Disease Examples

Measles

• A highly contagious viral disease in humans that is spread between people by cough and sneeze droplets (airborne).
• Symptoms- red skin rash and fever (high temperature).
• Serious complications like pneumonia or brain inflammation can occur that can be fatal.
• No proper treatment but there is a vaccine.
• Mainly seen in children so are often vaccinated against it at an early age.

HIV

• Viral disease that can lead to AIDS (Acquired Immunodeficiency Syndrome) in humans.
• Spread through sexual contact, exchanging bodily fluids (e.g. blood exchange when drug users share needles) and from mother to baby during birth and breast milk. 
• First appears as flu-like symptoms then travels to the lymph nodes to destroy cells involved in the immune response.
• Can stay hidden until the immune system is so damaged that it cannot cope with other infections and cancers (AIDS).
• Can be treated with antiretroviral drugs which slow the virus down by preventing it from attacking immune cells.

Salmonella

• Bacteria that causes food poisoning by releasing toxins.
• Symptoms- fever, abdominal cramps, vomiting and diarrhoea.
• Salmonella may have been acquired by the animal before it was killed for food or when the food was being prepared (if conditions were unhygienic).
• Poultry are vaccinated against salmonella (in the UK) to prevent the spread of the disease.

Gonorrhoea 

• Bacterial infection spread by sexual contact (it is a sexually transmitted disease, STD).
• Symptoms- thick yellow or green discharge from the vagina or penis and pain while urinating.
• Used to be treated with the antibiotic penicillin until strains of the bacteria became resistant. 
• Now, the spread of the disease is prevented using antibiotics and by encouraging people to use barrier methods such as condoms during sexual activities. 

Malaria

• Caused by a protist that gets transported between animals by mosquitos (vector).
• The protists are picked up by mosquitos when they feed on an infected animal. They complete part of their life cycle in the mosquito vector before being transferred to another human or animal when bitten by the mosquito.
• Symptoms- repeating fever episodes that can be fatal.
• The spread of malaria can be prevented by stopping the mosquitos breeding and protecting people with mosquito nets and insecticides.