It’s a common belief that men are more susceptible to sickness compared to their female counterparts.
The long held trope of women possessing a stronger immune system, or the idea that the presence of estrogen may help prevent sickness from afflicting women.
However, current research into the mechanics of this perception actually illuminates a different narrative than the one previously believed.
Vincent A. A. Jansen and Francisco Úbeda, authors of the study “The evolution of sex-specific virulence in infectious diseases”, examined the possible causes behind this assumption by analyzing the methods for transference of possible diseases, stating,
“Although this difference is often attributed to a stronger immune response in women, we show that differences in the transmission routes that the sexes provide can result in evolution favouring pathogens with sex-specific virulence.”
The methods of transmission they refer to are horizontal, or person to person transference, and vertical, the transference between mother and child through pregnancy or breastfeeding. The study also examined the difference found within vertical transmission of possible diseases,
“Because women can transmit pathogens during pregnancy, birth or breast-feeding, pathogens adapt, evolving lower virulence in women.”
Though despite the study’s awareness of the quicker immune response exhibited by women on average, the study found that rather than the selective sex of the infected host, the evolutionary structure of bacteria and viruses could have more to play with survival in mind.
“There is some evidence for the existence of such sex-specific strategies: bacteria can have different strategies to exploit their hosts, depending on whether the host are male or female. For instance, several strictly maternally transmitted bacterial symbionts selectively kill male, but not female offspring.”
Though not immediately identifiable, the researchers intend to bring more understanding to the behavior of selective sex pathogens in the hopes of potentially making their behavior less harmful to both men and women.