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Blind Men, Elephants, and Tick-Borne Disease
Everyone seems to have different ideas about tick-borne disease. It’s the story of the blind men describing the elephant: Everyone has a different perception that is determined by their point of view, and everyone believes that their perception is the correct one. Obviously, this cannot be true. Here, then, is one veterinarian’s perception.
Lyme disease is the poster child for tick-borne illness. Lyme was first recognized in the early 1970s, when a mysterious group of rheumatoid arthritis cases occurred among children in the town of Lyme, Connecticut. By the early 1980s, Dr. Willy Burgdorfer, established the connection between deer ticks and Lyme disease, and proved that a corkscrew-shaped bacterium (a spirochete, similar to the leptospirosis agent we discussed last month) caused the disease. His accomplishment was forever commemorated when the disease agent, Borrelia burgdorferi, was named in his honor. Lucky guy.
The Lyme agent is injected into the victim’s body when certain families of
tick, most commonly the black-legged tick (Ixodes pacificus) in our area. In data published by the Sonoma County Public Health Laboratory, between 2009 and 2014 roughly 2% of these ticks were found to contain Lyme bacteria. Black-legged ticks are smaller ticks with small (roughly 1/8 to 1/4 inch) orange bodies and black legs. Other local ticks, such as
those belonging go the Dermacentor
family, are not thought to transmit
Lyme disease, although they may
transmit other pathogens. Here is a
graphic showing Ixodes scapularis, a
species similar to local Ixodes ticks.
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involved joint. TICK-BORNE DISEASE cont’d on page 33
In humans, Lyme disease affects
many body systems to produce a
huge range of problems. Not all patients with Lyme disease have all symptoms, and many of the symptoms can occur with other diseases, making Lyme particularly difficult to identify. The incubation period from tick bite to the start of symptoms is usually one to two weeks, but can be shorter, or much longer.
The classic sign of local infection with Lyme disease is a circular, outwardly expanding rash, which occurs at the site of the tick bite three days to one month after the bite. The rash is red and may be warm, but is generally painless. Typically, the inner and outermost portions remain red and the area between fades, giving the rash a bull’s eye appearance. This rash is found in less than half of all human patients and almost never in animals, so lack of a rash does not rule out Lyme infection. Other signs, such as flu-like symptoms, headache, muscle soreness, fever, and malaise may occur with or without the rash.
Days to weeks after the onset of local infection, the Borrelia bacteria may begin to spread through the bloodstream. Rash may develop at sites far from the original tick bite. Other symptoms include migrating pain in muscles, joints and tendons, and dizziness.
An unknown but possibly large fraction of victims go on to develop nervous system problems such as facial palsy, and/or meningitis causing severe headaches, neck stiffness, and sensitivity to light. Inflammation of spinal cord nerve roots can cause shooting pains that may interfere with sleep and cause abnormal skin sensations. Inflammation of the brain may occur, leading to memory loss, sleep disturbances, mood changes, or even grand mal seizures. Some people have described altered mental status as their only symptom.
Adult female
Nymph Larva Adult male
Ultimately, Lyme disease victims can develop chronic, severe symptoms
in many parts of the body, such as the brain, nerves, eyes, joints, and heart. These impairments can be both permanent and disabling. Possibilities include polyneuropathy with shooting pains, numbness, and tingling in the hands
or feet. Lyme encephalopathy may occur causing subtle to severe cognitive difficulties, insomnia, a general sense of feeling unwell, and changes in personality, mental impairment, brain fog, migraines, balance issues, leg weakness, bladder problems, vertigo, and back pain.
Lyme disease is generally thought of as a disease causing arthritis, which usually involves the knees, but arthritis represents fairly small part of Lyme pathology. In a relatively small number of people the arthritis occurs in other joints, including the ankles, elbows, wrists, hips, and shoulders. Pain is often mild to moderate, though it can be quite severe, sometimes with swelling of the