A 29-year-old U.S. female has become Costa Rica’s first confirmed case of yellow fever in nearly 70 years, the country’s Ministry of Health announced Sunday.


Yellow fever is a mosquito-borne viral disease caused by the Flaviviridae RNA virus. Common symptoms include fever, chills, loss of appetite, nausea, muscle pain (especially in the back) and headaches.


Most patients recover within five days, but severe cases can cause abdominal pain, liver damage, jaundice, bleeding disorders, and kidney complications.


According to health authorities, the woman, whose name has not been released, entered Costa Rica on Wednesday, Oct. 8, after traveling from Peru.


Because she arrived from Peru, airport officials did not require proof of vaccination, as the requirement currently applies only to travelers arriving from Colombia.


Costa Rica mandates yellow fever vaccination for anyone leaving the country for Colombia, including both residents and tourists. The vaccine must be administered at least 10 days before travel. Travelers arriving from Colombia must also show proof of vaccination.




A few hours after her arrival, the woman sought treatment at a private hospital after developing symptoms consistent with yellow fever. Doctors, suspecting the disease, sent samples to the National Institute for Research in Nutrition and Health (INCIENSA), which confirmed the diagnosis.


She was later transferred to a Social Security public hospital (CCSS), where she remains under specialized care and close observation.


Health officials said the woman had traveled with another female U.S. citizen who had been vaccinated against yellow fever and later tested negative for the virus following laboratory testing.


In July, Costa Rica launched a nationwide vaccination campaign against yellow fever and administered 1,750 doses.


Authorities announced that a new vacination campaign will be launched in the coming weeks.


Currently, the vaccine is recommended, but not mandatory, for travelers visiting high-risk destinations such as Bolivia, Brazil, Ecuador, Guyana, French Guiana, Paraguay, Peru, Suriname, Venezuela, Trinidad and Tobago, and several African nations.


The Ministry of Public Health oversees both public and private healthcare systems and is responsible for implementing and enforcing health regulations.


The  Social Security (CCSS) is the state-owned organization in charge of the country's public health sector.