Over the last two decades, ticks that transmit Lyme disease have found their way into half of the counties in the nation. Lyme disease cases have tripled, and affects approximately 300,000 Americans every year, according to a study published in the Journal of Medical Entomology.

"Since the late 1990s, the number of counties in the northeastern United States that are considered high-risk for Lyme disease has increased by more than 320%," said Rebecca Eisen, a researcher at the U.S Centers for Disease Control and Prevention (CDC). "The tick is now established in areas where it was absent 20 years ago."

Although the tick population has increased, there's still a relatively low chance of coming into contact with one. However, health experts advise avoiding areas with thick vegetation, bathing after hiking, and using a strong repellent.

Unfortunately, even these precautions can sometimes fail to protect you from contracting Lyme and other serious diseases. Massachusetts-based author Jeffrey Diamond learned this the painful way.

Diamond, 67, was experiencing headaches, chills, high fever, and shortness of breath, but he chalked it up to bronchitis. Unfortunately, his condition soon worsened, and his wife rushed him to the hospital.

"I had the worst headache I'd ever had and I was feeling really wiped out," recalled Diamond. "It all came on so quickly and I felt so terrible, I decided waiting another 24 hours might not be smart."

But after tests came up negative, doctors were forced to send him home. The following day, his symptoms were worse than they ever were, so Diamond went to see his GP, who diagnosed him with a rare tick-borne disease that could've been been fatal had it not been caught in time.

What was Diamond suffering from?

Diamond's physician diagnosed him with Anaplasmosis, which is caused by a bacteria carried by the same tick that spreads Lyme disease.

"So when you see an increase in Lyme disease, you'll see an increase in the other tick-borne diseases, like anaplasmosis," said Stephen Morse, a professor of epidemiology at Columbia University's Mailman School of Public Health.

Just like Lyme disease, the CDC has seen a 31% increase in Anaplasmosis cases between 2014 and 2015, and that number has recently gone up.

The disease isn't nearly as fatal as other tick-borne illnesses like, Rocky Mountain Spotted Fever, but in 1 percent of the cases it does cause death, especially when the patient is over 60. This is why Diamond's case was extremely severe.

Luckily, his GP figured out what was wrong just in the nick of time and prescribed the antibiotic doxycycline.

The tricky thing about Anaplasmosis is that unlike Lyme, there is no bull's eye rash to determine if a tick bore into the skin. However, if you live in areas with a heavy black-legged tick population or you spend a lot of time outdoors, here are a few flu-like symptoms to watch out for, according to the CDC:

• Headcahe
• Fever
• Muscle Pain
• Fatigue
• Chills
• Nausea
• Abdominal Pain
• Cough
• Confusion

It has been months since Diamond received treatment for the disease, but his symptoms haven't all disappeared.

"I still have issues with my joints and hands and shoulders," he said. "And I'm still extremely tired. I sleep almost every afternoon," he explained.

He is using this experience to warn others about anaplasmosis. He has written about his illness in two columns published in The Berkshire Eagle.

Have you ever been diagnosed with a tick-borne illness? Let us know!