S9) Travel-related infections Flashcards

1
Q

Which parts of the infection model are most significant when looking at travel infections?

A

Patient:

  • Person – age, gender, physiological state, pathological state, social factors
  • Time – calendar/relative
  • Place – current/previous
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2
Q

Why is travel history an important consideration?

A
  • Recognise imported diseases (rare / unknown in UK)
  • Infection prevention on the ward/in the lab
  • Different strains of pathogen (impacts on protection/detection, antibiotic resistance)
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3
Q

What are the key aspects of patient travel history?

A
  • Any unwell travel companions /contacts?
  • Pre-travel vaccinations / preventative measures?
  • Healthcare exposure?
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4
Q

What are the guiding questions when dealing with travel-related infections?

A
  • Where have they been?
  • When did the symptoms begin?
  • What are the symptom/signs?
  • How did they acquire it?
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5
Q

Identify some common regions which are associated with travel-related infections

A
  • Sub-saharan Africa
  • S.E .Asia
  • S / C America
  • N. Africa
  • M. East S / C Asia
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6
Q

Identify and describe the different incubation periods for travel-related infections

A
  • < 10 days = acute
  • 10-21 days = sub-acute
  • > 21 days = chronic
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7
Q

Describe the 5 types of symptoms which result from travel-related infections

A
  • Resp: breathlessness, cough
  • GI: diarrhoea
  • Skin: rash
  • CNS: headache / meningism
  • Haematological: lymphadenopathy / splenomegaly / haemorrhage
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8
Q

Identify 5 common activities which cause people to acquire travel-related infections

A
  • Food/water
  • Insect/tick bite
  • Swimming
  • Sexual contact
  • Animal contact (bite/safari)
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9
Q

What is malaria?

A
  • Malaria is a mosquito-borne infectious disease, typically transmitted through an animal vector – an infected Anopheles mosquito
  • It is the commonest imported disease in the UK
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10
Q

Which species of the Plasmodium parasite cause malaria in humans?

A
  • Plasmodium falciparum (75% – mainly Africa)
  • Plasmodium vivax (~20% – mainly India)
  • Plasmodium ovale (~20% – mainly India)
  • Plasmodium malariae
  • Plasmodium knowlesii
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11
Q

Describe the prevalence of malaria

A
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12
Q

Describe how a patient with malaria presents (history & examination)

A
  • History – fever, chills & sweats (cycle every 3rd or 4th day)
  • Examination – often few signs except fever (± splenomegaly)
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13
Q

What is the incubation period for malaria?

A

Minimum 6 days:

  • P. falciparum – by 4 weeks
  • P. vivax/ovale – up to 1 year+
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14
Q

Describe 5 types of symptoms observed in severe falciparum malaria

A
  • CVS – tachycardia, hypotension, arrhythmias
  • Resp – ARDS
  • GI – diarrhoea
  • CNS – confusion, fits, cerebral malaria
  • Blood – thrombocytopenia, DIC
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15
Q

Briefly, describe the life cycle of the malaria parasite

A
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16
Q

Identify the 8 investigations for malaria

A
  • Blood film x3
  • FBC
  • U&Es
  • LFTs
  • Blood glucose
  • Coagulation
  • CXR
  • Head CT (if neurological symptoms)
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17
Q

Describe the treatment of malaria (dependent on species)

A
  • P. falciparum (‘malignant’): artesunate, quinine + doxycycline
  • P. vivax, ovale, malariae (‘benign’): chloroquine, dormant hypnozoites (liver), additional primaquine (if recurring)
18
Q

How can malaria be prevented?

A
  • Assess risk – knowledge of at-risk areas
  • Bite prevention – repellant, adequate clothing, nets
  • Chemoprophylaxis – specific to region (start before & continuefor 4 weeks after return)
19
Q

What is Enteric fever?

A
  • Enteric fever (typhoid & paratyphoid fever) is a potentially fatal, mutisystemic ilness caused by the bacterium Salmonella typhi
  • It is spread through the faecal-oral route (drinking/eating), due to poor sanitation
20
Q

What are the high risk areas for enteric fever?

