RALEIGH — I have studied tick-borne infectious agents for more than two decades - directing a vector-borne infectious disease diagnostic laboratory and a tick-borne disease research lab at N.C. State's College of Veterinary Medicine since 1982 - and I am very familiar with the potential outcomes of tick-transmitted diseases, which can include rapid onset illnesses or death or induction of chronic and insidious symptoms.
Consequently, I do "tick checks" after outdoor activity on my farm, but I recently missed one.
When I discovered the tick, I followed recommendation I've given to hundreds of individuals in lectures on tick-borne pathogens. I placed the parasite in a vial of alcohol and wrote the date of its removal on the label. This is an important step, as there are at least four tick species that attach to animals and people in North Carolina, and each species can transmit different bacteria that collectively cause a spectrum of diseases. Knowing the species can help the physician or veterinarian understand which infectious agent has been transmitted.
Tick size can be misleading. Each species has several life stages, so when someone says they found a small tick and presumes it is a "deer tick" ( Ixodes scapularis, which transmits Lyme disease) this can be meaningless. Also, only female ticks become engorged (the big, fat, blood-filled tick frequently found on dogs, deer and other animals). Following a blood meal, the mother tick detaches and lays a few thousand eggs to produce larval ticks. So assuming that because a tick is small it did not feed long enough to transmit bacteria is a dangerous assumption.
The small tick in my armpit remained attached long enough for my body to mount an inflammatory response (itching, swelling and pain) before I noticed and removed it. Not initially feeling an attached tick is the norm, since ticks have evolved the ability to secrete chemicals that block pain and decrease the body's inflammatory response.
Symptoms develop in seven to 14 days following transmission of most tick-borne organisms. If a person is healthy two weeks after an attachment episode, it is unlikely that the stored tick transmitted an organism that would induce disease.
Nine days after removing my tick I developed severe chills. The next day my symptoms progressed to include fever, muscle pain and headache - classic symptoms of Rocky Mountain spotted fever and human granulocytic or monocytic ehrlichiosis, the three most serious and frequent tick-transmitted diseases of dogs and people in the southeastern United States.
Typical of the early stages of these diseases, my white blood cell count (the body's first line of defense) was low. My bone marrow responded by sending new white blood cells to fight the infection. After blood was obtained for diagnostic testing, antibiotic treatment was started immediately. This is of critical importance, as a delay in diagnosis and initiation of antibiotics for 24-48 hours greatly increases the severity of illness and the chances of death.
One major focus of our ongoing research at the College of Veterinary Medicine is the development of sensitive and rapid diagnostic tests for the detection of tick-transmitted infectious agents in patient samples (animals and human patients). While I received an antibiotic early in my illness, we still tested my blood for DNA evidence (i.e., detecting specific gene targets of the infectious agents). Within hours we learned that both the tick and my blood contained Rickettsia DNA. This, in conjunction with the rash on my arms and legs, indicated Rocky Mountain spotted fever. In some instances ticks transmit more than one infectious agent, which complicates diagnosis and treatment. Fortunately for me, tests for other organisms were negative.
North Carolina, along with Oklahoma, generally reports the highest number of Rocky Mountain spotted fever cases each year. Approximately 6 percent of those who contract the disease die. When death occurs, it is usually due to a delay in medical care or because of a failure to recall and report a tick attachment. Unfortunately it is not unusual for a tick to bite, transmit an infectious agent and detach without the individual knowing that he or she was bitten.
As a veterinary internist, I took an oath to protect animal and human health. I appreciate the importance of One Health - how ecosystem health and health of wildlife, domestic animals and people are linked. I take ticks and the diseases they transmit very seriously.
This recent experience enhanced my belief that tick-transmitted diseases deserve respect and enhanced, comparative biomedical research. The next time you walk in the beautiful fields and valleys of North Carolina, apply a tick repellent and remember to check carefully for attached ticks when you return home.
Ed Breitschwerdt, D.V.M., is professor of medicine and infectious diseases in the College of Veterinary Medicine at N.C. State University and adjunct professor of medicine at Duke University Medical Center.