Fever of Unknown Origin

Question 1

Define ‘fever’ and ‘febrile illness’

Answer 1

Temperature above 38°C

Question 2

Define pyrexia/fever of unknown origin

Answer 2

Temperature above or = 38.1°C

No diagnosis after 3 weeks or 1 week of hospital tests

Question 3

Define ‘acute undifferentiated febrile illness’

Answer 3

Temperature above or = 38.0°C with no organ focus and < 2 weeks duration

Question 4

Which ‘occult infections’ can be responsible for causing a fever of unknown origin?

Answer 4

Endocarditis

Liver abscess

Biliary infections

UTI

LRTI

Question 5

What can a low temperature be indicative of especially in the elderly?

Answer 5

Sepsis

Question 6

Name 3 protozoa that can cause fever of unknown origin

Answer 6

Malaria

Leishmaniasis

Trypanosomiasis

Question 7

Name 4 bacterial infections that can cause fever of unknown origin

Answer 7

Enteric fever (salmonella species)

Tuberculosis

Q fever

Brucelossis

Question 8

Name 2 spirochaetes that can cause fever of unknown origin

Answer 8

Leptospirosis

Relapsing fever

Question 9

Name 2 rickettsia that cause fever of unknown origin

Answer 9

Typhus

Bartonelllosis

Question 10

Name some arboviruses that cause fever of unknown origin

Answer 10

Dengue

Chikungunya

Sand fly fever

Zika

Japanese encephalitis

Yellow fever

West nile fever

Question 11

Name some non-infectious causes of fever of unknown origin

Answer 11

Malignancy

Autoimmune disease

Heat illness

Question 12

Name some other viruses that can cause of fever unknown origin

Answer 12

HIV

CMV

Viral hepatitis

EBV

Hantavirus

Question 13

What information needs to be taken regarding a person with fever of unknown origin?

Answer 13

• Immunocompromise?
• Recent travel?- where/when
• Activities
• Accommodation/transport
• Food/water
• Insects/animal contact- bites/stings
• Sexual contacts and drugs- needles/blood products/protection used?
• Freshwater exposure and bare skin contact with the ground?
• Precautions and prophylaxis taken?

Question 14

What laboratory investigations should be conducted in fever of unknown origin?

Answer 14

Urinalysis: ?haematuria/proteinuria/WBCs

FBC: Hb/neutrophils/lymphocytes/platelets

U&Es:?AKI

LFTs:?hepatitis

CRP:?acute bacterial infection

ESR:?chronic bacterial infection/inflammation

Lactate:?tissue hypoperfusion/sepsis

Autoantibodies:?autoimmune disease

Question 15

Which microbiology investigations should be carried out in fever of unknown origin?

Answer 15

Blood cultures (+/- mycobacterial cultures)

Urine MC&S

Stool MC&S

Malaria blood films and antigen tests

Serology tests (for viral/rare/tropical infections)

PCR tests: esp for viral and rare infections

Question 16

In what circumstance would a mycobacterial blood culture be used in fever of unknown origin?

Answer 16

?Disseminated TB

Question 17

What does this CT Abdo show?

Answer 17

Liver abscess

Question 18

What infections must be excluded before a diagnosis of fever of unknown origin can be made?

Answer 18

LRTI and UTI