L40 Pyrexia of Unknown origin

Question 1

Pyrexia of unknown origin is a febrile illness without an initial obvious case. T/F?

Answer 1

F

Is a prolonged febrile illness without an established cause, after intensive evaluation

Question 2

Classical definition of PUO?
A. Fever higher than 38.3 degrees
B. Persisting without diagnosis for at least 3 weeks
C. After 1 week of investigation in hospital
D. Excluded fever with apparent causes like wound infection after surgery, or self-limiting diseases
E. Influenza-like illnesses are excluded

Answer 2

All of the above

**>38.3, >3 weeks

Question 3

What is nosocomial PUO? (3)

Answer 3

• Fever (38.3)
• infection not present not incubating on admission
• negative culture after 2 days

Question 4

What is neutropenic PUO? (3)

Answer 4

• Fever (38.3)
• Neutrophil <500/mm^3
• negative culture after 2 days

Question 5

What is HIV-associated PUO? (5)

Answer 5

• Fever (38.3)
• > 3 weeks in outpatient
• > 3 days in hospital
• HIV serologically positive
• negative culture after 2 days

Question 6

What are the Big Three causes for classical PUO?

Answer 6

1. Infections (30-40%)
2. Neoplasms (~20%)
3. Connective tissue diseases (~20%)

Question 7

What are specific pathogens that may cause pyretic infections?

A. Bartonella 
B. Q-fever
C. Typhoid fever
D. Extra-pulmonary TB
E. Malaria

Answer 7

All of the above

A and B are fastidious

Question 8

PUO of very long duration e.g. 3-6 months is unlikely to e due to infection. T/F?

Answer 8

T!

- microbiological diagnosis is unlikely (not infection)

Question 9

Other than routine history like social history, PMH, medication history, what do you have to ask?

Answer 9

TOCC

• Travel
• Occupation (working environment)
• Contact
• Cluster

Fever patterns - Tertain/ quartan patterns of malaria
Pets/ animal contact

Question 10

Which parts of the body we should pay attention in P/E? (5)

Answer 10

• Skin rash/lesion
• Eye and fundi
• Oral cavity
• Lymph nodes
• Abdomen

Question 11

Post-test probability can be less than 50% for a diagnostic test with satisfactory sensitivity and specificity if the prevalence is low.

Answer 11

True

e.g. Brucella: sheep, goat, cattle, pigs in middle East

Question 12

For PUO, after repeated history, P/E review, and repeated sampling of blood, what should be considered?

Answer 12

Fastidious organisms
Further tests
- Specific antibodies and serological tests
- Malarial blood smears (thick and thin)
- Non-invasive radiological investigations (CT scab, nuclear medicine testing)

Question 13

Therapeutic trials literally means “do something”.

What medications are indicated when infectious cause is unlikely? (2)

Answer 13

Steroids/ prostaglandin inhibitors

Locally - anti-tuberculous trial