Travel Medicine and Vaccination
Medical specialty encompassing pre-travel risk assessment, travel vaccinations, malaria chemoprophylaxis, and management of post-travel illness. Key considerations include destination-specific risks, mandatory versus recommended vaccines, and travellers' diarrhoea prevention. The Green Book and NaTHNaC provide UK guidance.
Key Facts
NaTHNaC (National Travel Health Network and Centre): provides UK travel health guidelines Yellow fever vaccine: live attenuated; required for entry to some countries; International Certificate of Vaccination Malaria chemoprophylaxis: atovaquone-proguanil (Malarone) or doxycycline 100mg OD; mefloquine weekly if contraindications Hepatitis A: inactivated vaccine; recommended for most destinations outside Western Europe/N. America/Australasia Typhoid: Vi polysaccharide (IM) or Ty21a (oral live); recommended for Indian subcontinent, parts of Africa/S. America Japanese encephalitis, rabies, tick-borne encephalitis: risk-based pre-travel vaccines Travellers' diarrhoea: most common travel illness (~30–50% of travellers); usually self-limiting; azithromycin if severe Live vaccines contraindicated in pregnancy and immunosuppression (BCG, yellow fever, oral typhoid, MMR, varicella)
Overview
Key Facts
Travel medicine encompasses a wide range of preventive and therapeutic interventions. Pre-travel consultation should occur at least 4–6 weeks before departure to allow time for vaccine courses.
Epidemiology
- ~70 million UK residents travel abroad annually
- ~30–50% of travellers to developing countries experience health problems
- Travellers' diarrhoea: most common (~30–50%)
- ~1,500 imported malaria cases/year in UK
- ~500 imported enteric fever cases/year in UK
Aetiology
- Infectious: malaria, dengue, typhoid, hepatitis A, travellers' diarrhoea, respiratory infections
- Environmental: heat-related illness, altitude sickness, envenomation
- Non-infectious: DVT from long-haul flights, road traffic accidents (leading cause of death in young travellers)
Pathophysiology
- Exposure to novel pathogens without pre-existing immunity
- Change in climate, food/water sources, and hygiene standards
- Insect vectors (Anopheles for malaria, Aedes for dengue/Zika)
- Contaminated water/food (enteric infections)
Clinical Presentation
Pre-Travel Assessment
- Destination, duration, type of travel (backpacking vs hotel)
- Medical history, medications, immunosuppression, pregnancy
- Previous vaccinations
- Planned activities (safari, diving, altitude)
Common Travel-Related Illness
- Travellers' diarrhoea: acute watery diarrhoea, usually 1st week of travel
- Malaria: fever in returning traveller — must exclude (see Pyrexia in the Returning Traveller)
- Dengue: fever, myalgia, rash, thrombocytopenia
- Enteric fever (typhoid): insidious fever, relative bradycardia, rose spots
- Respiratory: influenza, COVID-19, TB
Red Flags
- Fever in returning traveller (malaria until proven otherwise)
- Haemorrhagic symptoms (viral haemorrhagic fever — isolate immediately)
- Meningism in returning traveller
- Severe diarrhoea with dehydration
Differential Diagnosis
| Diagnosis | Key Features | Investigation |
|---|---|---|
| Malaria | Fever, cyclical rigors, splenomegaly | Thick/thin blood films, rapid antigen test |
| Dengue | Fever, myalgia, rash, thrombocytopenia | Dengue NS1 antigen, IgM/IgG |
| Typhoid | Insidious fever, relative bradycardia | Blood culture, Widal test (unreliable) |
| Hepatitis A | Jaundice, raised ALT, recent travel | HAV IgM |
| Travellers' diarrhoea | Acute watery diarrhoea, self-limiting | Stool culture if severe/persistent |
Diagnosis / Investigation
Pre-Travel
- Review vaccination history
- Baseline bloods if starting mefloquine (LFTs) or chloroquine (eye check)
Post-Travel Illness
- Malaria films: thick and thin films ×3 over 24–48 hours if fever
- FBC: eosinophilia (helminth), thrombocytopenia (dengue, malaria)
- Blood cultures: enteric fever
- Stool MC&S + ova/parasites: persistent diarrhoea
- LFTs: hepatitis screen
- HIV, hepatitis B/C serology: if risk exposure
- CXR: if respiratory symptoms (TB)
Special Tests
- Dengue NS1 + serology: febrile traveller from endemic area
- Schistosoma serology + eosinophilia: freshwater exposure in endemic area
- Strongyloides serology: if eosinophilia and tropical exposure
Management
Pre-Travel Vaccination
Routine (ensure up-to-date):
- MMR, diphtheria-tetanus-polio, meningococcal
Travel-specific:
- Hepatitis A: single dose; booster at 6–12 months for long-term protection
- Typhoid: IM Vi polysaccharide (single dose, lasts 3 years) or oral Ty21a
- Yellow fever: single dose live vaccine; lifelong (since 2016); International Certificate
- Rabies: 3-dose pre-exposure course (days 0, 7, 21–28)
- Japanese encephalitis: 2-dose course
- Cholera: oral vaccine (Dukoral) — 2 doses
Malaria Prophylaxis
- Atovaquone-proguanil (Malarone): 1 tablet OD; start 1–2 days before, continue 7 days after
- Doxycycline 100mg OD: start 1–2 days before, continue 4 weeks after
- Mefloquine 250mg weekly: start 2–3 weeks before, continue 4 weeks after
- Plus: insect repellent (DEET 50%), bed nets, cover exposed skin at dusk/night
Travellers' Diarrhoea
- Oral rehydration salts
- Loperamide for symptom relief (avoid if dysentery)
- Azithromycin 500mg OD for 3 days if severe
Referral Criteria
- NaTHNaC or travel clinic: complex itineraries, immunosuppressed travellers
- Infectious diseases: serious post-travel illness
- Public health: notifiable diseases
Prognosis
- Travellers' diarrhoea: self-limiting in 3–5 days in most cases
- Malaria: excellent if diagnosed and treated promptly; fatal if delayed (P. falciparum)
- Typhoid: <1% mortality with appropriate antibiotics
- Prevention: pre-travel vaccination and prophylaxis are highly effective
- Long-haul travel DVT risk: ~1 in 4,500 flights >4 hours
Other Relevant Information
Travel Vaccine Summary
| Vaccine | Type | Schedule | Duration |
|---|---|---|---|
| Hepatitis A | Inactivated | 1 dose (+booster 6–12m) | 25+ years |
| Typhoid (IM) | Vi polysaccharide | 1 dose | 3 years |
| Yellow fever | Live | 1 dose | Lifelong |
| Rabies | Inactivated | 3 doses (0, 7, 21–28) | Long-term |
| Japanese encephalitis | Inactivated | 2 doses (0, 28) | ~5 years |
Malaria Prophylaxis Comparison
| Drug | Start | Continue After | Key Side Effects |
|---|---|---|---|
| Atovaquone-proguanil | 1–2 days before | 7 days after | GI upset |
| Doxycycline | 1–2 days before | 4 weeks after | Photosensitivity |
| Mefloquine | 2–3 weeks before | 4 weeks after | Neuropsychiatric |