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[ ESA 3- Infection and Immunity > Travel Infections > Flashcards

Travel Infections Flashcards

1
Q

What points of the infection model are particularly relevant when considering travel related infections?

A

Calendar time
Relative time
Recent places

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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

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3
Q

Why is relative time important when considering travel related infections?

A

Infectious diseases have varying incubation periods

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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

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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

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6
Q

Give two examples of bacterium that are more common outside of the UK

A

Rickettsia

Spirochaete

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7
Q

What category of parasites are more common outside of the UK?

A

Both protozoa and helminths

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8
Q

What do the types of pathogens likely to infect people vary depending on?

A

The person affected

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9
Q

Who are at highest risk of developing travel related infections?

A

Extreme age

Immunocompromised

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10
Q

What is key to identifying the source of a travel related infection?

A

Taking a good history

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11
Q

Why must some patients with travel related infections be isolated?

A

To stop the spread of infections in this country

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12
Q

What is the most important travel related infection to consider first?

A

Usually, malaria

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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

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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

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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

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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

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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

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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

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19
Q

Where is infection prevention important in travel related infections?

A

Both on wards and in laboratories

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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

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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

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22
Q

What are the important places a patient may have been to consider?

A

Sub-saharan Africa
South East Asia
South/Central America

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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

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24
Q

What can discovering when the symptoms begun help identify?

A

The incubation period

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25
Q

What may identifying the incubation period help determine?

A

The pathogen

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26
Q

What are the potential incubation periods?

A

<10 days
10-21 days
>21 days

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27
Q

What are the potential signs and symptoms of travel related infections?

A 
Respiratory problems
GI problems
Skin
Jaundice
CNS
Haemotological problems
Eosinophilia
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28
Q

What are the potential respiratory problems with travel related infections?

A

SOB

Cough

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29
Q

What are the potential GI problems with travel related infections?

A

Diarrhoea

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30
Q

What are the potential skin problems with travel related infections?

A

Rash

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31
Q

What are the potential CNS problems with travel related infections?

A

Headache

Meningism

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32
Q

What are the potential haemotological problems with travel related infections?

A

Lymphadenopathy
Splenomegaly
Haemorrhage

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33
Q

How could someone acquire a travel related infection?

A 
Food/water
Insect/tick bite
Swimming
Sexual contact
Animal contact 
Beach/recreational activities
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34
Q

What key aspects of a person’s travel history is it helpful to know?

A

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?

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35
Q

What is malaria caused by?

A

One of five species of the protozoal genius, Plasmodium

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36
Q

What are the most common plasmodiums causing malaria?

A

Plasmodium vivax

Plasmodium falciparum

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37
Q

What % of malaria cases are caused by Plasmodium vivax?

A

~80%

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38
Q

Where is plasmodium vivax most prevalent?

A

In India and other countries outside of sub-Saharan Africa

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39
Q

What % of malaria cases are caused by Plasmodium falciparum?

A

~15% of cases

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40
Q

Where is plasmodium falciparum most prevalent?

A

Africa

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41
Q

What are the less common plasmodiums causing malaria?

A

Ovale

Malariae

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42
Q

By what method is malaria transmitted?

A

Vector

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43
Q

What is the vector for malaria transmission?

A

The female Anopheles mosquito, or an infected, blood contaminated needle

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44
Q

How many cases of malaria are there per year globally?

A

250 million

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45
Q

How many deaths from malaria are there per year globally?

A

1 million

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46
Q

What is the most commonly imported infection to the UK?

A

Malaria

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47
Q

How many cases of malaria are there in the UK per year?

A

1500

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48
Q

How many deaths from malaria are there in the UK per year?

A

Up to 11

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49
Q

What % of cases of malaria in the UK are caused by P. Falciparum?

A

75%

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50
Q

Are deaths from malaria in the UK avoidable?

A

Most should be

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51
Q

Describe the life cycle of malaria plasmodium

A

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

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52
Q

What happens if large numbers of erythrocytes rupture at once in malaria?

A

It can cause a sudden onset of fever

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53
Q

Why can large numbers of erythrocytes rupturing at once cause fever in malaria?

A

As large amounts of toxins are released

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54
Q

What is the consequence of RBC lysis?

