Can anyone explain how STD are created, in basic terms ? Ive heard of mild versions which only cause rashing or itching. Compared to things like HPV and HIV. I heard once before, that most people have some type of bacteria on them, at any given time. But our skin, and immune system prevent the bacteria from being of any worry. Because sex exposes more vulnerable parts of the body, I guess bacteria is more dangerous... I don't really know. I know not to touch open wounds or my eyes when cooking in the kitchen with raw ingredients, because of something similar to what I'm trying to say. Lol.

If both partners in a relationship are 100% clean, and never sleep with anyone else, do they ever have to worry about a STD ? What about having sex during a period... or if one of the partners has a cold or flu ? Can these create mild STD ? I heard someone tell a guy not to have sex after shaving down there, because the fluids could cause a rash on the exposed skin... could that become a serious STD if the rash isn't treated ?

I know to wear a condom.
Just curious about how STD come into existence.

I'd like you to read this about chickens. Chicken safety: Dangerous bacteria, Contamination I think it an answer some on your questions in general terms.

But first, let's chat a bit about viruses and bacteria.

HIV is a virus. He body has to fight it on it's own. Any drug we take only makes us more comfortable. Influenza is a virus. Influenza is constantly mutating, so our bodies defenses are kept off guard. We can help our bodies become more prepared by getting a flu shot. The shot contains a deactivated version of the virus, but with enough genetic material that our body will recognize the invader as foreign and hopefully it will be destroyed. There are so many versions of the flu and this we cannot vacinate against all strains. Only the vaccines that are guesses for this year's outbreak are grown for the flue season.

SARS Severe acute respiratory syndrome - Wikipedia, the free encyclopedia and Ebola Ebola - Wikipedia, the free encyclopedia are extremely deadly viruses and opon upon a time Polio Poliomyelitis - Wikipedia, the free encyclopedia was a problem.

Bacteria is everywhere. Some good, some bad. They help us digest our food. They make bread rise. E Coli and salmanella are bad bacteria. Bacteria can generally be killled by antibiotics.
MRSA is one that's resistant. Methicillin-resistant Staphylococcus aureus - Wikipedia, the free encyclopedia

You must finish ALL antibiotics prescribed so the strain doesn't become resistant.

STD's basically mean the method of transmission is PRIMARILY through sexual contact. An open sore will do. Herpes Herpes simplex - Wikipedia, the free encyclopedia and HIV are viruses. We have no vaccine.

A women's vagina is full of good bacteria too. Antibiotics can alter the balance and she can get a yeast infection. Candidiasis - Wikipedia, the free encyclopedia This is a fungus.

Any open sore or mucous membrane brings a vunerability. Ears (swimming), Eyes, mouth (swimming, dust, pollen, rain, hand contact), nose/lungs (breathing), anus, vagina, penis are all points of entry and are reasonably protected.

A wound is not protected.

I hope this helps.