It's a sound that many thought was long gone, but it's a sound that has been creeping back up in the United States.
Colorado has reported more than 1,000 cases of it this year alone.
It's the sound of whooping cough.
According to Dr. Jeffrey Thomas from Lovelace Health Center, whooping cough is caused by the bacterium Bortetella pertussis.
"It's a highly contagious disease that's spread from person to person through respiratory droplets, like sneezing and coughing," Thomas said.
Infants are more at risk to contract the disease, but not the only ones. La Cueva High School has reported 32 of their students have whooping cough with two more possible cases.
"Everyone is susceptible to whooping cough, especially those who haven't been vaccinated," stated Dr. Thomas.
The best way to try and prevent the disease is to get the vaccine.
People who complete their five shots before the age of six years old are eight times less likely to get whooping cough than those who are never vaccinated.
Our 4 On Your Side team has been searching for clues as to why there has been a resurgence of whooping cough and other childhood diseases we thought were long gone.
What they uncovered will surprise you, especially when you learn which areas are most at risk.