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Pathology Term 2 > Week 2 - HEAD & NECK > Flashcards

Week 2 - HEAD & NECK Flashcards

Pyrexia of Unknown Origin, Arboviral Fevers, Tropical Infections, Malarial Microscopy

1
Q

What is the definition of pyrexia/fever?

A
  • increase in body temp by 1-4 degrees
  • protective mechanism
  • NOT fully understood
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2
Q

What is the term for substances that produce fever and what are the 2 types?

A

Pyrogens

  1. Exogenous
    - bacterial products, LPS
  2. Endogenous
    - IL-1, IL-6, TNF-alpha
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3
Q

What is meant by a bacteria being coagulase + and give an example?

A
  • produces an enzyme causing clot formation to prevent immune system from penetrating the area of infection
  • coagulase test distinguishes between S. aureus and other types of Staph.
  • S. aureus = coagulase +
  • All other Staph. = coagulase -
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4
Q

What is meant by a bacteria being catalase + and give an example?

A
  • produces an enzyme that catalyses the conversion of H2O2 –> water
  • distinguishes between Staph and Strep
  • Staph = catalase +
  • Strep = catalase -
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5
Q

How do pyrogens produce fever?

A

Pyrogens –> increase COX –> increase synthesis of prostaglandins –> PGE2 in hypothalamus –> resets thermal clock –> FEVER

  • peripheral vasoconstriction
  • central vital organ vasodilation (increase core body temp)
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6
Q

What class of drug is commonly use to provide fever relief and how do they function?

A

NSAIDs

  • inhibit COX in hypothalamus
  • decrease PGE2
  • decrease systemic effects of pyrexia

*ALSO –> decrease local tissue injury without significantly affecting defense/immune mechanism (unline steroids)

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7
Q

What is the key difference between NSAIDs and steroids?

A

NSAIDs do NOT significantly affect immune function while steroids have immunosuppressant effects

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8
Q

Give an example of defective inflammation

A

Diabetes Mellitus

  • abnormality of BVs
  • immunosuppression results in increased infections
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9
Q

What are the systemic protective effects of inflammation?

A

Brain

  • fever via PGs in hypothalamus
  • IL-1, 6, TNF-alpha

Liver

  • increase acute phase proteins
  • IL-1, 6

Bone Marrow

  • stimulates leukocyte production
  • IL-1, 6, TNF-alpha
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10
Q

What are the systemic pathological effects of inflammation?

A

Heart

  • decrease CO; shock in case of septicemia
  • TNF-alpha

Endothelium/BVs

  • thrombosis
  • vascular damage
  • increase permeability
  • TNF-alpha

Multiple tissues

  • defective muscle metabolism due to insulin resistance
  • weakness
  • loss of weight
  • IL-1, TNF-alpha
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11
Q

What is the definition of PUO and its 4 types?

A

*Lack of Dx. of cause of fever

  1. Classic PUO - >38, >3wks
  2. Nosocomial PUO - >38.3, >1wk inpatient OR >3days intensive Ix.
  3. Neutropenic PUO - >38.3, <1x10^9 neutrophils
  4. HIV-associated PUO - >38.3, >4wks outpatient/>3days inpatient
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12
Q

What are the common causes of PUO?

A
  1. Infective
    - hidden abscess, TB, viral, parasitic
  2. Malignant
    - HL/NHL
  3. Inflammatory
    - giant cell arteritis, SLE, ARF, sarcoidosis, rheumatic
  4. Undetermined
    - MI, PE, drugs, endocrine, hepatic, CVA, allergic, etc

*UNKNOWN IN 19% cases

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13
Q

True or False?

Arboviral infections cannot spread from person to person

A

True

  • Arbo = insects
  • insects –> man
  • zoonotic (therefore infections of wild animals)
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14
Q

Why is there an increase incidence of arboviral infections nowadays?

A

Global Warming –> epidemics

-causes increased mosquito numbers = increased vectors for spread of infection

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15
Q

What arbovirus commonly causes polyarthralgia?

A

RRV

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16
Q

Which arbovirus is the commonest for fever and rash?

A

Dengue

RRV also

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17
Q

What are the common alphaviruses and flaviruses?

A

Alphavirus:

  • RRV
  • BFV
  • Chikungunya

Flavivirus:

  • Kunjin
  • Dengue
  • MVE
  • JE
  • WNE
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18
Q

Where are arboviruses more common?

A

Tropical areas

-NQ/NT/Asia Pacific

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19
Q

What is Australia’s most prevalent arbovirus and what is it also referred to as?

A

RRV

-endemic polyarthritis (as pts. have long term joint pain)

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20
Q

What type of arbovirus is RRV and what mosquito transmits it?

