TL;DR

• Malaria is rare in the US, with roughly 1,500 cases reported annually, almost all imported.
• Most infections come from travelers returning from sub‑Saharan Africa or South‑East Asia.
• The native mosquito species capable of transmission are limited to a few southern states.
• Prompt diagnosis and appropriate drug treatment prevent severe disease.
• Travelers should use CDC‑recommended chemoprophylaxis and bite‑prevention measures.

When you hear the phrase malaria in the United States, you probably picture swarms of mosquitoes and endless fevers. In reality, the picture is far more nuanced. Below we break down what malaria really looks like on American soil, who’s at risk, and what you can do to stay safe whether you live here or are just passing through.

Malaria in the United States is a public‑health condition defined by the occasional appearance of Plasmodium‑infected individuals within U.S. borders, most often linked to recent international travel rather than local transmission. The disease is monitored by the Centers for Disease Control and Prevention (CDC) and reported to state health departments for rapid response.

What Exactly Is Malaria?

Malaria is a blood‑borne infection caused by Plasmodium parasites. The five species that infect humans-P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi-vary in severity and geographic distribution. In the United States, the overwhelming majority of cases involve P. falciparum and P. vivax because these are the species most common in Africa and Asia, the regions most traveled by Americans.

Current Epidemiology: Numbers and Trends

According to the CDC’s annual malaria surveillance report, the United States recorded 1,473 cases in 2023, 1,538 in 2024, and 1,502 in the first nine months of 2025. That steadiness masks a clear pattern: over 95% of cases are imported, with only a handful (usually fewer than five per year) linked to local mosquito‑borne transmission.

Geographically, imported cases cluster in large metropolitan areas (New York, Los Angeles, Chicago) reflecting travel volume. The handful of locally acquired infections have all come from the Gulf Coast-primarily Florida, Texas, and Arizona-where resident Anopheles mosquitoes can act as vectors under warm, humid conditions.

How Do Cases Arrive?

Three pathways dominate:

1. International travel: Tourists, business travelers, military personnel, and immigrants returning from endemic regions bring parasites in their bloodstream.
2. Blood transfusion: Though rare, malaria can survive in donated blood; strict screening has reduced this risk dramatically.
3. Local transmission: In the few southern counties where competent Anopheles species persist, an infected traveler can seed a limited outbreak if mosquitoes bite them and later bite a local resident.

The CDC operates an “airport screening” program at major international hubs. While the program does not stop all imported cases, it helps flag high‑risk individuals for early testing.

Key Vectors and Species Present in the U.S.

Only a subset of the roughly 40 North American Anopheles species can transmit malaria, with Anopheles quadrimaculatus and Anopheles freeborni being the most competent. Their distribution is limited to the southeastern United States and parts of the Pacific Northwest, respectively. Even where they exist, seasonal temperature thresholds (≈18°C) constrain transmission to the summer months.

Diagnosing Malaria Quickly

Early diagnosis saves lives. The standard work‑up includes:

• Microscopic blood smear: The gold standard; technicians count parasites per microliter to gauge severity.
• Rapid diagnostic test (RDT): Detects Plasmodium antigen; useful in settings without microscopy.
• Polymerase chain reaction (PCR): Confirms species, especially when mixed infections are suspected.

Hospitals with emergency departments near international airports typically have RDT kits on hand, while larger academic centers maintain full microscopy capability.

Treatment Options and Prophylaxis Comparison

Once malaria is confirmed, treatment depends on species and severity. For uncomplicated P. falciparum, the CDC recommends an artemisinin‑based combination therapy (ACT) such as artemether‑lumefantrine. Severe cases require intravenous artesunate.

Travelers can prevent infection by taking chemoprophylaxis before, during, and after their trip. Below is a side‑by‑side look at the three most commonly prescribed drugs.

Pre‑Travel Prevention Checklist

• Schedule a visit to a travel medicine clinic at least 4weeks before departure.
• Choose a chemoprophylaxis regimen that fits your health profile and itinerary.
• Pack DEET‑based insect repellent, permethrin‑treated clothing, and a portable mosquito net.
• Stay in screened or air‑conditioned rooms; use bed nets only when necessary.
• Know the signs-fever, chills, headache, nausea-so you can seek care promptly after returning.

U.S. Public Health Response

The Centers for Disease Control and Prevention (CDC) coordinates nationwide surveillance through the National Notifiable Diseases Surveillance System (NNDSS). When a case is reported, the CDC works with state health departments to:

1. Confirm diagnosis via reference laboratories.
2. Conduct case investigations to identify travel history and potential contacts.
3. Implement vector‑control measures if local transmission is suspected.

Data from these investigations feed into annual reports that guide clinicians, travel agencies, and policy makers.

What If You Suspect Malaria?

Don’t wait for a fever to clear up on its own. If you’ve returned from a malaria‑endemic country in the past 30days and develop flu‑like symptoms, take these steps:

1. Contact your primary‑care physician or nearest urgent‑care center immediately.
2. Inform them of your travel dates, destinations, and any chemoprophylaxis taken.
3. Ask for a rapid diagnostic test; if negative but suspicion remains, request a thick and thin blood smear.
4. Follow treatment instructions precisely; complete the full drug course even if you feel better.

Frequently Asked Questions

Understanding malaria’s place in the United States helps you stay ahead of the few but serious cases that do arise. With solid prevention habits, quick diagnostics, and the right drug regimen, you can travel confidently and protect your health at home.