MI: Fever in the Returning Traveller Pt.1

Question 1

How to take a good travel history

Answer 1

• 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)

Question 2

List some diseases caused by mosquitoes.

Answer 2

• Malaria
• Elephantiasis
• Dengue
• Yellow fever
• West Nile virus
• Zika virus

Question 3

What is the vector for malaria?

Answer 3

Anopheles mosquito (female)

Question 4

What are the five species of Plasmodium.

Answer 4

• Plasmodium falciparum (75%)
• Plasmodium vivax (20%)
• Plasmodium ovale
• Plasmodium malariae
• Plasmodium knowlesi

Question 5

Outline the life cycle of Plasmodium within humans.

Answer 5

• 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

Question 6

Why does falciparum cause greatest mortality?

Answer 6

• Invades RBCs of all stages
• May be drug resistant

Question 7

What is the incubation time for malaria

Answer 7

Up to 1 month for falciparum

Longer for others

Question 8

Which malaria types is this?

Answer 8

Falciparum

• Little headphones
• More than one in each cell

Question 9

List the components of malaria prevention.

Answer 9

• Awareness of risk
• Bite prevention - repellants / nets
• Chemoprophylaxis eg. malarone
• Diagnose promptly and treat without delay

Question 10

Describe the clinical features of malaria.

Answer 10

• 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)

Question 11

What is this?

Answer 11

Schizont
A malaria parasite which has matured and contains mainy merozoites
Indicative of severe malaria

Question 12

What is the definition of severe malaria?
List some clinical features.

Answer 12

• 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

Question 13

What is the main investigation for malaria?

Answer 13

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)

Question 14

Which stain would you use in malaria blood film?

Answer 14

Field’s or Giemsa stain

Question 15

List two examples of malaria rapid antigen tests.

Answer 15

Paracheck-PF (plasmodial HRP-II)

OptiMAL-IT (parasite LDH)

Question 16

Outline the treatment options for non-falciparum malaria.

Answer 16

Chloroquine + primaquine

Question 17

What must you do before giving someone primaquine?

Answer 17

Screen for G6PD deficiency as primaquine can cause extensive haemolysis

Question 18

What are the complications of non-falciparum malaria?

Answer 18

Very rare but there are reports of splenic rupture

Question 19

What counts as ‘mild’ falciparum malaria?

Answer 19

• Not vomiting
• Parasitaemia < 2 %

Question 20

Outline the treatment options for mild falciparum malaria.

Answer 20

• First line - artemisinin-based combined therapy (ACT) e.g. Riamet (artemether-lumefantrine)
• Malarone (atovaquone and proguanil)
• Quinine and doxycycline

Question 21

Outline the management of severe falciparum malaria.

Answer 21

• ABCDEFG approch
• Correct hypoglycaemia
• Cautious hydration
• Organ support if necessary
• IV artesunate 1st line
  (SEAQUMAT trial)
• Daily parasitaemia monitoring
• Follow on with oral antimalarials

Question 22

Why is quinine not first-line in severe falciparum malaria?

Answer 22

Extensive side effects:

• Cinchonism: tinnitus, dizziness, nausea and vomiting
• Arrhythmias
• Hyperinsulinaemia

Question 23

What is the vector for dengue?

Answer 23

Aedes mosquito

Question 24

What typs of virus is the dengue virus?

Answer 24

RNA virus with 4 main serotypes

Question 25

Outline the clinical features of dengue.

Answer 25

Febrile phase lasts for around 4 days