Disease Flashcards

All 18 cards in this deck

How does the World Health Organization (WHO) define health?

A state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.

What is a communicable disease?

A disease caused by a pathogen that can be spread from one organism to another.
e.g. tuberculosis, cholera

What is a non-communicable disease?

A disease that cannot be passed from one organism to another.
e.g. type 2 diabetes, cancer, cardiovascular disease

True or false? A person who has no disease is automatically in good health.

False. WHO health also requires mental and social well-being, not just the absence of disease.

What effect does being infected with HIV have on a person's chance of catching other infections such as tuberculosis?

It increases it — HIV destroys white blood cells, so the immune system cannot defend against other pathogens.

What are the steps to calculate the percentage increase in the number of cases of a disease?
e.g. cases rise from 200 to 300

1. Subtract: $300 - 200 = 100$
2. Divide by the original: $100 \div 200 = 0.5$
3. Multiply by 100: $0.5 \times 100 = 50\%$ increase

What is a pathogen?

An organism that causes disease.

What are the four types of organism that can be pathogens?

Viruses, bacteria, fungi and protists.

What are the steps of the lytic pathway of a virus lifecycle?
e.g. a virus infecting a bacterial cell

1. The virus attaches to the host cell and injects its genetic material.
2. The host cell's machinery copies the viral genetic material and makes new viruses.
3. The cell lyses (bursts), releasing the new viruses to infect other cells.

What are the steps of the lysogenic pathway of a virus lifecycle?
e.g. a virus infecting a bacterial cell

1. The virus injects its genetic material into the host cell.
2. The genetic material joins the host DNA as a provirus and is copied each time the cell divides; no new viruses are made.
3. A trigger activates the provirus, which leaves the host DNA and enters the lytic pathway.

True or false? In the lysogenic pathway the host cell is destroyed straight away.

False. The viral genetic material lies dormant as a provirus in the host DNA; the cell is only destroyed once the virus switches to the lytic pathway.

True or false? Chalara ash dieback is caused by a fungus.

True. Its airborne spores infect ash trees, causing leaf loss and bark lesions.

Which type of pathogen causes cholera, and what symptom does it produce?

Bacteria; they cause diarrhoea.
Spread in contaminated water.

Which type of pathogen causes tuberculosis (TB), and what damage does it do?

Bacteria; they damage the lungs.
Spread through the air (airborne droplets).

Which type of pathogen causes malaria, and what damage does it do?

Protists; they damage the blood and the liver.
Carried from person to person by a vector, the mosquito.

Which type of pathogen is HIV, and what does it do to the body?

A virus; it destroys white blood cells, leading to the onset of AIDS.
Spread in body fluids, e.g. during unprotected sex or by sharing needles.

How is Chlamydia spread, and how can its spread be reduced?

By unprotected sexual contact; reduced by using a condom.
Screening and treating infected people also reduces spread.

Which type of pathogen causes Ebola, and what illness does it cause?

A virus; it causes haemorrhagic fever.
Spread in body fluids.