A

ALPHAVIRUS

-Culex/Aedes mosquito

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21
Q

What is the IP and classic presentation of RRV?

A

-IP approx. 3-11days
Symptoms:
-fever, fatigue, arthritis, rash (red, non-pruritic, maculopapular rash), headache, lymphadenopathy

*self-limited (4-7mths)

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22
Q

What is the rough IP for most arboviruses?

A

1 week

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23
Q

What is ross river disease?

A

-NO fever present

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24
Q

How is RRV diagnosed?

A

Serology:

-4-fold increase in serum IgG/IgM confirms Dx.

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25
True or False? | There is a cure and effective Tx. for RRV
False
26
What vector is responsible for Dengue and what is interesting about it?
Aedes aegypti - "white band" - it feeds during the DAY - other mosquitos are night-time feeders
27
What are the symptoms of dengue and what is it also referred to as?
Sx. - fever/rash - myalgia/arthralgia - abdominal pain - headache - serositis Marked muscle + joint pains --> AKA: breakbone fever
28
What is significant about the fever pattern in dengue?
Fever 5-7 days - biphasic - initially high fever, drops down, then back up again * SADDLEBACK FEVER CURVE
29
True or False? | Adults are affected by dengue more commonly than children
False
30
What are the 2 clinical forms of dengue?
1. Febrile form (flu-like) | 2. Classic dengue fever (DF) --> muscle/joint pain
31
What are the 2 immune complications of dengue fever?
1. DHF 2. DSS *v. high mortality rate :(
32
What is the pathophysiology of denge?
- infection (with potential Ab-dependent enhancement) - inflammatory rush with cytokines/activated T cells - endothelial damage - plasma + protein leakage --> severe dehydration, shock, hypoalbuminemia --> ascites - platelet activation --> thrombocytopenia - serositis + hepatitis --> ascites from serositis - SHOCK --> due to severe dehydration
33
Define DHF and what are the 4 grades?
- fever/recurrent Hx. of fever - haemorrhagic manifestations - decreased platelet count --> endothelial damage (severe bleeding) - objective evidence of leaky capillaries --> increased Hct, ascites, plearual effusions, hypoalbuminemia Grades: 1. fever + non-specific Sx. 2. spontaneous bleeding 3. circulatory failure 4. profound shock (DSS)
34
What are the initial warning signs of DHF?
- disappearance of fever (saddleback fever curve) - decreased platelets - increase Hct
35
What are the 4 criteria for DHF?
1. Fever 2. Haemorrhagic manifestations 3. Increased capillary permeability 4. <100 x 10^9 platelets (thrombocytopenia)
36
What are the alarming signals of DHF?
- shock - prolonged vomiting - fever --> hypothermia - altered LOC
37
What is the name of the bacteria that are being used (trialled) to kill dengue infected mosquitos?
Wolbachia
38
What vector causes MVE?
Culex mosquito
39
What are the Sx. of MVE and what can manifest in severe forms?
Sx. - fever - headache (increased ICP) - nausea/vomiting Severe: - meningitis/encephalitis - drowsiness - confusion - convulsions
40
How is MVE diagnosed?
Serology - 4-fold increase in serum IgG/IgM - viral culture of blood/CSF
41
True or False? | MVE, WNV and Kunjin have cross-reacting Abs?
True | -positive serology could mean ANY of these 3 are the cause
42
What virus does Chikungunya have cross-reacting Abs with?
RRV (similar Sx.) | -but chikungunya prevalent in India, Malaysia, Thailand (therefore Travel Hx. = very important)
43
True or False? | BFV is the 2nd commonest arbovirus in Aus. and it is "truly aussie" - i.e. only seen in Australia
True + True
44
What vector causes BFV and what are the Sx.?
``` vector = Aedes mosquito Sx. = fever, rash, headache, myalgia/arthralgia ```
45
True or False? | NSAID use is beneficial for arboviral infections
False | -can cause more damage than benefits due to increased bleeding
46
What is the causative organism of leptospirosis and how is it transmitted?
Leptospira icterohemorrhagica - bacterial spirochaete - zoonotic disease in wild animals - spreads to humans through contact with water, food or soil containing the URINE of infected animals --> because the bacteria resides in renal tubules
47
Why is leptospirosis referred to as a biphasic illness?
1. First flu phase: -fever, chills, myalgia, headaches | 2. Second (Weil's Disease): - jaundice, fever, haemorrhage (rash), renal/liver/CNS involvement
48
How is leptospirosis diagnosed?
CULTURE * blood (<1wk) * urine (>1wk)
49
