MI: Fever in the Returning Traveller Flashcards
How to take a good travel history
- Where did you go (exactly) + Stopovers
- Rural vs Urban
- When did you go + timing of symptoms
- Why did you go = (VFR - visting friends and relatives, higher risk)
- Pre-travel vaccines / prophylaxis (malaria)
List some diseases caused by mosquitoes.
- Malaria
- Elephantiasis
- Dengue
- Yellow fever
- West Nile virus
- Zika virus
What is the vector for malaria?
Anopheles mosquito (female)
What are the five species of Plasmodium.
- Plasmodium falciparum (75%)
- Plasmodium vivax (20%)
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
Outline the life cycle of Plasmodium within humans.
- Mosiquito bite infects humans with sporozoites
- Within humans there is an exoerythrocytic stage (liver) and an erythrocytic stage
- It replicates within liver and can remain dormant for years (vivax and ovale [hypnozoites])
- It then infects erythrocytes and asexually reproduces, the ruptures to release the parasite
Why does falciparum cause greatest mortality?
- Invades RBCs of all stages
- May be drug resistant
What is the incubation time for malaria
Up to 1 month for falciparum
Longer for others
Which malaria types is this?
Falciparum
- Little headphones
- More than one in each cell
List the components of malaria prevention.
- Awareness of risk
- Bite prevention - repellants / nets
- Chemoprophylaxis eg. malarone
- Diagnose promptly and treat without delay
Describe the clinical features of malaria.
- Fevers - cyclical or continuous with spikes
- Malaria paroxysms - chills, high fever, sweats
Malarae - 3 days
Others - 2 days
Usually 10-15 days after bite
Vivax - much longer - hypnozoite stage (liver)
What is this?
Schizont
A malaria parasite which has matured and contains mainy merozoites
Indicative of severe malaria
What is the definition of severe malaria?
List some clinical features.
- High parasitaemia - >2% (low transmission areas) or >5% (high transmission areas)
- OR visualised schizont
Organ failures
- Altered consciousness
- Respiratory distress or ARDS
- Hypoglycaemia
- Metabolic acidosis
- Circulatory collapse
- Renal failure, haemoglobinuria (blackwater fever)
- Hepatic failure
- Coagulopathy +/- DIC
- Severe anaemia or massive intravascular haemolysis
What is the main investigation for malaria?
Perform 3 thick and thin blood films
- Thick - screening for parasites (sensitive)
- Thin - identifying the species and quantifying the parasite (proportion of red cells that have been parasitised)
Which stain would you use in malaria blood film?
Field’s or Giemsa stain
List two examples of malaria rapid antigen tests.
Paracheck-PF (plasmodial HRP-II)
OptiMAL-IT (parasite LDH)
Outline the treatment options for non-falciparum malaria.
Chloroquine + primaquine
What must you do before giving someone primaquine?
Screen for G6PD deficiency as primaquine can cause extensive haemolysis
What are the complications of non-falciparum malaria?
Very rare but there are reports of splenic rupture
What counts as ‘mild’ falciparum malaria?
- Not vomiting
- Parasitaemia < 2 %
Outline the treatment options for mild falciparum malaria.
- First line - artemisinin-based combined therapy (ACT) e.g. Riamet (artemether-lumefantrine)
- Malarone (atovaquone and proguanil)
- Quinine and doxycycline
Outline the management of severe falciparum malaria.
- ABCDEFG approch
- Correct hypoglycaemia
- Cautious hydration
- Organ support if necessary
-
IV artesunate 1st line
(SEAQUMAT trial) - Daily parasitaemia monitoring
- Follow on with oral antimalarials
Why is quinine not first-line in severe falciparum malaria?
Extensive side effects:
- Cinchonism: tinnitus, dizziness, nausea and vomiting
- Arrhythmias
- Hyperinsulinaemia
What is the vector for dengue?
Aedes mosquito
What typs of virus is the dengue virus?
RNA virus with 4 main serotypes
Outline the clinical features of dengue.
Febrile phase lasts for around 4 days
What are the complications of dengue? In which circumstances does this tend to occur?
Dengue haemorrhagic fever and dengue shock - occurs in individuals who have previously been infected with a different dengue serotype and are then infected by another serotype
List some diagnostic tests for dengue.
- Blood/urine PCR
- Serology (IgM 5-7 days)
- RDT
How is dengue treated?
Identify those at risk of severe disease
Supportive
What is the term used to describe a high temperature with a relatively normal heart rate? List some causes.
Sphygmothermic dissociation
- typhoid,
- brucellosis,
- yellow fever,
- tularaemia
What is typhoid fever caused by?
Salmonella typhi and paratyphi
What type of organism is Salmonella typhi?
Gram-negative rod
Outline the clinical features of typhoid fever.
- High prolonged fever (no rigors)
- Classical ‘pea green diarrhoea’
- Headache
- Relative bradycardia (sphygmothermic dissociation)
- Rose spots (rare)
- Constipation
- Hepatosplenomegaly
- Dry cough
Describe the stages of typhoid?
- Constipation, gradual rise in body temperature, relative bradycardia
- Pesistant fever, hepatosplenomegaly, rose spots
- GI bleeding, sepsis
What is the incubation period of typhoid?
1-2 weeks
List some complications of untreated typhoid.
- GI bleeding - congested Peyers patches
- Perforation
- Septicaemia
- Encephalopathy
How is typhoid diagnosed?
- Cultures - stool, blood, bone marrow (rarely)
- Serology
Widel (RDT) - cheap but false positives
What is the treatment for Typhoid?
Oral rehydration solution
Antibiotics
- Uncomplicated empirical - azithromycin
- Complicated - IV ceftriaxone
What is mononucleosis caused by?
EBV or CMV
What is a characteristic clinical feature of mononucleosis?
Tonsillar enlargement with exudates
List some investigations for mononucleosis.
- Monospot
- IgM EBV/CMV
NOTE: always consider HIV
What is a characteristic microscopic feature of mononucleosis?
Atypical lymphocytes
What is leptospirosis and how is it spread?
Infection caused by Leptospira (spirochetes)
Commonly spread by rodents - associated with sewers and dirty water contaminated by rodent urine
Describe the clinical presentation of leptospirosis
Weil’s - jaundice, renal failure, haemorrhage
Causes positive agglutination test - vascular
How is leptospirosis diagnosed and treated?
Diagnosis
- PCR serum/urine/CSF
- Serology - IgM ELISA
Treatment
- Doxycycline
- Ceftriaxone
- Penicillin
What is Lyme disease and how is it spread?
Infection by Borrelia
Spread by Ixodes ticks
Describe the clinical presentation of lyme disease.
How is Lyme disease diagnosed and treated?
Diagnosis
- Clinical
- ELISA
- PCR blood/CSF (imperfect)
Treatment
- Doxycyline
- Amoxicillin
- Ceftriaxone in neuroborreliosis
What is lymphogranuloma venereum (LGV)?
STD caused by Chlamydia trachomatis (invasive serovars)
Sexual transmission then travels from innoculation site into lymphatic system
Describe the clinical presenation of LGV
How is LGV diagnosed and treated?
Diagnosis
- Serology
- Direct fluorscent antibody test
- PCR infected area/pus
Treatment
- Drainage of buboes/abscesses
- Antibiotics - doxycycline (1st), azithromycin (2nd)
(Contact tracing)
