such as fleas.
As reported in an article by Edie Lau for the Veterinary Information Network News Service:
Twenty years ago, only two Bartonella species were known. One, B. henselae, was identified as the agent behind cat scratch disease, a condition believed to be transmitted by a cat scratch or bite that causes swelling of the lymph nodes along with fever, headache, fatigue and/or poor appetite. Conventional wisdom said — and says still — that “cat scratch fever” is nothing to worry about for most people: Except in those with immune system deficiencies such as AIDS, the infection goes away on its own or with a short course of antibiotics. Bartonella became synonymous with mild illness.
But researchers say the picture is more complicated than that. Today, the number of Bartonella species identified is 26 and counting. Species exist that co-evolved with dogs, cattle, squirrels and ground hogs. Arthropods including fleas, lice and possibly ticks transmit the germ to mammals.
Those who study Bartonella characterize it as a “stealth pathogen” because of its ability to evade detection even at levels that cause illness. The bacterium has been found to invade and colonize a variety of cell types — not only blood cells such as erythrocytes and macrophages but vascular endothelial cells and dendritic cells of the nervous system, as well.
This enables the microbe to disperse throughout the body and manifest in a wide range of debilitating conditions, including neuromuscular problems and endocarditis, a serious infection in the valves of the heart. Complicating diagnosis, many symptoms are non-specific. They include fatigue, headache, memory loss, insomnia, muscle pain and joint pain.
While human medicine is just beginning to understand Bartonella’s possible involvement in a host of human illnesses, the pathogen has been known for more than a century. There are reports from the 1850s of Indians in the Peruvian mountains having lesions that we now know were caused by these bacteria. The genus is named after Alberto Leonardo Barton Thompson, a Peruvian scientist who announced his findings in 1905 after studying an outbreak of illness among workers who built the Oroya-Lima railway through Peru’s mountains.
“We are finding many different species of Bartonella in a surprising number of animal hosts,” says Dr. Ed Breitschwerdt, professor of internal medicine at the NC State College of Veterinary Medicine, director of the CVM Intracellular Pathogens Research Laboratory, and one of the world’s leading experts on Bartonella. “At one time the accepted thinking was that Bartonella did not exist in North America.This assumption was clearly wrong.
“Current evidence suggests that this pathogen appears to be extremely successful in evolving and thriving in insects and in a spectrum of mammalian hosts. What is of major interest is that our research indicates that this pathogen can produce persistent infection in immunocompetent people—healthy individuals—and ultimately make them ill. So it’s not just the immunocomprised people, like HIV patients, or transplantation recipients that are at risk. We are beginning to recognize the human impact of bartonellosis.”
The most recent finding by Dr. Breitschwerdt’s research team links Bartonella infection to rheumatologic symptoms in patients with historical diagnoses of Lyme disease, arthritis, chronic fatigue, and fibromyalgia. The report is in the May issue of the Centers for Disease Control’s Emerging Infectious Disease Journal.
An earlier study by Dr. Breitschwerdt’s laboratory in the NC State Center for Comparative Medicine and Translational Research discovered that Bartonella infection can be passed to human babies by the mother, causing chronic infections and raising the possibility of bacterially induced birth defects. That study appeared in the Journal of Clinical Microbiology.