As "part of an evolutionary mechanism ensuring, unconsciously, avoidance of a risky romantic partner", women have the ability to sniff out men with sexually transmitted diseases, a new study has found. In the study, armpit sweat was collected from 34 Russian men, ages 17 to 25. Thirteen of the men had gonorrhea, 16 were healthy, and five had had gonorrhea in the past, but recovered. The men wore T-shirts with cotton pads in the armpits for one hour, and the pads were then placed in glass vials, Live Science reported. The researchers asked 18 healthy women to sniff the vials and rate the pleasantness of the smell on a 10-point scale with higher scores indicating a more pleasant smell, and also to choose a word from a list to describe the odour including "putrid", "floral', "vegetable", "woody', "minty' and "fruity"). The researchers found that the women rated the infected men's sweat as less than half as pleasant as the healthy men's sweat. And the women said about 50 per cent of men who had gonorrhea had sweat that smelled "putrid", whereas only 32 per cent of the healthy men were described as putrid. While 26 per cent of the healthy men smelled "floral", just 10 per cent of those with gonorrhea were described that way. According to the researchers, the men's immune systems might be involved because they found a link between the concentration of disease-fighting proteins called antibodies in the men's saliva and how pleasant their sweat smelled to women: the higher the antibody concentration, the lower the score. Previous studies in animals have found that infecting the mice with parasites or viruses reduces the attractiveness of their smell to female mice.