Lyme disease: What is the tick-borne illness that has affected a number of celebrities, from Bella Hadid to Shania Twain to Justin Bieber?

Photos of Bella Hadid receiving health treatments
Model Bella Hadid is being treated for ongoing health problems. Photo credit: @bellahadid / Instagram

By Katia Hetter of CNN

As model Bella Hadid opens up about Lyme disease and other health issues, her ordeal brings up many questions. What exactly is Lyme disease, and how is it contracted and spread? How is the illness diagnosed and treated? What does it mean when someone has "chronic Lyme"? Is there a vaccine for Lyme disease?

To help us with these questions, I spoke with Dr Leana Wen, an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She previously served as Baltimore's health commissioner.

CNN: Can you start by explaining what Lyme disease is?

Dr Leana Wen: Lyme disease is a bacterial infection. The bacterium Borrelia burgdorferi is the most common cause. In rare cases, Borrelia mayonii may cause the illness also. In the United States, Lyme is the most common disease spread by vectors, which are animals like mosquitos and ticks that spread infections. Lyme disease is transmitted through the bite of a particular tick, the black-legged tick (Ixodes scapularis and Ixodes pacificus).

There are three stages of Lyme disease. The first stage is early localised disease that begins within a day to four weeks after the tick bite. People develop flu-like symptoms such as headache, muscle aches and fatigue. Some develop a characteristic "bull's-eye" rash known as erythema migrans.

The second stage occurs three to 12 weeks after the initial infection. This is the "early disseminated" stage in which people have more widespread symptoms. These can include dizziness, chest pain, palpitations, arthritis and facial nerve paralysis.

The third stage is "late disseminated" disease, which can occur months after infection. Here, again, there is a constellation of symptoms. They include ongoing joint pain, fatigue, depression, palpitations, and other neurological, rheumatological and cardiac involvement.

CNN: How is Lyme disease treated, and why is it important to get prompt treatment?

Wen: Early diagnosis and prompt treatment can prevent complications and the progression to the next stages of disease. The standard treatment is antibiotic therapy. Most people are cured after taking oral antibiotics for 10 to 14 days.

Preventive therapy is common, too. If someone has been bitten by a black-legged tick, also known as a deer tick, in an area of the country known to have Lyme, they could take one dose of the antibiotic doxycycline to prevent Lyme infection. This should be done within 72 hours of the tick bite. It's important to carefully remove the tick if it's still attached. Take a picture and take it with you to the doctor's appointment, or send the picture to your provider if you're having a telemedicine visit.

CNN: Is there a blood test one could take to see whether they have Lyme disease?

Wen: Yes, though there are several limitations. The most common tests are antibody tests, which detect antibodies the body makes in response to infection. These tests probably don't turn positive until several weeks after infection, so if someone just got infected and took the test, it will be negative even if the person has Lyme. In addition, the antibodies could persist in the blood for months or even years, but their presence alone does not signify that Lyme disease is the cause of all the symptoms a person may have. False positives can also occur, with some other tick-borne diseases and autoimmune illnesses triggering a positive result in the absence of Lyme disease.

CNN: Then how is Lyme disease diagnosed?

Wen: Typically, it's diagnosed through careful symptom documentation and an exposure history. Physical signs, such as the characteristic rash, enlarged lymph nodes or joint swelling, can aid in the diagnosis, as well. Blood testing can help but has limitations, as I mentioned earlier. The provider often presumptively treats with antibiotics based on the clinical history.

CNN: What does it mean when someone has "chronic Lyme"?

Wen: There is a condition called post-treatment Lyme disease syndrome, or PTLDS. This refers to people who have had Lyme disease but, six months or longer after completing treatment, still have persistent symptoms. These symptoms can include fogginess, difficulty thinking, ongoing fatigue, and nerve and joint pain.

It's not known why some people develop PTLDS. There are several hypotheses, including a persistent infection or autoimmune response. The symptoms of PTLDS can be treated, but there is no proven cure.

The term "chronic Lyme disease" includes people who have PTLDS. It is sometimes also used to describe symptoms in people who have not been diagnosed with Lyme disease. According to the National Institute of Allergy and Infectious Diseases, "because of the confusion in how the term (chronic Lyme disease) is employed, and the lack of a clearly defined clinical definition, many experts in this field do not support its use."

In my experience as a physician and patient advocate, I have met many people who believe they have this condition and are really suffering. Many are debilitated as a result and unable to function as they previously did. Just like long COVID and other similar conditions, there is much that we do not understand about this condition. Far more research needs to be done in order to alleviate the very real agony and distress that these patients are experiencing.

CNN: Is there a vaccine for Lyme disease?

Wen: There are several vaccines against Lyme disease for dogs. For humans, there are some late-stage clinical trials that are ongoing, including one by Pfizer that could be submitted for regulatory approval by 2025.

CNN: What are ways to avoid contracting Lyme?

Wen: Without a vaccine, the best way to prevent Lyme disease is to prevent tick bites. If you are going to areas where ticks known to carry Lyme are found, wear long-sleeved shirts and pants. Use insect repellent that contains DEET. Once you return indoors, examine yourself - and children and pets - for ticks. Remove the tick if found, and immediately contact your primary care provider to ask about preventive antibody treatment. And stay alert for symptoms, since early antibiotic therapy is crucial to prevent longer-term consequences.

Note: According to DermNet New Zealand, Lyme disease is common in parts of the United States (particularly in Massachusetts) and Europe but is reported from many areas of the world.

In New Zealand and Australia, cases have only been confirmed in people that have recently travelled from an endemic area.