Dengue cases in Costa Rica are up almost 58% this year, and chikungunya, a mosquito-borne disease that had been absent from the country for nearly a decade, has now passed 1,000 cases. Most of the chikungunya cases are in Guanacaste. The Ministry of Health has counted 6,594 dengue cases so far in 2026, compared with 4,181 at the same point last year. Of those, 105 were classified as dengue with warning signs, the stage that can turn severe.
As of Nov. 2, three patients were hospitalized with dengue, according to the Costa Rican Social Security System (CCSS). The rise follows a September notice in which the US Centers for Disease Control and Prevention flagged Costa Rica for higher-than-expected dengue risk. Alajuela province has the most dengue cases at 2,791, followed by Puntarenas with 981 and San José with 880. By county, Grecia leads with 727, then Alajuela with 658, Orotina with 591, San José with 418 and Puntarenas with 416.
Orotina stands out. It has 2,323.8 cases per 100,000 people, about 18 times the national rate. The town sits on Route 27, the main highway from San José to the Central Pacific beaches. Chikungunya reached 1,049 cases through the 42nd epidemiological week of the year, in mid-October. Of those, 916 were confirmed by lab tests and 133 are probable cases still under study, an increase of 126 in two weeks.
The Chorotega health region, which covers Guanacaste, has 602 chikungunya cases, or 57% of the national total. La Cruz, near the Nicaraguan border, has 389, Carrillo has 90 and Santa Cruz has 64. Outside Guanacaste, Alajuela has 136 and San José has 71. Local transmission was first confirmed in July in a Guanacaste beach town and in Alajuela. In September, the virus reached Pavas, on the west side of San José.
Both diseases spread through mosquito bites, so the best protection is not getting bitten. Use repellent, especially during the day, when the mosquito that carries them is most active, and wear long sleeves when you can. Empty anything around your home that holds water, such as plant saucers, buckets, old tires and clogged gutters. That is where these mosquitoes lay their eggs.
If you get a fever, headache or body aches, see a doctor. Don’t take ibuprofen or aspirin until dengue has been ruled out, because these drugs can raise the risk of bleeding if you have dengue. Get care right away if you notice intense abdominal pain, repeated vomiting, bleeding from your gums or nose, or extreme weakness. These are signs that dengue is turning severe.
The dry season, which began this month in Guanacaste and the Central Valley, means fewer puddles. Water stored in tanks and buckets during the dry months can still breed mosquitoes, so keep containers covered.
