S8 Travel Related Infections Flashcards
What factors related to the patient in the infection model are important to consider in travel ranted infections?
- calendar time
- relative time
- recent
What pathogens are most commonly associated with travel related infections?
- bacterium e.g. rickettsia or spirocheate
- parasites - protozoa or helminths
Both spread usually via a vector
Why is the travel history important?
- to recognise imported diseases that are rare/unknown in the UK
- to recognise strains of pathogens e.g. antigenically different, antibiotic resistance, etc
- for infection prevention on the ward and lab, etc
What are common locations of travel that result in travel related infections?
- sub-saharan africa
- south east Asia
- south/central america
- North Africa
- Middle East
- south/Central Asia
- north Australia
- North America
What are common symptoms and signs of travel related infections?
- respiratory issues - cough, short of breath
- GI - diarrhoea
- skin - rash
- jaundice
- CNS - headache, meningitis
- haematological - lymphadenopathy, splenomegaly, haemorrhage
- eosinophilia
How do people acquire travel related infections?
- food/water
- insect/tick bite
- swimming
- sexual contact
- animal contact (bite/safari)
- recreational activities
When do symptoms from travel related infections usually start?
- less than 10 days (viral/bacterial)
- 10-21 days (bacterial/parasites)
- more than 21 days (unusual bacteria)
What aspects of travel history should be considered?
- where?
- when?
- how long?
- activities?
- any unwell travel companions/contacts?
- what pre-travel vaccines/preventative measures were carried out?
- any healthcare exposure (exposure to MDR infections)?
What is the most common types of malaria in Africa and in Asia?
Africa - Plasmodium falciparum
Asia - Plasmodium vivax/ovale
What is the vector for malaria?
Female Anopheles mosquitos
What is the incubation period for malaria?
Minimum of 6 days
- up to 4 weeks for P. falciparum
- up to 1 year + for P. vivax/ovale
What are the common symptoms of malaria?
- headache
- fever
- fatigue
- pain
- chills
- sweating
- dry cough
- splenomegaly
- nausea and vomiting
What would you see on examination of someone with malaria? What would they history be?
Often few signs expect a fever maybe with splenomegaly
Fever chills and sweats
When is malaria severe? What are the symptoms?
If parasite count is over 2%
- CVS - tachycardia, hypotension, arrythmias
- respiratory
- GI tract - diarrhoea, bilirubin, abnormal liver function tests
- renal - acute kidney injury
- CNS - confusion, fits, cerebral malaria
- blood - low WCC, thrombocytopenia, DIC
- metabolic - metabolic acidosis, hypoglycaemia
- secondary infection
What is one of the main effects malaria has on the body?
Destruction of RBCs
What is the life cycle of malaria?
- The vector, a mosquito, drinks the blood of a person with malaria
- In the mosquito, the malaria travels from the gut to the salivary gland
- The mosquito then goes to bite another person, passing the malaria into this person’s blood stream
- The malaria goes into the liver and then into the blood stream
What investigations are used to determine malaria?
- do 3 blood films
- FBC, U&Es (urinary and electrolyte - for testing renal function), liver function tests, glucose, coagulation
- head CT scan to see if any neurological symptoms
- chest x-ray
How is malaria treated?
Treated dependent on the species
* P. falciparum - artesunate or quinine and doxycycline
- P. vivax, ovale, malariae - chloroquine
- to treat dormant hypnozoites of vivax, ovale and malariae in the liver - primaquine
How do you prevent malaria?
- assess the risk
- use bite prevention
- use chemoprophylaxis - antimalarial drugs
Where are typhoid and paratyphoid (enteric fever) mostly found?
In Asia (but some cases in Africa and South America)
What is the mechanism of infection for typhoid and paratyphoid (enteric fever)
Faecal-oral from contaminated food/water
What is a common type of typhoid and paratyphoid (enteric fever)?
Salmonella typhi
Salmonella paratyphi (A/B/C)
What type of bacteria is Salmonella typhi?
An enterobacteria that is an aerobic gram-negative bacillus
What are the virulence factors of Salmonella typhi?
- low infectious dose - don’t need much to cause infection
- survives in gastric acid
- fimbriae on the outer surface of the bacteria adhere to epithelium over Peyer’s patches so can get into the RES and so bloodstream
- reside in macrophages
What are the signs and symptoms of enteric fever?
- bacteraemia/sepsis
- fever
- headache
- abdominal discomfort
- dry cough
- a little bradycardia
What is the incubation period for Salmonella typhi?
7 to 14 days
What are the complications of enteric fever?
- intestinal haemorrhage and perforation
* 10% chance of death if untreated
What investigations do you carry out to determine if someone has enteric fever?
- liver function tests - transaminase and bilirubin
- blood culture
- faeces culture
- serology
- WCC
How do you treat enteric fever?
It is MDR
- use fluoroquinolones (but increasing resistance to these)
- usually treat with IV ceftriaxone or azithromycin for 7-14 days
How do you prevent enteric fever?
- food and hygiene precautions
* typhoid vaccine
You can get non-typhoidal salmonella infections, what are these? What are the common symptoms of these? What is their outcome?
‘Food poisoning’ salmonellas - S. typhimurium or S. enteritidis
- diarrhoea, fever, vomiting, abdominal pain
Generally self-limiting
What is dengue fever?
A common arbovirus transmitted by mosquitos
Can be asymptomatic, can have febrile symptoms
There are 4 serotypes so can be reinfected with a different serotype
What is myiasis?
Fly larva (tumbu/bot fly) that burrow into skin
