Infection Session 5 Flashcards

1
Q

What are important patient factors to consider in travel-related infections?

A

Calendar and relative time
Recent places
Social factors (inc. those at destination)

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2
Q

What important information might a travel history reveal in suspected infection?

A

Healthcare exposure abroad
Any prophylactic Tx
Recreational activities
Whether travel companions are also affected

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3
Q

What does an increase in atopy as a S/S indicate?

A

Slight increase –> eosinophilia

Large increase –>helminth infection

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4
Q

How might a travel related infection be acquired?

A
Ingestion of food/water
Insect/tick bite
Swimming
Sexual contact
Animal contact
Beach/recreational activities
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5
Q

What finding on histological examination indicates a medical emergency in malaria?

A

Multiple parasites in one RBC

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6
Q

What are the four main species of Plasmodium?

A

Falciparum
Vivax
Ovale
Malariae

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7
Q

Which species of Plasmodium causes the most severe malarial disease?

A

Falciparum

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8
Q

What is the vector for Plasmodium?

A

Female Anopheles mosquito

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9
Q

Can malaria be spread from pt–>pt?

A

No

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10
Q

Which species of Plasmodium causes the majority of malaria deaths?

A

Falciparum

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11
Q

What is the typical incubation period of malaria?

A

1-3 weeks

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12
Q

What is the typical Hx for malaria?

A
Fever, chills and night sweats which cycle every 3/4 days
Headache
Muscle fatigue +/- pain
Nausea
Vomiting
Dry cough
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13
Q

O/E what would you expect to find in malaria?

A

Few signs except fever +/- splenomegaly

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14
Q

What investigations would you perform in suspected malaria?

A
3x blood smears (thick and thin)
FBC
U&Es
LFTs
Coagulation tests
Head CT if GCS decreased
CXR if respiratory distress syndrome suspected
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15
Q

Describe the general management plan for malaria infection.

A

Start with IV floroquinolones or artemisinin depending of species and then treat orally once controlled

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16
Q

Describe the ABC approach to malaria infection prevention.

A

Assess risk
Bite prevention (repellant, clothing etc)
Chemoprophylaxis (specific to destination region)

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17
Q

Do regular/returning travellers need to take chemoprophylaxis?

A

Yes, resistance is rapidly lost

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18
Q

Describe how an uninflected mosquito can go on to transmit malaria to a human.

A

Uninfected mosquito bites infected man ingesting gametocytes which are present in blood
Plasmodium undergoes sexual stage in mosquito
Now infected mosquito bites uninfected man, transmits plasmodium which can undergo asexual reproduction to produce gametocytes

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19
Q

Which stage of the plasmodium life cycle is exo-erythrocytic?

A

Liver

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20
Q

Which stage of the plasmodium life cycle is erythrocytic?

A

Blood

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21
Q

Why is there no easy target for malaria prevention?

A

It has a complex life cycle

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22
Q

What are the S/S of severe falciparum malaria when the parasite count is high?

A
Tachycardia, hypotension, arrythmias
Acute RDS (lungs fill with fluid)
Diarrhoea, deranged LFTs
AKI
Metabolic acidosis
Confusion, fits, cerebral malaria
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23
Q

What are malaria pts at especially high risk of?

A

Secondary infection from G-ve pathogens

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24
Q

Which enteric fever is generally milder, typhoid or paratyphoid?

A

Paratyphoid

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25
How is enteric fever transmitted?
Faecal-oral
26
Why is the source of enteric fever only cases/carriers?
It is a human pathogen only
27
What is the incubation period of enteric fever?
7-14 days
28
What is the typical history of a pt with enteric fever?
``` Fever Headache Abdominal discomfort Constipation Dry cough ```
29
What ah be found O/E of a pt with enteric fever?
Reactive bradycardia | Fever
30
What would you expect to find on investigation of a pt with enteric fever?
Moderate anaemia Relative lymphopenia Raised transaminase and bilirubin Positive blood and faecal culture
31
How can enteric fever be prevented?
``` Food and water hygiene precautions Typhoid vaccine (live or attenuated) ```
32
What is the problem with typhoid vaccine?
Only gives 75% protection
33
What are 'food poisoning' salmonellas?
Non-typhoidal salmonella infections that have widespread distribution inc. UK
34
What are the S/S of 'food-poisoning' salmonella infections?
Diarrhoea Fever Vomiting Abdominal pain
35
What are the outcomes of S.thyphimurium and S.enteritidis?
Usually self-limiting Can develop bacteraemia Can develop deep seated infection
36
How is dengue fever transmitted?
Arthropod vector
37
Where is dengue fever mainly seen?
Africa Asia Indian subcontinent
38
What happens on first infection with dengue fever?
Asymptomatic --> severe febrile illness lasting 1-5 days which improves 3-4 days after non-specific rash appears
39
Can specific treatments be used in the first dengue infection of an individual?
No, supportive only
40
What happens in reinfection of an individual with a different dengue fever serotype?
Pre-existing antibodies can bind but not neutralise the new serotype and instead facilitate easier monocytes infection
41
What can an increased viral load on reinfection of dengue fever lead to?
Dengue haemorrhagic fever | Dengue shock syndrome
42
What are the S/S of dengue haemorrhagic fever?
Haemorrhage DIC Petichae rash
43
Why is the rash seen in first dengue fever infection said to be non-specific?
Also seen in measles, rubella, parvovirus, EBV, CMV, acute HIV and rickettsia
44
What can increase the risk of influenza strains 'jumping species' and causing a pandemic?
Intensive farming
45
What is SARS?
Novel coronavirus - Severe Acute Respiratory Syndrome
46
Is MERS easily transmittable?
No
47
Which human influenza viruses cause seasonal epidemics?
A & B
48
How is human influenza A split into two subtypes?
According to hemagglutinin and neuraminidase expression on the viral surface
49
Which two lineages do currently circulating influenzae Bviruses belong to?
Yamagata | Victoria
50
Does influenza B circulate in animals?
No, humans exclusively
51
What is the primary natural reservoir for all influenza A subtypes?
Birds
52
How often does antigenic shift occur?
Occasionally
53
How often does antigenic drift occur?
Continuously
54
What happens in antigenic shift?
Two subtypes of virus infect the same host, reassort and form new virus with most genes from one but hemagglutinin +/- neuraminidase from the other to create new subtype
55
Why does antigenic shift cause pandemics?
It creates a new subtype which few people have resistance to as it has not been seen before in human influenza
56
Which type of influenza virus can undergo antigenic shift?
A
57
Which types of influenza virus NA undergo antigenic drift?
A & B
58
What happens in antigenic drift?
Virus infects healthy cell --> DNA polymerase makes mistakes creating new virus with antigenic variants --> pre-existing host antibodies exert selection pressure --> slightly different strain circulates in population
59
Why does the flu vaccine have to be reviewed every year?
Antigenic drift cussing slightly different strains to circulate in the population
60
Why are a greater range of foreign endemic diseases being seen in UK healthcare?
``` More exotic destinations Travellers with underlying health conditions More aid workers Migration Global warming ```