Flashcards in Travel Infections Deck (176):
What points of the infection model are particularly relevant when considering travel related infections?
Why is calendar time particularly important when considering travel related infections?
Different parts of the world are experiencing different seasons, and so different pathogens will be prevalent
Why is relative time important when considering travel related infections?
Infectious diseases have varying incubation periods
What is it important to consider when looking at relative time and travel infections?
How long ago a person travelled
Which diseases could present after the length of time
Why is it important to consider recent places with travel infections?
When travelling, recent places will more than likely vary from the current, and so its important to consider what infections are prevalent in these places
Give two examples of bacterium that are more common outside of the UK
What category of parasites are more common outside of the UK?
Both protozoa and helminths
What do the types of pathogens likely to infect people vary depending on?
The person affected
Who are at highest risk of developing travel related infections?
What is key to identifying the source of a travel related infection?
Taking a good history
Why must some patients with travel related infections be isolated?
To stop the spread of infections in this country
What is the most important travel related infection to consider first?
How does the prevalence of pathogens differ in different regions of the world?
Different pathogens have a higher prevalence in different regions of the world, even for the same disease
Give an example of where the prevalence of different pathogens causing the same disease differ depending on region of the world
Plasmodium falciparum commonly causes malaria in Africa, but in India it is more commonly caused by Plasmodium vivax/ovale
Why is it so important that a good travel history is taken when looking at travel related diseases?
The ability to recognise imported disease
There are different strains of the same pathogen
Why is it important to recognise imported disease?
Most imported diseases will be rare in the UK and some will have been unknown to have occurred in the UK, so often little will be known about them by most people
Why is it important to consider that there are different strains of the same pathogen?
Can be antigenically different
Different strains can exhibit different levels of antibiotic resistance to different antimicrobials
Why is it important to consider that different strains of the same pathogen may be antigenically different?
This impacts protection/detection from/of the causative organism
Where is infection prevention important in travel related infections?
Both on wards and in laboratories
What does a good travel history allow regarding infection prevention?
Staff to take the appropriate measures to prevent the spread of infection
What questions is it important to ask when someone presents with a potential travel related infection?
Where have they been
When did the symptoms begin
What are the signs and symptoms
How did they acquire it
What are the important places a patient may have been to consider?
South East Asia
What are the less important, but still notable, places a patient may have been to consider?
North Africa and the Middle East
What can discovering when the symptoms begun help identify?
The incubation period
What may identifying the incubation period help determine?
What are the potential incubation periods?
What are the potential signs and symptoms of travel related infections?
What are the potential respiratory problems with travel related infections?
What are the potential GI problems with travel related infections?
What are the potential skin problems with travel related infections?
What are the potential CNS problems with travel related infections?
What are the potential haemotological problems with travel related infections?
How could someone acquire a travel related infection?
What key aspects of a person's travel history is it helpful to know?
Any unwell companions/contacts?
Any pre-travel vaccinations/preventative measures?
What recreational activities did they take part in?
What sort of health care were they exposed to, if any?
What is malaria caused by?
One of five species of the protozoal genius, Plasmodium
What are the most common plasmodiums causing malaria?
What % of malaria cases are caused by Plasmodium vivax?
Where is plasmodium vivax most prevalent?
In India and other countries outside of sub-Saharan Africa
What % of malaria cases are caused by Plasmodium falciparum?
~15% of cases
Where is plasmodium falciparum most prevalent?
What are the less common plasmodiums causing malaria?
By what method is malaria transmitted?
What is the vector for malaria transmission?
The female Anopheles mosquito, or an infected, blood contaminated needle
How many cases of malaria are there per year globally?
How many deaths from malaria are there per year globally?
What is the most commonly imported infection to the UK?
How many cases of malaria are there in the UK per year?
How many deaths from malaria are there in the UK per year?
Up to 11
What % of cases of malaria in the UK are caused by P. Falciparum?
Are deaths from malaria in the UK avoidable?
Most should be
Describe the life cycle of malaria plasmodium
Plasmodium sporozoites are injected into the bloodstream and migrate to the liver
They form cyst-like structures containing thousands of merozoites
The merozoites are then released and infect RBCs and use Hb for nutrition
Eventually the infected RBCs rupture, releasing merozoites that can infect other RBCs
What happens if large numbers of erythrocytes rupture at once in malaria?
It can cause a sudden onset of fever
Why can large numbers of erythrocytes rupturing at once cause fever in malaria?
