Malaria, dengue, and yellow fever — port-by-port risk
Vector-borne disease risk varies dramatically by port. Which prophylaxis, which vaccine, which port — practical guidance for voyage-planning.
Vector-borne disease is a leading cause of mid-voyage sign-off in tropical trades. Malaria (chloroquine-resistant P. falciparum) remains endemic in West + East Africa, PNG, Solomon Islands, and Amazon basin. Dengue is expanding — now endemic across most tropical port zones and increasingly common in South-East Asia + Latin America. Yellow fever is enforced via International Certificate of Vaccination for many African + Latin American ports — no valid certificate can mean no shore leave.
Practical steps
- Check destination-port disease risk before joining — WHO International Travel and Health + national travel-clinic sites are authoritative.
- Malaria prophylaxis (mefloquine, doxycycline, or Malarone) starts 1-2 weeks before entering a malaria zone — timing matters.
- Yellow fever vaccine at least 10 days before first port call in a yellow-fever-endemic region — International Certificate valid for life.
- Dengue prevention is entirely mosquito avoidance — DEET-based repellents + covered clothing at dawn + dusk.
When to escalate
- Fever + chills after any port visit in a malaria zone within 6 months — treat as suspected malaria until proven otherwise; TMAS consultation immediately.
- Sudden high fever + rash + retro-orbital pain — suspected dengue; hospital-grade care within 24 hours if severe dengue develops.
- Yellow fever certificate missing or expired at a required-vaccination port — will not be allowed ashore + typically not allowed off the vessel.
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