Micro Biology

Pertussis, sometimes called "whooping cough," is a sometimes severe respiratory illness caused by the bacterium Bordetella pertussim or. B. pertussi, which is Gram-negative (Todar, 2002). Its reservoir is restricted to humans and possibly other higher primates such as chimpanzees (Todar, 2002). Pertussis can be a mild disease in adults, sometimes misdiagnosed as bronchitis (AMA, 2002), but has a significant rate of mortality in infants. Until a vaccine was developed for B. pertussi, pertussis was a frequent and severe illness among infants in the United States as well as the rest of the world.

It is spread through exposure to the bacteria, by inhaling the B. pertussi from others who have coughed or sneezed (AMA, 2002). Pertussis has an incubation period of one to three weeks (CHP, 2002). Once the infected person becomes ill, the disease presents in two stages. During the first stage, it resembles a milder respiratory illness, with fever, coughing and a general feeling of being ill.

Over the first ten days or so, the symptoms become more severe, especially in young children (Todar, 2002) as the bacteria colonize and grow within the host body. Once inside the lungs, pertussis bacteria produce toxins that interfere with the respiratory tract's normal ability to eliminate germs. Pertussis bacteria also produce chemicals that cause inflammation, damaging the lining of the breathing passages (AMA, 2002). Some of these toxins may aid in the disease's progress by breaking down cell walls and making it easier for the bacteria to take hold (Todar, 2002).

During the second phase of the illness, called the "toxemic" stage," (Todar, 2002) the patient's symptoms become more characteristic of pertussis. The person experiences severe coughing episodes that grow in length as the disease progresses. Severe coughing spells are often followed by a characteristic "whooping" sound as the person gasps for air. The coughing fits are often severe enough to trigger vomiting as well (CHP, 2002). During this second stage, cultures taken from the patient may not reveal the presence of B.

pertussi, although it can be cultured from mucous samples during the first stage. By the second stage of the disease, antibiotics may be ineffective (Todar, 2002). As the disease progresses, the cough, which is dry and forceful, becomes more and more severe. The second, acute stage may last for several weeks, with symptoms lingering for sometimes after the patient is no longer acutely ill (CHP, 2002). Simple life activities can trigger a coughing fit, including eating, crying, or even low levels of activity (CHP, 2002).

Because the early stage of pertussis may not look like a condition requiring early and aggressive medical treatment, and because of the significant mortality rate, especially in infants, prevention is the most important treatment for pertussis. The vaccine, first developed in the 1940's, (AMA, 2002) prevents most cases but is not always effective. If a person does catch pertussis, early treatment with antibiotics (often erythromycin) is crucial, as the disease is much harder to treat in the second stage (Todar, 2002; CHP; 2002).

Once someone has come down with pertussis, all those who have come in contact with that person during the contagion period should be treated with a preventative course of antibiotics or a vaccine booster shot.