The number of pertussis cases in Minnesota is surging, approaching 700 cases of the highly-contagious respiratory disease, according to the Minnesota Department of Health.
That's more than double the number of cases reported earlier this month, and exceeds the total number of cases reported last year.
Pertussis causes an uncontrollable, violent cough. The disease is often referred to as whooping cough because of the sound that many people make as they gasp for breath.
It's a scary and sometimes fatal disease. Infants are most at risk for severe complications including pneumonia, dehydration and seizures. Even adults can have a hard time recovering from the intense cough.
"Sometimes they can cough so hard that they break ribs or break the blood vessels in their eyes," said nurse practitioner Patsy Stinchfield, director of Infectious Disease Services at Children's Hospitals and Clinics of Minnesota.
"They call it the 100-day cough. And it really is true that you can have these cough spasms for up to 100 days," she said.
People who have pertussis are usually infectious for the first three weeks of their illness. The disease spreads easily during this time, which is why outbreaks are often seen in clusters at the community level.
Minnesota's outbreak is scattered across several counties including Hennepin and Ramsey Counties. Nearby Wright County, just west of the metro area, is also reporting a higher than usual number of cases, with 77 so far. Pertussis clusters are centered mainly in the eastern part of the county around St. Michael, Rockford, Delano and Monticello.
"All of 2010, we had 97 cases for the entire year and that was a record for us," said Christine Austin-Roehler, health promotion coordinator for Wright County Public Health. "If you look at the fact that we have 77 cases already and the year's not even half over with, it is a lot of cases."
Most children are vaccinated for pertussis before enrolling in school. But the vaccine starts to wear off by adolescence. A booster vaccine has been available for adolescents and adults since 2005, but many people don't get the booster.
The state has had good vaccination rates among adolescents who are due for the booster shot, said Claudia Miller, the vaccine-preventable disease surveillance supervisor for the Minnesota Department of Health. That's because they tend to see their health care providers regularly.
But Miller suspects the vaccination rate could be better among adults.
"We don't have a good way to measure our coverage in the adult population, but we're concerned that we're not seeing the coverage that would be necessary to turn this pertussis incidence around," Miller said. "This is a vaccine-preventable disease and we really should not be seeing hundreds of cases each year if we have good immunization coverage."
Pertussis is a bacterial infection and can be treated with antibiotics. However, the drugs don't do a lot to cure the symptoms, but mainly help reduce the amount of infectious particles a person can pass on to others.