Infectious Diseases In Humans

Question 1

Infectious Diseases

Answer 1

• Can be spread from person to person (Via body fluids, food and water)
• Involves transmission of a pathogen (or microorganism too small to be seen by naked eye)

Pathogen -> Disease causing agent (Bacteria, viruses, etc.)

Question 2

Non-Infectious Diseases

Answer 2

• Cannot be spread from person to person
• Caused by factors other than pathogens (or microorganisms)
• NOT CAUSED OR TRANSMITTED BY INFECTIOUS AGENTS
• Caused by a combination of genetics, environmental factors and lifestyle

Question 3

Nucleic Acid

Answer 3

• Either DNA or RNA, not both
• Store genetic information coding for viral protein components

Question 4

Capsid

Answer 4

• Protein coat that either surrounds the nucleic acid or encloses it
• Protect the viral genome from
  damage

Question 5

Lipid Envelope

Answer 5

• Additional phospholipid membrane, derived from the host cell which the virus infects, acquiring a membrane coat while budding off their host cell and are termed enveloped viruses
• Protect the viral genome from
  damage

Question 6

Spike Protein

Answer 6

• Glycoproteins on capsid (lipid envelope, encoded by genetic material of virus)
• Facilitate attachment to host cell’s receptor (protein) for entry

Glyco -> Short carbohydrate chains added to protein

Question 7

Typical Virus

Answer 7

A typical virus has a protein coat enclosing its genetic material and reproduces only in living host cells

Question 8

Typical Bacteria

Answer 8

A typical bacteria cell has a cell wall and DNA without a nucleus; some are pathogenic and some non-pathogenic

Question 9

Chromosomal DNA

Answer 9

• Double-stranded DNA
• Not enclosed in a membrane and thus no distinct nucleus
• Located in region of cytoplasm known as nucleoid
• Stores genetic material of cell

Question 10

Plasmid

Answer 10

• One or many circular double-stranded DNA
  relatively fewer genes than chromosome replicate independently of bacterial chromosomal DNA
• Encode advantageous traits (e.g. antibiotic resistance)

Question 11

Cell Wall
(NOT cellulose, made of peptidoglycan)

Answer 11

• Made of peptidoglycan, a network of modified-sugar polymers cross-linked by short polypeptides
• Rigid structure enclosing cell surface membrane
• Prevents cell from bursting when they take in too much water
• Maintains shape of bacterium
• Protects from harsh environmental conditions

Question 12

Capsule

Answer 12

• Layer of sticky polysaccharide (carbohydrate,
  saccharide -> sugar)
• Prevents the cell from bursting when they take in too much water
• Protects from harsh environmental conditions
• Protect from viral infection
• Adhere to their substrate (surfaces) or to other individuals in a colony
• Shield pathogenic bacteria from attacks by their host’s immune system

Question 13

Flagellum
(Plural: Flagella)

Answer 13

• threadlike appendage (Appendage -> structure that sticks out)
• Move from one place to another
  (Motile)

Question 14

Fimbriae
(Singular: Fimbria)

Pili
(Singular: Pilus)

Answer 14

• Fimbriae are usually more numerous and shorter than pili
• Thin, protein tubes originating from the cytoplasmic membrane of many bacteria
• Allow bacteria to stick to their substrate or to one another

Question 15

Influenca S&S

Answer 15

• Symptoms usually:
  High fever
  Sore throat
  Cough
  Headache
  Muscle and joint pain
  Stuffy nose
• Other symptoms
  Sneezing
  Nasal discharge
  Loss of appetite
  Fatigue

Question 16

Transmission of Influenza

Answer 16

• Spreads when an infected person coughs, sneezes, or speaks
• Flu viruses are transmitted into the air through aerosol droplets and other people breathe in the droplets containing the viruses
• When these viruses enter the nose, throat or lungs of a person, they begin to multiply, causing symptoms of flu
• Spread indirectly -> person touches surface with influenza virus on it and touches his / her nose or mouth

Question 17

Method to kill Influenza

Answer 17

• Get a flu vaccine yearly
• Practise healthy habits - healthy diet and regular exercise
• Practice good personal hygiene – thorough washing of hands with soap and water, especially before touching eyes, nose or mouth and also after using the toilet
• Be socially responsible
• Do not spit in public places
• Cover your mouth and nose with a tissue when coughing or sneezing,
• Wear a surgical mask if you are unwell
• See a doctor if you are feeling unwell
• Do not go to school or work when you are ill
• When sharing food at meal times, use a serving spoon
• Antiviral medications can be taken within the first 2 days of the infection, so as to slow down or to reduce the symptoms caused by the viral infection

• Antibiotics are NOT effective as they work only for bacterial infections.
• Misuse and overuse of antibiotics may lead to emergence of antibiotic-resistant bacteria.

Question 18

Transmission of Pneumococcal Disease

Answer 18

• Direct contact with respiratory secretions (e.g. saliva, mucus)
• Many people (esp children) have the bacteria in their nose or throat at one time or another without being ill (Carriers)

Question 19

Pneumococcal Disease S&S

Answer 19

• Pneumonia
• Fever
  Cough
  Chest pain, difficulty breathing
  Fatigue
  Confusion or decrease in mental alertness
• Pneumococcal Meningitis
• Stiff neck
  Fever
  Headache
  Confusion
• Blood infection
• ^ Kills 1 in 8 adults. Survivors may get septicaemia, leading to loss of limb(s)
• Fever
  Chills
  Low alertness
• Sepsis
• Middle ear infection

Question 20

Methods to kill Pneumococcal Disease

Answer 20

• Vaccines are available to prevent pneumococcal disease

Question 21

Vaccines

Answer 21

Contain an agent that resembles a pathogen and prevent infectious diseases by stimulating white blood cells to produce antibodies when the pathogen invades