CHAP 8 INFECTIOUS DISEASE IN HUMANS

Question 1

what is a disease?

Answer 1

a condition that causes the body to function less effectively

Question 2

what are signs of a disease?

Answer 2

can be observed or measured
[ rashes, fever, coughing & vomiting ]

Question 3

what are symptoms of a disease?

Answer 3

can be described or felt by the patient
[ nausea, headache & fatigue ]

Question 4

what are pathogens?

Answer 4

pathogens are disease causing organisms such as virus & bacteria

Question 5

what are some examples of infectious disease?

Answer 5

• HIV
• influenza
• covid 19
• pneumococcal disease

Question 6

what causes non-infectious diseases?

Answer 6

• air pollution
• malnutrition
• lifestyle choices
• inherited diseases - type 2 diabetes

Question 7

what are examples of non-infectious disease?

Answer 7

• sickle anaemia
• coronary heart disease - caused by excessive consumption of polyunsaturated fats and trans fats
• atherosclerosis- caused by excessive cigarette smoking
• liver cirrhosis- caused by excessive alcohol consumption

Question 8

how many ways can infectious disease spread?

Answer 8

3

Question 9

in what ways does infectious disease spread?

Answer 9

• through tiny droplets in the air
• through direct contact
• by contaminated food & water

Question 10

how does tiny droplets in the air spread infectious disease?

Answer 10

cough/sneeze->numerous tiny respiratory droplets are expelled->droplets might contain pathogens->anyone within close range (1m) may breathe in these droplets->be infected

Question 11

how does infectious disease spread by DIRECT CONTACT?

Answer 11

• sexually transmitted disease (STIs) & human immunodeficiency virus (HIV) - can be transmitted when exchanging of bodily fluids during sexual intercourse
• hepatitis B & syphilis can be transmitted through breastfeeding ( mother & baby )
• can be spread through blood - when BLOOD of infected comes in contact with the MUCOUS MEMBRANES ( eg. membrane lining the eye,nose and mouth ) OR BLOOD STREAM of uninfected

Question 12

how to prevent the spread of water-borne & food-borne diseases? [4]

Answer 12

• practice hygienic food preparation & storage
• practice good personal hygiene
• ensure proper sewage treatment
• maintain clean water supply

Question 13

what is an INFLUENZA & what causes it?

Answer 13

a disease that attacks the respiratory system
influenza virus

Question 14

how is INFLUENZA TRANSMITTED & what are some methods to prevent transmission? [3]

Answer 14

• through droplets in air / someone touches eye, mouth or nose after touching an object that is contaminated by virus
  a) get influenza vaccination
  b) cover nose & mouth when cough/ sneeze with tissue & properly dispose used tissue
  c) avoid close contact with sick people

Question 15

what is PNEUMOCOCCAL DISEASE & what causes it?

Answer 15

• a disease that attacks different parts of the body such as spinal cords , brain, lungs & blood
• pneumococcal bacteria -> streptococcus pneumoniae

Question 16

what are signs & symptoms of pneumococcal disease?

Answer 16

fever , cough , rapid breathing , headache , vomiting & chest pain

Question 17

what are methods to reduce PNEUMOCOCCAL DISEASE transmissions?

Answer 17

a) pneumococcal vaccine
b) take antibiotics prescribed by doctors

Question 18

what are vaccines?

Answer 18

• an agent that resembles pathogens & prevents infectious disease by stimulating WBC to quickly produce antibodies when pathogens invade

Question 19

how does vaccines work?

Answer 19

vaccine ( contains agent that reassembles a pathogen) -> enters the body-> WBC binds to agent -> WBC stimulated to divide -> WBC produce antibodies -> antibodies destroy the pathogen in vaccine

Question 20

antibodies are _______

Answer 20

specific - binds to certain virus / antigen

Question 21

what are antibiotics used for?

Answer 21

-drugs used to treat bacterial infections -> made by microorganisms & used to kill/ inhibit the growth of bacteria

Question 22

why are antibiotics used to kill bacteria? [4]

Answer 22

a) weakening the bacteria cell wall -> allowing water to enter the cell by osmosis -> cause cell to swell -> burst
b) inhibit some enzymes -> inhibit growth of bacteria
c) preventing ribosomes from making proteins & enzymes -> killing bacteria
d) breaking up cell membrane

Question 23

why are antibiotics INEFFECTIVE against viruses? [3]

Answer 23

viruses do not have:
- cell wall
- cell membrane
- ribosomes

Question 24

how can a person recover from a viral infection? [2]

Answer 24

• requires rest -> body will recover with time
• antivirals -> medications that help body fight off disease causing viruses.

Question 25

how does misuse of antibiotics cause ANTIBIOTIC RESISTANCE?

Answer 25

a population of bacteria -> some bacteria are more sensitive and some less sensitive to antibiotics -> initial doses of antibiotics -> bacterial cells that are more sensitive killed -> bacteria less sensitive not easily killed & may survive

a) IF prescribed course of antibiotics completed -> higher chance that all bacterial cells are killed
b) IF prescribed course of antibiotics NOT completed -> less sensitive bacterial cells that survived will multiply & increase in numbers -> overtime generations of bacterial cells -> increasingly less sensitive to antibiotics -> population of cells becomes resistant to antibiotic -> antibiotic unable to kill bacteria-> other types of antibiotics required to treat bacterial infections.

Question 26

how can antibiotic resistance be REDUCED ? [3]

Answer 26

• not misuse / overuse antibiotics
• complete full course of antibiotics prescribed by doctor-> all bacteria killed
• using antibiotics ONLY when necessary