Washtenaw County had highest number of reported whooping cough cases statewide in 2010

Washtenaw County had more reported cases of pertussis than any county in the state in 2010, health officials said Wednesday.

Health care providers reported 233 cases of pertussis, commonly called whooping cough, in 2010 to the Washtenaw County Public Health Department, officials there said this week.

"It is certainly unprecedented in the past 20 years," said Laura Bauman, epidemiologist for the Health Department. The Health Department began tracking pertussis in 1992, she said; through the 1990s, the county had recorded one to three cases each year.

Across the state, health officials reported 1,564 cases of the bacterial infection, the most since 1962, said Joel Blostein, the vaccine preventable disease epidemiologist for the Michigan Department of Community Health.

Washtenaw County health professionals treated a high number of whooping cough cases in 2010.

While the cause for the spike hasn’t officially been determined, Blostein said several reasons could account for the high instance of the disease statewide.

Whooping cough has been traditionally thought of as a child’s illness, he said. But a booster for the vaccine, called Tdap, was developed for adults in the mid-2000s. A Tdap vaccine protects against tetanus, diphtheria and cellular pertussis.

“Once you have an intervention you can use, it sparks interest,” he said. It could have always been occurring in adults all along without being diagnosed, he said.

Better recognition of the disease combined with improved testing methods could also account for the high number of cases. Additionally, he said, pertussis tends to peak on a natural cycle.

Unlike in years past, in 2010, 56 percent of cases were found in adolescents 10 and older and adults.

“If you had looked at pertussis 15 or 20 years ago, you wouldn’t have found much being reported in that age group. It wasn’t that it wasn’t there, it’s that it wasn’t being looked for there,” he said.

The vaccine is not 100 percent effective in preventing the disease, which can be deadly, especially to infants. In February 2010, a 3-month-old child from St. Clair County died from the disease, the only reported whooping cough death in 2010.

Whooping cough in southeast Michigan

In 2010, 1,564 cases of whooping cough were reported to the Michigan Department of Community Health, officials said. Washtenaw County had more cases reported than any other county in the state.

Washtenaw County, 233 cases
Livingston County, 125 cases
Wayne County, 123 cases (29 in Detroit)
Oakland County, 173 cases

The MDCH recommends the siblings, grandparents and care givers of young children receive the Tdap vaccine in order to create a “cocoon” around those most vulnerable to the disease “so the bug doesn’t get to them,” Blostein said.

Other ideas put forth as possible reasons for the surge of whooping cough cases include the theory that the organism responsible for the infection has evolved over time to become more virulent or better able to evade immunity.

“It’s intriguing, but there is no good evidence,” Blostein said.

Whooping cough — its scientific name is pertussis — is highly contagious via respiratory droplets coughed and sneezed out.

According to the public health department, initial symptoms appear seven to 10 days after exposure and usually include:

Low-grade fever, runny nose, sneezing and occasional coughs. The cough becomes more severe in one to two weeks and can last for a month or longer.
Vomiting during severe coughing episodes and turning blue of nails and lips from lack of air.
A feeling and appearance of relative health in between coughing episodes.

In children under 1 year old, complications from the disease can include pneumonia, convulsions and, rarely, brain damage. Pertussis deaths typically occur in infants younger than 2 months.

Juliana Keeping is a health and environment reporter for AnnArbor.com. Reach her at julianakeeping@annarbor.com or 734-623-2528. Follow Juliana Keeping on Twitter