Tick-borne diseases are on the rise as climate change affects the growth of ticks and their distribution across the US. The emergence of ticks after the winter thaw brings with it a growing risk of zoonotic infections, which are infections that are transmitted from animals to humans. Lyme disease, one of the most common tick-borne infections, was previously limited to the Northeast, Minnesota, and Wisconsin, but is now found throughout the Midwest and along the East Coast. Anaplasmosis, spotted fevers, Babesiosis, Ehrlichia, and other infections are also becoming more prevalent. In addition to infections, tick bites can also cause red meat allergy or alpha-gal syndrome. To protect against these illnesses, it’s important to take preventive measures, which will be discussed in an upcoming post. If symptoms such as an unusual headache or rash occur after a tick bite, it’s essential to seek medical attention from a doctor who is familiar with the types of infections seen in their region.
Tick-borne diseases, including Lyme disease, are becoming more prevalent due to climate change and the increasing range of ticks. In the US, approximately 476,000 people are diagnosed and treated for Lyme disease each year, which is a significant increase from previous years. Although the disease was initially limited to the Northeast, Minnesota, and Wisconsin, it’s now found throughout the Midwest, the East Coast, and in some cases, in California and the Pacific Northwest. Rural Lyme disease has increased by 357% from 2007 to 2021, and the fragmentation of forested areas has contributed to the spread of the disease as the predators for the host white-footed mice decrease. A recent meta-analysis suggests that antibodies to Borrelia burgdorferi sensu lato, the bacteria that causes Lyme disease, are found in more than 14% of the world’s population, including Europe and eastern Asia.
There are an increasing number of tick-borne illnesses to be aware of, such as anaplasmosis, which is transmitted by the black-legged tick (Ixodes scapularis or Ixodes pacificus in the west). A person who suddenly experiences symptoms such as a bad headache, chills, nausea, and achiness while in areas where these ticks are prevalent may have contracted anaplasmosis. Diagnostic tests for many tick-borne illnesses are often unreliable, and an accurate diagnosis may require the expertise of a physician who is familiar with the disease. Although anaplasmosis is less common than Lyme disease, with only around 5,600 cases reported in 2019, it can be severe if left untreated.
Spotted fevers are another group of tick-borne illnesses to be aware of. While Rocky Mountain Spotted Fever is the most well-known, the rickettsial infection transmitted by the dog tick is most commonly seen in the Carolinas, Tennessee, Missouri, Arkansas, and Oklahoma. This type of infection can be fatal, with a death rate of 5-10%. Similar spotted fevers are found in the West, and the CDC now groups these illnesses together. In 2019, there were 5,200 reported cases of spotted fever infections, with a recent increase in cases in Arizona.
Babesiosis is another parasitic infection that is transmitted by the black-legged or deer tick. In addition to the flu-like symptoms mentioned earlier, this disease can also cause a particular type of anemia called hemolytic anemia, which is characterized by the destruction of red blood cells. Babesiosis can also lead to jaundice and dark urine. People with weakened immune systems, such as those with cancer, AIDS, or who have had their spleen removed, as well as the elderly, are particularly vulnerable to this disease. The parasites that cause Babesiosis can be observed under a microscope, making diagnosis possible. Treatment usually involves a combination of antibiotics.
Ehrlichia is a disease that is transmitted by the Lone Star tick. Cases of Ehrlichia have increased tenfold in the past two decades, with around 2,000 cases reported annually. Most patients with Ehrlichia are located in the Southeast or South Central US, as well as New York. Unfortunately, there are no unique symptoms or reliable diagnostic tests for Ehrlichia. Treatment for Ehrlichia, like most other tick-borne infections, usually involves the use of doxycycline.
Other tick-borne infections:
Tularemia is a rare disease that can be transmitted by dog ticks, wood ticks, or Lone Star ticks, as well as skin contact or aerosolizing infection from dead rabbits or landscaping. Symptoms of Tularemia can range from ulcers to swollen glands to pneumonia. Fortunately, this disease is rare, with only 150-250 cases reported annually. Specific antibiotics and specialist care are required for treatment.
The Powassan virus is unique to the Northeast in that the tick only needs to be attached to a person for a few minutes, as opposed to hours, to transmit the disease. Heartland virus, which is transmitted by Lone Star ticks, is found in the Midwest and South, and has been reported in fewer than 100 cases total. Symptoms are similar to those of Ehrlichia and can include low white blood cell and platelet counts.
STARI (Southern tick-associated rash illness) is characterized by a rash that is similar to Lyme disease and is transmitted by the Lone Star tick. Rickettsia parkeri, which is transmitted by the Gulf coast tick and has recently been spotted in Arizona, can cause a scab or eschar at the site of the tick bite, with symptoms similar to those of Rocky Mountain spotted fever but milder.
Tick-borne relapsing fever (TBRF) is transmitted by soft ticks in the Western US and Rocky Mountains and is associated with cabins and vacation homes. 364D rickettsiosis (Rickettsia phillipi) can cause Pacific Coast tick fever and rickettsialpox, which are associated with an eschar or dark scab at the site of a tick or mite bite.
In addition to infections, tick bites can also cause Alpha-gal syndrome, a red meat allergy that typically follows bites from Lone Star ticks. Symptoms can include rash and diarrhea and may be severe.
Symptoms of tick-borne infections
Tick-borne infections can have a range of symptoms, which can make diagnosis challenging. However, some common symptoms of tick-borne infections include fever, headache, muscle aches, and fatigue. Some infections, such as Lyme disease, may also cause a characteristic bull’s-eye rash at the site of the tick bite. Other symptoms can vary depending on the specific infection and may include joint pain, swollen lymph nodes, nausea, vomiting, and diarrhea. In severe cases, tick-borne infections can lead to neurological symptoms such as confusion, paralysis, or seizures. It is important to seek medical attention if you experience any of these symptoms after a tick bite or exposure to tick habitats.
As the ranges of ticks and the diseases they transmit continue to expand, it is becoming increasingly important to be aware of the potential risks associated with tick bites. Diagnosis of many of these infections may require the expertise of an infectious disease specialist or a local physician with knowledge of the infections prevalent in their area. It is essential for patients to provide a detailed history of exposure to potential tick habitats, such as hiking trails or camping sites, as this can aid in diagnosis.
Symptoms of tick-borne infections can vary greatly, and it is crucial to seek medical attention if unusual symptoms such as severe headaches, muscle aches, or rashes develop after a tick bite. Some infections may present with an eschar or scab, which can be a critical clue in identifying the underlying cause.
Preventing tick bites is the best approach to avoid these illnesses, as many of the ticks that carry infections such as Lyme disease are small and may be difficult to spot. In an upcoming post, we will explore the most effective preventive measures to help reduce the risk of tick-borne illnesses.
Centers for Disease Control and Prevention. (2021, April 21). Tickborne diseases of the United States. Retrieved from https://www.cdc.gov/ticks/tickbornediseases/index.html
Updates on Borrelia burgdorferi sensu lato complex with respect to public health – PubMed (nih.gov)
Please note that the information provided is not intended to replace the advice of a medical professional. If you are experiencing any symptoms or concerns, it is important to seek medical attention from a qualified healthcare provider.