Early Release: Oropouche Virus Disease Among U.S. Travelers — United States, 2024. Image Credit: CI Photos / Shutterstock
In a recent article published in the journal Morbidity and Mortality Weekly Report, researchers from the United States (U.S.) Centers for Disease Control and Prevention (CDC) and various state departments of health reported 21 new cases of Oropouche viral disease among travelers returning from Brazil and Cuba and discussed the public health implications and measures associated with this outbreak.
Oropouche virus
Oropouche virus belongs to the genus Orthobunyavirus and has been reported to cause disease in humans in the Caribbean, Central, and South American regions. The virus is thought to use vertebrate hosts such as sloths, birds, and non-human primates in the sylvatic cycle and humans as hosts in the urban cycle, with biting midges and possibly Culex mosquitoes acting as the vectors.
Two-toed Sloth (Choloepus didactylus). Image Credit: Diego Grandi / Shutterstock
The symptoms of Oropouche virus infections are similar to those observed with Zika, dengue, and chikungunya, with sudden onset of fever, headache, chills, and muscle and joint pain. Other symptoms include pain behind the eyes, photophobia, diarrhea, vomiting, abdominal pain, fatigue, and maculopapular rash.
A unique symptom of Oropouche virus disease is the recurrence of symptoms within days or weeks after the initial infection has cleared. This disease recurrence was reported by close to 70% of the patients. In rare cases, the illness can have hemorrhagic and neuroinvasive outcomes. Currently, the treatment options for Oropouche virus disease are all supportive, and no vaccine or treatments exist.
Oropouche virus outbreak in the U.S.
While disease outbreaks have been reported from the Amazon regions that are endemic for the Oropouche virus, reports from Cuba and South America have indicated the incidence of the disease from previously unreported areas. Countries such as Peru, Columbia, Bolivia, Cuba, and Brazil have had nearly 8,000 confirmed cases of Oropouche virus disease.
However, 19 recent cases have been reported among European travelers returning from Brazil and Cuba. Furthermore, two deaths among the cases in Brazil and one case of pregnancy-associated complications and fetal death due to vertical transmission of the virus have increased the concerns about the Oropouche virus outbreak.
The Department of Health in New York State and the CDC are conducting plaque reduction neutralization tests among travelers returning from regions with the known circulation of the Oropouche virus. Additionally, real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) is also being conducted using samples collected within a week of symptom onset.
Suspected cases of Oropouche virus disease were also identified in Florida by the Department of Health through interviews with individuals who exhibited clinical symptoms compatible with Oropouche virus disease but were negative for dengue, which has a significant overlap in symptoms with Oropouche virus disease.
Of the 21 cases in the U.S., one was in New York, and the remaining were in Florida. Most of the patient evaluations occurred during the initial acute illness, but three patients were re-evaluated when their symptoms recurred after the initial symptoms were resolved. Close to 95% of the patients reported having fever, and myalgia, headache, malaise, and joint pain were reported by 86%, 76%, 62%, and 57% of the patients, respectively.
Public health implications and recommendations
Although thus far, the symptoms of Oropouche virus disease have been mild, two deaths among young and otherwise healthy individuals in Brazil have been cause for concern. Furthermore, the Pan American Health Organization also issued an alert in July regarding the potential transmission of the disease from mother to fetus and adverse outcomes during the pregnancy, such as congenital abnormalities or even fetal death due to the disease.
The CDC requests clinicians to report any suspected cases of Oropouche virus disease to local or state health departments to improve testing and prevention measures. The CDC website also includes information for clinicians and healthcare providers on the symptoms, diagnostic features, and management of Oropouche virus disease.
Furthermore, given the hemorrhagic manifestations in some cases of Oropouche virus disease, the CDC recommends that patients avoid any non-steroidal anti-inflammatory medications to decrease bleeding risk.
Additionally, since dengue and Oropouche virus disease have similar symptoms and can co-circulate, patients are advised to follow the clinical recommendations for the management of dengue until it can be ruled out.
The CDC believes that the local transmission risk in the continental U.S. is likely low, but sustained transmission risk in the U.S. Virgin Islands and Puerto Rico is unknown. However, research is underway to determine the drivers of the current outbreak, the factors that impact transmission, and the role of the Culicoides biting midges and Culex mosquitoes in the transmission of the disease.
Conclusions
Overall, this report brought attention to the gradually emerging cases of Oropouche virus disease among travelers returning from Cuba and Brazil and explained the clinical symptoms of the disease. The scientists have also provided information on the symptoms and diagnosis of the disease and recommendations for clinicians to help manage and prevent the spread of Oropouche virus disease.