A
  • Mainly Asia
  • Also Africa & S America
21
Q

Identify the salmonella organisms which cause enteric fever

A
  • Typhoid fever: Salmonella typhi
  • Paratyphoid fever: Salmonella paratyphi A, B or C
22
Q

What kind of bacteria are salmonella organisms?

A

Enterobacteriaceae: aerobic Gneg bacillus

23
Q

Describe the virulence of the salmonella organisms

A
  • Low infectious dose
  • Survives gastric acid
  • Fimbriae adhere to epithelium over ileal lymphoid tissue (Peyer’s patches) → RE system / blood
  • Reside within macrophages (liver/ spleen/ bone marrow)
24
Q

What is the incubation period for enteric fever?

A

7-14 days

25
Q

What are the signs and symptoms of enteric fever?

A
  • Bacteraemia & sepsis
  • Fever
  • Headache
  • Constipation
  • Dry cough
  • Relative bradycardia
26
Q

What are the complications of typhoid fever?

A
  • Intestinal haemorrhage
  • Intestinal perforation
  • 10% mortality (untreated)
27
Q

What are the investigations for enteric fever?

A
  • FBC (anaemia, lymphopenia)
  • LFTs (raised transaminase & bilirubin)
  • Blood culture
  • Faecal culture
  • Serology – antibody detection (not reliable)
28
Q

In light of its multi-drug resistance (including penicillins), outline the treatment for enteric fever

A
  • Fluoroquinolones (e.g. ciprofloxacin) may work, but increasing resistance
  • Usually, IV ceftriaxone / azithromycin for 7-14 days
29
Q

How can enteric fever be prevented?

A
  • Food & water hygiene precautions
  • Typhoid vaccine (high-risk travel & lab personnel)
  • Capsular polysaccharide antigen / live attenuated vaccine
30
Q

Identify some travel-related infections which present with fever & rash

A
  • Childhood viruses – measles, rubella, parvovirus
  • Infectious mononucleosis (EBV / CMV)
  • Acute HIV infection
  • Rickettsia (spotted fever)
31
Q

What is Dengue fever?

A
  • Dengue fever is a mosquito-borne tropical disease caused by the dengue virus
  • It is commonest arbovirus and has 4 serotypes
32
Q

What are the high risk areas for Dengue fever?

A
  • Africa
  • Asia
  • Indian SC
33
Q

How does Dengue fever present?

A

First infection ranges from asymptomatic to non-specific febrile illness:

  • Lasts 1-5 days
  • Improves 3-4 days after rash
34
Q

With Dengue fever, a patient can be re-infected with different serotype.

What are the consequences of this?

A

Antibody dependent enhancement:

  • Dengue haemorrhagic fever (children, hyper-endemic areas)
  • Dengue shock syndrome
35
Q

How is Dengue fever treated?

A

Supportive treatment only

36
Q

Identify some emerging diseases

A
  • Influenza pandemics
  • Novel coronaviruses:

I. SARS

II. MERS

37
Q

What is Ebola?

A
  • Ebola is a viral haemorrhagic fever caused by a filovirus, spread by direct contact with body fluids
  • It presents with flu-like symptoms (+ vomiting, diarrhoea, headaches, confusion, rash) as well as internal/external bleeding at 5-7 days
38
Q

What are the high risk areas for Ebola?

A
  • Nigeria
  • Guinea
  • Liberia
  • Sierra Leone
39
Q

What is the treatment for Ebola?

A

Vaccine under development

40
Q

What is Zika virus?

A
  • Zika virus is an arbovirus (flavivirus) transmitted through the Aedes mosquito & through sexual contact
  • It presents with mild dengue-like symptoms (only in 20%) and causes congenital microcephaly and/or foetal loss
41
Q

What are the high risk areas for the Zika virus?

A
  • Americas
  • Caribbean
  • Pacific
42
Q

What is the treatment for Zika virus?

A

No treatment, no vaccine