Thursday, 17 February 2011

Tick-transmitted Infectious Diseases In North Carolina: Local, National and Global Implications



Session 6 on 15-February 2011 was entitled “Tick-transmitted Infectious Diseases In North Carolina: Local, National and Global Implications”. The panel consisted of Dr. Ricardo Maggi, and Dr. Ed Breitschwerdt.


Dr. Maggi is Research Assistant Professor of Molecular Microbiology in the Department of Clinical Sciences at the College of Veterinary Medicine at North Carolina State University. He is also Chief Technical Officer and Assistant Director of Research and Development at Galaxy Diagnostics in RTP. Dr. Maggi’s topic of discussion was Borrelia in Ixodes ticks in North Carolina. Borrelia burgdoferi is the leading cause of Lyme disease.

According to Dr. Maggi, while 30-50% of Ixodes scapularis carry B. burgdoferi in New England, only 5% of I. scapularis do in Virginia. This figure drops to 0.3% in North Carolina. In contrast, among Ixodes affini ticks in North Carolina, 64% are infected with B. burgdoferi. This infection is more prevalent in female ticks than male ticks. 55% of male I. affini are infected while 77% of females are infected. Therefore, the epidemiology of B. burgdoferi infection in ticks appears to be different in North Carolina compared to the Northeastern states.

Dr. Ed Breitschwerdt is Professor of Medicine and Infectious Diseases at North Carolina State University College of Veterinary Medicine, Adjunct Professor of Medicine at Duke University Medical Center, and a Diplomate, American College of Veterinary Internal Medicine (ACVIM). Dr. Breitschwerdt discussed several tick-borne illnesses, including his groundbreaking research in Bartonella infections.

Dr Breitschwerdt started his talk by discussing how tick borne diseases are important because they can result in death. Ticks secrete toxins, which target lower motor neurons and cause paralysis. Paralysis can be generalized and cause death by affecting respiratory muscles. Dr Breitschwerdt then talked about dogs as sentinels for tick borne infections and the use of C6 ELISA methodology to detect canine infection with tick borne diseases.

According to Dr Breitschwerdt, Rocky Mountain Spotted Fever is the most important tick borne disease in North Carolina because it is potentially fatal. Features include fever, rash, gangrene and anemia. It is important that veterinarians not miss this diagnosis because a delayed or missed diagnosis can cause death in both animals and their human owners. Even though RMSF is usually thought of as a disease of the countryside, it has been found in places like New York City. After all, it only takes one tick to transmit the disease. Dr Breitschwerdt then proceeded to discuss other tick borne diseases like Ehrlichia, Anaplasma phagocytophilum and Bartonellaceae. Bartonellaceae is unique because it can infect multiple cells in the body, and is becoming an increasingly important cause of tick borne disease in the state. The vector that transmits Bartonella henselae is Ixodes ricinus. Animals are important reservoirs for the vectors.

A theme that Dr. Breitschwerdt returned to throughout his talk was that of the importance of having a high index of suspicion for tick borne illnesses and how every patient whom the veterinarian or physician suspects to have a tick borne illness should be treated with doxycycline. Other measures like removal of fleas and ticks from dogs are also important in preventing the risk of disease transmission.

Questions from students, faculty members, professionals, and attendees covered a wide range of topics:

  • Could mandating tick prevention in dogs lessen tick-borne infections in humans?
  • What are the possible reasons for the difference in the prevalence of Borrelia in Ixodes scapularis and Ixodes affinis?
  • Given that most tick borne illnesses are treated with doxycycline, how does determining the differences in tick and pathogen epidemiology in North Carolina help change management and treatment of tick borne diseases?
  • Do tick borne illnesses caused by different bacterial species (rickettsia, borrelia, bartonella) present similarly?
  • Since tick borne illnesses affect both humans and their animal pets, is there much collaboration between physicians and veterinarians in managing this group of diseases?
The session concluded with a discussion of the need for collaboration and data sharing between veterinarians, physicians, public health professionals, and environmental scientists.