One of the interesting aspects of this epidemic is the connection between gender and infection. Men are much more likely to be infected and also have a worse prognosis once infected. Generally women incur lower levels of bacterial and viral infections, and yet suffer from a higher incidence of autoimmune diseases. There are at least two factors: hormones and the X chromosome of which women have two, one from each parent. Normally one of the X chromosomes is deactivated but in 10% of women this is thought not to occur and this can have both positive and negative consequences.