Ticks stealthily attack both animals and humans and feed on their victims’ blood. But the dangers these tiny bloodsuckers pose go far beyond a bite. Ticks can spread serious and even potentially fatal diseases. And the risk is growing.
A recent policy statement by the Entomological Society of America concluded it’s time to take the threat of ticks very seriously. “Environmental, ecological, sociological, and human demographic factors [have] created a near ‘perfect storm’ leading to more ticks in more places throughout North America,” the report warned.
Milder winters in some parts of the country are one reason ticks have flourished over recent years and, as they’ve increased in numbers and locations, more cases of tick-borne diseases have been reported.
A case in point: The Centers for Disease Control and Prevention (CDC) states there are about 300,000 cases of tick-borne Lyme disease in the U.S. annually. That’s ten times more than the number of people estimated to have Lyme disease just three years ago.
In all, the CDC lists over a dozen diseases that can be transmitted by various ticks in many parts of the U.S. Some, like Rocky Mountain spotted fever, which was discovered over 100 years ago, have long been on doctors’ radars. Others, like Lyme and ehrlichiosis, have been recognized and studied for a few decades, while a couple of tick-borne illnesses, including the Heartland virus, were only identified recently, according to infectious disease specialist Henry Wu, MD, assistant professor of medicine at Emory University.
The diseases tick bites can cause range from mild to life-threatening. Sometimes the symptoms are downright bizarre. For example, Lyme disease often produces a rash that looks like a bull’s eye and the Lone Star tick’s bite can trigger ongoing and potentially fatal allergic reactions to meat.
“Many people who are identified with tick-borne illness often don’t recall being bitten by a tick,” said Wu, who is director of the Emory TravelWell Center, which provides travel-related health care in collaboration with the CDC.
“That’s why it’s important for both patients and their doctors to know what tick-spread diseases are present locally and to think about any potential activities that could be related to tick exposure.”
Here are five of the most worrisome tick-borne diseases in the U.S, where people are in most danger of contracting them, and the symptoms that mean you should seek medical help.
Rocky Mountain spotted fever (RMSF) is transmitted to humans by the bite of three infected tick species – the American dog tick (Dermacentor variabilis), the Rocky Mountain wood tick (Dermacentor andersoni), and the brown dog tick (Rhipicephalus sanguineus).
People have contracted RMSF throughout most of the country, but more than 60 percent of cases occur in North Carolina, Oklahoma, Arkansas, Tennessee, and Missouri. In most places where there are RMSF-carrying ticks, the risk is highest during the summer months, especially June and July. However, in recent years, RMSF has infected people in eastern Arizona from April to October.
Typical RMSF symptoms include fever, red eyes (conjunctivitis), headache, abdominal pain, vomiting, muscle pain and, sometimes, a rash. Doxycycline is an effective treatment, but the antibiotic needs to be started before the fifth day of symptoms. “Rocky Mountain spotted fever can have a high fatality rate if not treated in a timely manner,” Wu pointed out.
Lyme disease, caused by the bacterium Borrelia burgdorferi, is transmitted to humans through the bite of infected blacklegged ticks, which thrive in the Northeast and Mid-Atlantic States (from northeastern Virginia to Maine), the North central states (primarily Wisconsin and Minnesota), and on the West Coast, especially in northern California.
Most humans are infected through the bites of hard-to-see immature ticks called nymphs that strike mostly during the spring and summer months. Although adult ticks can also transmit Lyme disease bacteria, they are much larger than nymphs – so they’re easier to spot and remove before they make you sick.
If you have any early symptoms of Lyme, including fever, headache, fatigue, and a skin rash that looks like a bull’s eye, seek medical care right away. Left untreated, the disease can spread to your heart, joints, and nervous system, and also cause facial paralysis. Usually, Lyme disease can be treated successfully with a few weeks of antibiotics. However, some patients continue to suffer from symptoms such as fatigue and joint and muscle aches long after the treatment, a condition called post-treatment Lyme disease syndrome.
The Heartland virus is transmitted via the bites of mosquitoes and sandflies as well as ticks. So far, only residents of Missouri and Tennessee have been infected with this newly discovered virus; the cases occurred during the months of May through September. It’s not known yet if the virus is in other areas of the U.S.
Symptoms of the Heartland virus include fever and extreme fatigue, headaches, muscle aches, diarrhea, loss of appetite, and nausea. The virus can produce changes in the immune system and cause blood clots. Most patients required hospitalization for their illness and, while full recovery with treatment is expected, one person with the Heartland virus has died.
