Health and disease (Transmission)

Question 1

What is health?

Answer 1

A state of mental, physical and social wellbeing, not just the absence of disease.

Question 2

What constitutes good health?

Answer 2

• Absence of disease.
• Ability to carry out normal mental and physical tasks in modern society.
• Good, balanced diet.
• Positive mental state.
• Good sanitation habits.
• Well integrated into society.

Question 3

What is disease?

Answer 3

Disease is departure from good health caused by a malfunction of the mind and body. There are several types of diseases; physical diseases are ones that involve a malfunction of the body caused by inheritance (genetic) or pathogens (infectious) whereas mental ones involve either inheritance or external stimuli.

Question 4

What are the main agents of disease?

Answer 4

1. Parasites: Multicellular organisms that depend on hosts in order to obtain nutrients and generally causes substantial stress on the host’s body in the process. Parasites that live on the host are called ectoparasites and parasites that live on the inside of the host are called endoparasites.
2. Bacteria: Single-celled prokaryotes that survive as a parasite inside the body of the host. They cause disease by damaging cells or releasing toxins.
3. Fungi: Usually lives on surface of skin and reproduce to cause skin diseases like athlete’s foot and ringworm infections.
4. Viruses: Not really classified as living. They invade host cells and inject their genetic information into the host, using it to reproduce. Once their numbers increase, the host cell bursts, spreading the new viruses around the body to invade new cells. They cause diseases like HIV and the flu.
5. Protoctista: Single-celled organisms that enter host cells and feed on its nutrients, causing diseases like malaria and dysentry.

Question 5

What is malaria?

Answer 5

• Malaria is cause by a family of protoctista called plasmodium.
• Malaria causes flu-like symptoms including fever, headaches, sweating, vomitting and diarrhoea. However, if untreated, can lead to severe anaemia.

Question 6

How is malaria primarily transmitted?

Answer 6

1. Malaria uses a vector (the female anopheles mosquito) to travel from one host to another.
2. The mosquito travels to an infected host and feeds on his/her blood.
3. Malarial gametes in the blood enter the mosquito’s stomach, fuse, develops and multiplies; eventually migrating to the mosquito’s salivary glands.
4. When the mosquito bites another person, it injects some saliva into bloodstream as anticoagulant, so malaria enters the person’s bloodstream.
5. Malaria migrates to the liver where it increases in numbers before reentering the blood and red blood cells in the blood.
6. They produce gametes in infected red blood cells and wait for the current host to be bitten by a mosquito to continue the cycle.

Question 7

What other methods of malaria transmission are there?

Answer 7

1. Unhygienic, unsterilised medical equipment.
2. Unscreened blood transfusions.
3. Unhygienic hospital environments.

Question 8

What is AIDS (Acquired Immunodeficiency Syndrome)?

Answer 8

• AIDS is caused by HIV (Human Immunodeficiency Virus).
• The virus attacks and destroys T-helper cells in the immune system, severely weakening the effectiveness of the body’s immune response.
• A weakened immune system means that the body is open to opportunistic infections, diseases caused by pathogens that would usually be eliminated by a healthy immune system before they caused the disease.

Question 9

How is AIDS transmitted?

Answer 9

1. Unscreened blood transfusions or any blood contact.
2. Unprotected intercourse.
3. Unsterilised medical equipment.
4. Sharing of hypodermic needles.
5. From mother to child across placenta, during childbirth or breast feeding.

Question 10

What is TB (tuberculosis)?

Answer 10

• TB is caused by 2 types of bacteria: Mycobacterium tuberculosis and M. bovis.
• TB usually infects the lungs. The symptoms of TB includes persistent coughing, fever, sweating, loss of appetite…
• If untreated, TB could lead to extrapulmonary infections affecting other parts of the body.

Question 11

How is TB transmitted?

Answer 11

1. Transmission from contaminated milk or meat of infected cattle.
2. Airborne saliva droplets containing the pathogen, which can become more effective under these conditions:
   - Overcrowding.
   - Poor ventilation.
   - Compromised immune system (from AIDS or immunosuppressants).
   - Living or working with people from TB common countries.

Question 12

What are the roles of health organisations?

Answer 12

They collect information such as:

• Identifying the causes of disease.
• Identifying risk factors.
• Determine frequency of disease.
• Determine mortality and morbidity of disease.
• Determine the seriousness of disease.
• Identify the most affected countries.

Question 13

What can be done to reduce the rate of transmission of disease?

Answer 13

• Educate people on the risks of getting the disease and how to avoid them.
• Run screening programmes for the disease.
• Provide vaccination programmes against the disease.
• Fund research programmes trying to find a cure to the disease.