Part 3: Transmission of diseases

What are the two types of diseases

1. Infectious/tranmissible/communicable diseases

2. Non-communicable/non-transmissible/non-infectious

What are transmissible diseases

diseases caused by pathogens that can spread from one living thing to another

How can transmissible diseases be spread

through direct or indirect contact

Give examples of direct contact transmission

• touching an infected person

• kissing

• sexual intercourse

• blood exchange

Give examples of indirect transmission methods

1. Contaminated surfaces: Touching contaminated surfaces and then touching your mouth, nose or food can spread diseases like influenza ect.

2. Contaminated food: Like eating uncooked meat with salmonella causes food poisoning

3. Contaminated air (droplet infection): If an infected person coughs or sneezes, tiny droplets carrying pathogens spread through the air and are inhaled by others. This can cause the transmission of measles, chickenpox, Covid-19

4. Drinking contaminated or untreated water: Can spread diseases like cholera, typhoid, dysentery

5. Animals (houseflies): houseflies land on waste, then on food, carrying the pathogens with them (in their saliva). This can spread diseases like food poisoning, amoebic dysentery, polio. Houseflies act as vectors (organisms that carry pathogens)

What are the 4 types of infectious diseases

• Viral diseases (caused by a virus): Measles, meningitis, influenza, HIV

• Bacterial diseases (caused by bacteria): Gonorrhea, pneumonia, Syphilis

• Fungal diseases (caused by fungi): Athlete’s foot, ringworm

• Protozoan diseases (caused by protists): Malaria

Can transmissible diseases be direct-only, indirect-only or both

yes

What are HIV and AIDS, and how does HIV affect the immune system?

HIV (Human Immunodeficiency Virus) is a virus that attacks and destroys lymphocytes, weakening the immune system. Over time, this can lead to AIDS (Acquired Immunodeficiency Syndrome), a condition in which the immune system is severely damaged and the body becomes much more vulnerable to infections and diseases.

What are non-transmissible/non-communicable/non-infectious diseases

• diseases that cannot be spread from person to person

• usually caused by genetics, lifestyle choices, and environmental factors

What are the 3 types of non-transmissible diseases

• hereditary

• nutritional

• degenerative

Give 3 examples of hereditary diseases

1. Sickle cell anemia: results in some red blood cells to be shaped like sickles or crescent moons rather than bi-concave discs like normal blood cells. These sickle cells have a lower ability to transport O₂ around the body due to a smaller surface area.

2. Haemophilia: blood disorder where blood does not clot properly, causing prolonged bleeding after injuries.

3. Cystic fibrosis: causes thick, sticky mucus to build up in the lungs and digestive system, making breathing and digestion difficult

What are 3 examples of nutritional diseases

1. Iron-deficiency anemia - Caused by a lack of iron in the body, leading to a reduce number of red blood cells

2. Scurvy: caused by a serious vitamin C deficiency and can lead to bleeding gums

3. Rickets: caused by an extreme and prolonged vitamin D deficiency. Causes softening and weakening of bones in children.

What are two examples of degenerative diseases

1. Alzheimer's Disease: a brain disorder that slowly destroys memory and thinking skills, and eventually the ability to carry out simple tasks.

2. Parkinson's Disease: a disorder of the nervous system that affects movement and gradually worsens over time.

How does a virus reproduce (5 steps)

1. Attachment – The virus attaches to a host cell.

2. Entry – The virus enters the cell and releases its genetic material.

3. Replication – The host cell copies the viral genetic material and makes viral proteins.

4. Assembly – The viral genetic material and viral proteins are assembled together to form complete new viruses.

5. Release – The host cell bursts and releases the new viruses (identical to the original virus), which then infect other cells and repeat the process.