Infectious Diseases

• Pathogens are microorganisms that cause infectious disease.
• Pathogens include bacteria and viruses, which are the focus of this video.
• Pathogens also include protists and fungi, which will be discussed in later videos.
• Bacteria are a type of pathogen that cause food poisoning, with around 300,000 people in the UK getting food poisoning from this type of bacteria every year.
• Fortunately, most people recover from food poisoning, but sometimes it can be fatal.
• Many bacterial diseases can kill us.
• The key fact about bacteria is that once inside the human body, they reproduce very rapidly under ideal conditions, and can divide every 20 minutes.
• Bacteria can release harmful chemicals called toxins, which damage tissues and make us feel ill.
• A pathogen is an organism that causes disease.
• Bacteria and viruses cause illness by invading the host cell and reproducing inside it, which is very damaging to the cell.
• Pathogens are usually spread in three ways: in the air, through water, and through contact between individuals.
• Practicing basic hygiene, providing clean drinking water, and reducing direct contact between individuals are ways to prevent the spread of pathogens.
• In the UK, drinking water contains chlorine which kills microorganisms.
• Another way of reducing the spread of pathogens is to use a condom during sexual intercourse, which reduces the spread of HIV.
• In the case of highly infectious diseases such as Ebola, patients may be isolated to prevent the pathogen from spreading to other people.
• Vaccination is another way of reducing the spread of pathogens.
• Another type of pathogen that causes a lot of human diseases is viruses, with HIV being a virus that can lead to AIDS.
• Viruses are very different to bacteria because they cannot be produced by themselves and can only reproduce inside a host cell.
• Viruses are pathogens that cause infectious diseases and cannot be killed by antibiotics.
• Measles is a highly infectious disease with the first symptom often being a fever, followed by a red skin rash.
• HIV, the first symptom of which is often a flu-like illness, usually disappears after one or two weeks as the virus attacks the cells of the patient's immune system.
• Over time, the immune system becomes severely damaged due to HIV, leaving the patient vulnerable to other infections and cancer.
• When the immune system reaches a highly damaged stage, the patient can easily contract other infections such as TB and develop cancer.
• People infected with HIV can be treated using antiretroviral drugs, which stop the virus from multiplying inside the patient, preventing the virus from damaging the patient's immune system.
• Patients who take antiretroviral drugs do not go on to develop AIDS and can lead a normal life expectancy.
• HIV is transmitted through the exchange of fluids between humans, and can be spread by unprotected sexual intercourse and when drug users share infected needles.
• Salmonella food poisoning is caused by the bacteria Salmonella, which are spread by ingesting infected food.
• Symptoms of Salmonella food poisoning include a fever, abdominal cramps, vomiting, and diarrhea.
• Salmonella bacteria are sometimes found in poultry such as chicken, but in the UK, all chicken are vaccinated against Salmonella, controlling the spread of the disease.
• Gonorrhea is a sexually transmitted disease (STD) that is transmitted by sexual intercourse.
• Symptoms of gonorrhea include a thick yellow or green discharge from the penis or the vagina, and pain when urinating.
• Gonorrhea is a bacterial disease, and in the past, it was easily treated using the antibiotic penicillin.
• Antibiotic resistant strains of bacteria are now common, and different antibiotics are used to treat gonorrhea.
• Using a condom during sexual intercourse stops the spread of gonorrhea.
• People who have unprotected sex should be tested for gonorrhea, and if they are positive, they should be treated with antibiotics to kill the bacteria before they cross it onto another person.
• Malaria is a common disease in certain parts of the world that causes over 400,000 deaths every year.
• Malaria is a communicable disease spread by a pathogen, and the malaria pathogen is an example of a protist.
• Malaria is a serious disease that causes repeated bouts of fever and can be fatal.
• The life cycle of the malaria pathogen involves a human being being bitten by a mosquito, the malaria pathogen passing into the mosquito, and the mosquito biting a different person.
• Scientists call the mosquito a vector because it carries a pathogen from one person to another person.