Fever and PUO

Question 1

Define PUO

Answer 1

Prolonged illness of 2-3 weeks duration
Fever (above 38.3C) on several occasions
No diagnosis after intelligent investigations

Question 2

Where is body temperature regulated?

Answer 2

In the anterior hypothalamus (pre-optic region) by temperature sensitive neurons (with E-prostanoid receptors)

Question 3

How is heat production aided by hormonal mechanisms?

Answer 3

Thyroid hormone, glucocorticoids and catecholamines are released

Question 4

What is the relationship of oral temperature to core body temperature?

Answer 4

<CBT by 0.5C

Question 5

What is the relationship of axillary temperature to core body temperature?

Answer 5

<CBT by 1C

Question 6

What is the relationship of ear probe temperature to core body temperature?

Answer 6

Closer

Question 7

What is the optimum temperature range for various immune, endocrine and physiological mechanisms associated with an infection?

Answer 7

39.5C

Question 8

How does infection produce a fever?

Answer 8

PAMPs, complement or Ag-Ab complexes activate phagocytes
Phagocytes release TNF-a, IL-1B, IL-6 and IFN-y
Cytokines induce COX-2, resulting in production of PGE2
PGE2 acts on E-prostanoid receptor on neurons in the pre-optic region of the hypothalamus
Heat-producing mechanisms are initiated
N.B. LPS (often in G- organisms) can stimulate E-prostanoid receptors directly to produce rapid fever

Question 9

What does a very high CRP suggest?

Answer 9

Bacterial infection

Question 10

What does a high ESR suggest?

Answer 10

Non-specific

High with prolonged bacterial infection or vasculitis

Question 11

What does atypical lymphocytosis suggest?

Answer 11

Infectious mononucleosis syndrome (e.g. EBV, CMV, acute HIV/seroconversion illness)

Question 12

List 4 infections which may present as a PUO

Answer 12

Subacute bacterial endocarditis (low-grade organism e.g. viridans strep)
TN
Intra-abdominal abscess
HIV-related opportunistic infection
Other (EBV, CMV, brucella, Q fever, psittacosis, malaria)

Question 13

List 7 connective tissue diseases which may present as a PUO

Answer 13

Polymyalgia rheumatica
Giant cell arteritis
Vaculitis (polyarteritis nodosa)
Adult Still's disease
SLE
Acute thyroiditis
Granulomatous disease (sarcoidosis, Crohn's)

Question 14

What is the most common cause of fatal community-acquired pneumonia in the Top End?

Answer 14

Melioidosis

Question 15

What additional immunisations are required for medical students travelling to remote northern or central Australia?

Answer 15

Hepatitis A
Japanese encephalitis
Hepatitis B
MMR

Question 16

What is the most common illness acquired during travel in a developing country?

Answer 16

Traveller’s diarrhoea

Question 17

What is the main group of travellers who acquire malaria?

Answer 17

Travellers visiting friends/relatives

Question 18

What is the biggest group for morality from imported P. falciparum malaria?

Answer 18

> 65 y.o.

Question 19

What is the relationship between mortality from P. falciparum malaria and no. of cases seen by hospital?

Answer 19

Inverse relationship (centres with more experience with the disease have fewer mortalities proportionally)

Question 20

How is resistance to artemisinin acquired by malarial parasites?

Answer 20

Single point mutation in kelch13 gene (results in higher gametocytaemia)

Question 21

What geographical region has the highest incidence of P. vivax in travellers?

Answer 21

PNG and Oceania

Question 22

What % of travellers have behavioural risk factors for blood-borne viruses?

Answer 22

30-40%