when we think of bacteria we often think of disease however most bacteria don't have anything to do with humans and most of the ones that do actually help us for example there are trillions of bacteria in your intestines right now helping you break down your dinner in this video though we're going to focus on those few bad ones that infect humans and cause disease if you remember from our cells video bacteria are single celled organisms and are about 100 times smaller than our own cells although they can reproduce by themselves bacteria often replicate rapidly within our bodies because of the good food supply at the same time though they might produce toxins which make us feel ill by damaging our cells and tissues an example of this is the case of Salmonella bacteria which causes food poisoning we can catch it from any food that's been contaminated with the bacteria but most often it's by eating chicken that caught the disease whilst it was alive in the UK though most chickens have to be vaccinated against salmonella so it's relatively rare however if you do happen to catch it then you're likely to get a fever stomach cramps vomiting and diarrhea which if you think about it kind of makes sense because it affects your intestines so you get Tummy problems generally it passes by by itself within a week and people just need to make sure that they stay well hydrated and have a sick bow close by another bacterial disease is goria and it's an example of a sexually transmitted disease or STD like all STDs is passed on through sexual contact for example having unprotected sex the main symptoms are pain when urinating and a thick yellow or green discharge from the vagina or penis when you think about any disease you should think about prevention and treatment as two separate categories for garia the best prevention is avoiding unsafe sex and using barrier methods of contraception like condoms for treatment we used to better use the common antibiotic penicillin which would cure it without any issues however now lots of Gara strains which just means the different types of Gara have become resistant to penicillin so we're having to use rarer and more expensive antibiotics if you haven't heard yet you can find all of our videos on our website Cognito toorgle questions and pass papers and we track all of your progress so that you always know what to study next so sign up for free by clicking here or browse our playlist here on YouTube