Travel Infections Flashcards
(176 cards)
1
Q
What points of the infection model are particularly relevant when considering travel related infections?
A
Calendar time
Relative time
Recent places
2
Q
Why is calendar time particularly important when considering travel related infections?
A
Different parts of the world are experiencing different seasons, and so different pathogens will be prevalent
3
Q
Why is relative time important when considering travel related infections?
A
Infectious diseases have varying incubation periods
4
Q
What is it important to consider when looking at relative time and travel infections?
A
How long ago a person travelled
Which diseases could present after the length of time
5
Q
Why is it important to consider recent places with travel infections?
A
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
6
Q
Give two examples of bacterium that are more common outside of the UK
A
Rickettsia
Spirochaete
7
Q
What category of parasites are more common outside of the UK?
A
Both protozoa and helminths
8
Q
What do the types of pathogens likely to infect people vary depending on?
A
The person affected
9
Q
Who are at highest risk of developing travel related infections?
A
Extreme age
Immunocompromised
10
Q
What is key to identifying the source of a travel related infection?
A
Taking a good history
11
Q
Why must some patients with travel related infections be isolated?
A
To stop the spread of infections in this country
12
Q
What is the most important travel related infection to consider first?
A
Usually, malaria
13
Q
How does the prevalence of pathogens differ in different regions of the world?
A
Different pathogens have a higher prevalence in different regions of the world, even for the same disease
14
Q
Give an example of where the prevalence of different pathogens causing the same disease differ depending on region of the world
A
Plasmodium falciparum commonly causes malaria in Africa, but in India it is more commonly caused by Plasmodium vivax/ovale
15
Q
Why is it so important that a good travel history is taken when looking at travel related diseases?
A
The ability to recognise imported disease
There are different strains of the same pathogen
Infection prevention
16
Q
Why is it important to recognise imported disease?
A
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
17
Q
Why is it important to consider that there are different strains of the same pathogen?
A
Can be antigenically different
Different strains can exhibit different levels of antibiotic resistance to different antimicrobials
18
Q
Why is it important to consider that different strains of the same pathogen may be antigenically different?
A
This impacts protection/detection from/of the causative organism
19
Q
Where is infection prevention important in travel related infections?
A
Both on wards and in laboratories
20
Q
What does a good travel history allow regarding infection prevention?
A
Staff to take the appropriate measures to prevent the spread of infection
21
Q
What questions is it important to ask when someone presents with a potential travel related infection?
A
Where have they been
When did the symptoms begin
What are the signs and symptoms
How did they acquire it
22
Q
What are the important places a patient may have been to consider?
A
Sub-saharan Africa
South East Asia
South/Central America
23
Q
What are the less important, but still notable, places a patient may have been to consider?
A
North Africa and the Middle East
South/Central Asia
North Australia
North America
24
Q
What can discovering when the symptoms begun help identify?
A
The incubation period
25
What may identifying the incubation period help determine?
The pathogen
26
What are the potential incubation periods?
<10 days
10-21 days
>21 days
27
What are the potential signs and symptoms of travel related infections?
```
Respiratory problems
GI problems
Skin
Jaundice
CNS
Haemotological problems
Eosinophilia
```
28
What are the potential respiratory problems with travel related infections?
SOB
| Cough
29
What are the potential GI problems with travel related infections?
Diarrhoea
30
What are the potential skin problems with travel related infections?
Rash
31
What are the potential CNS problems with travel related infections?
Headache
| Meningism
32
What are the potential haemotological problems with travel related infections?
Lymphadenopathy
Splenomegaly
Haemorrhage
33
How could someone acquire a travel related infection?
```
Food/water
Insect/tick bite
Swimming
Sexual contact
Animal contact
Beach/recreational activities
```
34
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?
35
What is malaria caused by?
One of five species of the protozoal genius, Plasmodium
36
What are the most common plasmodiums causing malaria?
