Disease guideMosquito-borne parasitic infection

Malaria

Malaria is a serious, sometimes fatal disease spread by night-biting Anopheles mosquitoes. There's no vaccine for travelers, but prophylactic medication plus bite prevention are highly effective. Symptoms (fever, chills, flu-like illness) can appear weeks to months after travel.

This guide is a draft pending clinical review. Verify details with the CDC, WHO or a travel-medicine provider before relying on them.

Vaccine

None for travelers

Preventive medication

Available

Incubation

Typically 7–30 days, but some forms can relapse or emerge months after exposure.

How it spreads

Transmitted through the bite of infected female Anopheles mosquitoes, which bite mainly between dusk and dawn.

Where it's a risk

Much of Sub-Saharan Africa, parts of South and Southeast Asia, Oceania, and Central/South America. Risk varies sharply by region, altitude and season.

Seasonal pattern

Transmission generally rises during and after rainy seasons when mosquito populations peak.

Symptoms to watch for

  • Fever, chills and sweats (often cyclical)
  • Headache, muscle aches and fatigue
  • Nausea, vomiting and diarrhea
  • In severe cases: confusion, seizures, organ failure — a medical emergency

How to prevent it

  1. 1Take prophylactic antimalarial medication exactly as prescribed
  2. 2Use insect repellent (DEET or picaridin) on exposed skin
  3. 3Sleep under an insecticide-treated bed net in unscreened rooms
  4. 4Wear long sleeves and trousers at dusk and dawn
  5. 5Treat clothing and gear with permethrin

Treatment

Malaria is treatable with prescription antimalarial drugs; the choice depends on the species, severity and where it was acquired. Prompt diagnosis is critical — falciparum malaria can become life-threatening within 24 hours. Seek care immediately for any fever during or after travel to a malaria area.

Who's most at risk

All travelers to malaria-endemic areas. Pregnant travelers and young children are at highest risk of severe disease.

Frequently asked questions

Is there a malaria vaccine for travelers?▼

No. The malaria vaccines in use are for young children in high-transmission regions, not travelers. Travelers rely on prophylactic medication plus mosquito-bite prevention.

How soon after travel can malaria appear?▼

Usually 7–30 days after exposure, but some types can appear months later. Any fever within a year of travel to a malaria area should be evaluated urgently, and mention your travel history.

Where to watch for it

Country guides where this is a notable risk.

TH flagThailandModerate risk

Thailand carries a CDC Level 1 travel health notice. Malaria risk exists primarily in border provinces with Burma, Cambodia, and Malaysia. Key travel vaccines: COVID-19, Hepatitis A, Hepatitis B.

Related disease guides

Dengue FeverVaccine

Dengue is a viral infection spread by day-biting Aedes mosquitoes, common in tropical and subtropical cities. There's no specific treatment and no prophylactic drug, so bite prevention is the main defense. Most cases resolve in about a week, but severe dengue is a medical emergency.

Prepare before you go

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Sources: CDC Travelers' Health · WHO International Travel and Health. Last updated 2026-07-31. This page is informational and not a substitute for advice from a travel-medicine provider.