Dengue Alert in Costa Rica: A Small Mosquito Deserves Our Attention
Story and Art by Staff Writer Claudia
Costa Rica remains at the U.S. Center for Disease Control’s (CDC) lowest travel-health level, but a recent increase in dengue cases is a timely reminder to inspect our homes, gardens, and construction sites.
On September 3, 2026, the U.S. Embassy in San José sent a STEP health message concerning dengue in Costa Rica. The U.S. Centers for Disease Control and Prevention had identified Costa Rica among countries experiencing higher-than-expected dengue activity.
Before anyone starts setting up a mosquito net large enough to cover the entire house, an important clarification: Costa Rica remains at Level 1—Practice Usual Precautions. The CDC has not raised the country’s travel-health level or recommended avoiding travel here.
The message simply means dengue cases are appearing more frequently than expected, either within Costa Rica or among travelers returning from the country. It calls for greater awareness, not panic.
Meet the Aedes mosquito
Dengue is caused by a virus transmitted through the bite of an infected Aedes mosquito. Unlike the mosquito that announces itself beside your ear at 2:00 a.m., dengue-carrying mosquitoes may bite during both the day and night.
They also do not require a pond, pool, or dramatic jungle swamp to reproduce. A small amount of stagnant water inside a bucket, flowerpot saucer, clogged drain, discarded container, uncovered barrel, wheelbarrow, folded tarp, or construction material can become a mosquito nursery.
At Ecovilla San Mateo, where gardens are flourishing and construction is occurring throughout the village, prevention begins with paying attention to the small places where rainwater quietly collects.
The ten-minute mosquito patrol
Once a week, and after heavy rain, take a short walk around your property. Look for anything holding water and:
Empty and scrub buckets, planters, saucers, pet bowls, and other containers.
Turn unused containers and wheelbarrows upside down.
Keep water-storage containers tightly covered.
Clear roof gutters, drains, and drainage channels.
Check tarps, construction materials, toys, and outdoor furniture for trapped water.
Replace water in birdbaths or decorative containers regularly.
Repair or report damaged window and door screens.
This is one village responsibility where everyone can contribute. Mosquitoes do not recognize lot boundaries, property lines, or HOA portfolios.
Protect yourself from bites
The Embassy recommends using an EPA-registered repellent containing DEET, picaridin, or IR3535. Long, loose-fitting sleeves and pants provide additional protection, especially when spending extended time outdoors. But of course, there are plenty of alternatives to harsh chemicals that many of us prefer!
Screens, mosquito nets, and air-conditioned spaces can also reduce exposure. The CDC notes that dengue mosquitoes may bite during the day as well as at night, so repellent is not only an evening accessory. (CDC dengue-prevention guidance)
Know the symptoms
Dengue symptoms may not appear immediately and can develop up to two weeks after infection. The most common symptom is fever, often accompanied by:
Headache or pain behind the eyes
Muscle, bone, or joint pain
Nausea or vomiting
Rash
Minor bleeding, such as bleeding from the nose or gums
Symptoms generally last two to seven days, and most people recover in about a week. However, dengue can sometimes become severe very quickly. (CDC symptoms and warning signs)
Seek medical care if you develop symptoms, and tell the healthcare provider that you live in, or recently traveled in, an area with dengue activity.
One especially important warning
If dengue is suspected, the CDC recommends acetaminophen, also known as paracetamol, for fever or pain and specifically advises against taking aspirin or ibuprofen, which may increase bleeding risk.
Rest, stay well hydrated, and follow the instructions of a medical professional rather than attempting to diagnose or treat dengue on your own. (CDC dengue-treatment guidance)
Watch particularly carefully during the 24 to 48 hours after the fever goes away. Warning signs of severe dengue can include:
Severe abdominal pain or tenderness
Vomiting three or more times within 24 hours
Bleeding from the nose or gums
Blood in vomit or stool
Extreme tiredness, restlessness, or irritability
These symptoms require immediate medical attention. Severe dengue is a medical emergency and often requires hospitalization.
Awareness is our best defense
The Embassy’s message is not a reason to fear Costa Rica’s tropical environment. It is a reminder that living close to nature comes with responsibilities as well as rewards.
A bottle cap of water may seem insignificant. To an Aedes mosquito, it can look like beachfront property.
A few minutes spent eliminating standing water, maintaining screens, and protecting ourselves from bites can make our homes, and the entire village, safer.
U.S. Embassy San José:+506 2519-2000
This article summarizes a STEP health message issued by the U.S. Embassy in San José and current CDC dengue guidance. It is provided for general information and is not a substitute for professional medical care.