Febrile returned traveller

Question 1

History key points of travelled patient

Answer 1

Where have you been and what did you do?- Organism exposure

When were you there and when did you start to get sick- timeline fit with incubation

Question 2

Infections with clinical features and incubation:

Influenza; TB; salmonella typhi and enteritidis; campylobacter jejuni; hep A; malaria; dengue;HIV; syphilis

Answer 2

• resp, few days; air
• resp, many months; air
• non specific and diarrhoea, days; water + food
• diarrhoea, days; water + food
• jaundice, weeks; water + food
• non specific, weeks; vectors
• muscle aches, days; vectors (aedes mosquito)
• non specific, weeks to months; people
• variable, weeks to months; people

Question 3

Malaria causing organisms

Answer 3

Protozoa, inside anophles mosquito vector

Common: plasmodium falciparum (potentially fatal) and vivax (pretty benign)
Rare: Ovale and malariae

Question 4

Places with anophles mosquitos and thus higher risk of acquiring malaria

Answer 4

PNG, Solomons an Vanuatu

None in New caledonia, Fiji, Samoa, Tonga etc

Question 5

Plasmodium pathogenesis

• Infected ____ mosquito feeds on blood, and injects ___, containing _____ (infects new host)
• ______ invade ____ cells and replicate (10 days)
• ______ (from liver cell replication) are released from liver and invade _____
• Replicate in ______ and rupture them, ___, rigors, sweats
• Reinfects blood cells
• Some _____ mature into male or/and? female gametocytes which are source of sexual replication in mosquito salivary gland

body can keep under control and have low levels of circulating protozoa

Answer 5

• Infected female mosquito feeds on blood, and injects saliva, containing sporozoites (infects new host)
• Sporozoites invade liver cells and replicate (10 days)
• Merozoites (from liver cell replication) are released from liver and invade RBC’s
• Replicate in erythrocytes and rupture them causes, fever, rigors, sweats
• Reinfects blood cells
• Some merozoites mature into male or/and? female gametocytes which are source of sexual replication in mosquito salivary gland

body can keep under control and have low levels of circulating protozoa

Question 6

Differences between plasmodium falciparum and vivax

Answer 6

Falciparum: able to infect any RBC; changes membrane proteins, causing capillary adherence, blocking blood flow; sequestration in capillaries in brain and kidneys; death from coma and renal failure
Vivax: Young RBC’s; no RBC sequestration; has hypnozoites that remain in liver and cause relapse

Question 7

Malaria treatment

Answer 7

P. falciparum: Qunine and doxycycline or artemether+ lumefantrine to kill merozoites

P. vivax: chloroquine, primaquine to kill dormant hypnozoites

Question 8

Malaria prevention

Answer 8

Avoid malarious areas; mosquito control; bed nets, long sleeves etc; insect repellant; doxycycline, mefloquine

Question 9

Dengue fever: features; incubation; symptoms

Answer 9

RNA virus, aedes mozzy, multiplies in macrophages
2-7 days
Breakbone fever: muscle aches, mylgia, bone pain
1 week to recover

Question 10

Salmonellae

Answer 10

Enteritidis: from animals and birds, infects mucosa in colon= colitis. gastroenteritis

Typhi: from people and infects peyers patches (terminal ileum)- causing bactaraemia and septicaemia. Typhoid fever

Question 11

Typhoid fever presentation and treatment

Answer 11

fever, rigors, sweats, cough, headache, confusion, ot usually diarrhoea but constipated
Risk of peritonitis or ileal vessel erosion= bleeding
Long term bladder colonisation

Treat with ceftriaxone IV or ciprofloxacin O.