Micro - Fever in the Returning Traveller

Question 1

What are the causes of fever in a returning traveller

Answer 1

Tropical diseases e.g. malaria, typhoid, dengue, viral haemorrhagic fever, Chikungunya
Bacterial diarrhoea e.g. E. coli, cholera
UK e.g. UTI, pneumonia, influenza
STIs e.g. HIV seroconversion

Question 2

What diseases do mosquitos carry

Answer 2

Malaria [Anopheles Mosquito]
Elephantiasis
Dengue
Yellow fever
West Nile virus
Zika virus

Question 3

What is malaria and what are the risk factors

Answer 3

Protozoal infection (Plasmodium spp.) spread by female Anopheles mosquito (bites at night, attracted by heat + CO2)

Returning traveller from endemic areas (Asia / Africa / South America) – ask about whether they took malaria prophylaxis while away

Question 4

Describe the life cycle of malaria

Answer 4

1. Bite
2. Exo-erythrocytic cycle: Liver stage (where the parasite lies dormant in the liver = hypnozoite stage) → schizont formed
3. Erythrocytic stage: trophozoite (ring stage) → schizont → ruptured schizont → Malaria breaks down red cells → haemolysis

Question 5

What are the types of malaria and what are the features on blood film

Answer 5

Falciparum: P. falciparum (most common and most severe)
- Double dotted rings

Non-falciparum: Symptoms less severe, 48hr tertian fever
- P. vivax: Schüffner’s/Schaffner’s dots
- P. ovale: Schüffner’s/Schaffner’s dots, enlarged red cells, comet forms
- P. knowlesi: daisy-head appearance, square ring forms

Question 6

How is malaria prevented

Answer 6

A, B, C, D:
Awareness of risk - geographical (high altitudes - different transmission), individualise e.g. pregnancy, season, accomodation
Bite prevention e.g. bite repellent, insecticide-treated nets (ITNs)
Chemoprophylaxis e.g. malarone, mefloquine, doxycycline (varies by region)
Diagnose promptly and treat without delay

Question 7

What are the symptoms of malaria

Answer 7

Fevers – cyclical or continuous with spikes
Malaria paroxysm – chills, high fever, sweats

Question 8

What are the features of severe malaria

Answer 8

End-organ damage:
High parasitaemia (>2%) or ONE schizont
Altered consciousness with/without seizures
ARDS or pulmonary oedema
Metabolic acidosis (pH <7.3)
Renal failure, haemoglobinuria (blackwater fever)
Hepatic failure
Severe anaemia (<8g/dl)
Coagulopathy ± DIC
Circulatory collapse / shock (BP <90/60)
Hypoglycaemia (<2.2)

Question 9

How is malaria diagnosed

Answer 9

3x thick and thin blood smears (Field’s or Giemsa stained)
- Thick = screen for parasites
- Thin = identify species and quantify parasitaemia (how many RBCs are parasitised)
FBC: thrombocytopenia
Malaria antigen detection testing
- Paracheck-PF (Detect plasmodial HRP-II)
- OptiMAL-IT (Detect parasite LDH)

Question 10

What classifies mild and severe parasitaemia

Answer 10

Mild = not vomiting, low parasitaemia, ambulant
Child, severe = >2%
Adult, severe = >10%

Question 11

What is the management for non-falciparum malaria

Answer 11

1. Chloroquine (3 days)
2. Primaquine for hypnozoites (14 days) - MUST CHECK G6PD BEFORE

Question 12

What is the management for mild falciparum malaria

Answer 12

1. Artemisinin Combination Therapy (ACT): artemisinin + lumefantrine
2. Oral malarone

Question 13

What is the management for severe falciparum malaria

Answer 13

1. A-E
2. Correct hypoglycaemia
3. IV fluids (careful not to overload0
4. IV artesunate

Question 14

What is dengue fever and how is it spread

Answer 14

Flavivirus
Vector: Aedes aegypti mosquito
Short incubation (matter of days)
Urban disease

Question 15

What are the clinical features of dengue fever

Answer 15

Main features: Fever (high), Headache (retro-orbital), Myalgia, Erythrodermic rash (50%)
Other features: Bleeding, Hepatitis
Severe: Encephalitis, Myocarditis

Can progress to dengue haemorrhagic fever and dengue shock (those previously infected with a different serotype) after day 4-5 (as fever comes down)

Question 16

What investigations should be done for dengue fever

Answer 16

Serology (IgM 5-7 days)
PCR
Dengue cross-reacts with other flavivirus IgG (JE, yellow fever)

Question 17

What is the treatment for dengue fever

Answer 17

Self-limiting: supportive treatment
Identify high risk patients: high Hct, low platelets

Question 18

What is typhoid fever caused by

Answer 18

Salmonella typhi or paratyphi (Gram-negative rod)
Insidious onset (incubate 7-18 days; up to 60d)
Most from South Asia (Indian Subcontinent)

Question 19

What are the clinical features of typhoid fever

Answer 19

High prolonged fever
Headache
Rose spots (rare)
Constipation
Dry cough

Question 20

What are the complications of untreated typhoid fever

Answer 20

1. Fever, fluctuations with bradycardia, malaise, headache, cough, epistaxis
2. Extreme fatigue, high fever, plateau, bradycardia, delirium, rose spots, distended and painful abdomen, hepatosplenomegaly
3. Complications
   - intestinal haemorrhage (bleeding in congested Peyer’s patches)
   - Perforation in the distal ileum → septicaemia
   - Respiratory complications
   - Encephalitis

Question 21

What is the treatment for typhoid fever

Answer 21

Oral rehydration solution
Empirical ceftriaxone (IV, 2g) →Azithromycin (PO, 500mg BD, 7 days)
Vaccinate (Vaccine is only partially protective against S. typhi and offers no protection against S. paratyphi)

Question 22

What is mononucleosis caused by and what are the features on investigations

Answer 22

EBV or CMV
Tonsillar enlargement with exudates
Atypical lymphocytosis
Monospot
IgM +ve for EBV/CMV

Question 23

What is Rickettsial disease

Answer 23

Arthropod vector (ticks, lice, mites)
Spotted fever (RMSF, MSF, African tick bite fever)
Typhus - epidemic (lice) and endemic
Scrub typhus
Fever, headache, myalgia ± eschar
Obligate intracellular bacteria
Invades endothelial cells → vasculitis

Question 24

What investigations/treatment is indicated for rickettsial disease

Answer 24

Diagnosis: acute and convalescent serology

Treatment: doxycycline

Question 25

What is suggested by skin rash + eosinophilia

Answer 25

KATAYAMA FEVER
associated with swimming in fresh water