Man flu does exist! Viruses want to kill men more than women, study finds
Men are mocked for 'man flu' - supposedly over-exaggerating their symptoms when all they have is a sniffle.
But according to a new study, some viruses such as HPV and diseases like tuberculosis really are hell-bent on killing more men than women.
Researchers at Royal Holloway University have found certain pathogens have adapted to cause less-severe disease and fewer deaths in women, while wreaking havoc in men.
Indeed, when men contract a virus like HPV they are five time more likely to die from it than women.
Until now, researchers assumed that was because women have a stronger immune system.
Part of the reason viruses are less aggressive in women, they believe, is that women are more valuable hosts.
Women are more likely to spread the virus by passing it on to babies through nursing.
Men, however, transmit fewer viruses to other people - but viruses have developed to fester inside them.
'Survival of the fittest is relevant to all organisms, not just animals and humans,' said lead author Dr Francisco Ubeda.
'It is entirely probable this sex-specific virulent behavior is happening to many other pathogens causing diseases.
'It is an excellent example of what evolutionary analysis can do for medicine.'
The findings underline health officials' demands for more boys to get the HPV vaccine.
For years, the vaccine was marketed to young girls, since the virus has a strong link with cervical cancer.
However, HPV is also known to cause a number of other cancers, including head and neck cancer - which is particularly common among men.
And Dr Ubeda's study, published today in Nature Communications, warns HPV - one of the most common sexually-transmitted diseases in the world - is more likely to ravage men than women.
Dr Ubeda and his colleague Vincent Jansen suggest their findings may also explain variations in the progression of human T-lymphotropic virus 1 (HTLV-1), which can cause leukemia.
There is no difference in the frequency of progression of HTLV-1 infection to ATL between the two sexes in the Caribbean.
However, progression of HTLV-1 infection to ATL is more frequent in men than women in Japan, where a higher proportion of mothers breastfeed their children, and do so for a more extended period, compared to women in the Caribbean.