Oropouche virus: Emerging threats, symptoms, and prevention

By Dr. Priyom Bose, Ph.D.Reviewed by Benedette Cuffari, M.Sc.Mar 19 2025

A new study examines the emerging Oropouche virus, its transmission, symptoms, and preventive measures, highlighting potential risks for travelers.

Study: Oropouche virus. Image Credit: CI Photos / Shutterstock.com

A recent Canadian Medical Association Journal study provides an overview of the emerging Oropouche virus.

Oropouche virus outbreaks

Outbreaks of Oropouche virus infections have emerged in the Caribbean, Central America, and South America. Since late 2023, several Oropouche cases have been reported among Canadian and American travelers returning from Bolivia, Brazil, Cuba, and Peru. In regions affected by Oropouche, several other concerning viruses are also endemic, such as Zika, Malaria, dengue, and chikungunya.

Sustained transmission of Oropouche in the United States is unlikely due to differences in climate between the U.S. and nations where Oropouche infection is endemic. The widespread use of air conditioning in the United States, combined with low biting midge and mosquito populations, also reduces the risk of sustained transmission.

Symptoms

Oropouche virus has an incubation period ranging from three to 10 days. Mild symptoms or asymptomatic infection is frequently reported in Oropouche infection.

Some of the most common symptoms associated with this infection include fever, chills, headache, and myalgia that persist for two to seven days. Less common symptoms associated may include dizziness, nausea and vomiting, diarrhea, severe abdominal pain, and hemorrhagic symptoms including epistaxis, gingival bleeding, melena, menorrhagia, and petechiae.

After recovering from Oropouche infection, symptoms recur in about 60% of patients within a few days up to several weeks. Severe manifestations of the infection include maculopapular rash, vomiting, abdominal pain, aseptic meningoencephalitis, and death; however, these are rare events.

Like Zika virus, Oropouche infection may lead to adverse pregnancy outcomes including birth defects like microcephaly, still birth, and miscarriage. Oropouche virus does not appear to transmit to the infants of breastfeeding mothers, thus indicating that mothers who are suspected to be infected with Oropouche can continue breastfeeding.   

Viral transmission

Oropouche virus is transmitted through bites from infected Culicoides paraensis biting midges and Culex quinquefasciatus mosquitoes. Biting midges are not known to transmit other viruses like dengue, Zika, or chikungunya.

Culex quinquefasciatus are also capable of spreading West Nile and St. Louis encephalitis viruses. Although Culex quinquefasciatus mosquitoes are present in the southern United States, local transmission of Oropouche virus has not been reported.

A recent research letter published by the U.S. Centers for Disease Control and Prevention (CDC) Emerging Infectious Diseases reported the detection of replication-competent Oropouche virus ribonucleic acid (RNA) material in the semen of a febrile man who had recently travelled to Cuba. Viral RNA persisted in both semen and whole blood samples until 58 days following symptom onset, thus indicating that Oropouche virus has the potential to be transmitted through sexual contact.

Prevention and treatment

The use of mosquito nets, long-sleeved clothing, and chemical insect repellents such as deltamethrin, icaridin, or N,N-diethyl-metatoluamide (DEET) can prevent Oropouche infection.

Polymerase chain reaction of blood and urine samples taken within seven and 10 days of symptom onset is the primary method for diagnosing this infection. In addition to viral RNA detection, other abnormal laboratory findings that may be related to Oropouche infection include lymphopenia, leukopenia, high C-reactive protein (CRP) levels, and mildly elevated liver enzymes.

At early stages of infection, treatment is supportive; however, acetaminophen should be the preferred anti-analgesic rather than nonsteroidal anti-inflammatory medications. There are currently no vaccines or antivirals to prevent or treat the disease.

Current government guidance

The Pan American Health Organization (PAHO) – in collaboration with the World Health Organization Member States, is actively monitoring the epidemiological situation of Oropouche virus disease.”

The Public Health Agency of Canada has published recommendations that travelers take necessary precautions and avoid insect bites. Pregnant individuals and those planning pregnancies should also consider deferring travel to areas from where Oropouche outbreaks have been reported.