High-Risk Scenarios: Infants and Malignant Pertussis

For most people, whooping cough is a long and exhausting illness. However, for infants—especially those under three months of age—it can occasionally become a severe medical emergency known as malignant pertussis ^[1][2].

Important Note: While these descriptions of intensive care are frightening, it is important to know that malignant pertussis is a rare complication ^[3]. We provide this information so you know what to look for and can advocate for your child, not to cause unnecessary panic.

What is Malignant Pertussis?

Malignant pertussis is defined by a dangerous “perfect storm” of three main factors:

1. Hyperleukocytosis: An extremely high white blood cell count ^[3][4].
2. Pulmonary Hypertension: Dangerously high blood pressure in the arteries of the lungs ^[1][5].
3. Respiratory Failure: The inability of the lungs to get enough oxygen into the blood ^[1].

The Danger of High White Blood Cells

White blood cells are usually the “soldiers” that fight infection. However, in malignant pertussis, the body produces so many of them that they begin to clump together ^[6]. These clumps can physically block the tiny blood vessels in the lungs, making it nearly impossible for blood to flow through and pick up oxygen ^[6][5]. This blockage is a primary cause of pulmonary hypertension, which puts immense strain on the baby’s heart ^[1].

Red Flags for Parents and Guardians

In the earliest stages, severe pertussis may look like a standard infection. Watch for these “red flags” that indicate the disease may be progressing toward a more severe state:

• Rapid Breathing (Tachypnea): Breathing that remains very fast even when the baby is not coughing ^[7].
• Fast Heart Rate (Tachycardia): A heart rate that stays high even during sleep ^[8].
• Poor Feeding and Lethargy: A baby who is too tired to eat or difficult to wake up ^[7].
• Low Urine Output (Oliguria): Fewer wet diapers than usual, which can be a sign that the heart is struggling to pump blood to the kidneys ^[1].

Specialized ICU Care

If a baby develops malignant pertussis, they will require care in a Pediatric Intensive Care Unit (PICU). You may hear the medical team discuss advanced treatments designed to bypass the blocked lung vessels and lower the white blood cell count.

Exchange Transfusion and Leukapheresis

These are specialized procedures aimed at rapidly reducing the number of white blood cells. Exchange transfusion slowly removes the baby’s blood and replaces it with donor blood to “wash out” excess cells and toxins ^[9][8]. Leukapheresis is a mechanical filtering method used alongside transfusions to directly filter and remove white blood cells from the bloodstream ^[10]. When performed early, these can be life-saving interventions to reduce the pressure on the lungs and heart ^[8].

ECMO (Extracorporeal Membrane Oxygenation)

In the most critical cases, the medical team may use ECMO ^[11]. This is a machine that acts as an external heart and lung. It takes the baby’s blood, adds oxygen, removes carbon dioxide, and pumps it back into the body, allowing the heart and lungs to rest while the infection clears ^[11][12].

While these treatments are intensive, they are the most powerful tools available to help the smallest patients survive the most severe form of whooping cough ^[8]. Early recognition and transfer to a specialized hospital are the most important steps in managing this high-risk scenario ^[13][14].