Pertussis

Introduction to Pertussis and Transmission

Pertussis, commonly known as whooping cough, is a highly contagious acute respiratory infection caused by the bacterium Bordetella pertussis. It remains a significant public health concern in Nigeria, particularly affecting infants and young children who have not completed their routine immunizations. The disease spreads easily through airborne droplets when an infected person coughs or sneezes. Household contacts, especially older siblings and parents with mild or unrecognized infections, are frequent sources of transmission to vulnerable newborns.

Clinical Stages of Pertussis

The clinical course of pertussis progresses through three distinct stages:

1. Catarrhal stage: Lasts one to two weeks, presenting with mild upper respiratory symptoms resembling a common cold, such as lacrimation, low-grade fever, and an occasional mild dry cough. This is the most contagious phase.
2. Paroxysmal stage: Lasts two to six weeks or longer. Characterized by severe, rapid coughing fits ending in a characteristic high-pitched 'whoop' during the inspiratory phase. Post-tussive vomiting and cyanosis are common during this time.
3. Convalescent stage: Lasts weeks to months. Coughing episodes gradually decrease in frequency and severity as the respiratory tract heals.

Pathophysiology and Complications

Bordetella pertussis attaches to the cilia of the respiratory epithelium, producing toxins that paralyze the cilia and cause inflammation of the respiratory tract. This prevents the clearance of mucus, leading to paroxysmal coughing spasms.

Severe complications frequently arise in infants. These include hypoxia, apnea, pneumonia, seizures, and encephalopathy secondary to anoxia. Physical strain from intense coughing can also cause subconjunctival hemorrhages, epistaxis, and umbilical hernias.

Diagnostic Evaluation

Diagnosis is primarily clinical, based on the classic history of paroxysmal cough with a whoop. Laboratory confirmation can be achieved through a nasopharyngeal swab for polymerase chain reaction (PCR) testing or bacterial culture, which is most useful during the early catarrhal or early paroxysmal stages. Complete blood count typically reveals a marked leukocytosis with an absolute lymphocytosis.

Medical Management

Management of pertussis involves supportive care and targeted antimicrobial therapy. Macrolide antibiotics, such as erythromycin or azithromycin, are the drugs of choice. While antibiotics do not immediately stop the coughing spasms if the paroxysmal stage has already begun, they eradicate the bacteria from the nasopharynx, shorten the duration of illness if given early, and reduce disease transmission to others.

Nursing Care and Supportive Management

Nursing care focuses on maintaining patent airways, supporting nutrition, and preventing exhaustion.

• Airway Management: Suction secretions gently as needed, administer humidified oxygen during hypoxic episodes, and keep emergency suction and resuscitation equipment at the bedside.
• Environmental Control: Minimize triggers that can provoke coughing spasms, such as dust, smoke, sudden movements, and loud noises.
• Nutritional Support: Offer small, frequent feeds rather than large meals to prevent post-tussive vomiting from causing malnutrition or aspiration.

Prevention and Immunization

Prevention is achieved primarily through active immunization with the pertussis vaccine, which is routinely administered as part of the pentavalent vaccine (Diphtheria, Pertussis, Tetanus, Hepatitis B, and Haemophilus influenzae type b) in childhood immunization schedules. Pregnant women are also encouraged to receive a booster dose during the third trimester to passively protect newborns before they receive their own vaccinations. Chemoprophylaxis with macrolide antibiotics is recommended for close household contacts of a confirmed case, regardless of their immunization status.