Plasmodium vivax
| Plasmodium falciparum
37
What % of malaria cases are caused by Plasmodium vivax?
~80%
38
Where is plasmodium vivax most prevalent?
In India and other countries outside of sub-Saharan Africa
39
What % of malaria cases are caused by Plasmodium falciparum?
~15% of cases
40
Where is plasmodium falciparum most prevalent?
Africa
41
What are the less common plasmodiums causing malaria?
Ovale
| Malariae
42
By what method is malaria transmitted?
Vector
43
What is the vector for malaria transmission?
The female Anopheles mosquito, or an infected, blood contaminated needle
44
How many cases of malaria are there per year globally?
250 million
45
How many deaths from malaria are there per year globally?
1 million
46
What is the most commonly imported infection to the UK?
Malaria
47
How many cases of malaria are there in the UK per year?
1500
48
How many deaths from malaria are there in the UK per year?
Up to 11
49
What % of cases of malaria in the UK are caused by P. Falciparum?
75%
50
Are deaths from malaria in the UK avoidable?
Most should be
51
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
52
What happens if large numbers of erythrocytes rupture at once in malaria?
It can cause a sudden onset of fever
53
Why can large numbers of erythrocytes rupturing at once cause fever in malaria?
As large amounts of toxins are released
54
What is the consequence of RBC lysis?
Anaemia
55
What is the most dangerous plasmodium causing malaria?
P. Falciparum
56
Why is P. Falciparum the most dangerous plasmodium?
As it infects red blood cells of all ages
57
What will P. Malariae, vivax, and ovale invade?
Either young or old red cells, but not both
58
What is the results of the specific invasion of RBCs by P. Malariae, vivax, and ovale?
Causes a milder form of the disease
59
What is the incubation period for malaria?
Minimum 6 days
60
What is the incubation period for P. Falciparum?
Up to 12 days
61
What is the incubation period of p. Vivax/ovale?
Can take up to 1 year +
62
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
63
What systems can the symptoms of severe falciparum malaria affect?
```
Cardiovascular
Respiratory
GI
Renal
CNS
Blood
Metabolic
Secondary infections
```
64
What are the cardiovascular symptoms of severe falciparum malaria?
Tachycardia
Hypotension
Arrhythmias
65
What are the respiratory symptoms of severe falciparum malaria?
ARDS
66
What are the GI symptoms of severe falciparum malaria?
Diarrhoea
Deranged LFTs
Bilirubin
67
What are the renal symptoms of severe falciparum malaria?
Acute kidney injury
68
What are the CNS symptoms of severe falciparum malaria?
Confusion
Fits
Cerebral malaria
69
What are the blood symptoms of severe falciparum malaria?
Low/normal WCC
Thromocytopenia
DIC
70
What are the metabolic symptoms of severe falciparum malaria?
Metabolic acidosis
| Hypoglycaemia
71
Who should malaria be managed by?
An infectious diseases physician
72
How should malaria be investigated for?
```
3x blood smears
FBC
U&Es
LFTs
Glucose
Coagulation
Head CT if CNS symptoms
Chest x-ray
```
73
How should P. Falciparum malaria be treated?
Artesunate
| Quinine + doxycycline
74
How does P. Vivax, ovale, and malariae be treated?
Chloroquine + primaquine
| Hynozoites
75
When should P. Vivax, ovale, and malariae be treated with hypnozoites?
Liver stage
76
How can malaria be prevented?
Assessment of risk
Bite prevention
Chemoprophlaxis
77
What is meant by assessment of risk in the prevention of malaria?
Knowing the risk posed to regular/returning travellers from at risk areas
78
How can bites spreading malaria be prevented?
Repellant
Adequate clothing
Nets
79
What chemoprophylaxis is given against malaria?
Specific to region
80
When should chemoprophylaxis for malaria be taken?
Start before, and continue after return (generally 4 weeks)
81
What is enteric fever also known as?
