Lyme disease outbreaks are already being reported this spring, and experts say there’s a long way to go before we grasp the scope and impact of this serious tick-borne illness.

In the early 1990s, Dr. Neil Spector began experiencing odd symptoms.

At times, his heart would beat 200 times a minute. He also suffered crippling fatigue and had “brain fog” so intense he once gave a lecture and had no recollection of it.

Blood tests showed his body was producing high levels of antibodies, but specialists couldn’t determine what was triggering his immune system’s response.

“It said my body was mounting a defense against something,” Spector told Healthline. “They just kept chalking it up to stress.”

More symptoms began appearing — slow heartbeat, arthritis pain, and burning in his heels — but experts dismissed Spector’s theory that they could be signs of Lyme disease, the most common vector-borne infection in humans.

Spector’s symptoms began right after he moved from Boston to Miami, but Lyme disease is uncommon in Florida. Spector said he doesn’t remember ever having the trademark bulls-eye rash of Lyme disease.

Spector, an associate professor of oncology at the Duke University School of Medicine, had no formal training in Lyme disease, but that changed as he searched for an explanation for his symptoms.

“Unfortunately, I had to learn more about the disease than I ever cared to know,” he said. “I could have dropped dead at any moment. During that time, I developed two cancer drugs and traveled the world.”

Initial tests gave false-positive results, but later tests confirmed that Spector’s symptoms were caused by Lyme disease. He was given an aggressive course of intravenous antibiotics for three months.

“I don’t think I have Lyme disease anymore, but the damage to my heart was already done by the time I was diagnosed,” he said.

By 2009, only 10 percent of Spector’s heart was functioning and he underwent a life-saving heart transplant. He recently completed his second half marathon in six months, and detailed his story in the book, “Gone in a Heartbeat: a Physician’s Search for True Healing.”

Spector urges patients to be their own best advocates, just as he did as a medical insider.

“I just don’t think we understand chronic Lyme disease, and the only people suffering are the patients. Nothing in medicine is black and white,” he said. “There’s a significant portion of patients who fall through the cracks of the medical system.”

Get the Facts: What Is Lyme Disease? »

The latest statistics from the U.S. Centers for Disease Control and Prevention (CDC) say that 300,000 Americans are diagnosed with Lyme disease each year. In 2013, the CDC adjusted their annual estimates, saying Lyme disease infection rates were likely 10 times higher than the yearly reported number.

Reported Lyme disease cases were at their lowest in 1995, with 11,700 cases, and peaked at nearly 30,000 in 2013. Ninety-five percent of those cases occurred in 14 states, with the most infections occurring in the Northeast and along the Mississippi River border between Minnesota and Wisconsin.

This spring, Lyme disease outbreaks have been reported in Pennsylvania and Massachusetts. Celebrities suffering from Lyme disease, including Ashley Olsen and Avril Lavigne, have also been drawing attention to the condition.

Amesh A. Adalja, an infectious disease physician at the University of Pittsburgh Medical Center said awareness has increased since Lyme disease was first recognized in the 1970s.

“People need to realize this is imminently preventable,” he said.

Lyme disease develops following an infection with the bacteria Borrelia burgdorferi.It’s transmitted to humans through the bite of infected blacklegged ticks. The tick must be attached to its host for 36 to 48 hours to transmit the bacteria.

Since the ticks live in wooded and high grass areas, preventative measures include wearing clothing to cover exposed skin, using repellant containing DEET, and bathing and inspecting for ticks within two hours of being outdoors.

The blacklegged tick’s prime season is summer. Lyme Disease Awareness Month is May, the usual start of tick season.

However, new research suggests climate change could further accelerate the spread of Lyme disease by giving ticks a longer feeding season.

A 19-year field study published in the journal Philosophical Transactions B of The Royal Society found that warmer years produce feeding tick nymphs — the stage in the tick’s lifecycle in which it’s most likely to infect humans — three weeks earlier than colder years.

Read More: Ticks Infected with Lyme Disease Found in California Parks»

About 36 hours after a tick has found a host, up to 80 percent of infected people develop a rash similar to a bulls-eye — a solid center with a ring around it. Other symptoms that can develop in the coming weeks include fever, chills, aches, and pains.

Doctors diagnose Lyme disease by taking into account a patient’s exposure to ticks, an inventory of symptoms, and a three-part blood test. But the current tests are only effective several weeks after the initial infection, according to the CDC.

Dr. Gary Wormser, a professor of medicine at New York Medical College, saw his first case of Lyme disease in 1981 in Westchester County. Since then, he’s become an expert on tick-borne diseases. He said results from the three-part blood test aren’t foolproof, which is why clinical judgement is so important before treating for Lyme disease.

A 10-day course of standard antibiotics (doxycycline, cefuroxime, or amoxicillin) is typically enough to treat most early Lyme infections. But with potential adverse effects associated with antibiotics — disrupted gut flora, allergic reactions, and drug-resistant bacteria — doctors must be judicious when prescribing them, Wormser said.

“There are lots of reasons why you might want to give an antibiotic, but you don’t,” he said.

There is currently no vaccine against Lyme disease for humans, although there is one available for dogs. In 1998, the company now known as GlaxoSmithKline licensed the first Lyme vaccine for humans, LYMERix. They withdrew it from the market in 2001 amid negative press coverage, poor sales, and lawsuits over short-term adverse reactions.

“Low demand for the vaccine and its subsequent withdrawal from the market represent a loss of a powerful tool for Lyme disease prevention,” a 2007 article in journal Epidemiology & Infection concluded.

A European biotechnology company is developing a new vaccine that acts similarly to LYMERix.

Read More: Chronic Lyme Disease Debate Reaches Washington, D.C.»

Lyme disease, if not initially treated with antibiotics, can cause facial palsy, severe headaches, swelling in large joints, shooting pains, and changes in heartbeat, much like the symptoms Spector experienced.

“Even with all that, I couldn’t convince people it was Lyme disease,” he said.

Up to 20 percent of Lyme disease cases can cause lasting symptoms, including arthritis in the joints, cognitive difficulties, chronic fatigue, and sleep disturbances, even after antibiotic treatment, according to the CDC. This condition is known as post-treatment Lyme disease syndrome (PTLDS).

Outside the medical community, this condition is often called “chronic Lyme disease,” and many who have it believe they have an ongoing infection that warrants regular and continued use of antibiotics. These include some people with no diagnosed history of Lyme disease.

While the cause of PTLDS remains elusive, experts stress these symptoms aren’t related to continued infection with B. burgdorferi. The best evidence to date suggests it may be an autoimmune response to the initial infection.

“They really have a fix on what they believe, but there’s no evidence of infection,” Adalja said.

He added there’s no evidence chronic Lyme disease patients get any benefit from long-term antibiotic treatment.

Dr. Richard Horowitz, a Lyme disease expert and author of “Why Can’t I Get Better? Solving the Mystery of Lyme & Chronic Disease,” said a shift away from the one-cause, one-illness paradigm needs to occur to fully understand why people experience such long-term symptoms.

His theory is that chronic infection coupled with environmental factors contribute to “autoimmune dysfunction.”

“When people come and see me for chronic Lyme, I’ve found there is more than one cause,” he said. “The reason they’re staying sick is because of the chronic inflammation.”

Having treated more than 12,000 patients, Horowitz calls Lyme disease “the great imitator” because its symptoms mimic other conditions like Alzheimer’s disease, chronic fatigue, fibromyalgia, and multiple sclerosis.

“I think the numbers are much higher than we realize,” he said. “No one has any idea why people are getting all of these conditions.”