S9) Travel-related infections Flashcards
Which parts of the infection model are most significant when looking at travel infections?
Patient:
- Person – age, gender, physiological state, pathological state, social factors
- Time – calendar/relative
- Place – current/previous
Why is travel history an important consideration?
- 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)
What are the key aspects of patient travel history?
- Any unwell travel companions /contacts?
- Pre-travel vaccinations / preventative measures?
- Healthcare exposure?
What are the guiding questions when dealing with travel-related infections?
- Where have they been?
- When did the symptoms begin?
- What are the symptom/signs?
- How did they acquire it?
Identify some common regions which are associated with travel-related infections
- Sub-saharan Africa
- S.E .Asia
- S / C America
- N. Africa
- M. East S / C Asia
Identify and describe the different incubation periods for travel-related infections
- < 10 days = acute
- 10-21 days = sub-acute
- > 21 days = chronic
Describe the 5 types of symptoms which result from travel-related infections
- Resp: breathlessness, cough
- GI: diarrhoea
- Skin: rash
- CNS: headache / meningism
- Haematological: lymphadenopathy / splenomegaly / haemorrhage
Identify 5 common activities which cause people to acquire travel-related infections
- Food/water
- Insect/tick bite
- Swimming
- Sexual contact
- Animal contact (bite/safari)
What is malaria?
- 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
Which species of the Plasmodium parasite cause malaria in humans?
- Plasmodium falciparum (75% – mainly Africa)
- Plasmodium vivax (~20% – mainly India)
- Plasmodium ovale (~20% – mainly India)
- Plasmodium malariae
- Plasmodium knowlesii
Describe the prevalence of malaria
Describe how a patient with malaria presents (history & examination)
- History – fever, chills & sweats (cycle every 3rd or 4th day)
- Examination – often few signs except fever (± splenomegaly)
What is the incubation period for malaria?
Minimum 6 days:
- P. falciparum – by 4 weeks
- P. vivax/ovale – up to 1 year+
Describe 5 types of symptoms observed in severe falciparum malaria
- CVS – tachycardia, hypotension, arrhythmias
- Resp – ARDS
- GI – diarrhoea
- CNS – confusion, fits, cerebral malaria
- Blood – thrombocytopenia, DIC
Briefly, describe the life cycle of the malaria parasite
Identify the 8 investigations for malaria
- Blood film x3
- FBC
- U&Es
- LFTs
- Blood glucose
- Coagulation
- CXR
- Head CT (if neurological symptoms)
Describe the treatment of malaria (dependent on species)
- P. falciparum (‘malignant’): artesunate, quinine + doxycycline
- P. vivax, ovale, malariae (‘benign’): chloroquine, dormant hypnozoites (liver), additional primaquine (if recurring)
How can malaria be prevented?
- Assess risk – knowledge of at-risk areas
- Bite prevention – repellant, adequate clothing, nets
- Chemoprophylaxis – specific to region (start before & continuefor 4 weeks after return)
What is Enteric fever?
- 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
What are the high risk areas for enteric fever?
- Mainly Asia
- Also Africa & S America
Identify the salmonella organisms which cause enteric fever
- Typhoid fever: Salmonella typhi
- Paratyphoid fever: Salmonella paratyphi A, B or C
What kind of bacteria are salmonella organisms?
Enterobacteriaceae: aerobic Gneg bacillus
Describe the virulence of the salmonella organisms
- 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)
What is the incubation period for enteric fever?
7-14 days
What are the signs and symptoms of enteric fever?
- Bacteraemia & sepsis
- Fever
- Headache
- Constipation
- Dry cough
- Relative bradycardia
What are the complications of typhoid fever?
- Intestinal haemorrhage
- Intestinal perforation
- 10% mortality (untreated)
What are the investigations for enteric fever?
- FBC (anaemia, lymphopenia)
- LFTs (raised transaminase & bilirubin)
- Blood culture
- Faecal culture
- Serology – antibody detection (not reliable)
In light of its multi-drug resistance (including penicillins), outline the treatment for enteric fever
- Fluoroquinolones (e.g. ciprofloxacin) may work, but increasing resistance
- Usually, IV ceftriaxone / azithromycin for 7-14 days
How can enteric fever be prevented?
- Food & water hygiene precautions
- Typhoid vaccine (high-risk travel & lab personnel)
- Capsular polysaccharide antigen / live attenuated vaccine
Identify some travel-related infections which present with fever & rash
- Childhood viruses – measles, rubella, parvovirus
- Infectious mononucleosis (EBV / CMV)
- Acute HIV infection
- Rickettsia (spotted fever)
What is Dengue fever?
- Dengue fever is a mosquito-borne tropical disease caused by the dengue virus
- It is commonest arbovirus and has 4 serotypes
What are the high risk areas for Dengue fever?
- Africa
- Asia
- Indian SC
How does Dengue fever present?
First infection ranges from asymptomatic to non-specific febrile illness:
- Lasts 1-5 days
- Improves 3-4 days after rash
With Dengue fever, a patient can be re-infected with different serotype.
What are the consequences of this?
Antibody dependent enhancement:
- Dengue haemorrhagic fever (children, hyper-endemic areas)
- Dengue shock syndrome
How is Dengue fever treated?
Supportive treatment only
Identify some emerging diseases
- Influenza pandemics
- Novel coronaviruses:
I. SARS
II. MERS
What is Ebola?
- 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
What are the high risk areas for Ebola?
- Nigeria
- Guinea
- Liberia
- Sierra Leone
What is the treatment for Ebola?
Vaccine under development
What is Zika virus?
- 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
What are the high risk areas for the Zika virus?
- Americas
- Caribbean
- Pacific
What is the treatment for Zika virus?
No treatment, no vaccine
