B5- Comminicable Diseases Flashcards
What are communicable( infectious) diseases caused by?
Pathogens such as bacteria and viruses that can be passed from one person to another. / caused by microorganisms called bacteria, viruses,fungi and protists.
Non-communicable diseases cannot be transmitted from one person to another
What is the difference between how pathogens cause disease
Bacteria divides rapidly by splitting in two (called binary fission). They may produce toxins (poisons) that affect your body and make you feel ill. Sometimes they directly damage your cells.
Viruses take over the cells of your body. They live and reproduce inside the cells damaging and destroying them.
Bacteria can produce toxins that make you feel ill.
Name 3 ways pathogens can be spread?
Direct contact, by air or by water.
How are uncontaminated culture of microorganisms grown by?
Using sterilised Pétri dishes and agar. You stérilisé the inoculating loop before use and fix the lid of the Pétri dish to prevent unwanted microorganisms getting in.
Why are uncontaminated cultures of microorganisms needed?
For investigating the action of disinfectants and antibiotics.
Why should cultures be incubates at a maximum temp of 25 degrees Celsius in schools and colleges?
To reduce the likelihood of pathogens growing that might be harmful to humans
How can you investigate the effects of disinfectants and antibiotics on bacterial growth?
using agar plates and calculating the cross-sectional area of colonies grown or of clear areas of agar.
How do you calculate the number of bacteria in a population?
Step 1 calculate how many times the bacteria will divide in how many hours
Step 2: Use the equation
Bacteria at the end of growth period = bacteria at the beginning of the growth period x2^ number of divisions
How can the spread of disease be prevented?
By simple hygiene measures e.g. washing hands
By destroying vectors
By isolation of infected individuals
By vaccination
Who discovered that we need to wash our hands?
What other discoveries were made
Ignaz Semmelweis
Louis Pasteur showed that microorganisms caused disease. He developed vaccines against diseases such as anthrax and rabies
Joseph lister started to use antiseptic chemicals to destroy pathogens before they caused infection in operating theatres
As microscopes improved it became possible to see pathogens more clearly. This helped convince people that they were really there
What is measles?
Measles virus is spread by droplet infection. It causes fever and a rash and can be fatal. There is no cure. Isolation of patients and vaccination prevents spread
What is hiv
HIV initially causes flu like illness unless it is successfully controlled with antiretroviral drugs the virus attacks the bodies immune cells. Late stage HIV infection or AIDS occurs when the bodies immune system becomes so badly damaged it can no longer deal with other infections or cancers HIV is spread by sexual contact or by the exchange of body fluids such as blood which occurs when drug users share needles
What is tobacco mosaic virus?
It is spread by contact and vectors. It damages leaves and reduces photosynthesis, there is no treatment. Spread is prevented by field hygiene and pest control.
How is salmonella spread?
Through undercooked food and poor hygiene. Symptoms include fever, abdominal cramps, diarrhoea, and vomiting caused by the toxins produced by the bacteria .
What is gonorrhoea?
It is a sexually transmitted disease. Symptoms include discharge from the penis and vagina and pain on urination. Treatment involves using antibiotics, although many strains are now resistant
