Pertussis is a respiratory illness often called Whooping Cough. It is caused by the bacteria Bordetella pertussis. These bacteria release toxins that can damage part of our respiratory system. It causes airway swelling. This can be particularly dangerous in babies. 

(Specifically, if you're curious, the bacteria harms the cilia, which are like tiny hairs that help clean our airways.) 

Pertussis is very contagious and spreads only among people.

Usually, it spreads when someone is coughing or sneezing. It can also spread in close quarters with someone who is infectious. It can cause a cough that lasts for weeks even months. Pertussis is infectious for the first 2 weeks of the cough.

There is a vaccine that can reduce your chance of getting the infection. It is included in many Tetanus vaccines (Tdap - which also includes the Diphtheria vaccination).

1. Pertussis is very serious in babies, who are too young to be vaccinated.

Before the vaccine, 8000 people died a year. As vaccination rates have dropped, more infections have been seen, especially in babies, whose immune systems are too young to respond to the vaccine - and to fight off the bacteria. From 2000 through 2014, there were 277 deaths from Pertussis in the US - almost all (241) in babies under 3 months. 

Babies who become infected may

  • need to be hospitalized
  • have pneumonia (a lung infection)
  • have seizures
  • have problems breathing and need to be on oxygen
  • have brain damage

2.Despite there being a vaccine, the disease still spreads

Many do not use the vaccine. This means that communities do not have herd immunity. To have herd immunity, between 93-95% need to be vaccinated. Some states may have decent vaccination rates - like say 90% in California - but will have clusters where parents do not vaccinate their children as frequently, with overall rates in the 80s.

In these clusters, there are more cases of Pertussis due to the community risk.

In 2014, Pertussis made about 30,000 people ill in the US. Many cases are never tested for, never diagnosed, and never reported. However, we are also be recognizing the disease more. Doctors and nurses may identify it in patients and test for it more, with better tests.

The disease also cycles with cases going up and down if a large number of people are not vaccinated. It peaks every 3-5 years. California saw a spike in cases in 2010 with 10 babies who died.

In rare cases a similar bacteria, called Bordetella parapertussis, spreads. It seems like Pertussis, but the vaccine won't protect against it.

3. You might infect someone when you're not sick

It's not just low vaccination rates that lead to the spread of pertussis. It appears that some people can be vaccinated and still transmit mild infections that they aren't aware of. The vaccine protects them from getting sick. However, they may get sick from someone else, not know it, and spread it to someone else - who might be more vulnerable (a baby, immunocompromised) or not vaccinated.

4. You should get vaccinated in pregnancy

You are not at higher risk when you are pregnant, but your baby will be at risk when born. This will help to keep your baby safe. Although you won't then transmit the infection to the baby, it's important that everyone else - dad, grandma, big brother, and the babysitter also try to keep their Pertussis vaccination up to date.

It turns out pertussis tends to spread to babies from siblings, not mom.

5. The vaccine doesn't protect you for life

Immunity appears to lasts 4 to 20 years. Sometimes it's even shorter and wears off in young kids.

The vaccine changed in the 1990s to become an acellular vaccine, to reduce any risk of side effects. There is concern that immunity does not last as long with this vaccine.

As a result, even a day care full of immunized kids may still face Pertussis. This stresses the importance of having everyone vaccinated to reduce the seriousness of the disease.

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