Microbiology - PUO + Fever in Returning Traveller + Malaria

Question 1

What is a pyrexia of unknown origin?

Answer 1

Fever >38.3C on several occasions, persisting for >3/52, without diagnosis despite >1/52 of intensive Ix

Question 2

What is a classical PUO and some examples?

Answer 2

• PUO + >3/7 in hospital OR >3 OP visits with ambulatory Ix

E.g:
- Infections (inc. abscesses, endocarditis, TB)
- Malignancy
- Connective Tissue Disease

Question 3

What is a healthcare-associated PUO and some examples?

Answer 3

• PUO that develops in a patient following >24hrs in hospital

E.g:
- Hospital-acquired infections (LRTI, C. diff, UTI)
- Medical devices (catheter, IV line, bacteraemia)
- Surgery
- Drugs (Vancomycin, penicillins, serotonergics)
- Immobilisation

Question 4

What is neutropenic PUO and some examples?

Answer 4

• Fever concomitant with neutropenia (<500/uL) + subsequent lack of cellular response
• MEDICAL EMERGENCY

E.g:
- Chemotherapy
- Haematological malignancies
- Drugs (clozapine, carbimazole)

Question 5

What is HIV-associated PUO and some examples?

Answer 5

• HIV +ve patients frequently have PUO

E.g:
- Seroconversion
- Infection (TB, bacteria, PCP, MCV etc.)
- Malignancy (Kaposi’s sarcoma, lymphoma)
- Drugs

Question 6

What is the workup for a febrile neutropenia?

Answer 6

• Blood cultures
• Immediately start empirical Abx
• Try to identify source as will guide Abx choice

Question 7

What are some investigations to rule out other causes of PUO?

Answer 7

• Vasculitis screen: pANCA, cANCA, Rho, La (Rheum r/v IF arthritis)
• Bence Jones/protein electrophoresis (e.g. myeloma)
• Dip urine/casts
• Familial diseases (e.g. FMF, Fabry’s disease, cyclic neutropenia)
• Fever in returning traveller
• Still’s disease

Question 8

What is the general treatment for a fever in a returning traveller?

Answer 8

Doxycycline

Question 9

What are some causes of a fever in a returning traveller?

Answer 9

• Tropical diseases (e.g. Malaria, Typhoid, Dengue, Viral haemorrhagic fever)
• Bacterial diarrhoea (E. coli, cholera)
• UK causes = UTI, pneumonia, influenza
• STIs = HIV seroconversion

Question 10

What are the causative organisms for typhoid and their features?

Answer 10

• Salmonella typhi + paratyphi
• Anaerobic gram -ve bacilli

Question 11

What are the common features of typhoid?

Answer 11

• Travel to India
• Transmitted in food + water
• Incubation = 1-2wks
• Transmission = faeco-oral route

Question 12

How does Typhoid cause enteric fever?

Answer 12

Infects Peyers patches in intestines

Question 13

How does typhoid classically present?

Answer 13

• Fever
• Headache
• Constipation
• Epistaxis
• ROSE SPOTS
• Relative bradycardia (Faget’s sign)
• Hepatosplenomegaly
• Cytopenias

Question 14

How is typhoid diagnosed?

Answer 14

• Gold standard = Blood/BM cultures
• Stool cultures
• Widal’s test

Question 15

What is the management of Typhoid?

Answer 15

• IV ceftriaxone
• PO Azithromycin

Question 16

What is a complication of Typhoid?

Answer 16

GI perforation

Question 17

How is Denque caused?

Answer 17

• 4 Denguevirus serovars
• Flavivirus spread by ADES MOSQUITO

Question 18

What are the features of Denque?

Answer 18

• South East Asia
• Urban environments
• Short incubation (days)
• Reasonably mild + self-limiting

Question 19

How does Dengue classically present?

Answer 19

• Myalgia
• Fever
• Rash (sun-burn rash)
• Retro-orbital headache

Question 20

What happens if someone is re-infected with a different serotype of Dengue?

Answer 20

• Dengue haemorrhagic fever
• Dengue shock syndrome
• Rare in travellers
• Supportive Mx

Question 21

How is Malaria caused?

Answer 21

• Protozoal infection (Plasmodium spp.) spread by FEMALE ANOPHELES MOSQUITO (bites at night + attracted by heat + CO2)
• Life cycle involves mosquitos + humans (RBCs + liver)

Species Calssification = Falciparum vs Non-Falciparum
Non-Falciparum:
- P. vivax
- P. ovale
- P. Malariae
- P. knowlesi

Question 22

What are some general features of malaria?

Answer 22

• Returning traveller from endemic regions (Asia/Africa/South America)

Question 23

What are some features of Non-falciparum Malaria?

Answer 23

• Sx for falciparum but less severe
• 48hr fever (P. malariae = 72hrs)

Question 24

How is non-falciparum malaria diagnosed?

Answer 24

Schuffner’s dots on blood film

Question 25

How is non-falciparum malaria treated?

Answer 25

• Chloroquine
• Primaquine

Question 26

What are some features of falciparum malaria?

Answer 26

• Most common + most severe cause of malaria
• 48hrly fever (paroxysms of fever + rigors)
• Generally unwell
• Hepatosplenomegaly
• Anaemia
• Jaundice
• Renal impairment (Haemoglobinuria)
• Impaired consciousness/seizures
• Acidosis (pH <7.3)
• Hypoglycaemia (<2.2mmol/L)
• Pulmonary oedema / ARDS
• Spontaenous bleeding/DIC

Question 27

How is P. Falciparum Malaria diagnosed?

Answer 27

• Thick + thin blood films
• Thick demonstrates malaria
• Thin demonstrates species

Question 28

How is P. falciparum malaria treated?

Answer 28

Mild:
- Artemesin combination therapy (Riamet = artemether + lumefantrine)

Severe:
- IV artesunate

Question 29

What are some indications for IV therapy of falciparum malaria?

Answer 29

• Parasitaemia >2%
• Pregnancy
• Vomiting

Question 30

What are some complications of malaria?

Answer 30

• Shock
• ARDS
• Cerebral malaria
• Black water fever
• DIC

Question 31

How are paroxysms of fevers + rigors caused in malaria?

Answer 31

The rupture of RBCs