Crash course: PUO, Fever in the returning traveller Flashcards
What is pyrexia of unknown origin?
Repeated pyrexia >38.3ᵒC for >3w without a known cause, despite at least 1w of Ix
What are the 4 classifications of PUO?
Classical
Nosocomial PUO: fever >24h, no fever on admission
Neutropaenic PUO: neutrophil count <500
HIV-associated PUO: >4w OP or >3d IP
Give 3 causes of classical PUO
Infection
Malignancy
Collagen vascular disease
Give 4 causes of nosocomial PUO
C diff enterocolitis
Drug induced
PE
Septic thrombophlebitis
Give 4 causes of neutropenic PUO
Opportunistic bacteria
Aspergillosis
Candidiasis
Herpes virus
Give 4 causes of HIV associated PUO
CMV
MAC
PCP
Kaposi sarcoma
Give 4 other causes of fever
Non-obvious infections: unusual infections/ foci
AI conditions: rheum, vasculitis, Still’s
Malignancy: haem ca
Rare familial diseases: periodic fever syndromes, Fabry’s
What is the cause of Typhoid fever? How is it transmitted? When does it present?
Salmonella typhi or Salmonella paratyphi
Classically travel from India
Faeco-oral route
After 1-2w incubation
Give 5 non-specific signs of Typhoid fever
Fever
Malaise
Headache
Epistaxis
Constipation
Give 4 more specific signs indicative of Typhoid fever
Faget’s sign: relative bradycardia (would expect ↑ with fever)
Rose spots
Hepatosplenomegaly
Cytopenias
Why does Typhoid cause GI disease?
Typhoid resides in Peyer’s patches
What investigations are used for typhoid fever?
Blood culture (stool -ve in early disease)
Serology (Widal test in developing countries)
GS: Bone marrow culture
What is treatment for Typhoid fever?
IV Ceftriaxone
Fluoroquinolones: Ciprofloxacin
What go to inflammatory cause of PUO should be considered in young patients and old patients?
Young: Adult-onset Stills
Old: GCA
What is Dengue fever caused by? What is this associated with? How is it transmitted? When does it present?
1 of 4 Dengue serovars
Travel from SE Asia
Mosquito bites
After 2w incubation
Give 4 non-specific signs/ symptoms of Dengue
Fevers
Rigors
Myalgia
Weakness
Give 2 buzzwords associated with Dengue presentation
Retro-orbital headache
Sunburn rash
What are the 2 rare but severe syndromes Dengue can present with? How?
Dengue shock syndrome
Dengue haemorrhage fever
If get infected with different serovar, preformed Ab to original serovar carries the virus to T, B cells + macrophages
Dengue spread to more cells it can infect
What is malaria?
Parasitic infection caused by Plasmodium spp.
Falciparum
Vivax + Ovale
Knowlesi
Malariae
How does malaria present?
Variable incubation dependent on species
Paroxysms of fever + rigors
Propensity for effecting liver: jaundice, hepatosplenomegaly, haemolytic anaemia, haemoglobinuria
Name 5 potentially fatal complications of malaria
Shock
ARDS
Cerebral malaria
Blackwater fever
DIC
What is blackwater fever?
Complication of malaria
Pronounced haemolysis
Leak lots of Hb into urine
Damages kidney + causes production of v dark black urine
What investigations are used for malaria?
3x Blood smears: Thick + Thin blood films = GS
Whats the difference between thick and thin blood smears?
Thick: high sensitivity, best initial test
Thin: lower sensitivity, high specificity, confirmatory test
What is the lifecycle of plasmodium falciparum?
- Bitten by mosquito- releases Sporozoites into blood
- Sporozoites travel to liver + “set up shop”: Infect hepatocytes forming Hepatic Schizont (big ball of developing malaria parasites)
- Gets increasingly bigger
- Schizont ruptures, releasing loads of immature parasite into blood stream
- Each parasite goes into a RBC + matures, turning into erythrocytic schizont
- Erythrocytic shizont gets bigger + bigger, once fully developed, ruptures RBC, releasing more immature parasites that go on to infect more RBCs
Why are there paroxysms of fever in malaria?
Cycle of invading RBCs/ rupture
Fevers, rigors, really unwell is due to RBCs rupturing + causing acute inflammation
Feel better when the immature parasites are invading new RBCs + developing
How does the lifecycle of plasmodium vivax and ovale differ to falciparum?
Produce Hypnozoites
When infecting the liver, instead of all the parasites forming schizonts, rupturing + releasing parasites, some become quiescent
Hypnozoites can become reactivated years later, presenting with an acute malaria, having not been exposed to it since infection
Ramifications for Tx
Antimalarials that treat the active parasite in the blood don’t kill hypnozoites
Need slightly different Tx if vivax or ovale
What is the treatment for severe falciparum malaria?
IV Artesunate
Give 4 features of clinically severe malaria
Parasitaemia >2%
Hypoglycaemia
Metabolic/ lactic acidosis
Severe anaemia
If non-severe, what is the treatment for falciparum malaria?
Artemesin combination therapy or chloroquine
Most common ACT= Artemether + Lumefantrine
What additional drug is required for vivax and ovale?
Subsequent primaquine to kill hypnozoites
