It's something doctors sometimes have trouble diagnosing since most have never seen it during their careers.
That's what happened to one local teen, 16-year-old Michael Safranka, and his family.
After getting diagnosed with a normal throat infection, things seemed to go wrong quickly.
What his mom, Dawn Safranka, thought was a regular case of strep throat turned into something much more dangerous.
They ended up visiting several doctors, but once Michael started to get sicker and sicker, he ended up at The Children's Hospital in Aurora.
By then, he was so sick he did not even know where he was, and his organs began shutting down.
According to his mom, at one point he could not even open his eyes or lift his head off the pillow. The only thing he kept saying over and over again was that he had a terrible headache.
As she cared for him in the hospital, she remembers he remained in bed and in the fetal position for around three days, not responding too much around him.
Dr. Mary Glode and others at The Children's Hospital were able to diagnose his condition as Lemierre's syndrome. This is something most doctors have not seen since the introduction of antibiotics in the 1940s.
What makes this different from a normal throat infection is how quickly it can spread.
According to Glode, the infection starts in the throat, spreads to the lymph nodes, next to the infected tonsil, and then gets into a nearby blood vessel.
Once there, it forms an infected blood clot. As the clot starts to break up, every piece ends up landing somewhere else in the body and that sets up other sites of the infection.
Once the infection starts to spread this way, the body starts to shut down.
In Michael's case, the infection spread to his lungs, which started to produce infected blood clots of their own.
Luckily for Michael and his family, doctors were able to use clinical clues and lab tests to diagnosis his condition as Lemierre's syndrome.
Once they got the diagnosis, they were able to start a treatment that worked.
After a few days on heavy antibiotics, Michael's mother says he was starting to act normally again. He began to get hungry - a great sign of a healthy teenager.
Although he was discharged from the hospital and is recuperating at home, Michael is still getting intravenous antibiotics three times a day. He has recovered to the point were he is getting a bit antsy just being at home and is ready to get back to school and his friends.
Although Lemierre's syndrome still isn't very common, doctors are seeing more cases nowadays.
According to Glode, most cases occur in adolescents and Children's ends up seeing 5 to 10 cases a year.
According to her, the important lesson from all of this is for parents to know their child. If they appear sicker than you expect for a normal throat infection, or suddenly take a turn for the worse, seek medical attention.
(KUSA-TV © 2010 Multimedia Holdings Corporation)