This is an official

CDC HEALTH ADVISORY

Distributed via the CDC Health Alert Network

August 16, 2024, 4:00 PM ET

CDCHAN-00515

Increased Oropouche Virus Activity and Associated Risk to Travelers

disease were reported, including two deaths and five cases of vertical transmission associated with fetal

death or congenital abnormalities. Countries reporting cases include Brazil, Bolivia, Peru, Colombia, and

Cuba. In the United States and Europe in 2024, travel-associated cases have been identified in travelers

returning from Cuba and Brazil. As testing and surveillance for Oropouche virus disease increase in the

Americas, reports of cases from additional countries are expected. This Health Advisory advises on

evaluating and testing travelers who have been in impacted areas with signs and symptoms consistent

with Oropouche virus infection. It also raises awareness of the possible risk of vertical transmission (e.g.,

from gestational parent to fetus during pregnancy) and associated adverse effects on pregnancy and

highlights prevention measures to mitigate additional spread of the virus and potential importation into

unaffected areas, including the United States.

areas and new areas outside the Amazon basin; countries reporting locally acquired (autochthonous)

cases include Brazil, Bolivia, Peru, Colombia, and Cuba. Although travel-associated cases have been

identified in the United States (n=11), no evidence of local transmission currently exists within the United

States or its territories.

Sylvatic (enzootic) transmission of Oropouche virus occurs in forested areas between mosquitoes and

non-human vertebrate hosts (e.g., sloths, non-human primates, domestic and wild birds, and rodents).

Humans can become infected while visiting forested areas and are likely responsible for introducing the

virus into urban environments. Humans contribute to the transmission cycle in urban environments since

infected humans develop sufficient viremia to serve as amplifying hosts. Biting midges (Culicoides

can include retroorbital (eye) pain, photophobia (light sensitivity), nausea, vomiting, diarrhea, fatigue,

maculopapular rash, conjunctival injection, and abdominal pain. Clinical laboratory findings can include

lymphopenia and leukopenia, elevated C-reactive protein (CRP), and slightly elevated liver enzymes.

Initial symptoms typically resolve after a few days, but a high proportion (about 70%) experience recurrent

symptoms days to weeks after resolution of their initial illness. Although illness is typically mild, it is

estimated less than 5% of patients can develop hemorrhagic manifestations (e.g., epistaxis, gingival

bleeding, melena, menorrhagia, petechiae) or neuroinvasive disease (e.g., meningitis,

meningoencephalitis). Neuroinvasive disease symptoms may include intense occipital pain, dizziness,

confusion, lethargy, photophobia, nausea, vomiting, nuchal rigidity, and nystagmus. Clinical laboratory

infections transmitted by vectors (e.g., people aged 65 years or older, or those with underlying medical

conditions, such as immune suppression, hypertension, diabetes, or cardiovascular disease). Earlier this

year, Brazil reported two deaths in otherwise healthy non-pregnant women, and five cases in pregnant

people with evidence of vertical transmission of the virus to the fetus associated with fetal death or

congenital abnormalities, including microcephaly. This was the first report of deaths and Oropouche virus

vertical transmission and associated adverse birth outcomes.

Laboratory diagnosis is generally accomplished by testing serum. Cerebrospinal fluid can also be tested

in patients with signs and symptoms of neuroinvasive disease. Diagnostic testing is available at some

public health laboratories (e.g., Wadsworth Center, NYS Department of Health) and at CDC. CDC and

chikungunya, Zika, leptospirosis, malaria, or infections caused by various other bacterial or viral

pathogens (e.g., rickettsia, group A streptococcus, rubella, measles, parvovirus, enteroviruses,

adenovirus, Mayaro virus).

No specific antiviral treatments or vaccines are available for Oropouche virus disease. Treatment for

symptoms can include rest, fluids, and use of analgesics and antipyretics. Acetaminophen is the preferred

first-line treatment for fever and pain. Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs)

should not be used to reduce the risk of hemorrhage. Patients who develop more severe symptoms

should be hospitalized for close observation and supportive treatment. Pregnant people with laboratory

evidence of Oropouche virus infection should be monitored during pregnancy and live-born infants should

encourages jurisdictions to report voluntarily to ArboNET, the national arboviral disease surveillance

system.

Recommendations for Healthcare Providers

• Consider Oropouche virus infection in a patient who has been in an area with documented or

suspected Oropouche virus circulation within 2 weeks of initial symptom onset (as patients may

experience recurrent symptoms), and the following:

arthralgia, photophobia, retroorbital/eye pain, or signs and symptoms of neuroinvasive

disease (e.g., stiff neck, altered mental status, seizures, limb weakness, or cerebrospinal

• Contact your state, tribal, local, or territorial health department to facilitate diagnostic testing.

• Rule out dengue virus infection in travelers with suspect Oropouche virus infection because these

viruses often cocirculate and cause similar clinical presentations during acute illness. Early

clinical management of dengue can improve health outcomes.

• Be aware that a high proportion of patients (about 70%) with Oropouche virus disease may

experience recurrent symptoms days to weeks after resolution of their initial illness.

• Be aware of the risk of vertical transmission and possible adverse impacts on the fetus, including

fetal death or congenital abnormalities. Monitor pregnancies in people with laboratory evidence of

Oropouche virus infection and provide thorough infant evaluations.

• Manage travelers with suspect Oropouche virus disease with acetaminophen as the preferred

first-line treatment for fever and pain. Aspirin and other NSAIDS should not be used to reduce the

risk of hemorrhage.

• Be aware that people who may be at higher risk for complications or severe disease include

pregnant people, older adults (e.g., aged 65 years or older), and people with underlying medical

conditions (e.g., immune suppression, hypertension, diabetes, or cardiovascular disease).

• Direct all travelers going to areas with Oropouche virus transmission to use measures to prevent

insect bites during travel and for 3 weeks after travel, or if infected, during the first week of illness

to mitigate additional spread of the virus and potential importation into unaffected areas in the

United States.

• Share Oropouche virus prevention messages for travelers and pregnant persons with healthcare

providers, travel health clinics and the public.

• Perform surveillance for Oropouche virus disease cases in travelers who have been in areas with

Oropouche virus transmission and be aware of risk of possible local transmission in areas where

biting midges (Culicoides paraensis) and mosquitoes (Culex quinquefasciatus) are currently

active.

• Keep current on CDC’s evolving testing and case reporting guidance.

• Assist healthcare providers with obtaining appropriate testing for diagnosing Oropouche virus

infection.

• Voluntarily report confirmed and probable Oropouche virus infections to CDC via ArboNET, the

• Pregnant people considering travel to countries with an Oropouche virus Level 2 Travel Health

Notice should reconsider non-essential travel. If travel is unavoidable, pregnant travelers should

strictly follow Oropouche virus prevention recommendations to prevent insect bites during travel.

• Travelers should be aware that the most common symptoms of Oropouche virus are fever and

headache and that symptoms usually begin 3-10 days after being bitten by an infected midge or

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