Typhoid and paratyphoid fever
82
Where does enteric fever occur?
Asia, but also Africa and South America
83
What does enteric fever occur due to?
Poor sanitation
84
How many cases of enteric fever are there per year?
21million
85
Who are most of the cases of enteric fever in?
Children
86
How many travel related UK cases of enteric fever are there a year?
~500
87
Where are most of the UK cases of enteric fever from?
The Indian subcontinent
88
How does enteric fever infection occur?
By faecal-oral route from contaminated food/water
89
What species can enteric fever affect?
Human pathogen only
90
What can the source of enteric fever be?
Either a case or a carrier
91
What pathogen causes typhoid?
Salmonella enterica serovar
92
Give 4 Samonella enteric serovar
Typhi
| Paratyphi A, B, or C
93
What kind of bacteria are Salmonella enterica?
Aerobic, gram negative rods
94
How do salmonella enterica cause disease?
Via a gram negative endotoxic
Invasion
Fimbriae
95
What does invasion by salmonella enterica allow?
Intracellular growth
96
What do the fimbriae of Salmonella enterica do?
Adhere to epithelium over ileal lymphoid tissue (Peyer's patches)
97
What can enteric fever cause?
Systemic disease (bacteraemia)
98
What is the incubation period of enteric fever?
7-14 days
99
What signs will someone with enteric fever present with?
```
Fever
Headache
Abdominal discomfort
Constipation
Dry cough
Relative bradycardia
```
100
What complications can arise from enteric fever?
Intestinal haemorrhage and perforation
101
What is the mortality rate of untreated enteric fever?
10%
102
How does paratyphoid fever usually present?
As a milder infection
103
What would investigations show with enteric fever?
Mild anaemia
Relative lymphopenia
Raised LFTs
104
What LFTs will be raised in enteric fever?
Transaminase
| Bilirubin
105
What cultures would be performed in enteric fever?
Blood
| Faeces
106
When will blood cultures be positive for enteric fever?
After 1 week
107
When will faeces sample be positive for enteric fever?
2nd week
108
Is serology a reliable test for enteric fever?
No
109
How is enteric fever usually treated?
With ceftriaxone or azithromycin for 7-14 days
110
Why is enteric fever usually treated with ceftriaxone or azithromycin?
Because ciprofloxacin resistance has become common
111
How can enteric fever be prevented?
Food and water hygiene precautions
| Typhoid vaccine
112
When is the typhoid vaccine given?
High risk travel
| Laboratory personnel
113
What type of vaccine is that for enteric fever?
Vi capsular polysaccharide antigen or live attenuated vaccine
114
How effective is the typhoid vaccine?
Has protective effect in 50-75% of cases, but doesn't affect paratyphoid
115
What is the most common arbovirus?
Dengue fever
116
How is dengue fever transmitted?
Mosquito
117
How many cases of Dengue fever are there per year?
100million, and rising
118
How many deaths from Dengue fever are there per year?
25,000
119
What % of returning travellers to Leicester's Infectious Diseases unit have Dengue fever?
~6%
120
How many serotypes of Dengue fever are there?
4
121
Where is Dengue fever common?
In subtropical and tropical regions, including Africa, Asia, and the Indian subcontient
122
How can Dengue fever be identified?
By a positive Dengue PCR and Dengue serology
123
How does the first infection of Dengue fever present?
From asymptomatic to severe febrile illness
124
How long does first infection of Dengue fever usually last?
1-5days
125
When does the first infection of Dengue fever improve?
3-4 days after rash
126
What is the treatment for the first infection of Dengue fever?
Supportive treatment only
127
What can re-infection of Dengue fever with a different serotype lead to?
Antibody dependant enhancement
128
What antibody dependant enhancement in Dengue fever lead to?
Dengue haemorrhagic fever
| Dengue shock syndrome
129
What is the prognosis for Dengue shock syndrome?
