The spread of illnesses from mosquito, tick and flea bites more than tripled from 2004 to 2016 in what the Centers for Disease Control and Prevention has called an increasing public health risk. While new diseases such as Zika have popped up in recent years, old stalwarts like Lyme disease are also affecting more people. Dr. Kalpana D. Shere-Wolfe, an assistant professor of medicine at the University of Maryland School of Medicine and director of the Integrated Lyme Program at the University of Maryland Medical Center, talks about how people can protect themselves from Lyme disease this summer.
What is Lyme disease?
Lyme disease is a tick-borne illness caused by the bacteria Borrelia burgdorferi. The infection is transmitted by a tick called Ixodes scapularis.
What are the symptoms?
Early in the infection people may experience fever, headache, fatigue, swollen glands or a skin rash called erythema migrans, or a bull’s eye. Even though the rash is indicative of Lyme disease, it is important to remember not everyone develops a rash — only about 70 to 80 percent of folks do.
In days to weeks after the initial bite, the infection can affect the heart, nervous system and joints. People may experience joint pains that migrate or move from joint to joint, headache, stiff neck, facial palsy, nerve pain or sensory changes, enlarged spleen, sore throat, irregular heart beat or palpitations.
Months later, patients can experience intermittent attacks of joint swelling and pain, usually in large joints like the knee. People can also develop encephalopathy, or subtle cognitive changes.
Is this the time of year doctors start to see more cases of Lyme disease?
Yes, Lyme is most common in spring and summer months — the highest number of cases usually occur from May to September.
How is it diagnosed and why is it sometimes hard to detect?
Most people think Lyme is diagnosed by a blood test and that is not true, especially in early disease. Lyme diagnosis depends on symptoms, physical findings, tick exposure history and lab tests. Because the bacteria is difficult to culture, we rely on a serology blood antibody test to help us. The CDC recommends two-tier testing, which means an ELISA antibody test; if positive or equivocal, then a Western Blot test. The Western Blot test measures your body’s antibody response to Borrelia antigens.
Typically when we have an infection, our body first produces IgM antibody that takes about four weeks to be positive. IgM antibiodies are the first antibody produced when you are infected with new bacteria. It rises first before the IgG [also an antibody] and then declines after a few weeks. They usually start to appear one to two weeks following tick bite and peak around three to six weeks but then decline over next few weeks/months. Only 30 percent of people with Lyme disease will have positive IgM after infection in the first few weeks, but after four weeks about 70 percent will have positive IgM. The IgG test will be positive in most patients with Lyme disease for four to six weeks. IgG are also antibodies, but they take longer to become detectable and they usually will last many years, usually decades or even a lifetime.
In what ways could people be putting themselves at risk if they don’t know they have the disease?
Untreated Lyme infection in symptomatic people can lead to disseminated infection to the heart, nervous system and joints.
Why do you think we are seeing a rise in Lyme disease and other tick-borne illnesses?
It is not clear why this is happening. It may be related to climate changes and an increase in tick population as well as deer and mouse populations. Fragmentation of forests where there are fewer predators can result in an increase in the mouse population, which carry Borrelia — the ticks that feed on the mice can then be infected. These ticks can then pass the infection to humans.
How long does a tick need to be attached for a person to contract Lyme disease?
Thirty-six to 48 hours of feeding is typically required for a tick to have fed and then transmit the bacterium that causes Lyme disease.
How can people prevent contracting Lyme disease and other tick-borne illnesses?
You can prevent Lyme disease by eliminating exposure to ticks, but that is not always possible. You can decrease your risk by the following measures:
If possible, avoid tick-infested areas. Ticks like humid moist areas in wooded and grassy areas. That’s why they also like moist, humid parts of the human body like the armpits and groin areas.
Wear sneakers or shoes instead of sandals and long pants. Ticks can't fly or jump. Instead, they wait for a host, resting on the tips of grasses and shrubs, and then attach on. They are usually closer to the ground, so wearing long pants and tucking pant legs into socks, and wearing shoes instead of sandals, makes sense too.
Keep to the center of the trails.
Use insect repellents containing DEET (N,N-diethyl-meta-toluamide) or permethrin, but with caution. Check the CDC website about which insect repellent is right for you.
Do daily tick checks if out in the woods often. Look especially in the groin and armpits. In small children, they can also be found on the head and neck, so be sure to check there as well.
Adult ticks are approximately the size of a sesame seed, and nymphal ticks are approximately the size of a poppy seed; most people are infected by nymphal ticks.
Shower after being outdoors to wash off ticks and also find ticks more easily.
Infected ticks need to be attached 24 to 72 hours before transmission of the spirochete [bacteria] occurs. Removal of a tick within 24 hours of attachment is usually sufficient to prevent Lyme disease.
If a tick is in place longer than 36 hours, then a single, 200-mg dose of doxycycline usually prevents Lyme disease when given within 72 hours after the tick bite occurs.
You can also discourage deer from your yard.