Anaplasmosis is a tick-borne disease caused by both adult and nymph black-legged ticks (Ixodes scapularis) and western black-legged ticks (Ixodes pacificus) infected with the bacterium, Anaplasma phagocytophilum. Ninety percent of all reported cases of the disease have been in New York, Connecticut, New Jersey, Rhode Island, Minnesota, and Wisconsin, although a few people in the Southern states have been infected. Infections with anaplasmosis can occur year round, but they peak in the summer, especially in June and July.
The typical symptoms – fever, headache, chills, and muscle aches – don’t start until a week or two after you’re bitten by an infected tick. Symptoms and lab tests can determine if you have anaplasmosis, which is treated with the antibiotic doxycycline.
Babesiosis is caused by the extremely tiny (about the size of a poppy seed) nymph form of Ixodes scapularis ticks. Instead of bacteria or viruses, they transmit microscopic Babesia parasites with their bites. People are most likely to come down with babesiosis during the warm months in the Northeast and upper Midwest states.
The good news about this tick-borne disease is that many who contract it have only mild symptoms – or none at all. The bad news is others can be extremely ill with fever, nausea, fatigue chills, sweats, headaches, low blood pressure, and body aches. What’s more, Babesia parasites can destroy red blood cells, resulting in hemolytic anemia that can be fatal, especially in people who have a weak immune system – such as cancer patients, and those who have liver problems or are elderly.
Babesiosis is diagnosed in symptomatic people by examining blood specimens under a microscope to spot Babesia parasites inside red blood cells. The treatment is a course of multiple antibiotics for several weeks.
Ehrlichiosis is the name for several bacterial diseases transmitted by both adult and nymph Lone Star ticks. Ehrlichiosis can occur during any time of the year, but the risk is highest in the summer months, typically in June and July.
Symptoms, which develop within a couple of weeks of a tick bite, include muscle pain, fever, headache, fatigue, and sometimes a rash. Even people who were previously healthy can experience additional severe symptoms, such as breathing difficulties and bleeding disorders, which can be fatal. Blood tests can identify the infection and the antibiotic doxycycline is usually effective in treating the disease – if it is given early enough.
All the news about ticks and the sickness they can cause doesn’t mean you have to live in fear of the creeping (and creepy) bloodsuckers. “It is important to emphasize that the overwhelming majority of tick bites will not result in an infection,” Wu emphasized.
“However, although they might not be common in all areas, tick-borne infections can be present throughout the U.S., and tick bites are certainly a nuisance worth avoiding.”
Ticks, which are technically invertebrate animals called arachnoids and are related to spiders and scorpions, typically are found in and near wooded and grassy areas. So the CDC advises sticking to the center of trails if you hike, and avoid walking through tall bushes and other vegetation.
Also apply a repellent with DEET, which can be used on skin or clothing, or permethrin (for clothing and camping gear) to keep ticks away. The Food and Drug Administration offers guidelines for using these repellents appropriately and safely.
It’s a good idea to perform daily tick checks if you’ve been working in your yard or participating in other activities in areas where ticks are common. Most tick bites don’t cause pain, so it’s important to search your entire body for ticks using a hand-held or full-length mirror. Check your children and your pets regularly for ticks, too.
If you find ticks on your clothes, the CDC suggests throwing them in the dryer on high to kill the bloodsuckers.
If you find a tick on your body or that of a child or pet, stay calm and remove it safely. “A tool such as tweezers should be used to remove ticks by carefully applying steady, gentle upwards pressure while grabbing them as close to the skin surface as possible,” Wu explained. “The idea is to not squeeze the body (and potentially push more infected fluid into your skin), or to twist the tick (and potentially result in mouth parts breaking off and remaining in the skin).”
After removing a tick, the CDC advises thoroughly washing the bite area and your hands with rubbing alcohol, iodine, or soap and water. If the tick is still alive, drown it in alcohol, place it in a sealed bag or container, wrap it tightly in tape, or flush it down the toilet.
“Note the appearance (size, color) of the tick, as well as the time of likely initial exposure and time of removal,” Wu said. “This might be helpful in case illness develops to determine if the tick might be a source. “
While the odds are great most tick bites won’t make you sick, if you’ve been bitten by a tick, contact your doctor if any signs of a tick-borne illness develop days to weeks later. “The symptoms most commonly are fevers, chills, aches, and rash,” Wu said. “In limited circumstances, preventative therapy Lyme disease may be considered following a recent bite of a deer tick that was attached for at least 36 hours.”
May 16, 2016
Christopher Nystuen, MD, MBA