Statins may be able to fight deadly typhoid fever as well as lowering cholesterol, according to new research.
Scientists from Duke University in the US, made their discovery while trying to find out why some people appear immune to the highly infectious disease while others contract it.
At the turn of the last century, the Irish immigrant Mary Mallon earned the moniker ‘Typhoid Mary’ after she left more than 50 people in New York City sick.
She did not become ill from the bacteria she carried, and many people who came into contact with the infamous cook never contracted the disease.
Scientists have now discovered that some people may be more susceptible to the highly contagious disease through a gene variant.
This mutation raises cholesterol levels which binds Salmonella Typhi, the culprit behind the nasty infection, to a person’s cells, thus increasing the risk of typhoid fever.
The research, published in the Journal Proceedings of the Academy of Sciences, also showed that a common cholesterol-lowering drug, ezetimibe or Zetia, could provide protection against this bacteria.
Typhoid fever is most common in parts of the world that have poor sanitation and limited access to clean water. Approximately 21 million cases and 222 000 typhoid-related deaths occur annually worldwide, according to the World Health Organization.
It is transmitted through the ingestion of food or drink contaminated by the faeces or urine of infected people.
Now experts at Duke University School of Medicine in North Carolina hope that statins – one of the most commonly prescribed medicines in the US and UK – can help protect those who are most vulnerable.
Study author assistant professor Doctor Dennis Ko has long been intrigued by the case of Typhoid Mary, but he said trying to explain the differences between people when it comes to susceptibility to infectious disease can be tricky.
His team used cell from healthy human volunteers and exposed them to the exact same dose of Salmonella Typhi, which had been tagged with a green fluorescent marker.
They then looked for genetic differences between cells that had higher rates of bacterial invasion from those that did not.
Typhoid is caused by the bacteria Salmonella Typhi (file photo)
The researchers discovered a DNA variation – in a gene called VAC14 – that was linked with the infection.
When they knocked out the gene, the cells were invaded more readily and more of the cells glowed brightly with green bacteria.
They also unexpectedly found that those more susceptible cells had higher levels of cholesterol, helping the Salmonella to bind.
STATINS COULD HELP PEOPLE WITH KIDNEY DISEASE
Statins should be offered to an extra two and a half million patients with chronic kidney disease, according to the health watchdog.
The guidelines mean some 20 million adults in England – almost half the population – are now eligible to take the cholesterol lowering pills.
Patients with chronic kidney disease are at a much higher risk of having a heart attack or stroke as the condition leads to the accumulation of fatty deposits in arteries.
Approximately 2.6 million adults in England have chronic kidney disease and it is more common in the elderly and amongst black and Asian ethnic groups.
The condition leads to 60,000 deaths a year and many are due to heart disease which includes heart attacks and strokes.
The health watchdog NICE announced last month is recommending that GPs offer statins to all adults with kidney disease on the basis that they are safe and clinically effective.
Statin drug clears infection in fish
Dr Ko wanted to see whether the genetic difference was relevant to the human population.
He linked up with a researcher working in Vietnam, Dr Sarah Dunstan, who had been studying typhoid fever in that country.
When Dr Dunstan tested DNA from subjects in a group of 1,000 Vietnamese -half of whom had typhoid fever and half of who didn’t – she found that the VAC14 gene variant was associated with a moderately elevated risk of typhoid fever.
The next step was investigating if there was a way to correct that susceptibility.
Further tests then revealed that when they injected zebrafish with Salmonella Typhi, those with cholesterol-lowering drug (ezetimibe or Zetia) added to their water were more likely to clear the bacteria out of their system and survive.
Researchers plan to next test the effect of the drug on mice, which are biologically similar to humans.
‘This is just the first step,’ said Dr Ko.
‘We need to try this approach in different model organisms, such as mice, and likely with different pathogens, before we can consider taking this into the clinic.
‘What’s so exciting is that our study provides a blueprint for combining different techniques for understanding why some people are more susceptible to disease than others, and what can be done about it.’