travel infections

Question 1

dengue - classic features

Answer 1

1. severe myalgia (break bone fever)
2. retroorbital pain
3. very very high fever that is biphasic
4. positive torniquet test
5. relative bradycardia
6. fever 1 week max

Question 2

why do we care about dengue - what are we worried about?

Answer 2

dengue haemorrhagic fever - 95% will occur in <15yo:

• fever
• low plt
• haemorrhage
• Objective evidence of plasma leakage caused by increased vascular permeability

Question 3

subtypes of plasmodium and their key features

Answer 3

1. plasmodium falciparum - most common, severe disease
2. plasmodium vivax - moderate disease, asia, dormant (dormant liver stage via hypnozoite)
3. plasmodium ovale - mild, africa (also recurs but dont care)
4. plasmodium knowlesi - zoonotic
5. plasmodium malariae - chronic malaria, africa

Question 4

incubation of malaria

Answer 4

10-14 days for most inc falciparum; but p. malariae can be up to 40 days

Question 5

life cycle of plasmodium

Answer 5

exoerythrocytic phase: bite > blood > reproduction in liver > rupture and release merozoites into blood

erythrocytic phase: merozoites enter RBC > gametes +/- rupture

Question 6

fever corresponds to what part of the plasmodium life cycle? special feature of malaria fevers?

Answer 6

when erythrocytes rupture and release merozoites into the circulation > occurs cyclically

• p.malariae = quartan fever ( every 72h)
• p. vivax and ovale = tertian fever (every 48h)
• p. knowlesi = daily fever
• p. falciparum = variable, can be daily (malignant tertian fever)

Question 7

why do you need both thick and thin films for malaria

Answer 7

• thick film = confirm the presence of parasites and percentage of erythrocytes containing parasites
• Thin film = identify Plasmodium species

Question 8

why is falciparum so bad

Answer 8

causes cytoadherence of RBC to stop flow into spleen and RBC destruction, but also causes reduced flow to other organs

also esp causes cerebral malaria

Question 9

treatment of malaria

Answer 9

uncomplicated:
- falciparum = artemether-lumefantrine 1st line
- others = chloroquine
- primaquine for vivax/ovale liver hyponozoites

complicated: IV artesunate

Question 10

primaquine WHAT TO REMEMBER

Answer 10

check for G6PD!

Question 11

salmonella typhi and paratyphi- incubation period

Answer 11

typhi: 8–14 days, but this depends on the infective dose and can vary from 3 days to 1 month.
paratyphi: 1–10 days.

Question 12

typhoid/paratyphoid symptoms

Answer 12

fever, abdominal pain, constipation followed by diarrhea
rose or salmon-colored spots on the chest and abdomen
Hepatomegaly and splenomegaly
in asplenics: OM

Question 13

hepatitis A incubation

Answer 13

a month!

Question 14

thinking by incubation periods:

• short
• intermediate
• long

Answer 14

• short: dengue (1 week), enteric fever (1-2 weeks), malaria (6-30 days), flu, chikungunya (1-14 days), camp (1-7 days)
• intermediate: p.vivax, hep A (1 month), hep E (1-2mo), HIV (2-4weeks), ebola (up to 3 weeks)
• long: TB, hep B (3 months!!)

Question 15

typhoid Rx

Answer 15

azith/cipro or IV ceftx