Some infectious diseases have evolved to be more harmful to men than women, a new study has found – suggesting those who scoff at so-called ‘man flu’ may have to think twice.

Certain viruses may ‘go easy’ on women in an attempt to be passed on to children through pregnancy, birth or breast-feeding, according to researchers at Royal Holloway, University of London.

This means men could be harder hit by the infection and can suffer more severe symptoms of any resulting illness.

“Viruses may be evolving to be less dangerous to women, looking to preserve the female population,” said researcher Francesco Ubeda.

“The virus wants to be passed from mother to child, either through breastfeeding, or just through giving birth.“

Men are more likely than women to die if they are infected with a number of diseases including chickenpox and tuberculosis, which is one and a half times more fatal for men, according to the New Scientist.

While this difference in mortality rates between the sexes is often put down to a stronger immune system in women, the study suggests mutations in the virus itself may actually be to blame.

Dr Ubeda’s co-author Vincent Jansen said a virus might be able to tell if its host were a man or a woman by detecting hormonal and other differences, although it was not yet clear how exactly it would do this.

He told the New Scientist it could therefore be possible to manipulate a virus by tricking it to “think it’s in a female body rather than a male body and therefore take a different course of action”.

The researchers used a mathematical model to study the role that gender played in the behaviour of viruses.

Their findings showed it was theoretically possible that viruses could be evolving to be less dangerous to women, Dr Ubeda told the BBC.

“We're turning it on its head and taking the pathogen's eye view,” he said.

The Zika virus - in pictures Show all 5 1 /5 The Zika virus - in pictures The Zika virus - in pictures A three-month-old, who has microcephaly, in Recife, Brazil. A rise in microcephaly cases is thought to have been caused by the spread of the Zika virus in affected countries Getty Images The Zika virus - in pictures A mother holds her baby who has microcephaly Getty Images The Zika virus - in pictures A five-month-old baby, who has microcephaly, in Recife, Brazil Getty Images The Zika virus - in pictures A pediatric infectologist examines a two-month-old baby, who has microcephaly, in Recife, Brazil Getty Images The Zika virus - in pictures A baby affected with microcephaly

“We show theoretically it is possible, which is challenging, but we haven't proven what the mechanism is that would trigger this difference, or that there will be a difference in the pathogen's behaviour between in men and women.”