Hillary Clinton’s pneumonia diagnosis explained

Despite advances, pneumonia remains a potentially fatal illness, especially in the elderly

Footage of Hillary Clinton prematurely leaving a 9/11 memorial event on Sunday show someone who was feeling weak and unwell.

There are many possible medical causes for a near faint, but the revelation that Mrs Clinton had been diagnosed with pneumonia two days previously could explain what her doctor subsequently described as an episode of “dehydration and overheating.”

Dr Lisa Bardack said in a statement, that 68 year-old Mrs Clinton has been experiencing a cough related to allergies and that an examination on Friday showed that she was suffering from pneumonia.

Pneumonia is a type of chest infection that affects the lungs and lower airways. Bronchitis is an infection of the upper and middle airways in the lung. Most bronchitis cases are caused by viruses, whereas most pneumonia cases are due to bacteria.

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Despite the advent of powerful antibiotics, pneumonia remains a potentially fatal illness, especially in the under-5s and in older people.

In the US, about 2 to 3 million people develop pneumonia each year, and 60,000 of them die. Pneumonia, along with influenza, is the eighth leading cause of death in America.

Mrs Clinton’s illness is classified as community acquired pneumonia (CAP). The annual incidence of CAP in the western world is estimated at between 5 and 11 cases per 1,000 adults.

More than 100 different microbes have been linked with pneumonia; however the most common culprits are Streptococcus pneumoniae and Haemophilus influenzae.

Mild cases of CAP are treated at home by taking oral antibiotics, drinking plenty of fluids and getting plenty of rest. The fact that Mrs Clinton was still following a busy schedule on Sunday, some 48 hours after being diagnosed, suggests a hard campaigning politician who was possibly reluctant to take medical advice to rest.

The term “walking pneumonia” has been used in some media reports about Mrs Clinton. Apparently used to suggest a mild case of pneumonia that does not require rest, it is not a recognised medical term.

Now that she is resting, the Democratic presidential candidate should respond well to treatment. Complications are possible, however, and the need for hospitalisation cannot be ruled out if the infection doesn’t settle.

The main complication is pleurisy, where a thin lining between the lungs and the ribcage becomes inflamed. Fluid builds up in this space, causing severe pain and difficulty breathing. And like any other infection in the body, the bugs causing the pneumonia can invade the blood stream causing septicaemia.

This serious illness warrants hospital admission for intravenous antibiotics and fluids, and oxygen.

Even if she recovers rapidly, Mrs Clinton can expect to feel tired for a number of weeks. The cough which has been bothering her will persist for up to four weeks after the bacteria has been eliminated from her lungs.

As to the future, Mrs Clinton will be advised to have up to date influenza and pneumococcal vaccine jabs. And a chest X-ray in a number of weeks time to confirm the pneumonia has completely gone would be a wise move.

Muiris Houston

Dr Muiris Houston

Dr Muiris Houston is medical journalist, health analyst and Irish Times contributor