It’s tick season again, North America. As the weather warms and people go outside, the chances of encountering one of these bloodsucking arthropods increases. In fact, tick problems today appear to be worse than they were 50 or 60 years ago, experts told Live Science.
It pays to be careful; ticks cause at least 50,000 cases of illness in the United States each year, and these are only the illnesses that are diagnosed and reported to the Centers for Disease Control and Prevention (CDC).
In fact, the actual occurrence rates of tick-borne diseases are likely much, much higher. For example, an estimate 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, because sometimes people are treated for Lyme as a precaution after being bitten by a tick.)
Although there is no single national surveillance system that detects all cases of tick-borne disease, the risk clearly varies from state to state. In the Northeast, where the deer tick (Ixodes scapularis) thrive, Lyme is a concern. In the Southeast, where the dog ticks (Dermacentor Variable) tend to reside, spotted fevers, including the somewhat misleadingly named Rocky Mountain spotted fever, dominate.
Related: 9 out of 10 ticks in this Pennsylvania park carried a potentially deadly neurological virus
Encounters with ticks are increasing
Ticks are effective disease spreaders because they can feed on multiple host animals and because they stay attached to their hosts for several days, allowing enough time for pathogens to spread, said Jerome Goddard, professor extension course in medical entomology at Mississippi State University.
Booming deer populations are a major reason for increased tick encounters, Goddard told Live Science. Ticks find food by ambushing passing animals, he said, and if the ticks don’t find a host, they die. When more deer are present, more ticks survive, which means deer and tick populations are intimately linked. The development of rural areas, bringing people closer to ticks, also plays a role, According to the CDC. To finish, climate change can alter ranges of ticks and tick pathogens in ways that are not yet fully understood, also potentially increasing the likelihood that people will interact with ticks.
According to the CDC Tick bite data tracker, May and June are the peak months for tick bites that send people to the emergency room. During those months, the Northeast sees the most tick-related ER visits per 100,000 people, followed by the Midwest and then the Southeast.
Lyme disease, caused by bacteria Borrelia burgdorferi 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 at higher risk for spotted fevers, including Rocky Mountain spotted fever, which is caused by the bacteria Rickettsia rickettsia.
Ehrlichiosis, a bacterial infection transmitted by both deer ticks and the lone star tick (Amblyomma americanum), is most commonly reported in the mid-Atlantic, south, and in Arkansas, Missouri, Oklahoma, and Kansas.
Typically, these tick-borne bacterial infections present with symptoms such as fever, headache, rash, and chills. They can all be treated with antibiotics when caught early, but missed infections can be deadly. Infections can also cause long-term problems. For example, a subset of people who get ehrlichiosis subsequently develop an allergy to red meat, Previously reported Live Science.
These bacterial diseases have long been a consequence of tick bites. More recently, however, doctors and scientists have identified a host of viral diseases that ticks also transmit. These include Heartland and Bourbon viruses, which have been reported primarily in the South and Midwest. These viruses can cause fever, fatigue, headache, diarrhea, joint pain, and sometimes a drop in the number of platelets and white blood cells. There is no treatment for these viruses. Most people recover, but some patients have died. More serious is the Powassan virus, spread most often by ticks in the Northeast and Great Lakes regions, which is capable of infecting the brain and membranes around the spinal cord.
Control of 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 working to develop vaccines against emerging tick-borne viruses, particularly the Powassan virus. These viruses transmit immediately when a tick bites, Thangamani told Live Science, so vaccines are needed that prevent the viruses from replicating in the human body and spreading beyond the skin.
Bacterial diseases are another story. In most cases, the bacteria that cause these illnesses take 24 to 36 hours after the initial bite to spread. Instead of trying to develop vaccines for each individual disease, Thangamani and other scientists are looking for vaccines that target the ticks themselves.
An effective tick vaccine would work by targeting a cocktail of proteins found in tick saliva. Ticks inject a dynamic mix of these proteins during their feeding days to anesthetize the skin and escape the host. immune system. Animal tests conducted by researchers at Yale University have shown that a tick vaccine may interfere with tick feeding and cause them to rapidly deposit their host, Live Science previously reported.
“I think in the next three to five years we should have good candidates” for vaccines, Thangamani said.
In the meantime, the best defense is a good offense. To avoid tick bites in the first place, dress appropriately when in areas with high tick density, Goddard advised. Pulling your pants into rubber boots — or at least your socks — can ward off ticks.
“If you’re wearing boots, leather boots, that come up to your ankles and your pant legs flutter in the breeze, it’s a highway to your pant legs,” Goddard said.
Treating your clothes with a spray containing the insecticidal permethrin will kill ticks on contact. (Bug sprays containing DEET also help, Goddard said, but not as effectively.) Finally, it’s essential to check your body for ticks after outdoor activities, Goddard said. If you find an attached tick, remove it immediately with tweezers by grasping it close to the skin and pulling upwards.
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 will test ticks for disease, 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 managed by Thangamani’s laboratory. The researchers tested nearly 20,000 ticks, mostly from New York state, and have a real-time state data dashboard showing which pathogens are present in which counties.
“The real-time presentation of data is what’s very unique and very, very powerful,” Thangamani said.
Originally posted on Live Science
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