Chicken Pox: Chickenpox and shingles are caused by a virus called the Herpes Zoster virus. Mostly in children. Measles: a highly contagious viral disease giving red spots followed by a rash; occurs mostly in children. Antibiotics: Antibiotics only work against infections caused by bacteria. They don't work against any infections caused by viruses. Viruses cause colds, the flu, and most coughs and sore throats. MRSA: these organisms are resistant to most antibiotics and can spread quickly in dirty places. Tuberculosis (commonly abbreviated as TB) is an infection caused by the bacterium Mycobacterium tuberculosis, which most commonly affects the lungs but can also affect the nervous system (meningitis). Immunosupressive drugs: Drugs taken to stop the immune system starting an unwanted attack e.g. transplant patients. Salmonella: Salmonella is a type of bacteria. It is usually found in poultry, eggs, unprocessed milk and in meat and water. It may also be carried by pets like turtles and birds. Sinus infection: (or sinusitis) is an inflammation of the sinuses and nasal passages. A sinus infection can cause a headache or pressure in the eyes, nose, cheek area, or on one side of the head. Rheumatoid arthritis: occurs when the body's immune system goes into action when there's no threat and starts attacking the joints and sometimes other parts of the body. It's not yet known why the immune system acts in this way in some people. Anaphylaxis: (anaphylactic shock) an explosive overreaction of the body's immune system. Anaphylactic shock is a violent allergic reaction. Symptoms are itching skin, hives, breathing trouble, collapse of the circulatory system, and sometimes vomiting, diarrhoea, and cramps in the abdomen. Anthrax: an infection in the lungs with cold or flu-like symptoms for several days, followed by severe (and often fatal) breathing difficulties. If not treated soon after exposure, before symptoms appear, inhalation of anthrax will cause death. After inhalation of anthrax, symptoms can appear within a week or can take up to 42 days to appear. Antibiotics are used to treat all three types of anthrax. It is important to treat it early. Antigen: Every cell has unique protein markers on its surface called antigens. Vaccine: a weakened form of disease injected into the body. The immune system produces antibodies to fight the disease and it then remembers.