Whooping cough evolving into a superbug
Whooping cough bacteria are becoming smarter at colonising and feeding off unwitting hosts - whether they have been vaccinated or not - strengthening calls for a new vaccine.
According to UNSW researchers, Australia needs a new whooping cough vaccine to ensure our most vulnerable are protected from the emergence of superbug strains.
The current vaccine, widely used since 2000, targets three antigens in the bacteria of the highly contagious respiratory disease which can be fatal to infants.
Australia’s whooping cough epidemic from 2008 to 2012 saw more than 140,000 cases – with a peak of almost 40,000 in 2011 – and revealed the rise of evolving strains able to evade vaccine-generated immunity.
In a series of UNSW studies, researchers took this knowledge further and showed, in a world-first discovery, that the evolving strains made additional changes to better survive in their host, regardless of that person’s vaccination status. They also identified new antigens as potential vaccine targets.
First author and microbiologist Dr Laurence Luu, who led the team of researchers with Professor Ruiting Lan, said whooping cough’s ability to adapt to vaccines and survival in humans might be the answer to its surprise resurgence despite Australia’s high vaccination rates.
“We found the whooping cough strains were evolving to improve their survival, regardless of whether a person was vaccinated or not, by producing more nutrient-binding and transport proteins, and fewer immunogenic proteins which are not targeted by the vaccine,” Dr Luu said.
“This allows whooping cough bacteria to more efficiently scavenge nutrients from the host during infection, as well as to evade the body’s natural immune system because the bacteria are making fewer proteins that our body recognises.
“Put simply, the bacteria that cause whooping cough are becoming better at hiding and better at feeding – they're morphing into a superbug.”
Dr Luu said it was therefore possible for a vaccinated person to contract whooping cough bacteria without symptoms materialising.
“So, the bacteria might still colonise you and survive without causing the disease – you probably wouldn’t know you've been infected with the whooping cough bacteria because you don’t get the symptoms,” he said.
“Another issue with the vaccine is that immunity wanes quickly – so, we do need a new vaccine that can better protect against the evolving strains, stop the transmission of the disease and provide longer lasting immunity.”
In addition to babies under six months having a high risk of catching the disease, the elderly, people living with someone who has whooping cough and people who have not had a booster in the past 10 years, are also most at risk.
Whooping cough is characterised by a “whooping” sound and sufferers find it difficult to breathe.
The disease is more common during spring and spreads when an infected person coughs or sneezes and other people breathe in the bacteria.
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