Ah, the thought of singing birds: the thrush.

Forget it. Thrush is a yeast infection (candida albicans) that can affect infants, toddlers, breastfeeding mothers, older folks and anyone with a weakened immune system including those with cancer and HIV.

There are a multitude of causes for thrush. Generally, though, they can be boiled down to conditions being ripe for the change in balance of certain bacteria in the mouth that keep thrush in check. In more severe cases thrush can spread to the lungs, liver and skin.

Thrush appears as creamy white to yellow lesions in the mouth. It can cause pain or difficulty when swallowing and even fever if the infection is allowed to spread beyond the esophagus.

Treatment for oral thrush may include antifungal medications taken orally in the form of tablets, lozenges or liquids. More severe cases may require injections to bring the candidas bacteria under control.