MI: Fever in the Returning Traveller Flashcards
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
- Plasmodium vivax
- Plasmodium ovale
- Plasmodium malariae
- Plasmodium knowlesi
Outline the life cycle of Plasmodium within humans.
- Within humans there is an erythrocytic stage and an extra-erythrocytic stage
- It reproduces within red blood cells and causes haemolysis
- There is also a liver stage where the parasite lays dormant within the liver
List the components of malaria prevention.
- Awareness of risk
- Bite prevention
- Chemoprophylaxis
- Diagnose promptly and treat without delay
Describe the clinical features of malaria.
- Cyclical or continuous fevers with spikes
- Malria paroxysms - chills, high fever, sweats
List some clinical features of severe malaria.
- High parasitaemia (technically >2% - but might not make people from Africa particularly ill) OR 1 schizont (cell with multiple parasites)
- Altered consciousness
- ARDS
- Circulatory collapse
- Metabolic acidosis
- Renal failure
- Hepatic failure
- Coagulopathy
- Severe anaemia
- Hypoglycaemia
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)
List two examples of malaria rapid antigen tests.
Paracheck-PF
OptiMAL-IT
Which stains are used for malaria?
Giemsa
Field’s
Outline the treatment options for non-falciparum malaria.
- Chloroquine - 3 days
- Primaquine - 30 mg for 14 days
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 = Artemisin combination therapy (ACT) e.g. Riamet (artemether-lumefantrine)
- Occasionally oral malarone (atovaquone and proguanil)*
Outline the treatment of severe falciparum malaria.
- ABCDE approch
- Correct hypoglycaemia
- Cautious hydration
- Organ support if necessary
- IV artesunate
- Daily parasitaemia monitoring
- Follow on with oral antimalarials
Why is quinine not used in this situation?
Extensive side effects:
- Cinchonism: tinnitus, dizziness, nausea and vomiting
- Arrhythmias
- Hyperinsulinaemia
What is the vector for dengue?
Aedes mosquito
Outline the clinical features of dengue.
- Fever
- Headache
- Myalgia
- Erythrodermic rash
- Bleeding
- Hepatitis
- Severe: encephalitis, myocarditis
What are the complications of dengue? In which circumstances does this tend to occur?
- Dengue haemorrhagic fever and dengue shock
- This occurs in individuals who have previously been infected with a different dengue serotype
Which tropical virus is similar to dengue? What is a key difference?
- Chikungunya
- Arthralgia is more severe
List some diagnostic tests for dengue.
- Serology (IgM 5-7 days)
- PCR
How is dengue treated?
Identify those at risk of severe disease
Supportive
Outline the clinical course of dengue.
Fever reduces after about 4-5 days
What is the term used to describe a high temperature with a relatively normal heart rate? List some causes.
- Sphygmothermic dissociation
- Causes: typhoid, yellow fever, brucellosis, 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.
- High prolonged fever
- Headache
- Rose spots
- Constipation
- Dry cough
What is the incubation period of typhoid?
7-18 days
List some complications of typhoid.
- GI Bleeding
- Perforation
- Encephalopathy
What is the treatment for Typhoid?
- Empirical ceftriaxone (2 g IV OD)
- Azithromycin PO 500 mg BD 7 days
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
