Chapter 10 Infectious Diseases

Question 1

What are infectious diseases?

Answer 1

Transmissible disease caused by an organism such as a protoctist, bacterium or virus

Question 2

What pathogen causes cholera?

Answer 2

Vibrio cholerae

Question 3

What type of pathogen is Vibrio cholerae?

Answer 3

Bacterium

Question 4

How is cholera transmitted?

Answer 4

Water or food contaminated by the faeces of infected people

Question 5

Where does cholera act in the body?

Answer 5

Walls of small intestine

Question 6

What is the method of action of cholera?

Answer 6

Bacteria secretes choleragen toxin which binds to complementary receptors on intestinal cells via endocytosis, leading to loss of Na+ and Cl- from cells and water moving out of blood

Question 7

What are the symptoms of cholera?

Answer 7

Severe diarrhoea, severe dehydration, loss of water and salts, fatigue

Question 8

What is the treatment for cholera?

Answer 8

Oral-rehydration therapy

Question 9

How can cholera be prevented?

Answer 9

Proper sewage treatment, chlorinate water, drink bottled waters

Question 10

What are the pathogens causing malaria?

Answer 10

• Plasmodium falciparum
• Plasmodium vivax
• Plasmodium ovale
• Plasmodium malariae

Question 11

What type of pathogen causes malaria?

Answer 11

Protoctist

Question 12

How is malaria transmitted?

Answer 12

Vector female Anopheles mosquito, takes blood from infected person and inserts pathogen into uninfected person

Question 13

Where does malaria act in the body?

Answer 13

RBCs, liver, brain

Question 14

What is the method of action of malaria?

Answer 14

Parasite enters blood stream and matures in liver cells, enters RBCs, divides in RBCs causing it to lyse and infect other RBCs

Question 15

What are the symptoms of malaria?

Answer 15

Fever, anaemia, nausea, headaches, muscle pain, shivering, sweating, enlarged spleen

Question 16

What is the diagnosis method for malaria?

Answer 16

Dipstick test, microscopical analysis of blood

Question 17

What is the treatment for malaria?

Answer 17

Prophylactic drugs

Question 18

How can malaria be prevented?

Answer 18

• Use preventative drugs
• Nets
• Spray insecticides
• RTS,S ( Mosquirix ) injectable vaccine that provides partial protection in young children

Question 19

Full form of HIV

Answer 19

Human immunodeficiency virus

Question 20

What type of pathogen is HIV?

Answer 20

Virus

Question 21

How is HIV transmitted?

Answer 21

• Direct exchange of bodily fluids through semen/vaginal fluids during sexual intercourse - Blood transfusions
• Mother-to-baby across placenta/breast milk

Question 22

Where does HIV act in the body?

Answer 22

T-helper lymphocytes, macrophages, brain cells

Question 23

What is the method of action of HIV?

Answer 23

Viral RNA and reverse transcriptase (RT) enters T-helper cells, converts RNA to DNA, viral DNA incorporated into host DNA, and cell expresses viral protein

Question 24

What are the symptoms of HIV/AIDS?

Answer 24

HIV infection- flu-like symptoms and then symptomless
AIDS - opportunistic infections

Question 25

What is the diagnosis method for HIV?

Answer 25

Blood/saliva/urine test

Question 26

Is there a vaccination available for HIV?

Answer 26

No vaccination available

Question 27

What is the treatment for HIV/AIDS?

Answer 27

Drugs to slow down onset of AIDS: Zidovudine inhibits RT and viral enzymes, combination therapy

Question 28

How can HIV/AIDS be prevented?

Answer 28

- Use condoms - Provide HIV testing centres and contact tracing - Control mother-child transmission using drugs

Question 29

What pathogen causes tuberculosis?

Answer 29

- Mycobacterium tuberculosis - Mycobacterium bovis

Question 30

What type of pathogen is Mycobacterium tuberculosis?

Answer 30

Bacterium

Question 31

How is tuberculosis transmitted?

Answer 31

Aerosol infection from an infected person sneezing

Question 32

Where does tuberculosis act in the body?

Answer 32

Lungs

Question 33

What is the method of action of tuberculosis?

Answer 33

Slow infection that can stay dormant and become active later when the immune system is weakened

Question 34

What are the symptoms of tuberculosis?

Answer 34

Racking cough, shortness of breath, coughing blood

Question 35

What is the diagnosis method for tuberculosis?

Answer 35

Chest X-ray, microscopical examination of sputum

Question 36

What is the treatment for tuberculosis?

Answer 36

Combination therapy of several antibiotics to prevent resistance

Question 37

How can tuberculosis be prevented?

Answer 37

BCG vaccine, contact tracing, quarantine, pasteurise milk, masks

Question 38

What are antibiotics?

Answer 38

A substance derived from a living organism that is capable of killing or inhabiting the growth of a microorganism

Question 39

Outline how penicillin acts on bacteria

Answer 39

- It works by inhibiting the synthesis of peptidoglycan, bacterial cell wall - Penicillin blocks the enzyme involved in forming cross-links between peptidoglycan chains - This weakens the cell wall, especially during bacterial growth and division, when the wall needs to expand - As a result, water enters the bacterial cell by osmosis, causing it to swell and burst, leading to cell death

Question 40

Why do antibiotics not affect viruses?

Answer 40

Viruses do not have peptidoglycan cell walls, do not have their own metabolism, and live inside host cells

Question 41

How does resistance to antibiotics develop?

Answer 41

Overuse/misuse of antibiotics, not completing antibiotic courses, and selection pressure from antibiotics

Question 42

What is antibiotic resistance?

Answer 42

The ability of bacteria or fungi to grow in the presence of an antibiotic that would normally slow their growth or kill them; antibiotic resistance arises by mutation and becomes widespread when antibiotics are overused

Question 43

Consequences of antibiotic resistance

Answer 43

- Treatment becomes ineffective - Longer illness and hospital stays - Increased mortality - Higher medical costs - Spread of resistant strains

Question 44

Ways to reduce the impact of antibiotic resistance

Answer 44

- Appropriate use of antibiotics, complete prescribed course - Avoid overuse - Improve hygiene - Public education