32. Tropical infections
Tropical infections are endemic in countries where the climate supports the vector (e.g. mosquitoes for dengue fever) or where sewage is not safely disposed. Clinicians in other countries will encounter these infections in returning travellers or immigrants, who import these infections. Travel clinics have been established to prepare travellers before departure with vaccines (Table 3.32.1) and advice on prevention. Tropical infections may be broadly classified as those causing diarrhoea, fever and skin diseases.
Table 3.32.1 Vaccinations before travel to tropical countries for adults
| Vaccine | Dose | Protected period (years) |
|---|---|---|
| Diphtheria, tetanus | Booster | > 5 |
| Poliomyelitis | Booster | > 5 |
| Hepatitis A | 1 dose before departure | 10 |
| Hepatitis B | 3 doses within 3 weeks before departure | >20 |
| Typhoid fever | 3 doses of oral vaccine (Ty21a) over 5 days | 1 |
| Yellow fever | 1 dose > 10 days before departure | 10 |
| Rabies (for travellers with wild animal contact) | 3 doses within 4 weeks before departure | 3 |
| Japanese encephalitis (for rural Asia) | 3 doses within 4 weeks before departure | 3 |
| Tick-borne encephalitis (for forest trips in northern, central and eastern Europe) | 2 doses within 2 weeks before departure | 3 |
| Meningococcal meningitis (for Saudi Arabia) | Quadrivalent (ACW135Y) polysaccharide vaccine | 3 |
| Cholera | Not recommended by the World Health Organization |
Diarrhoea
Shigella flexneri and Shigella dysenteriae cause severe colitis, which in many cases require antibiotic therapy, for example quinolones or azithromycin depending on local resistance. Verotoxin-producing Escherichia coli (VTEC) is an invasive E. coli causing colitis and is harboured by cattle. Antibiotic treatment is not recommended, because it may induce haemolytic uraemic syndrome.
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