Overview
Pertussis, also known as whooping cough, is a respiratory illness caused by infection with the bacterium Bordetella pertussis. It is characterized by severe coughing fits that can last for weeks, often accompanied by a 'whooping' sound when breathing in, vomiting, and difficulty breathing. While the incidence of pertussis has been significantly reduced thanks to vaccination, it remains particularly dangerous for infants under one year of age, who face a higher risk of complications and death.Causes
Pertussis is caused by the bacterium Bordetella pertussis, a gram-negative organism for which humans are the sole host. It is transmitted via respiratory droplets, typically spread through close contact with an infected person. Adults and adolescents, who may have mild or unrecognized infections, are often the primary source of transmission to infants and children.Symptoms
The illness progresses through three distinct stages over a period of 6 to 8 weeks:1. Catarrhal Stage:
This initial phase, which lasts 1-2 weeks, is marked by symptoms of a mild upper respiratory infection, such as a runny nose, conjunctivitis, mild cough, and low-grade fever. This stage is also the most contagious.2. Paroxysmal Stage:
Starting around the second week of illness, patients experience sudden and intense coughing fits, often resulting in a distinctive 'whoop' as they struggle to breathe between coughs. The coughing may lead to facial redness, bloodshot eyes, and vomiting. Severe episodes may last 2-4 weeks or longer, and can result in complications such as apnea, cyanosis, nosebleeds, and eye swelling.3. Convalescent Stage:
In this recovery phase, the severity and frequency of coughing gradually diminish, though residual symptoms may persist for 1-2 weeks.Diagnosis
Pertussis is diagnosed based on the characteristic cough, history of exposure, and laboratory tests. A culture of nasopharyngeal secretions is often performed, and diagnostic methods such as polymerase chain reaction (PCR) or direct fluorescent antibody testing may be used to detect the bacteria. Additionally, blood tests may show an increase in white blood cells, particularly lymphocytes, during the later stages.Treatment
Infants under three months of age or those with preexisting heart, lung, or neurological conditions usually require hospitalization. Erythromycin is the antibiotic most commonly prescribed during the early stages of illness or within the first two weeks to lessen the severity and prevent transmission. Alternatives include Clarithromycin or Azithromycin. Respiratory isolation is required for at least five days after starting antibiotic therapy, or for up to three weeks from the onset of symptoms if antibiotics are not administered.Complications
Complications of pertussis are more common in infants, particularly those younger than six months. These include bronchopneumonia, atelectasis (lung collapse), bronchiectasis, and emphysema. In severe cases, pertussis can exacerbate pre-existing conditions like tuberculosis or cause middle ear infections. During the paroxysmal stage, low oxygen levels, intracranial hemorrhage, seizures, encephalopathy, and even death may occur.Gastrointestinal complications such as vomiting, ulcers, rectal prolapse, and hernias can also arise due to the violent coughing fits.
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