9. Travel-related infections Flashcards
What questions should be asked when taking a travel history?
Where did you go? How long did you go for? When did you return? What are the symptoms/signs? When did they start? What activities did they take part in? Any other travel companions suffering? What pre-travel vaccinations/preventative measures? Any healthcare exposure abroad?
Why is it important to know how long the patient was travelling for and when symptoms began?
In order to work out possible incubation period of a disease
How are travel-related infections categorised into acute, sub-acute and chronic?
< 10 days = acute
10-21 days = sub-acute
> 21 days = chronic
What is the vector for malaria?
Female anopheles mosquito
What are the 4 species of plasmodium that cause malaria?
- Falciparum
- Vivax
- Ovale
(4. Malariae) less common
Which patients are at higher risk of a severe malarial infection?
Young children
Pregnant women
Elderly
What type of virus is malaria?
Arbovirus
What is the minimum incubation period of malaria?
6 days
How do the incubation periods of P.falciparum and P.vivax/ ovale differ?
Falciparum- up to 6 months
P. Vivax/Ovale - up to 1 year
Why do P. vivax and ovale have a longer incubation period?
Lie latent in the liver as hypnozoites
What history is typical of malaria presentation?
Fever
Chills and sweats cycling every 3rd/4th day
What might be present upon examination of a patient presenting with malaria?
Splenomegaly
What symptoms are associated with malaria?
Skin - chills/sweating Systemic - fever Resp - coughing Stomach - nausea + vomiting Back pain Muscle pain and fatigue
What investigate is important to do in suspected malaria?
3 blood smears
How is P.falciparum malaria treated?
Artesunate
Quinine & doxycycline
How are P. vivax, ovale and malariae treated?
Chloroquine + primaquine
How can malaria be prevented?
‘ABC’
Assess risk - which areas
Bite prevention - repellant,nets, clothing
Chemoprophylaxis - start before and continue after return
What parasite load can cause severe falciparum malaria?
> 2%
What symptoms are associated with severe falciparum malaria?
CV - tachycardia, hypotension CNS - confusion, fits Resp - ARDS GI - diarrhoea Renal - acute kidney injury Metabolic acidosis , hypoglycaemia
What organisms can cause typhoid and paratyphoid?
Salmonella typhi
Salmonella paratyphi A,B or C
What are typhoid and paratyphoid?
Enteric fevers, paratyphoid is less severe
What it the incubation period of typhoid/paratyphoid?
7-14 days
What are the virulence factors of Salmonella?
- Fimbriae adhere to epithelium over peyer’s patches
What are the signs and symptoms of enteric fever?
Fever, headache, abdominal discomfort, constipation, dry cough, bradycardia
What are the complications of enteric fever?
Intestinal haemorrhage and perforation
How is typhoid transmitted?
Faecal-oral from contaminated food and water
How is enteric fever treated?
Ceftriaxone or azithromycin
What type of virus is dengue fever?
Arbovirus
What are the symptoms of dengue fever?
headache, fever, back pain, severe myalgia , widespread rash on trunk and back
How is dengue fever treated?
Supportive only
How can dengue fever be diagnosed?
PCR
Serology
What happens during the first infection of dengue fever?
asymptomatic to severe febrile illness
lasts 1-5 days
supportive treatment only
What happens if a person is re-infected with a different serotype of dengue fever?
Dengue haemorrhagic fever
Dengue shock syndrome
Briefly describe the malarial life cycle.
- Infected mosquito injects sporozoites
- Sporozoites migrate to liver where they form merozoites
- Merozoites released and invade RBC’s
- Merozoite becomes trophozoite in RBC
- In RBC, trophozoite multiplies, producing new merozoites. Merozoites released when cell ruptures.
- Some merozoites become gametocytes
- Female anopheles picks up gametocytes from infected human and forms sporozoites which are passed on.
