Whooping cough is a respiratory illness caused by the bacterium Bordetella pertussis, according to the U.S. Centers for Disease Control and Prevention. Whooping cough, or pertussis, is extremely contagious and usually spreads when an infected person shares breathing space, coughs or sneezes near another.
Early symptoms of whooping cough last about a week or two and include low-grade fever, mild cough and runny nose, explains the CDC. This is the most infectious stage, and babies may show a dangerous symptom known as apnea, which is a gap in the breathing pattern. After a week or two, symptoms become more noticeable, characterized by violent and repetitive coughing fits that end in a "whoop" sound when a person inhales and followed by exhaustion and nausea. This type of coughing may last up to 10 weeks or longer. In the final convalescent stage that lasts from two to three weeks, the coughing lessens although the sufferer is vulnerable to infection from other respiratory diseases.
The most effective prevention against whooping cough is the pertussis vaccine, adds CDC. However, the vaccine is not 100 percent effective. Thus, a vaccinated person is still open to a whooping cough infection if it is widespread, though his infection is in a milder form to that of others who are not vaccinated.