A

Anaemia

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55
Q

What is the most dangerous plasmodium causing malaria?

A

P. Falciparum

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56
Q

Why is P. Falciparum the most dangerous plasmodium?

A

As it infects red blood cells of all ages

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57
Q

What will P. Malariae, vivax, and ovale invade?

A

Either young or old red cells, but not both

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58
Q

What is the results of the specific invasion of RBCs by P. Malariae, vivax, and ovale?

A

Causes a milder form of the disease

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59
Q

What is the incubation period for malaria?

A

Minimum 6 days

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60
Q

What is the incubation period for P. Falciparum?

A

Up to 12 days

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61
Q

What is the incubation period of p. Vivax/ovale?

A

Can take up to 1 year +

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62
Q

How will a patient normally present with malaria?

A

Fever, chills, and sweats that cycle every 3rd or 4th day

Often few examinable signs other than fever and sometimes splenomegaly

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63
Q

What systems can the symptoms of severe falciparum malaria affect?

A 
Cardiovascular
Respiratory 
GI
Renal
CNS
Blood
Metabolic
Secondary infections
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64
Q

What are the cardiovascular symptoms of severe falciparum malaria?

A

Tachycardia
Hypotension
Arrhythmias

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65
Q

What are the respiratory symptoms of severe falciparum malaria?

A

ARDS

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66
Q

What are the GI symptoms of severe falciparum malaria?

A

Diarrhoea
Deranged LFTs
Bilirubin

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67
Q

What are the renal symptoms of severe falciparum malaria?

A

Acute kidney injury

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68
Q

What are the CNS symptoms of severe falciparum malaria?

A

Confusion
Fits
Cerebral malaria

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69
Q

What are the blood symptoms of severe falciparum malaria?

A

Low/normal WCC
Thromocytopenia
DIC

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70
Q

What are the metabolic symptoms of severe falciparum malaria?

A

Metabolic acidosis

Hypoglycaemia

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71
Q

Who should malaria be managed by?

A

An infectious diseases physician

72
Q

How should malaria be investigated for?

A 
3x blood smears
FBC
U&amp;Es
LFTs
Glucose
Coagulation 
Head CT if CNS symptoms
Chest x-ray
73
Q

How should P. Falciparum malaria be treated?

A

Artesunate

Quinine + doxycycline

74
Q

How does P. Vivax, ovale, and malariae be treated?

A

Chloroquine + primaquine

Hynozoites

75
Q

When should P. Vivax, ovale, and malariae be treated with hypnozoites?

A

Liver stage

76
Q

How can malaria be prevented?

A

Assessment of risk
Bite prevention
Chemoprophlaxis

77
Q

What is meant by assessment of risk in the prevention of malaria?

A

Knowing the risk posed to regular/returning travellers from at risk areas

78
Q

How can bites spreading malaria be prevented?

A

Repellant
Adequate clothing
Nets

79
Q

What chemoprophylaxis is given against malaria?

A

Specific to region

80
Q

When should chemoprophylaxis for malaria be taken?

A

Start before, and continue after return (generally 4 weeks)

81
Q

What is enteric fever also known as?

A

Typhoid and paratyphoid fever

82
Q

Where does enteric fever occur?

A

Asia, but also Africa and South America

83
Q

What does enteric fever occur due to?

A

Poor sanitation

84
Q

How many cases of enteric fever are there per year?

A

21million

85
Q

Who are most of the cases of enteric fever in?

A

Children

86
Q

How many travel related UK cases of enteric fever are there a year?

A

~500

87
Q

Where are most of the UK cases of enteric fever from?

A

The Indian subcontinent

88
Q

How does enteric fever infection occur?

A

By faecal-oral route from contaminated food/water

89
Q

What species can enteric fever affect?

A

Human pathogen only

90
Q

What can the source of enteric fever be?

A

Either a case or a carrier

91
Q

What pathogen causes typhoid?

A

Salmonella enterica serovar

92
Q

Give 4 Samonella enteric serovar

A

Typhi

Paratyphi A, B, or C

93
Q

What kind of bacteria are Salmonella enterica?

A

Aerobic, gram negative rods

94
Q

How do salmonella enterica cause disease?

