Whooping cough

Whooping cough, also known as pertussis, is a highly contagious bacterial respiratory infection that causes violent coughing spells that end in a characteristic "whoop" as the person tries to fill his or her lungs.


Causes/associated factors
Whooping cough is caused by the bacterium Bordetella pertussis. The infection typically spreads by inhaling infected respiratory droplets that were coughed or sneezed into the air. Then, the bacteria grow in the nasal passages and move down to the breathing tubes and lungs. There, the bacteria cause inflammation, resulting in the production of thick secretions that may block the airways and cause coughing, a lack of oxygen or pneumonia (a lung infection).
Whooping cough is most common in children younger than age 5, but it can affect older children and adults as well. The condition is most serious for infants. Whooping cough occurs at any time of the year, but may be more likely in the summer and fall. If you contract whooping cough once, you're unlikely to get it again. Reinfection years later is possible, however. Adolescents and adults who were immunized long ago or didn't receive the full series of immunizations can become infected. Although these adults often have mild symptoms, they can still spread the infection.

Although the incidence of whooping cough in the United States has increased recently, vaccination has greatly reduced the prevalence of whooping cough. Infants don't receive protective antibodies from their mothers at birth, so immunization must begin early.


Transmission
The incubation period (time from exposure until symptoms appear) for whooping cough is usually seven to 10 days, but may range from four to 21 days. Again, the bacteria usually enter your body when you inhale infected respiratory droplets in the air. It's quite common for members of the same household to infect each other. And the infection doesn't spread from children alone. Infected adults can transmit whooping cough to infants and susceptible children who haven't completed the vaccination series.
Whooping cough is highly contagious. You can spread the infection to others as early as seven days after you're exposed to the bacteria. You're the most contagious during the first stage of illness, before severe coughing begins. Without antibiotic treatment, you'll be contagious up to three weeks after the coughing stage begins. Antibiotics reduce this contagious period to just five days after beginning treatment.


Signs/symptoms
Whooping cough can last up to six to 10 weeks. The infection has three stages: early, cough and convalescent. The classic symptoms of whooping cough are most common in children between ages 6 months and 5 years. For this age group:
During the early stage, which lasts one to two weeks, symptoms often include a mild, dry cough; a runny nose; sneezing; lack of appetite; red, watery eyes; and possibly a slight fever.

During the cough stage, which usually lasts one to six weeks, the dry cough gets progressively worse as thicker secretions accumulate in the lungs. These secretions make it hard for the lungs to get oxygen into the body. The cough is the body's attempt to clear these secretions. When coughing attacks come one after the other, the lack of oxygen can be severe. Severe coughing attacks may last up to a minute and deprive the child of air, causing his or her face to turn red or blue. At the end of the coughing spell, there's a "whooping" sound as the child gasps for air. The child may then cough up thick, clear secretions and eventually vomit

During the convalescent stage, which lasts two to three weeks, the cough diminishes and gradually goes away. The cough may return if the child develops a cold or other respiratory infection in the months following the illness.
For infants younger than age 6 months, the early stage of the illness usually lasts only a few days. Sometimes, it's so mild it may go unnoticed. Then, there's choking and a gasping cough. Some infants actually have episodes of stopped breathing. The coughing may be induced by feedings.

Children older than age 5 and adults often have milder symptoms with a persistent dry cough, but no "whooping."


Diagnosis
The doctor will ask questions about your medical history and do a physical exam. Lab studies of nasal secretions or, in some locations, blood tests for antibody screening can confirm the presence of whooping cough, particularly early in the infection. Once the cough stage has begun, blood tests may indicate an extremely high white blood cell count.

Treatment
Infants who have whooping cough are usually hospitalized. Treatment may include suctioning the secretions, oxygen therapy and intravenous fluids (if it's hard for your baby to drink). Antibiotics or steroids may also be given. At home, make sure your baby gets plenty of rest, stays calm, avoids respiratory irritants, and eats and drinks often in small amounts.
For both children and adults, the antibiotic erythromycin is typically prescribed to treat whooping cough. It'll shorten the amount of time you're contagious, but won't ease the symptoms of the infection unless it's taken at the beginning of the cough stage or even earlier. For those who can't tolerate erythromycin, the medication trimethoprim-sulfamethoxazole may be prescribed.

If you think you've developed whooping cough, contact your doctor right away. Prompt treatment can reduce the chance that you'll spread the infection to your family or others. In some cases, the doctor may recommend isolation or antibiotic treatment for the entire family.


Complications
Infants younger than age 6 months have the highest risk for complications. Children in preschool who haven't completed the entire whooping cough vaccination series are also at risk for complications.
Although coughing usually helps clear the lungs, the characteristic cough of whooping cough is so violent that it actually causes problems. For example, forceful coughing may lead to:

ruptured blood vessels in the whites of the eyes
fine bruises on the upper body
nosebleeds
collapsed lung
broken ribs
retinal detachment (a separation of the retina from the back of the eye that can cause loss of vision or blindness without proper treatment)
hernia (protrusion of a loop of the intestine through the abdominal wall)
ruptured disc in the spinal column
angina (chest pain caused by inadequate circulation of blood to the heart muscle)
brain damage due to ruptured blood vessels in the brain
The most common complication of whooping cough is pneumonia. Other complications may include:

dehydration and weight loss from recurrent vomiting
ear infections
seizures
In extreme cases, pneumonia may become so severe that the body can't get enough oxygen to survive.


Pregnancy-specific information
Whooping cough appears to have no harmful effects on a developing baby.

Senior-specific information
Adults older than age 65 may be susceptible to whooping cough due to waning immunity, especially if booster doses haven't been given. In fact, whooping cough outbreaks have been reported among older adults.

Prevention
Before exposure
Vaccination is the best defense against whooping cough and its complications. The combination diphtheria, tetanus, pertussis vaccine (DTP) has been used for many years. However, the Centers for Disease Control and Prevention (CDC) now recommends a more sophisticated form of the vaccine called DTaP (for diphtheria, tetanus and acellular pertussis) to reduce the likelihood of side effects. Five injections of the vaccine are recommended before age 7 (at ages 2 months, 4 months, 6 months, 15 to 18 months, and 4 to 6 years), with a booster shot between ages 11 and 12.

After a whooping cough diagnosis
If you have whooping cough, early antibiotic treatment is important. Isolate yourself from anyone who may be susceptible to the infection -- especially young children and infants -- until your doctor says you're no longer contagious. Without antibiotic treatment, you'll be contagious up to three weeks after the coughing stage begins. If you're on antibiotics, you'll be contagious for the first five days of treatment.

Household and other close contacts
A 14-day course of the antibiotic erythromycin or trimethoprim-sulfamethoxazole is usually prescribed for anyone who lives with or has close contact with a person who's been diagnosed with whooping cough. For children younger than age 7 who haven't received four doses of the DTP or DTaP vaccine or who completed the primary series but haven't had a dose in the last three years, the vaccine is given as soon as possible.