Oropouche Virus Disease in U.S. Travelers Returning From Cuba, 2024

Oropouche virus is an emerging virus in the Americas, spread to people by infected biting midges and some mosquitoes. Beginning in late 2023, it caused large outbreaks both in Amazon areas where it was already known and in new areas of South America and the Caribbean. Infection usually causes a self-limited fever, but reports of two deaths and of transmission from mother to fetus linked to poor pregnancy outcomes have raised concern.

The virus

• It belongs to the Simbu serogroup (genus Orthobunyavirus) and is endemic to the Amazon; it has caused human disease in several countries of South and Central America and the Caribbean.
• In the wild it may circulate among animals such as sloths, nonhuman primates and birds and mosquitoes; in the urban cycle, people are the main hosts, with the midge Culicoides paraensis and possibly mosquitoes (such as Culex quinquefasciatus) spreading it.

Symptoms

It resembles dengue, Zika and chikungunya. After 3–10 days, symptoms start suddenly: fever, chills, headache, muscle pain and joint pain, sometimes pain behind the eyes, light sensitivity, vomiting, diarrhea, fatigue, rash, red eyes or abdominal pain. The first bout usually lasts only a few days — but up to 70% of patients have symptoms return within days to weeks. Rarely, it causes bleeding (nosebleeds, bleeding gums and others) or meningitis and meningoencephalitis. There is no vaccine or specific treatment; care is supportive.

Recent outbreaks

• From December 2023 to June 2024, large outbreaks struck known areas, and the virus appeared in new places in South America and Cuba.
• By August 2024, more than 8,000 lab-confirmed cases had been reported in Bolivia, Brazil, Colombia, Cuba and Peru.
• In June–July 2024, 19 European travelers were diagnosed — 18 returning from Cuba and one from Brazil.
• Brazil reported two deaths in previously healthy young people, and cases of transmission to the fetus linked to fetal death and possible birth defects. In July, the Pan American Health Organization issued an alert about these pregnancy outcomes.

The U.S. cases

CDC and New York's Wadsworth Center tested returned travelers with compatible illness, using antibody tests (PRNT90) and, for early specimens, RT-PCR. Florida found suspected cases mostly among people who had tested negative for dengue but had a matching illness and travel.

As of August 16, 2024, 21 U.S. residents who had traveled to Cuba had Oropouche virus disease — 20 in Florida and one in New York.

• Median age 48 (range 15–94); 48% female.
• Symptoms began in May (1), June (6) and July (14).
• At least three first sought care when symptoms came back after the initial illness.
• Three were hospitalized; no one died.

Fever with muscle pain occurred in 81%; fever with headache in 71%; all three in 62%.

• RT-PCR confirmed 13 cases, antibody testing seven, and both one. PCR-positive samples were taken a median of 2.5 days after symptoms began; antibody-positive samples a median of 17 days after.

Advice for clinicians

• Think of Oropouche in anyone who, within 2 weeks of being where the virus circulates, suddenly develops fever and headache plus muscle or joint pain, light sensitivity, eye pain or signs of neuroinvasive disease (stiff neck, confusion, seizures, limb weakness). Because symptoms can return, patients may come in more than 2 weeks after travel.
• Test for dengue too — the two viruses circulate together and look alike, and the Americas have had about 11 million dengue cases since late 2023. Manage suspected dengue as dengue until it's ruled out.
• Give supportive care and advise patients to avoid NSAIDs, to reduce bleeding risk.
• Collect paired specimens from pregnant patients to confirm recent infection.
• Report suspected cases to health departments. The disease isn't nationally notifiable, but CDC encourages voluntary reporting to ArboNET.

Advice for travelers

• Prevent mosquito and midge bites when traveling to affected areas — and for 3 weeks after returning, or during the first week of illness, to avoid spreading the virus where these insects are active.
• Pregnant people should learn the possible risks to the fetus, prevent bites, and consider postponing travel to areas with outbreaks.

The risk of sustained local spread in the continental United States is likely low; in Puerto Rico and the U.S. Virgin Islands it is unknown. Studies are under way on whether U.S. midges and mosquitoes (Culex quinquefasciatus and Aedes aegypti) can transmit the virus.

Sources

Based on Morrison A, White JL, Hughes HR, et al., "Oropouche Virus Disease Among U.S. Travelers — United States, 2024," Morbidity and Mortality Weekly Report, Centers for Disease Control and Prevention; a work of the United States government in the public domain. The imported copy was cut off in one place; the missing text and the report's tables were taken from the same report's full text in PubMed Central (PMC11376504).