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Clinical overview of Oropouche virus disease | Oropouche

Epidemiology”>

Epidemiology

The Oropouche virus belongs to the Simbu serogroup of the virus genus Orthobunya virus in the Peribunyaviridae family. The virus was first discovered in 1955 in a feverish forest worker in a village in Trinidad and Tobago called Vega de Oropouche, near the Oropouche River. The Oropouche virus is endemic to the Amazon basin.

Before 2000, outbreaks of Oropouche virus were reported in Brazil, Panama and Peru. During this period, evidence of infected animals was also found in Colombia and Trinidad. Over the past 25 years, cases of Oropouche have been identified in many countries, including Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Panama and Peru. In 2014, an infected child was identified in Haiti.

In late 2023, the Oropouche virus was found to be causing large outbreaks in endemic areas and new areas in South America. In June 2024, Cuba reported its first confirmed Oropouche case. There is currently no evidence of local transmission in the United States.

Clinical features”>

Clinical picture

The incubation period of Oropouche virus disease is 3–10 days. Typically, the disease begins with the sudden onset of fever (38–40 °C) with headache (often severe), chills, myalgia and arthralgia.

Other signs and symptoms include photophobia, dizziness, retroorbital or eye pain, nausea and vomiting, or maculopapular rash starting on the trunk and spreading to the extremities. Less common symptoms may include conjunctival injection, diarrhea, severe abdominal pain, and hemorrhagic symptoms (e.g., epistaxis, bleeding gums, melena, menorrhagia, and petechiae).

Symptoms usually last less than a week (2-7 days), but in up to 60% of patients, symptoms may recur a few days or even weeks later. Similar symptoms are reported in cases of relapse.

The symptoms of Oropouche virus disease can be similar to those of dengue, chikungunya, Zika virus or malaria.

Abnormal laboratory findings

Abnormal laboratory findings have been documented in some patients with oropouche virus disease, including lymphopenia and leukopenia, elevated C-reactive protein (CRP), and mildly elevated liver enzymes. Thrombocytopenia has also been reported in some cases.

Neuroinvasive disease

Oropouche virus can cause neuroinvasive disease (e.g., meningitis and encephalitis). It is estimated that up to 4% of patients develop neurologic symptoms after their initial febrile illness. Symptoms reported in patients with neuroinvasive disease include severe occipital pain, dizziness, confusion, lethargy, photophobia, nausea, vomiting, neck stiffness, and nystagmus. Laboratory abnormalities detected in the cerebrospinal fluid (CSF) of patients with neuroinvasive disease include pleocytosis and elevated protein levels.

forecast

Some patients have been noted to experience persistent weakness and malaise for up to one month after symptom onset. More severe signs and symptoms may require hospitalization. Patients usually recover without long-term sequelae, even in severe cases. Very few deaths have been reported among people infected with the Oropouche virus.

Vertical transmission

On July 17, 2024, the Pan American Health Organization (PAHO) issued an epidemiological alert

Counseling pregnant patients

Healthcare providers should be aware of the risk of vertical transmission and possible adverse effects on the fetus, including fetal death or congenital malformations.

Inform pregnant women of the potential risks to the fetus when traveling to areas where Oropouche virus has been transmitted. Advise these patients to consider the destination, the reason for travel, and their ability to prevent insect bites.

Pregnant women are currently advised to reconsider non-essential travel to areas with a Level 2 travel health alert for Oropouche virus. If a pregnant person decides to travel, advise her to strictly avoid insect bites during the trip.

Diagnosis”>

diagnosis

The provisional diagnosis of oropouche virus disease is based on the patient's clinical symptoms, the location where infection is likely to have occurred (including travel destinations and dates), and activities that pose a possible risk of infection.

Evidence of the virus can be detected in serum samples during the first week of infection. The virus is easily cultured during the first few days of infection and is usually not detected until after day 5. However, viral RNA can be detected for several days after the virus is no longer present. Towards the end of the first week of illness, IgM antibodies are formed, followed by IgG antibodies.

Viral RNA can be detected in patients with neuroinvasive disease, but it is often not present in the cerebrospinal fluid. Therefore, serological testing is the preferred method to look for signs of infection in the cerebrospinal fluid. Viral RNA was detected in one patient's saliva and urine 5 days after illness onset. However, testing of these specimen types is currently neither validated nor available in the United States.

Currently, CDC can perform real-time reverse transcriptase-polymerase chain reaction (RT-PCR) in the acute phase of illness to detect viral RNA in serum and CSF. CDC can also perform plaque reduction neutralization tests (PRNTs) to detect virus-specific neutralizing antibodies in serum and CSF. To confirm recent infection using serology testing, both acute and convalescent specimens are required to document at least a four-fold change in antibody titers.

How to request a test

Contact your state or local health department if you have a patient with acute illness and epidemiologic risk factors that may be consistent with oropouche virus disease. They can help you determine if specimens should be sent to the CDC's Arbovirus Diagnostic Laboratory for further testing. Specimens should be sent to the CDC through state health departments. All results will be sent by the CDC to the appropriate state health department.

Treatment”>

Treatment

There are no medications to treat oropouche virus disease. Supportive care is recommended for clinical management of patients. Treatment of symptoms may include rest, fluid intake, and the use of analgesics and antipyretics. Patients who develop more severe symptoms should be hospitalized for close observation and supportive care.

All patients with clinically suspected dengue fever should receive appropriate treatment without waiting for the results of diagnostic tests. Patients should be advised to avoid medications containing aspirin or other non-steroidal anti-inflammatory drugs until dengue fever can be excluded to reduce the risk of bleeding.

Prevention”>

prevention

The best protection against Oropouche is to avoid bites from midges and mosquitoes. There are no vaccines against Oropouche virus disease. In addition, there are no efficient or economically or ecologically feasible vector control measures for the primary vector. Culicoides paranesia.

Infection prevention and control

Laboratory workers, health care workers, and other personnel who come into contact with blood, other body fluids, or cultures from infected individuals may be at risk of contracting Oropouche virus. Health care workers should follow standard precautions when providing patient care, and laboratory personnel should follow standard laboratory procedures.

Blood donation

The CDC has not yet determined whether the Oropouche virus poses a risk to the blood supply. To date, no cases of transmission of the Oropouche virus through blood transfusion have been identified. During the first week of infection, the virus can be detected in serum, but virus and antibody dynamics are not currently well understood. Until more is known about the Oropouche virus, the FDA suggests

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