It’s tick season again, North America. As the weather warms and people move outside, the chances of encountering one of these blood-sucking arthropods increase. In fact, tick problems seem to be worse today than they were 50 to 60 years ago, experts told Live Science.
It’s worth being wary of; ticks cause at least 50,000 cases of disease in the US each year, and that’s just the diseases that are diagnosed and reported to the Centers for Disease Control and Prevention (CDC).
In fact, the actual rates of tick-borne illness are probably much, much higher. For example, an estimate for 2021 suggests that 476,000 Americans are treated for Lyme disease alone each year. (This may overestimate the true number of Lyme infections, according to the CDC, as people are sometimes treated for Lyme as a precaution after being bitten by a tick.)
While there is no single national surveillance system that covers all cases of tick-borne diseases, the risk clearly varies from state to state. In the northeast, where deer ticks (Ixodes scapularis) thrive, Lyme is a concern. In the southeast, where dog ticks (Dermacentor variable) tend to reside, spotted fever, including the somewhat misleadingly named Rocky Mountain spot fever.
Related: 9 out of 10 ticks in this Pennsylvania park carried a potentially deadly neurological virus
Tick encounters are increasing
Ticks are effective spreaders of disease because they can feed on multiple host animals and because they remain attached to their hosts for several days, giving pathogens ample time to transmit, said Jerome Goddard, a professor of medical entomology at Mississippi State University.
Budding deer populations are a major reason tick encounters are increasing, Goddard told Live Science. Ticks find food by ambushing passing animals, he said, and if ticks don’t find a host, they die. When more deer are present, more ticks survive, meaning deer and tick populations are closely related. The development of the countryside, bringing people into contact with ticks, also plays a role, According to the CDC† And last but not least, climate change may alter the range of ticks and tick pathogens in ways not yet fully understood, and may also increase the likelihood that humans interact with ticks.
According to the CDCs Tick Bite Data TrackerMay and June are the peak months for tick bites that send people to the emergency room. During these months, the Northeast sees the most tick-related ER visits per 100,000 people, followed by the Midwest, then the Southeast.
Lyme disease, which is caused by the bacteria Borrelia burgdorferic and transmitted by deer ticks, most commonly affects people in the Northeast and Midwest, as does anaplasmosis, another bacterial disease spread by deer ticks. People in the mid-Atlantic and Southeast are more at risk for spotted fever, including Rocky Mountain spot fever, which is caused by the bacteria Rickettsia rickettsia†
Ehrlichiosis, a bacterial infection spread by both deer ticks and the solitary star tick (Amblyomma americanum), is most commonly reported in the mid-Atlantic, south, and in Arkansas, Missouri, Oklahoma, and Kansas.
Usually, these tick-borne bacterial infections present with symptoms such as fever, headache, rash, and chills. All are treatable with antibiotics if caught early, but missed infections can be fatal. Infections can also cause problems in the long run. For example, a subgroup of people who get ehrlichiosis develop an allergy to red meat, Live Science previously reported†
These bacterial diseases have long been a result of tick bites. More recently, however, doctors and scientists have identified a large number of viral diseases that are also tick-borne. These include the Heartland and Bourbon viruses, which have been mainly reported from the South and Midwest. These viruses can cause fever, fatigue, headache, diarrhea, joint pain, and sometimes decreased platelet and white blood cell counts. There are no treatments for these viruses. Most people recover, but some patients have died. More serious is the Powassan virus, which is most often spread by ticks in the Northeast and Great Lakes regions, which can infect the brain and membranes surrounding the spinal cord.
Fighting back against tick-borne diseases
With tick-borne diseases a growing problem, researchers are looking for ways to fight back. At SUNY Upstate Medical University in Syracuse, New York, microbiologist and immunologist Saravanan Thangamani and his team are developing vaccines for emerging tick-borne viruses, particularly Powassan virus. These viruses are immediately transmitted when a tick bites, Thangamani told Live Science, so vaccines are needed that prevent the viruses from multiplying in the human body and spreading outside the skin.
Bacterial diseases are a different story. In most cases, it takes 24 to 36 hours after the first bite for the bacteria that cause these diseases to be transmitted. Rather than trying to develop vaccines for each individual disease, Thangamani and other scientists are pursuing vaccines that target the ticks themselves.
An effective anti-tick vaccine would work by targeting a cocktail of proteins found in tick saliva. Ticks inject a dynamic mixture of these proteins during the days they feed to numb the skin and evade the host. immune system† Animal experiments led by Yale University researchers have shown that a anti-tick vaccine can interfere with tick eating and make sure they drop off their host quickly, Live Science previously reported.
“I think in the next three to five years we should have some good candidates” for vaccines, Thangamani said.
Meanwhile, the best defense is a good offense. To avoid tick bites, dress appropriately in areas with a lot of ticks, Goddard advised. Tucking your pants into rubber boots — or at least your socks — can keep ticks at bay.
“If you’re wearing boots, leather boots, that come up to your ankles and your pant legs flutter in the wind, that’s a highway up to your pants legs,” Goddard said.
Treating your clothing with a spray containing the insecticide permethrin kills ticks on contact. (DEET-containing bug sprays also help, Goddard said, but not as effectively.) Finally, checking your body for ticks after outdoor activities is key, Goddard said. If you find a tick, remove it immediately with tweezers by grasping it close to the skin and pulling straight up.
Mark tick bites on a calendar so that if you get sick in the next few weeks, you can tell your doctor you were bitten and the date of the bite, Goddard said. There are some paid services that test ticks for diseases, as well as a limited number of state health departments and research organizations that will do the same for free. Such an organization, NYticks.org, is run by Thangamani’s laboratory. The researchers tested nearly 20,000 ticks, mostly from upstate New York, and have a real-time state data dashboard showing which pathogens are present in which counties.
“The real-time presentation of data is very unique and very, very powerful,” Thangamani said.
Originally published on Live Science