Microbiology - PUO + Fever in Returning Traveller + Malaria Flashcards
What is a pyrexia of unknown origin?
Fever >38.3C on several occasions, persisting for >3/52, without diagnosis despite >1/52 of intensive Ix
What is a classical PUO and some examples?
- PUO + >3/7 in hospital OR >3 OP visits with ambulatory Ix
E.g:
- Infections (inc. abscesses, endocarditis, TB)
- Malignancy
- Connective Tissue Disease
What is a healthcare-associated PUO and some examples?
- 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
What is neutropenic PUO and some examples?
- Fever concomitant with neutropenia (<500/uL) + subsequent lack of cellular response
- MEDICAL EMERGENCY
E.g:
- Chemotherapy
- Haematological malignancies
- Drugs (clozapine, carbimazole)
What is HIV-associated PUO and some examples?
- HIV +ve patients frequently have PUO
E.g:
- Seroconversion
- Infection (TB, bacteria, PCP, MCV etc.)
- Malignancy (Kaposi’s sarcoma, lymphoma)
- Drugs
What is the workup for a febrile neutropenia?
- Blood cultures
- Immediately start empirical Abx
- Try to identify source as will guide Abx choice
What are some investigations to rule out other causes of PUO?
- 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
What is the general treatment for a fever in a returning traveller?
Doxycycline
What are some causes of a fever in a returning traveller?
- Tropical diseases (e.g. Malaria, Typhoid, Dengue, Viral haemorrhagic fever)
- Bacterial diarrhoea (E. coli, cholera)
- UK causes = UTI, pneumonia, influenza
- STIs = HIV seroconversion
What are the causative organisms for typhoid and their features?
- Salmonella typhi + paratyphi
- Anaerobic gram -ve bacilli
What are the common features of typhoid?
- Travel to India
- Transmitted in food + water
- Incubation = 1-2wks
- Transmission = faeco-oral route
How does Typhoid cause enteric fever?
Infects Peyers patches in intestines
How does typhoid classically present?
- Fever
- Headache
- Constipation
- Epistaxis
- ROSE SPOTS
- Relative bradycardia (Faget’s sign)
- Hepatosplenomegaly
- Cytopenias
How is typhoid diagnosed?
- Gold standard = Blood/BM cultures
- Stool cultures
- Widal’s test
What is the management of Typhoid?
- IV ceftriaxone
- PO Azithromycin
What is a complication of Typhoid?
GI perforation
How is Denque caused?
- 4 Denguevirus serovars
- Flavivirus spread by ADES MOSQUITO
What are the features of Denque?
- South East Asia
- Urban environments
- Short incubation (days)
- Reasonably mild + self-limiting
How does Dengue classically present?
- Myalgia
- Fever
- Rash (sun-burn rash)
- Retro-orbital headache
What happens if someone is re-infected with a different serotype of Dengue?
- Dengue haemorrhagic fever
- Dengue shock syndrome
- Rare in travellers
- Supportive Mx
How is Malaria caused?
- 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
What are some general features of malaria?
- Returning traveller from endemic regions (Asia/Africa/South America)
What are some features of Non-falciparum Malaria?
- Sx for falciparum but less severe
- 48hr fever (P. malariae = 72hrs)
How is non-falciparum malaria diagnosed?
Schuffner’s dots on blood film
How is non-falciparum malaria treated?
- Chloroquine
- Primaquine
What are some features of falciparum malaria?
- 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
How is P. Falciparum Malaria diagnosed?
- Thick + thin blood films
- Thick demonstrates malaria
- Thin demonstrates species
How is P. falciparum malaria treated?
Mild:
- Artemesin combination therapy (Riamet = artemether + lumefantrine)
Severe:
- IV artesunate
What are some indications for IV therapy of falciparum malaria?
- Parasitaemia >2%
- Pregnancy
- Vomiting
What are some complications of malaria?
- Shock
- ARDS
- Cerebral malaria
- Black water fever
- DIC
How are paroxysms of fevers + rigors caused in malaria?
The rupture of RBCs
