Winnebago County has had 38 cases of whooping cough since the end of October, compared to just one case in all of last year.
The northern Illinois county's health department says 28 of the cases involve a private school. The other 10 are unrelated to that group.
The health department says school administrators and local medical facilities have been notified. Those striken range from infant-aged to 75 years old. No one has died or been hospitalized.
Whooping cough -- also known as pertussis -- is transmitted through coughing, talking and sneezing and produces a rattling
Symptoms typically appear five to 10 days after exposure but can take up to 21 days. The symptoms can linger for months and cause
patients to lose sleep and weight.