MFF0074: Bordetella


It’s Monday 10 July 2017. I’ve just returned from a week’s holiday. I was so happy to be warm and moist the whole time.

In some browsers, the embedded YouTube video doesn’t render. Here is the link https://youtu.be/WvuHTMAl_J8

So I’m back to the alphabet and after Acinetobacter tonight I’m looking at Bordetella.

Over the last week or so I’ve come across a couple of people with pertussis which is the medical name for whooping cough.

Whooping cough gets its name from the sound made, especially in infected children as they cough.

The cough is described as a paroxysm consisting of repeated coughs without breathing in which gets followed by a high-pitched whoop when the patient draws in a breath.

Sometimes, the paroxysm can be followed by vomiting.

The cough can last a month or more.

We’re currently seeing an upswing in whooping cough in adolescents and adults because the immunity associated with childhood vaccination wanes over time. It’s why we’re also seeing an increase in uptake of the vaccine in adults preparing to have children and grandparents who have an expectation of close contact with a new grandchild.

So, what’s the big deal with whooping cough? Why do public health authorities get so excited about?

It’s the complications that can occur. The list of complications can be quite scary and is a good reason for ensuring immunisation in children as part of a national program.

The complications include:

A spike in lung blood pressure

Pneumonia

Collapse of a lung

Seizures

Brain lesions

Weight loss

Hernias

Death

It’s the lung complications that are the worst. Just imagine those repeated paroxysms of coughing which means a patient cannot breathe in enough during a coughing fit. In a baby this may lead to poor blood oxygenation and the effort of coughing causes extreme exhaustion which leads to malnourishment. This leads to the brain lesion which can manifest as seizures.

Most of the severe complications and deaths occur in infants younger than 6 months. These patients are too young to be immunised. Their health relies on good population coverage of the immunisation.

It’s a fact that in communities with good vaccine coverage, severe complications and deaths are uncommon. Unless you and your children have a medical reason not to be immunised, failure to immunise contributes to deaths of children.

The greatest burden of disease is in communities where there is poor immunisation and widespread malnutrition along with widespread enteric and respiratory infections.

Whooping cough is caused by Bordetella pertussis. It’s a short Gram-negative bacillus. There are two other medically relevant species in the genus, but the pertussis species is the most important.

Humans are the main reservoir of infection.

The incubation period is around 9 to 10 days in most patients. This is the time between being exposed to the infection and the onset of the first symptoms.

Patients are most infectious during the catarrhal stage when the cough is more irritating rather than forming paroxysms. The level of infectivity drops after a week or so of the paroxysms and patients are not considered contagious after 5-days of specific treatment.

For unknown reasons infections are more common in female patients

Secondary infection rates in susceptible household contacts can be as high as 90%

Maternal antibodies can be transferred across the placenta so in some countries pregnant women are immunised.

I’m going to leave it here and continue this next week.

Whooping cough

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