Monica Weeks was 19 and a freshman in college when her first symptoms appeared.

And it took several visits to different doctors before she was finally diagnosed with Crohn’s disease.

More than five years later, she has a seemingly encyclopedic knowledge of the disease and has learned to manage her condition with infusions of Remicade every seven weeks, alongside eating healthy and exercising.

“People really need to know it can be a debilitating disease, but there are ways to deal with it,” said Weeks, 24, who grew up in Key Largo and now lives and works in Washington, D.C.

Crohn’s disease and ulcerative colitis — both grouped under the term irritable bowel diseases, or IBD — are becoming increasingly prevalent, and doctors don’t exactly know why.

Crohn’s disease is a chronic inflammatory condition of the gastrointestinal tract and may affect any part from the mouth of the tract to the anus. Ulcerative colitis, known as colitis, is a chronic inflammatory condition limited to the colon, otherwise known as the large intestine.

The diseases can manifest within a wide spectrum, from very mild to very severe, and they tend to appear either in the teens and 20s, or else later in life, in the 50s and 60s, doctors say.

Nedra Friedman was in her late 50s when she first experienced symptoms of colitis, and she has now lived with it for more than 15 years. Over that time, she has visited several doctors and tried various treatments. But while her symptoms, including a sudden, urgent need to go to the bathroom, used to come and go, in the last few years it has gotten worse. She is now involved in a clinical trial of a new infusion at the University of Miami.

Meanwhile, she stays away from certain foods that trigger her symptoms, such as dairy, and exercises regularly.

She said the disease hasn’t stopped her. She travels and still eats at restaurants — always making sure she is near a bathroom.

“I don’t cater to it,” said Friedman, who lives in Lake Worth. “If I’m having an attack, I will stay home and read a book or knit.’’

Crohn’s and colitis are known to be more prevalent among Caucasians, and particularly among Ashkenazi Jews. But recent research conducted at the University of Miami shows the diseases also affect more Hispanics than previously thought.

Doctors now believe that IBD may be due to genetic predisposition and environmental influences.

One theory for the increased incidence of IBD is that we may be living in too much of a sterile environment.

“Our immune systems, when we are born, are very immature, and they develop as we come into contact with germs and viruses in the environment, and that induces a kind of immune tolerance,” said Dr. Robert Goldberg, a gastroenterologist at Mount Sinai Medical Center and an associate professor at the University of Miami.

In people suffering from IBD, the immune system mistakes benign or beneficial cells and bacteria for harmful foreign substances. When this happens, the immune system can do harm to the gastrointestinal tract and produce the symptoms of IBD, including diarrhea and abdominal pain, according to the Crohn’s and Colitis Foundation of America.

“Any time diarrhea lasts for more than several weeks it needs to be raised in the differential diagnosis,” Goldberg said. “If it is accompanied by fever, weight loss, blood mixed in with stool, severe abdominal pain — those are indications that it is more than diarrhea.”