A rise in reported whooping cough, or pertussis, cases this year has the Centers for Disease Control and Prevention (CDC) predicting that 2012 will have the highest number of cases since 1959. Several factors have contributed to this rise in whooping cough, and researchers and officials are working to educate the public on prevention, as well as find new ways to enhance the effectiveness of the vaccine.

What is whooping cough?

Whooping cough is a highly contagious bacterial infection, Bordetella pertussis, that is spread by airborne droplets of fluid after coughing or sneezing. The bacteria affects the lining of the trachea and bronchi  -  the windpipe and two airways that branch out to the lungs.  Early symptoms of pertussis are similar to a cold, with runny or congested nose, a feeling of malaise, a slight fever, sore throat, sneezing, watery eyes and a dry cough.

These signs typically last for a couple of weeks before symptoms worsen. In later stages, whooping cough causes severe episodes of coughing with phlegm and a “whoop” sound as the person gasps for air. Coughing episodes can last for two minutes, with several episodes occurring one after the other.  These symptoms can last over two weeks, even after treatment.

Babies and young children may not make a whooping sound after the cough, and may instead gasp, gag or even stop breathing. This can become so severe that the child dies. So far this year nine children have died from whooping cough, according to NBC news.

Severe symptoms are less common in older children, adults and people who have been vaccinated.

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Who is at risk?

Babies and young children are most at risk for whooping cough, particularly babies and children who have not been vaccinated, says Kathryn Edwards, M.D., professor of pediatrics at Vanderbilt University, and secretary of the Infectious Disease Society of America.

Dr. Edwards, an infectious disease specialist in pediatrics, has been working on the whooping cough vaccine for many years.  “One vulnerability is that we are not able to vaccinate before six weeks of age,” she says.

Why is whooping cough in the news?

According to the CDC, 18,000 cases of whooping cough have been reported already this year, which is over double the total recorded for 2011 and is now considered an epidemic. In addition, some states have experienced a sharp rise in cases. Washington State has seen a 1,300 percent increase in cases during the first six months of 2011,  and it declared a state of emergency in April.  Several other states have also seen an uptick in cases, including Wisconsin, New York, Kansas, Arizona, Minnesota and Colorado.

Why is the rate so high?

There are a number of factors contributing to the high rates of whooping cough, says Dr. Edwards.  “We now have a greater appreciation that the youngest children are always at the greatest risk for whooping cough, particularly the ones so young that they haven’t been vaccinated.”