Pertussis, commonly known as whooping cough, is a highly contagious respiratory illness caused by the bacterium Bordetella pertussis. It spreads when an infected individual coughs or sneezes, releasing airborne droplets that are then inhaled, leading to infection. The disease is recognized for its characteristic severe coughing fits, which can make breathing difficult.
Age and Immunization Status
Infants younger than one year old face the highest risk for severe complications and death from pertussis. Their underdeveloped immune systems struggle to fight off the infection, especially if they have not yet received their full series of pertussis vaccinations or are entirely unvaccinated. These young children are particularly vulnerable to serious outcomes such as pneumonia, seizures, and encephalopathy.
Children who remain unvaccinated are significantly more susceptible to contracting pertussis compared to their immunized peers. The protective immunity gained from childhood vaccinations can also wane over time, leaving vaccinated teenagers and adults vulnerable to infection years later. This reduced immunity means that older individuals can still contract pertussis and, without realizing it, become carriers who transmit the bacteria to more susceptible populations, including infants. Regular booster shots are thus important for maintaining protection throughout life.
Exposure and Transmission
Being in close proximity to someone infected with pertussis increases the risk of acquiring the illness. Transmission occurs most readily through prolonged contact or when sharing the same breathing space with an infected individual. The bacteria spread efficiently through respiratory droplets, making crowded environments or close household settings particularly high-risk scenarios.
For infants, common sources of pertussis infection are often within their own household. Mothers, fathers, older siblings, and other primary caregivers are frequently the initial transmitters of the bacterium to vulnerable babies. These close family members may have mild or atypical symptoms, unknowingly spreading the infection before a diagnosis is made.
The likelihood of contracting pertussis increases during periods when the disease is more widespread in the community. During outbreaks or epidemics, the prevalence of Bordetella pertussis in the general population rises, increasing the chances of exposure. Public health agencies monitor these trends closely to inform the public about heightened risks and recommend appropriate preventative actions.
Underlying Health Conditions and Vulnerable Populations
Individuals with certain pre-existing medical conditions face a heightened risk of severe illness if they contract pertussis. Those with chronic cardiac, pulmonary, neuromuscular, or neurologic diseases may experience more serious complications due to the added strain the infection places on their already compromised systems. People with weakened immune systems, whether from illness or medication, also have a reduced ability to fight off the infection, leading to more severe outcomes. Asthma, a common respiratory condition, can likewise exacerbate the effects of pertussis, making breathing difficulties more pronounced.
Adults who are obese have a greater likelihood of being diagnosed with pertussis. The exact mechanisms linking obesity to increased susceptibility or diagnosis rates are still being explored, but it suggests that body composition can play a role in how the body responds to or presents with the infection.
Pregnant women are considered a vulnerable population due to the potential impact on both themselves and their unborn children. Receiving the Tdap vaccine during pregnancy is highly recommended to provide protection. This vaccination allows the mother’s body to produce antibodies that transfer across the placenta to the developing fetus. These maternal antibodies offer the infant passive, temporary protection against pertussis before their own vaccination series begins.