Men are sometimes mocked by women who fall ill of the 'man flu' and call them weaklings.  Actually, a gender-biased flu exists, and it hits hard on men than women, a new research shows.

Women Are A 'More Valuable Host'

Scientists found that some bugs are really more deadly in men because women are a "more valuable host".  Some viruses adapt to cause less severe disease and lower mortality rates in the female species so they can be passed on to their children during pregnancy, birth and breastfeeding. 

Royal Holloway University of London researchers say that women provide an additional route to infect more people.  This could also explain why women who suffer from a heavy cold recover more quickly and why some viruses are more vicious in men than women and children. 

Dr Francisco Ubeda, biologist and author of the study, said: "Viruses may be evolving to be less dangerous to women, looking to preserve the female population.  The reason these illnesses are less virulent in women is the virus wants to be passed from mother to child, either through breastfeeding, or just through giving birth."

Death Rate Due To Infectious Diseases Is Higher In Men Than Women

During the study, Dr Ubeda and co-author Professor Vincent Jansen used "mathematical modelling to show natural selection favours viruses that have a lower rate of fatality in women, if the virus can be passed from person to person and from mother to child."  They found that mortality due to infectious diseases is higher in men than women. 

Previous research already showed that men suffer more from high temperatures more when they have a flu, compared to women. "It is entirely probable this sex-specific virulent behaviour is happening to many other pathogens causing diseases.  It is an excellent example of what evolutionary analysis can do for medicine," the researchers concluded.