9. Travel related infections

Question 1

What are the 3 categories of incubation periods?

Answer 1

<10 days = acute
10-21 days = subacute
>21 days = chronic

Question 2

Where should all patients with fever returning from travel be treated?

Answer 2

side-room of infectious disease ward (until diagnosis)

Question 3

Which investigations should be performed in cases of travel-related infection?

Answer 3

1. blood cultures x2
2. malaria parasite screen x3
3. FBC
   
   • look for: anaemia/haemolysis, low platelets or lymphocytes, high eosinophils
4. U and E, LFTs, CRP
5. CXR
6. PCR/serology based on travel Hx/symptoms
7. HIV test

Question 4

Name 3 examples of emerging viral respiratory diseases.

Answer 4

• influenza pandemics
  novel coronarviruses:
• SARS-CoV (severe acute respiratory syndrome)
• MERS-CoV (middle east respiratory syndrome)

Question 5

Name a causative agent for viral haemorrhagic fever.

Answer 5

ebola virus

Question 6

What type of virus is ebola?

Answer 6

filovirus

Question 7

What are the symptoms of ebola?

Answer 7

flu-like illness with:

1. vomiting
2. diarrhoea
3. headaches
4. confusion
5. rash
6. internal/external bleeding at 5-7 days

Question 8

How is ebola virus transmitted?

Answer 8

direct contact with body fluids

Question 9

What are the treatment options for ebola?

Answer 9

experimental:

• Zmapp (monoclonal antibodies)
• antivirals

vaccine under dev.

Question 10

How is zika virus transmitted?

Answer 10

• Aedes mosquito

- sexual transmission

Question 11

What are the consequences of zika infection?

Answer 11

• 20% get mild, dengue-like symptoms

- in pregnant women causes: foetal loss or congenital microcephaly

Question 12

Which infections should be considered after travel to sub-Saharan Africa?

Answer 12

protozoa:
1. malaria (short incubation)
long incubation:
2. trypanosomiasis (African sleeping sickness)
3. amoebic liver abscess
4. visceral leishmaniasis (esp. if swimming)

helminths:
5. acute schistosomiasis

Question 13

Which investigation result indicates parasitic infection?

Answer 13

eosinophilia

Question 14

How are schistosomes (flat worm) transmitted?

Answer 14

Fresh water exposure - allows cercarial stage, which reside in and are released from water snails, to penetrate intact skin of swimmers.

Question 15

Name a sign of schistosomiasis.

Answer 15

Swimmer’s itch - localised reaction at the point of parasite penetration

Question 16

What is the difference between the acute and chronic stage of schistosomiasis?

Answer 16

Acute stage

• involves Katayama fever: immune complex phenomenon
• illness mostly self-limiting over a few weeks

Chronic stage (if untreated)
- mature adult schistosomes end up in venules of bladder and bowel and release eggs... immunological reaction to eggs may cause fibrosis of liver, bowel and bladder over many years

Question 17

How is chronic schistosomiasis diagnosed?

Answer 17

Stool and urine culuture: presence of ova

Serological testing

Question 18

How is schistosomiasis treated?

Answer 18

PRAZIQUANTEL

short course of oral corticosteroids to alleviate acute symptoms

Question 19

What is Legionnaire’s disease?

Answer 19

Pneumonia caused by Legionella pneumophila serogroup 1

Question 20

What type of bacteria is Legionella pneumophila?

Answer 20

• gram negative rod
• facultative intracellular bacteria
• aerobic

Question 21

How does L. pneumophila evade immune destruction?

Answer 21

prevents phagolysosome fusion and replicates within macrophage

Question 22

How is L. pneumophila transmitted?

Answer 22

aerosol inhalation (no case to case spread)

Question 23

What are the signs and symptoms of Legionnaire’s disease?

Answer 23

Symptoms:
1. SOB and productive cough

Signs:

1. fever
2. low O2 saturation levels
3. crackles on auscultation - pulmonary oedema
4. lung consolidation on X ray

Question 24

How is Legionnaire’s disease treated?

Answer 24

LEVOFLOXACIN (quinolone)