Whooping Cough Health Article

Definition

Whooping cough, also known as pertussis, is a highly contagious disease that causes classic spasms (paroxysms) of uncontrollable coughing, followed by a sharp, high-pitched intake of air, which creates the characteristic whoop of the disease's name.

Description

Whooping cough is caused by a bacterium called Bordetella pertussis. B. pertussis causes its most severe symptoms by attaching itself to those cells in the respiratory tract that have cilia. Cilia are small, hair-like projections that beat continuously, and serve to constantly sweep the respiratory tract clean of such debris as mucus, bacteria, viruses, and dead cells. When B. pertussis interferes with this normal, janitorial function, mucus and cellular debris accumulate and cause constant irritation to the respiratory tract, triggering coughing and increasing further mucus production.

Whooping cough is a disease that exists throughout the world. While persons of any age can contract whooping cough, children under the age of two are at the highest risk for both the disease and for serious complications including death. Apparently, exposure to B. pertussis bacteria earlier in life gives a person some, but not complete, immunity against infection with it later on. Subsequent infections resemble the common cold.

It is estimated that as many as 120,000 persons in the United States get whooping cough each year. The number of cases has been increasing, with the largest increases found in older children and adults. Between 1993 and 1996, the number of cases increased by 40% in five- to nine-year-old children, 106% in 10–19 year olds, and 93% for persons aged 20 years and older.

Causes & symptoms

Whooping cough has four stages that partially overlap: incubation, catarrhal stage, paroxysmal stage, and convalescent stage.

A person usually acquires B. pertussis by inhaling droplets carrying the bacteria that were coughed into the air by someone already suffering with the infection. Incubation is the symptomless period of seven to 14 days after breathing in the B. pertussis bacteria, and during which the bacteria multiply and penetrate the lining tissues of the entire respiratory tract.

The catarrhal stage is often mistaken for an exceedingly heavy cold. The patient has teary eyes, sneezing, fatigue, poor appetite, and an extremely runny nose (rhinorrhea). This stage lasts about 10–14 days.

The paroxysmal stage, lasting two to four weeks, begins with the development of the characteristic whooping cough. Spasms of uncontrollable coughing, the whooping sound of the sharp inspiration of air, and vomiting are all hallmarks of this stage. The whoop is believed to occur due to inflammation and mucus that narrow the breathing tubes, causing the patient to struggle to get air into his/her lungs; the effort results in intense exhaustion. The paroxysms (spasms) can be induced by overactivity, feeding, crying, or even overhearing someone else cough.

The mucus that is produced during the paroxysmal stage is thicker and more difficult to clear than the more watery mucus of the catarrhal stage, and the patient becomes increasingly exhausted attempting to clear the respiratory tract through coughing. Severely ill children may have great difficult, maintaining the normal level of oxygen in their systems, and may appear somewhat blue after a paroxysm of coughing, due to the low oxygen content of their blood. Such children may also suffer from swelling and degeneration of the brain (encephalopathy), which is believed to be caused both by lack of oxygen to the brain during paroxysms, and also by bleeding into the brain caused by increased pressure during coughing. Seizures may result from decreased oxygen to the brain. Some children have such greatly increased abdominal pressure during coughing that hernias result (hernias are the abnormal protrusion of a loop of intestine through a weak area of muscle). Another complicating factor during this phase is the development of pneumonia from infection with another bacterial agent, which takes hold due to the patient's weakened condition.

If the patient survives the paroxysmal stage, recovery occurs gradually during the convalescent stage, usually taking about three to four weeks. However, spasms of coughing may continue to occur over a period of months, especially when a patient contracts a cold, or other respiratory infection.