Travel Related Infections Flashcards
What does the increasing amount of global travel mean, in terms of infection possibility?
More exotic destinations are being travelled to, more people with underlying medical conditions are able to travel (e.g. Immunocompromised), war/natural disasters lead to migration of populations, we are aware of more emerging infections and there are also non-infectious problems (such as road traffic accidents in lower income countries).
Explain how time is very important when considering travel related infections.
Calendar time is considered in terms of duration of symptoms and relative time is looked at to see how long a patient was travelling and when they returned for estimation of the incubation period.
Tropical infections often travel from animals to humans, please give a couple of examples of infections that make use of vectors.
Rickettsia/spirochaete bacteria and protozoal parasites often use vectors (vessels for passing on an infection, often an insect).
Why is taking a competent travel history so important?
To recognise imported diseases (those unknown or less common in the U.K.), for infection prevention (isolation on the wards and appropriate labelling in the labs) and thinking about different strains - antigenically different, protection/detection impacts and antibiotic resistance.
What different things will you want to know about a patient’s disease?
Where? - tropical culprits of subsaharan Africa, SE Asia and S/C America (+N Africa, the ME, S/C Asia, N Australia and N America).
When? - symptoms begin <10 days=acute, 10-21=subacute and some viruses don’t present>21 days.
What? - signs/symptoms: resp, GI, jaundice, haematological, eosinophilia.
How? - acquired by: food/water, bite, swimming, sexual or animal contact, or recreational activities.
What key aspects should be found out in a travel history?
Any unwell companions/contacts?
Pre-travel prophylaxis (resistant strain) / preventative measures taken?
Recreational activities?
Healthcare exposure?
Considering a travel related infection, you would look at a patient’s observations, but what investigations would you carry out?
FBC (may be anaemia), biochemistry - urea, bilirubin, creatinine, CRP and other LFTs for liver and U&E for kidneys, blood culture (before antibiotics!) and film, chest X-ray if cough and fever, perhaps glucose and clotting.
When thinking about travel related infections, what should immediately be considered?
MALARIA
MALARIA may present insidiously, but how can it be confirmed?
The parasite can be seen on a blood film - need 3 negative tests to disregard.
A rapid antigen test is possible.
How many different species of malaria are there and how is it spread?
There are 5 main species (important ones are Plasmodium falciparum, P. vivax and P. ovale). There is no case to case transmission, but the disease is spread by a vector - the female Anopheles mosquito.
Malaria is the commonest imported infection to the U.K., what is the most common type and where does it come from?
75% of cases are Plasmodium falciparum (with 10-20% mortality) of which 90% are from Africa.
(The remainder of cases are Plasmodium vivax/ovale, mostly from India and and usually less dangerous)
In some communities, malaria is not thought of as a deadly disease that needs to be fought, but a common inconvenience, like the flu, partially because not all cases are severe, who has a higher rate of mortality from the infection?
Pregnant women and infants.
Malaria often presents with few signs, except from fever: maybe chills and sweats, nausea and vomiting, fatigue, pain etc, when would you expect to see them?
The minimum incubation period is 6 days after being infected. After that, P. falciparum can be up to 6 months and P. vivax/ovale can be a year +.
List some severe Plasmodium falciparum infection complications.
CVS-tachycardia, hypotension, arrhythmias, Respiratory, GIT-haemolysis, diarrhoea, Renal-acute kidney failure, CNS-confusion etc, blood including DIC, Metabolic-hypoglycaemia etc and potential secondary infection.
What is the transmission cycle of the malaria parasite?
The malaria Protozoa goes through its sexual cycle in the mosquito vector where it travels from its gut to salivary glands and then onto humans when they get bitten. In the liver it is exo-erythrocytic then it goes to erythrocytic in the blood where gametes are produced and then back into mosquito if the patient is bitten again.