Life threatening
130
What is Traveller's diarrhoea defined as?
Three loose stool movements within 24 hours
131
What is Traveller's diarrhoea caused by?
Most commonly bacteria, however viruses and protozoa can also sometimes be the cause
132
What are the common bacterial causes of Travellers diarrhoea?
Enterotoxigenic Escherichia coli (ETEC)
| Campylobacter jejuni
133
How should Traveller's diarrhoea be treated?
Fluid and electrolyte replacement
| In severe cases, antibiotics
134
What is the drug of choice for Campylobacter jejuni?
Ciprofloxacin
135
What is often required when treating E. Coli caused Traveller's diarrhoea?
Antibiotic sensitivity tests
136
Why are antibiotic sensitivity tests often needed when treating E. Coli Travellers diarrhoea?
Resistance is widespread
137
How can Traveller's diarrhoea be best prevented?
By thorough selection and preparation of food and water
| Ensuring proper surface sanitation when cooking
138
How can information be found on travel related infections?
Public Health England
Centre for Disease Control (US)
World Health Organisation
Travel Health Pro
139
What are influenza viruses?
Spherical, enveloped viruses with negative strand RNA genome
140
What types of influenza viruses infect humans?
Only types A and B
141
Where does type A influenza virus have a reservoir?
In animals
142
What is type A influenza virus divided into?
Subtypes
143
How is influenza virus spread?
Respiratory droplets
144
Where does the influenza virus affect?
It is an infection solely of the respiratory tract
145
Does viraemia and spread to other organ systems occur with the influenza virus?
It is rare
146
What does the influenza virus do once it has infected the host?
Destruction of respiratory epithelium
147
What is destruction of respiratory epithelium attributed to in the influenza virus?
The response of cytotoxic T cells
148
How does the influenza virus often present?
Non productive cough and chills, follower by;
fever
Muscle aches
Extreme drowsiness
149
What causes the muscle aches in the influenza virus?
Cytokines
150
Who can influenza virus cause serious complications in?
Very young
Elderly
Those with comorbidities
Immunocompromised
151
What have influenza viruses shown over the years?
Marked variation in antigenic properties
152
Where has the influenza virus shown marked variation in antigenic properties?
Specifically H and N outer viral proteins
153
Why have influenza viruses show marked variation over the years in antigenic properties?
Due to antigenic shift and antigenic drift
154
What does antigenic drift occur due to?
Minor changes in H and N proteins each year
155
Does antigenic drift change the viral subtype?
No
156
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
157
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
158
How often does antigenic shift in the influenza virus occur?
Less often, roughly every 10 to 20 years
159
Why does antigenic shift in influenza viruses occur?
Due to a mixture of visions infecting a cell
160
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
161
What is the result of the change in antigenic properties of the influenza virus?
Influenza vaccines change each year
162
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
163
What are legionella?
Intracellular parasites that cause primarily respiratory tract infections
164
What shape are legionella?
Rods
165
Are legionella encapsulated or unencapsulated?
Unencapsulated
166
What is the most common pathogen causing legionella?
Legionella pneumophilia
167
What % of legionella infections in humans are caused by legionella pneumophila?
85-90%
168
What are legionella parasites responsible for in a clinical setting? Q
Legionnaires disease (LD)
169
What is LD?
An atypical pneumonia with multisystem symptoms
170
In how many individuals exposed to a common source does LD develop in?
1 in 5
171
What is the case fatality rate of LD?
5 to 30%
172
What are the early symptoms of LD?
Fever
Malaise
Headache
Anorexia
173
What follows the early symptoms of LD?
A slightly productive cough, sometimes with respiratory compromise
174
In what % of LD cases does diarrhoea occur in?
25 to 50%
175
What other symptoms, other than the early ones, may occur in Legionnaires disease?
Nausea
Vomiting
Neurological symptoms
176
How can LD be treated?
Erythromycin or azithromycin
