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AC1 > Week 5 > Flashcards

Week 5 Flashcards

1
Q

Describe the structure of viruses

A
  • 20 nm - 1 microm in size
  • RNA or DNA
  • No independent metabolism and no organelles
  • Simple protein coat (& cell membrane from host cell)
  • Has a H spike and N spike
  • Has an envelope and capsid
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2
Q

What are koplik spots?

A

Little white spots on buccal mucosa - seen in early measles

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3
Q

What are the symptoms of Herpes Simplex Virus?

A

peri-oral (HSV-1) and genital (HSV-2) infections. Can also cause HSV encephalitis. May become latent in dorsal root ganglia –> recurrence

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4
Q

What is it called when HSV recurs in facial nerve?

A

Bell’s palsy

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5
Q

What are the symptoms of Varicella Zoster Virus?

A

fever and vesicles in a centripetal distribution. Can also cause VZV meningitis. Becomes latent in dorsal root ganglia –> recurrence

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6
Q

What is it called when VZV recurs in facial nerve?

A

Ramsey-Hunt syndrome (Herpes zoster oticus)

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7
Q

What are the clinical features of Epstein-Barr Virus?

A

Central: fatigue, malaise, loss of appetite, headache

Visual: Photophobia

Tonsils: Reddening, swelling, white patches

Lymph nodes: Swelling

Spleen: Enlargement, abdo pain

Gastric: Nausea

Systemic: Chills, fever, aches

Resp: Cough

Throat: Soreness, reddening

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8
Q

What is the treatment for Chronic HBV or HCV infection?

A

PEG-IFN-α for 48 weeks +/- other drugs

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9
Q

What does a change in neutrophils suggest?

A

bacterial infection

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10
Q

What happens to Hb in chronic infections?

A

Decreases

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11
Q

What does a change in lymphocytes suggest?

A

Viral infection

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12
Q

What happens to platelets in malaria and some viral infections?

A

Decreases

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13
Q

What happens to platelets in bacterial infections and some inflammatory disorders?

A

Increases

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14
Q

Give some examples of primary immunodeficiency

A

(intrinsic cause = usually genetic)
• Phagocyte deficiencies (innate cell-mediated immunity)
• Complement deficiencies (innate humoral immunity)
• Severe combined immuno-deficiencies (adaptive cell-mediated immunity)
• Predominantly antibody deficiencies (adaptive humoral immunity)

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15
Q

Give some examples of secondary immunodeficiency

A

(extrinsic cause = non-iatrogenic)
• Hyposplenism / Asplenism (eg. Have spleen removed)
• Haematological malignancies (cancer of blood cells)
• HIV / AIDS

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16
Q

Give some examples of immunosuppression

A

(extrinsic cause = iatrogenic)
• Steroids & other immunosuppressive drugs
• Cytotoxic chemotherapy (for malignancies)
• Total body irradiation (before bone marrow transplantation)

17
Q

Describe Chronic Granulomatous Disease (CGD)

A

Aetiology :
multiple possible defects (most frequently X-linked) → phagocytes being unable to destroy ingested microbes

Pathology : lack of oxidative burst to produce free radicals → excessive granuloma formation occurs instead

Clinical Features : persistent & recurrent infections especially …
pneumonia
skin infections
abscesses (skin & internal)
septic arthritis & osteomyelitis
bacterial & fungal blood stream infections
Staph. aureus, Salmonella, Klebsiella, Burkholderia
Aspergillus, Candida

Investigations : nitroblue-tetrazolium (NBT) test uses microscopy (normal phagocytes reduce NBT to a dark pigment)
dihydrorhodamine (DHR) test uses flow cytometry (normal phagocytes reduce DHR to a fluorescent pigment) genetic analysis to identify exact genetic defect

Treatment : early diagnosis & treatment of any infections prophylactic antibiotics (co-trimoxazole & imidazoles) recombinant IFN-gamma (70% less infections) bone marrow / stem cell transplantation (curative)

Prognosis : without treatment most children die within 10 years with treatment if X-linked → 20% die within 10 years with treatment autosomal recessive → 50% die in 35 yrs

18
Q

Describe Common Variable Immunodeficiency (CVID)

A

Aetiology : multiple possible defects (not X-linked) →
hypogammaglobulinaemia (IgG, usually IgA, possibly IgM)

Pathology : lack of antibodies to neutralise & opsonise pathogens → severe, persistent, unusual & recurrent infections & autoimmune, malignant, enteric & lymphoid disorders

Clinical Features :	 Streptococcus pneumoniae (LRTIs & septicaemia) Haemophilus influenzae (URTI/LRTIs & meningitis)
Neisseria meningitidis (meningitis & septicaemia) 			 Staphylococcus aureus (skin & soft tissue infections)
Pseudomonas aeruginosa (ear infections & LRTIs)
Giardia lamblia (intestinal infection) most common sites are ears & respiratory tract

Investigations : reduced immunoglobulins on simple blood test
↓ IgG always, ↓ IgA usually, ↓ IgM in ~50% normal B lymphocyte count, but immature types failure to produce antibodies in response to vaccines

Treatment : early diagnosis & treatment of any infections prophylactic immunoglobulin transfusions (IV every 3-4 weeks or SC every week)

immunoglobulin reactions can occur (“serum sickness”) “flu-like” symptoms (but no respiratory component) possible thrombotic events or anaphylaxis (very rare)

(less indication for bone marrow / stem cell transplantation)

Prognosis : good with regular immunoglobulin transfusions

19
Q

How would you investigate hyposplenism/asplenism?

A
  • Spleen function assessed by imaging (USS)

- Blood films show Howell-Jolly bodies in erythrocytes

20
Q

What cells does HIV infect?

A

Th lymphocytes (aka T4 or CD4 cells)

21
Q

What causes AIDS-defining diseases

A

CD4 < 200 cells/mm3

22
Q

Give some examples of re-emerging infectious disease

A

TB, Multi-drug resistance TB, Flu, Dengue

23
Q

What are some factors that contribute to emergence?

A

Agent:

  • Evolution of pathogenic infectious agents (microbial adaptation & change)
  • Development of resistance to drugs
  • Resistance of vectors to pesticides

Host:

  • Human demographic change (inhabiting new areas)
  • Human behaviour (sexual and drug use)
  • Human susceptibility to infection (immunosuppression)
  • Poverty & social inequality

Environment:

  • Climate & changing ecosystems
  • Economic development & land use (urbanisation, deforestation)
  • Deforestation forces animals into closer human contact - increased possibility for agents to breach species barrier between animals and humans
  • Natural disasters & related outbreaks of infectious diseases (Malaria, Cholera, Plague)
  • Global warming - spread of malaria, dengue, leishmaniasis, filariasis
  • Technology & industry (food processing & handling)

Others:

  • International travel and commerce
  • Breakdown of public health systems (war, unrest, overcrowding)
  • Deterioration in political systems and lack of political will
  • Donor Agencies and Funding
24
Q

Define incubation period

A

The time interval between initial contact with an infectious agent and the appearance of the first sign or symptom of the disease

25
Q

Define infectious period

A

This is the time during which an infected agent may be transferred from an infected person to another person

26
Q

What is Landsteiner’s Law?

A

If an agglutinogen is present on red blood cell membrane, the corresponding agglutinin must be absent in the plasma

If an agglutinogen is absent on red blood cell membrane, then corresponding agglutinin must be present in the plasma

AC1 (9 decks)

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