What is the causative organism of melioidosis (whitmore's disease) and how is it transmitted?
Burkholderia pseudomallei - facultative intracellular gram negative bacteria - saprophyte - in soil/fresh surface water in endemic regions (Northern Aus in wet season = hyperendemic) - spread via contact with contaminated soil/water - IP = 9days
50
What are the Sx. of melioidosis?
* pneumonia * multiple abscesses (splenic/liver/lung) - cough/pleuritis - bone/joint pain - cellulitis - fever, chills, rigors, cough, sputum - cutaneous melioidosis at site of organism entry - subacute/chronic presentation --> hemoptysis + night sweats (DDx. = TB)
51
What is the characteristic clinical feature of melioidosis?
Multiple abscesses - splenic - liver - lung
52
What is the causative organism of Q fever and how is it transmitted?
Coxiella burnetii - highly infectious (bioterrorism) - reservoir in cattle, sheep, goats, etc. (increased on farms) OR in contaminated dust/milk --> inhalation/ingestion *IP = 9-40days
53
What are the Sx. of Q Fever? And what is the characteristic/unique feature?
Sx. - fever - headache - fatigue - myalgia/arthralgia * most recover BUT some develop chronic fatigue, endocarditis + hepatitis *CHARACTERISTIC FEATURE = Granulomas in Liver
54
What are the 2 phases of Q Fever?
1. Acute phase: - 7-14 days - flu-like Sx. + severe headache, myalgia, arthralgia, cough + pneumonia 2. Chronic phase: - Q fever endocarditis --> in susceptible (IC) patients or people with previous valvular damage
55
How is Q fever diagnosed?
Serology: - IgG/IgM *increased IgG + IgA in Q fever endocarditis (chronic phase)
56
What are prevention techniques and Tx. for Q fever?
Prevention: - vaccine - pasteurisation of milk - safe animal product handling Tx. - acute: - doxycycline (3wks) - chronic: - doxycycline + quinolones (3yrs)
57
What is an important precaution with administration of the Q fever vaccine?
- pre-vaccine testing for previous exposure to Q fever is imperative - previous exposure to Q fever produces a severe reaction to the vaccine - test for previous exposure --> wait 7 days --> if negative, give vaccine. If positive, NO VACCINE
58
What mosquito causes malaria and what are the 2 commonest malaria species?
Anopheles mosquito 1. Plasmodium falciparum 2. Plasmodium vivax
59
Why is mild jaundice seen in malaria?
RBC hemolysis
60
What are the clinical features of malaria?
- fever - chills - rigors - fatigue - mild jaundice, splenomegaly, anemia --> chronic ?
61
What is the most severe malaria species and what can it cause?
P. falciparum - acute renal failure --> malarial hemogobinuria (BLACKWATER FEVER) - coma - severe acidosis - extensive RBC breakdown *due to adhesion proteins that make RBCs clog deeper veins ?
62
How is cerebral malaria caused?
- cerebral BVs clogged by parasites | - v. little inflammation
63
Why is there a cyclical fever in malaria?
- due to cyclical rupture of RBCs with subsequent release of merozoites causing fever. - P. falciparum = 48hrly - P. malariae = 72hrly
64
What is the pathophysiology of malaria?
- anopholes mosquito injects sporozoites into human - sporozoites invade hepatocytes - merozoites formed and released from liver - merozoites invade RBCs - merozoites --> trophozoites (ring form) in RBCs - trophozoites --> schizonts --> RBC rupture - RBC rupture releases more merozoites and produces cyclical fever - released merozoites invade further RBCs (blood stage) - some trophozoites --> gametocytes --> more mosquitos
65
How is malaria diagnosed?
PfHRP2 Ag - Ab-based detection ("pan malaria") - test = + even after clearing parasitemia with artemisinin Tx.
66
What is the most common stage of parasite seen in peripheral blood film of a malaria patient?
Trophozoite (ring form)
67
What is the commonest malaria species?
Plasmodium vivax
68
What is a characteristic microscopic feature of P. falciparum?
- increased parasitemia (can be >1 malaria parasite/RBC --> wheras P. vivax = 1 per RBC) - smaller rings (trophozoites) --> whereas P. vivax can have v. large rings - can also see gametocytes/schizonts
69
What is a hypnozoite?
Malaria parasites that lie dormant in heaptocytes (hepatic dormancy) --> can lie dormant for years *P. vivax + P. ovale
70
What is the gold standard for Dx. of malaria? And what are other diagnostic tests?
Blood film microscopy - Thick film --> to determine presence of malaria - Thin film --> to distinguish which parasite is present Other Dx. tests: - Ag detection by RDT - PCR molecular diagnosis - Serology --> ELISA

Pathology Term 2 (6 decks)

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