A

Via a gram negative endotoxic
Invasion
Fimbriae

95
Q

What does invasion by salmonella enterica allow?

A

Intracellular growth

96
Q

What do the fimbriae of Salmonella enterica do?

A

Adhere to epithelium over ileal lymphoid tissue (Peyer’s patches)

97
Q

What can enteric fever cause?

A

Systemic disease (bacteraemia)

98
Q

What is the incubation period of enteric fever?

A

7-14 days

99
Q

What signs will someone with enteric fever present with?

A 
Fever
Headache
Abdominal discomfort
Constipation 
Dry cough
Relative bradycardia
100
Q

What complications can arise from enteric fever?

A

Intestinal haemorrhage and perforation

101
Q

What is the mortality rate of untreated enteric fever?

A

10%

102
Q

How does paratyphoid fever usually present?

A

As a milder infection

103
Q

What would investigations show with enteric fever?

A

Mild anaemia
Relative lymphopenia
Raised LFTs

104
Q

What LFTs will be raised in enteric fever?

A

Transaminase

Bilirubin

105
Q

What cultures would be performed in enteric fever?

A

Blood

Faeces

106
Q

When will blood cultures be positive for enteric fever?

A

After 1 week

107
Q

When will faeces sample be positive for enteric fever?

A

2nd week

108
Q

Is serology a reliable test for enteric fever?

A

No

109
Q

How is enteric fever usually treated?

A

With ceftriaxone or azithromycin for 7-14 days

110
Q

Why is enteric fever usually treated with ceftriaxone or azithromycin?

A

Because ciprofloxacin resistance has become common

111
Q

How can enteric fever be prevented?

A

Food and water hygiene precautions

Typhoid vaccine

112
Q

When is the typhoid vaccine given?

A

High risk travel

Laboratory personnel

113
Q

What type of vaccine is that for enteric fever?

A

Vi capsular polysaccharide antigen or live attenuated vaccine

114
Q

How effective is the typhoid vaccine?

A

Has protective effect in 50-75% of cases, but doesn’t affect paratyphoid

115
Q

What is the most common arbovirus?

A

Dengue fever

116
Q

How is dengue fever transmitted?

A

Mosquito

117
Q

How many cases of Dengue fever are there per year?

A

100million, and rising

118
Q

How many deaths from Dengue fever are there per year?

A

25,000

119
Q

What % of returning travellers to Leicester’s Infectious Diseases unit have Dengue fever?

A

~6%

120
Q

How many serotypes of Dengue fever are there?

A

4

121
Q

Where is Dengue fever common?

A

In subtropical and tropical regions, including Africa, Asia, and the Indian subcontient

122
Q

How can Dengue fever be identified?

A

By a positive Dengue PCR and Dengue serology

123
Q

How does the first infection of Dengue fever present?

A

From asymptomatic to severe febrile illness

124
Q

How long does first infection of Dengue fever usually last?

A

1-5days

125
Q

When does the first infection of Dengue fever improve?

A

3-4 days after rash

126
Q

What is the treatment for the first infection of Dengue fever?

A

Supportive treatment only

127
Q

What can re-infection of Dengue fever with a different serotype lead to?

A

Antibody dependant enhancement

128
Q

What antibody dependant enhancement in Dengue fever lead to?

A

Dengue haemorrhagic fever

Dengue shock syndrome

129
Q

What is the prognosis for Dengue shock syndrome?

A

Life threatening

130
Q

What is Traveller’s diarrhoea defined as?

A

Three loose stool movements within 24 hours

131
Q

What is Traveller’s diarrhoea caused by?

A

Most commonly bacteria, however viruses and protozoa can also sometimes be the cause

132
Q

What are the common bacterial causes of Travellers diarrhoea?

A

Enterotoxigenic Escherichia coli (ETEC)

Campylobacter jejuni

133
Q

How should Traveller’s diarrhoea be treated?

A

Fluid and electrolyte replacement

In severe cases, antibiotics

134
Q

What is the drug of choice for Campylobacter jejuni?

A

Ciprofloxacin

135
Q

What is often required when treating E. Coli caused Traveller’s diarrhoea?

