MI: Fever in the Returning Traveller Pt.1 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 clinical features of dengue.
Febrile phase lasts for around 4 days