As large amounts of toxins are released
What is the consequence of RBC lysis?
What is the most dangerous plasmodium causing malaria?
Why is P. Falciparum the most dangerous plasmodium?
As it infects red blood cells of all ages
What will P. Malariae, vivax, and ovale invade?
Either young or old red cells, but not both
What is the results of the specific invasion of RBCs by P. Malariae, vivax, and ovale?
Causes a milder form of the disease
What is the incubation period for malaria?
Minimum 6 days
What is the incubation period for P. Falciparum?
Up to 12 days
What is the incubation period of p. Vivax/ovale?
Can take up to 1 year +
How will a patient normally present with malaria?
Fever, chills, and sweats that cycle every 3rd or 4th day
Often few examinable signs other than fever and sometimes splenomegaly
What systems can the symptoms of severe falciparum malaria affect?
What are the cardiovascular symptoms of severe falciparum malaria?
What are the respiratory symptoms of severe falciparum malaria?
What are the GI symptoms of severe falciparum malaria?
What are the renal symptoms of severe falciparum malaria?
Acute kidney injury
What are the CNS symptoms of severe falciparum malaria?
What are the blood symptoms of severe falciparum malaria?
What are the metabolic symptoms of severe falciparum malaria?
Who should malaria be managed by?
An infectious diseases physician
How should malaria be investigated for?
3x blood smears
Head CT if CNS symptoms
How should P. Falciparum malaria be treated?
Quinine + doxycycline
How does P. Vivax, ovale, and malariae be treated?
Chloroquine + primaquine
When should P. Vivax, ovale, and malariae be treated with hypnozoites?
How can malaria be prevented?
Assessment of risk
What is meant by assessment of risk in the prevention of malaria?
Knowing the risk posed to regular/returning travellers from at risk areas
How can bites spreading malaria be prevented?
What chemoprophylaxis is given against malaria?
Specific to region
When should chemoprophylaxis for malaria be taken?
Start before, and continue after return (generally 4 weeks)
What is enteric fever also known as?
Typhoid and paratyphoid fever
Where does enteric fever occur?
Asia, but also Africa and South America
What does enteric fever occur due to?
How many cases of enteric fever are there per year?
Who are most of the cases of enteric fever in?
How many travel related UK cases of enteric fever are there a year?
Where are most of the UK cases of enteric fever from?
The Indian subcontinent
How does enteric fever infection occur?
By faecal-oral route from contaminated food/water
What species can enteric fever affect?
Human pathogen only
What can the source of enteric fever be?
Either a case or a carrier
What pathogen causes typhoid?
Salmonella enterica serovar
Give 4 Samonella enteric serovar
Paratyphi A, B, or C
What kind of bacteria are Salmonella enterica?
Aerobic, gram negative rods
How do salmonella enterica cause disease?
Via a gram negative endotoxic
What does invasion by salmonella enterica allow?
What do the fimbriae of Salmonella enterica do?
Adhere to epithelium over ileal lymphoid tissue (Peyer's patches)
What can enteric fever cause?
Systemic disease (bacteraemia)
What is the incubation period of enteric fever?
What signs will someone with enteric fever present with?
What complications can arise from enteric fever?
Intestinal haemorrhage and perforation
What is the mortality rate of untreated enteric fever?
How does paratyphoid fever usually present?
As a milder infection
What would investigations show with enteric fever?
What LFTs will be raised in enteric fever?
What cultures would be performed in enteric fever?
When will blood cultures be positive for enteric fever?
After 1 week
When will faeces sample be positive for enteric fever?
Is serology a reliable test for enteric fever?
How is enteric fever usually treated?
With ceftriaxone or azithromycin for 7-14 days
Why is enteric fever usually treated with ceftriaxone or azithromycin?
Because ciprofloxacin resistance has become common
How can enteric fever be prevented?
Food and water hygiene precautions
When is the typhoid vaccine given?
High risk travel
What type of vaccine is that for enteric fever?
Vi capsular polysaccharide antigen or live attenuated vaccine
How effective is the typhoid vaccine?
Has protective effect in 50-75% of cases, but doesn't affect paratyphoid
What is the most common arbovirus?
How is dengue fever transmitted?
How many cases of Dengue fever are there per year?
100million, and rising
How many deaths from Dengue fever are there per year?
What % of returning travellers to Leicester's Infectious Diseases unit have Dengue fever?
How many serotypes of Dengue fever are there?
Where is Dengue fever common?
