Men, who have long been maligned for their self-indulgence of symptoms for sympathy when undergoing a bout of ill health, can feel some relief that new research suggests that the so-called ‘man flu’ may have some scientific merit. A study into the evolution of viruses suggests that they might cause weaker symptoms in women than men, though it is mostly because the virus sees the male of the species are largely dispensable.
Many infections are known to have more severe impacts on men, with male TB patients 1.5 times more likely to perish than their female counterparts. Scientists believe this pattern is because of differences in the human body’s immune system based on sex, but another theory posits that women make for more valuable hosts for the parasitic viral infections.
This is because women can pass on the disease to their children during pregnancy, birth, and when breastfeeding, so it is in a virus’s evolutionary interest to be less harmful to women in order to keep them around for longer.
Viruses infect other people by producing more and more copies of themselves when inside a host body, with the inevitable illness that their host suffers an unavoidable side effect. “That’s not something a pathogen particularly sets out to do because it’s shooting itself in the foot, should it have one,” says Vincent Jansen of the Royal Holloway University of London.
The researchers examined the virus Human T-cell Lymphotropic Virus Type 1 (HTLV-1), which can cause leukaemia in infected individuals, and which they believe has altered itself to stop it from rendering female hosts too sick.
“Viruses may be evolving to be less dangerous to women, looking to preserve the female population,” said Francisco Ubeda from the university’s School of Biological Sciences.
“The reason why 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. Pathogens are adapting to be less virulent in women to increase their chances of being passed on.”
Which means that the miserable man beside you in the office or on your couch, sniffling and complaining about his aches and pains, may not just be a case of symptom exaggeration.
“It’s entirely probably that this sex-specific virulent behaviour is happening to many other pathogens causing diseases,” said Dr Ubeda.
