In a follow-up on the suspected yellow fever case in Costa Rica, the Ministry of Health reports the confirmation of a positive case of yellow fever in the country, following the results issued by the laboratory of the Costa Rican Institute for Research and Teaching in Nutrition and Health (INCIENSA).
The patient is a 29-year-old American woman who recently traveled to the Amazon region of Peru. She first presented with symptoms on October 7 and entered the country on October 8, 2025.
The patient presented signs consistent with the disease and, after receiving initial care at a private hospital, underwent the corresponding tests, which confirmed the positive diagnosis. She is currently hospitalized in a Costa Rican Social Security Fund (CCSS) hospital, where she is receiving specialized medical care.
The patient’s partner, who has been vaccinated against yellow fever, tested negative for the disease after undergoing laboratory tests.
The Ministry of Health maintains active epidemiological surveillance and coordinates actions with national health services to ensure the protection of the population and prevent the spread of this disease.
The institution also reiterates the importance of all people planning to visit countries endemic for yellow fever, such as Bolivia, Brazil, Ecuador, Guyana, French Guiana, Paraguay, Peru, Venezuela, Suriname, and tropical African countries, getting vaccinated at least 10 days before their trip.
According to the latest data from the Pan American Health Organization (PAHO), between 29 December 2024 and 26 April 2025 (with data for Ecuador as of 2 May 2025), a total of 212 confirmed human cases of yellow fever, including 85 deaths (CFR 40%), have been reported to WHO by five countries in the Region of the Americas. The cases were reported from the following countries: Plurinational State of Bolivia (three cases, including one death (CFR 33%)); Brazil (110 cases, including 44 deaths (CFR 40%)); Colombia (60 cases, including 24 deaths (CFR 40%)); Ecuador (four fatal cases (CFR 100%)) and Peru (35 cases, 12 deaths (CFR 34%)).
Yellow fever is a severe viral disease with jaundice and hemorrhagic manifestations that is spread through the bites of infected mosquitoes.
Yellow fever vaccine is the best protection against this disease. Travelers to areas where vaccination is recommended should be vaccinated at least 10 days before travel. Preventing mosquito bites is also important.
Symptoms of yellow fever include fever, chills, headache, backache, and muscle aches, and develop 3–6 days after infection. About 15% of people infected with yellow fever virus will develop severe illness that can lead to liver disease, bleeding, shock, organ failure, yellowing skin and eyes (jaundice), and sometimes death.
Diagnosis is based on symptoms, laboratory testing, and travel history. There are no medications to treat or cure yellow fever.