A

Antibiotic sensitivity tests

136
Q

Why are antibiotic sensitivity tests often needed when treating E. Coli Travellers diarrhoea?

A

Resistance is widespread

137
Q

How can Traveller’s diarrhoea be best prevented?

A

By thorough selection and preparation of food and water

Ensuring proper surface sanitation when cooking

138
Q

How can information be found on travel related infections?

A

Public Health England
Centre for Disease Control (US)
World Health Organisation
Travel Health Pro

139
Q

What are influenza viruses?

A

Spherical, enveloped viruses with negative strand RNA genome

140
Q

What types of influenza viruses infect humans?

A

Only types A and B

141
Q

Where does type A influenza virus have a reservoir?

A

In animals

142
Q

What is type A influenza virus divided into?

A

Subtypes

143
Q

How is influenza virus spread?

A

Respiratory droplets

144
Q

Where does the influenza virus affect?

A

It is an infection solely of the respiratory tract

145
Q

Does viraemia and spread to other organ systems occur with the influenza virus?

A

It is rare

146
Q

What does the influenza virus do once it has infected the host?

A

Destruction of respiratory epithelium

147
Q

What is destruction of respiratory epithelium attributed to in the influenza virus?

A

The response of cytotoxic T cells

148
Q

How does the influenza virus often present?

A

Non productive cough and chills, follower by;
fever
Muscle aches
Extreme drowsiness

149
Q

What causes the muscle aches in the influenza virus?

A

Cytokines

150
Q

Who can influenza virus cause serious complications in?

A

Very young
Elderly
Those with comorbidities
Immunocompromised

151
Q

What have influenza viruses shown over the years?

A

Marked variation in antigenic properties

152
Q

Where has the influenza virus shown marked variation in antigenic properties?

A

Specifically H and N outer viral proteins

153
Q

Why have influenza viruses show marked variation over the years in antigenic properties?

A

Due to antigenic shift and antigenic drift

154
Q

What does antigenic drift occur due to?

A

Minor changes in H and N proteins each year

155
Q

Does antigenic drift change the viral subtype?

A

No

156
Q

How to the minor changes in H and N proteins occur in antigenic drift?

A

Via random mutations in the viral RNA, or small amino acid changes in the H and N proteins

157
Q

What is antigenic shift, with respect to the influenza virus?

A

A more dramatic change in the H and/or N proteins, and a change in subtype

158
Q

How often does antigenic shift in the influenza virus occur?

A

Less often, roughly every 10 to 20 years

159
Q

Why does antigenic shift in influenza viruses occur?

A

Due to a mixture of visions infecting a cell

160
Q

How does a mixture of visions infecting a cell lead to antigenic shift?

A

RNA from the visions is mixed, resulting a new virus with a new combination of genes

161
Q

What is the result of the change in antigenic properties of the influenza virus?

A

Influenza vaccines change each year

162
Q

How is it ensured the influenza vaccination accommodates for the change in antigenic properties?

A

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
Q

What are legionella?

A

Intracellular parasites that cause primarily respiratory tract infections

164
Q

What shape are legionella?

A

Rods

165
Q

Are legionella encapsulated or unencapsulated?

A

Unencapsulated

166
Q

What is the most common pathogen causing legionella?

A

Legionella pneumophilia

167
Q

What % of legionella infections in humans are caused by legionella pneumophila?

A

85-90%

168
Q

What are legionella parasites responsible for in a clinical setting? Q

A

Legionnaires disease (LD)

169
Q

What is LD?

A

An atypical pneumonia with multisystem symptoms

170
Q

In how many individuals exposed to a common source does LD develop in?

A

1 in 5

171
Q

What is the case fatality rate of LD?

A

5 to 30%

172
Q

What are the early symptoms of LD?

A

Fever
Malaise
Headache
Anorexia

173
Q

What follows the early symptoms of LD?

A

A slightly productive cough, sometimes with respiratory compromise

174
Q

In what % of LD cases does diarrhoea occur in?

A

25 to 50%

175
Q

What other symptoms, other than the early ones, may occur in Legionnaires disease?

A

Nausea
Vomiting
Neurological symptoms

176
Q

How can LD be treated?

A

Erythromycin or azithromycin

[ ESA 3- Infection and Immunity (15 decks)

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