In subtropical and tropical regions, including Africa, Asia, and the Indian subcontient
How can Dengue fever be identified?
By a positive Dengue PCR and Dengue serology
How does the first infection of Dengue fever present?
From asymptomatic to severe febrile illness
How long does first infection of Dengue fever usually last?
When does the first infection of Dengue fever improve?
3-4 days after rash
What is the treatment for the first infection of Dengue fever?
Supportive treatment only
What can re-infection of Dengue fever with a different serotype lead to?
Antibody dependant enhancement
What antibody dependant enhancement in Dengue fever lead to?
Dengue haemorrhagic fever
Dengue shock syndrome
What is the prognosis for Dengue shock syndrome?
What is Traveller's diarrhoea defined as?
Three loose stool movements within 24 hours
What is Traveller's diarrhoea caused by?
Most commonly bacteria, however viruses and protozoa can also sometimes be the cause
What are the common bacterial causes of Travellers diarrhoea?
Enterotoxigenic Escherichia coli (ETEC)
How should Traveller's diarrhoea be treated?
Fluid and electrolyte replacement
In severe cases, antibiotics
What is the drug of choice for Campylobacter jejuni?
What is often required when treating E. Coli caused Traveller's diarrhoea?
Antibiotic sensitivity tests
Why are antibiotic sensitivity tests often needed when treating E. Coli Travellers diarrhoea?
Resistance is widespread
How can Traveller's diarrhoea be best prevented?
By thorough selection and preparation of food and water
Ensuring proper surface sanitation when cooking
How can information be found on travel related infections?
Public Health England
Centre for Disease Control (US)
World Health Organisation
Travel Health Pro
What are influenza viruses?
Spherical, enveloped viruses with negative strand RNA genome
What types of influenza viruses infect humans?
Only types A and B
Where does type A influenza virus have a reservoir?
What is type A influenza virus divided into?
How is influenza virus spread?
Where does the influenza virus affect?
It is an infection solely of the respiratory tract
Does viraemia and spread to other organ systems occur with the influenza virus?
It is rare
What does the influenza virus do once it has infected the host?
Destruction of respiratory epithelium
What is destruction of respiratory epithelium attributed to in the influenza virus?
The response of cytotoxic T cells
How does the influenza virus often present?
Non productive cough and chills, follower by;
What causes the muscle aches in the influenza virus?
Who can influenza virus cause serious complications in?
Those with comorbidities
What have influenza viruses shown over the years?
Marked variation in antigenic properties
Where has the influenza virus shown marked variation in antigenic properties?
Specifically H and N outer viral proteins
Why have influenza viruses show marked variation over the years in antigenic properties?
Due to antigenic shift and antigenic drift
What does antigenic drift occur due to?
Minor changes in H and N proteins each year
Does antigenic drift change the viral subtype?
How to the minor changes in H and N proteins occur in antigenic drift?
Via random mutations in the viral RNA, or small amino acid changes in the H and N proteins
What is antigenic shift, with respect to the influenza virus?
A more dramatic change in the H and/or N proteins, and a change in subtype
How often does antigenic shift in the influenza virus occur?
Less often, roughly every 10 to 20 years
Why does antigenic shift in influenza viruses occur?
Due to a mixture of visions infecting a cell
How does a mixture of visions infecting a cell lead to antigenic shift?
RNA from the visions is mixed, resulting a new virus with a new combination of genes
What is the result of the change in antigenic properties of the influenza virus?
Influenza vaccines change each year
How is it ensured the influenza vaccination accommodates for the change in antigenic properties?
The circulating strains are monitored over the season and the vaccine is created to include protection against the most common of type A and type B viruses
What are legionella?
Intracellular parasites that cause primarily respiratory tract infections
What shape are legionella?
Are legionella encapsulated or unencapsulated?
What is the most common pathogen causing legionella?
What % of legionella infections in humans are caused by legionella pneumophila?
What are legionella parasites responsible for in a clinical setting? Q
Legionnaires disease (LD)
What is LD?
An atypical pneumonia with multisystem symptoms
In how many individuals exposed to a common source does LD develop in?
1 in 5
What is the case fatality rate of LD?
5 to 30%
What are the early symptoms of LD?
What follows the early symptoms of LD?
A slightly productive cough, sometimes with respiratory compromise
In what % of LD cases does diarrhoea occur in?
25 to 50%
What other symptoms, other than the early ones, may occur in Legionnaires disease?