According to Hygiene For Health, dirty clothes can harbor microorganisms, and wearing clothes with these microorganisms on them can lead to skin infections. Body odor can also occur wearing clothes with the bacteria and fungi found on them.
The National Health Service states that everyone has bacteria inside and outside the body. Clothes capture the bacteria, making them risky to wear again without washing. Dirty underwear has more traces of germs from body fluids and traces of defecation, which makes infection more likely if worn again without washing. The only way to prevent the spread of germs found on clothes from normal wear is to wash them, and it is important to wash hands after contact with dirty laundry.
The National Health Service describes high-risk dirty clothing as items containing vomit, bodily fluids from injury, sweat or contaminated foods or clothes that were in contact with animals. These clothes must be washed at 140 degrees Fahrenheit with a bleach-based product after removing any soil from the items. Washing these clothes separately from unsoiled items prevents contaminating other articles.
Hygiene For Health states that in order to clean clothing completely, clothes must be dried immediately upon washing. Mold can occur on clothing left wet for a prolonged period of time, which can cause odor and skin infections.