Toxoplasma Antibodies and Male Babies

Researchers report in Naturwissenschaften (via Science) that women who test positive for antibodies to the Toxoplasma gondii virus bear more boys than girls. The virus infects over 20% of the world's population. Transmitted through raw meat or cat feces, it causes "flu symptoms" like muscle aches and pains in humans it infects, but is not considered dangerous unless the person's immune system is compromised or if they are pregnant. However, for women who have antibodies to the virus (from being infected previously) the sex ratio is increased from 51, meaning there 104 boys born for every 100 girls, to 60, which translates to 150 boys born for every 100 girls. Women with the highest levels of antibodies, about 72, have 260 boy babies per 100 girl babies.