Parapertussis is a mild, respiratory disease caused by exposure to the Bordetella parapertussis (B. parapertussis) bacterium. Bronchial constriction associated with this bacterial illness often causes the individual to make a distinct sound when he or she coughs. It is from this physiological response that the illness’ common moniker of whooping cough is derived. Antibiotics are generally given to treat parapertussis infection. Prompt, appropriate treatment is necessary to prevent complications, including death.

Diagnosing this form of whooping cough is often a process of elimination. Symptoms of parapertussis closely resemble those of pertussis, a more severe form of whooping cough, so laboratory tests are generally necessary. Blood and nasal culture tests are usually performed to identify markers consistent with infection and the presence of B. parapertussis. It is possible to receive a dual diagnosis of parapertussis and pertussis.

Exposure to the B. parapertussis bacterium generally occurs when one inhales the noxious particles expelled in an infected person's cough. Settling in the lungs, the bacteria thrive, causing bronchial inflammation and mucus accumulation. In an effort to clear the constricted airways of excess mucus, the individual produces the distinctive, chronic cough. Individuals with bacterial-based whooping cough are usually considered contagious until they have received appropriate treatment.

The incubation period for whooping cough, from time of exposure to symptom onset, can be up to three weeks. It is possible for some people to contract whooping cough and remain asymptomatic, meaning they do not exhibit any signs or symptoms of illness. Initial signs and symptoms may resemble the common cold, specifically a persistent cough, congestion, and sneezing. As airway constriction and mucus accumulation worsens, the individual may cough up phlegm and demonstrate the characteristic “whoop” sound. Shortly after a coughing “fit” it is not uncommon for some individuals to become physically ill.

Significant coughing fits that cause one to strain may compromise blood vessel health and contribute to abdominal discomfort. Excessive mucus buildup can also increase one’s risk for pneumonia and other serious complications. Infection that remains untreated can result in encephalitis, which is an inflammation of the brain that can lead to permanent brain damage.

Individuals with whooping cough are generally given antibiotic medication that must be taken as directed and in its entirety to prevent reinfection. Depending on the severity of illness, hospitalization may be necessary. Individuals with compromised immunity and young children may have pronounced symptoms that trigger complications, including dehydration, necessitating more extensive treatment. Those who reside in the same dwelling as an infected individual may be placed on an antibiotic as a precaution.