What Is Pertussis?
Pertussis, also known as whooping cough, is a highly contagious infection of the respiratory tract caused by the bacterium Bordetella pertussis. It is transmitted only by humans through close respiratory contact with someone who is infected, according to the Centers for Disease Control and Prevention (CDC).
In 2007, pertussis affected about 17.6 million people and caused an estimated 279,000 deaths worldwide.
The number of pertussis cases in the United States peaked in the 1920s to 1930s, before a vaccine became available. At that time, the illness affected more than 250,000 people each year and caused up to 9,000 deaths annually. The prevalence of pertussis declined through 1976, with only 1,010 cases reported that year. Pertussis cases usually occur cyclically, with peaks occurring at three- to four-year intervals, the CDC says.
Since 1977, pertussis cases have been on the rise especially among pre-teens and adolescents ages 10 to 19 years and in infants younger than 5 months old. For instance, in 2007 the CDC reported 10 deaths related to this infection 10,000 cases of pertussis, compared to 4,600 cases reported in 1994.
Adults are a major source of transmission of pertussis to infants and children. Pertussis in adults is often misdiagnosed as bronchitis, because symptoms in adults are milder than in children. Many adults were vaccinated decades ago and, although their immunity has decreased somewhat, they still have enough immunity to reduce the severity of the illness.
It usually takes a week to 10 days after a child has been exposed to the bacteria for symptoms to occur, says the CDC. The symptoms at first are similar to a cold: sneezing, runny nose, fever, and a mild cough. After one to two weeks, however, the coughing becomes worse. The violent spells of coughing may be followed by difficulty in breathing. Symptoms progress to severe coughing spells that can go on for a minute, followed by long, deep breath or "whoop." This stage of the disease lasts one to six weeks, but can continue past that, according to the CDC.
Common complications of pertussis include otitis media (ear infections), pneumonia, periods of not breathing (apnea), acute encephalopathy, and difficulties getting enough nutrients because of vomiting. Some of these complications can be fatal. Pertussis causes 10 to 15 deaths a year in the United States, according to the CDC. Infants under the age of 12 months have more serious illness from pertussis and are more likely to have complications and be hospitalized than older people.
The CDC recommends that children need five DTaP shots for maximum protection against pertussis. A DTaP shot is a combination vaccine that protects against three diseases: diphtheria, tetanus, and pertussis. The first three shots are given at two, four, and six months of age. Between 15 and 18 months of age, the fourth shot is given, and the fifth shot is given when the child enters school at four to six years of age. At regular checkups for 11 and 12 year olds, a pre-teen should get a dose of DTaP. The DTaP booster contains tetanus, diphtheria, and pertussis. If an adult did not get a DTaP as a pre-teen or teen, then he or she should get a dose of DTaP instead of the Td booster. Adults should get a Td booster every 10 years, but it can be given before the 10-year mark. Always consult your physician for advice.