Causes
You don't catch candidiasis. The yeast is already there. A number of
factors can increase the chance of the yeast growing out of control. The leading
cause is overuse of antibiotics. Yeast must compete for the right to live on
us with various other species, many of them bacteria. These bacteria, which
live on the skin and in the intestine and vagina, among other places, are harmless
but good at fighting off yeast. When we take antibiotics to deal with less friendly
bacteria, we kill off these harmless ones as well. Yeast, which is unaffected
by antibiotics, moves into the vacated spots once occupied by bacteria, and
starts to grow and multiply.
Steroids and some cancer medications weaken the immune system and can allow
yeast to flourish. Candida albicans infections of the mouth (known as
"oral thrush") most often develop in people with diseases such as
cancer and AIDS. It can also develop in people with diabetes or in people who
have long-term irritation resulting from dentures. Taking birth control pills
increases your chances of getting vaginal candidiasis. Hot weather and tight
clothing are also risk factors, as they create the ideal environment for candida.
Other conditions that tend to encourage yeast include obesity and pregnancy.
Yeast generally infects intertriginous areas, that is, areas where skin
contacts skin. Overweight people have more folds in their skin. They also sweat
more, and Candida albicans is fond of moist skin. Pregnancy causes temporary
obesity and may weaken the immune system.
Experts disagree on the question of sexual transmission. Some research has suggested
that it's very unlikely for an infected woman to give a man candidiasis. On
the other hand, it's not unlikely that a man could give candidiasis back to
his partner once he has it. Recent research has actually found Candida albicans
in the sperm of men whose partners suffered from recurrent yeast infections.
You should be aware of this possibility if a yeast infection keeps coming back.