Clinical Diagnosis, Treatment, and Prevention of Usutu Virus Disease

Epidemiology

Usutu virus is a mosquito-borne flavivirus closely related to West Nile virus. It was first isolated from Culex species mosquitoes in South Africa in 1959.

As of September 2022, nearly 200 people have been infected with Usutu virus in Africa and Europe. Most people who were infected did not develop symptoms and were identified through screening of the blood supply. More than 50 people reportedly developed symptoms.

At this time the virus has not been found in the United States. Prior to 2001, Usutu virus was only thought to circulate in parts of Africa. Usutu virus likely now circulates in parts of Europe, Africa, and the Middle East, and may co-circulate with West Nile virus.

Clinical features

Usutu virus infection can cause human disease, but the incidence, symptomatic-to-asymptomatic ratio, and clinical spectrum are not known.

Reported Usutu virus disease cases have ranged from a systemic febrile illness that can include rash, hepatitis, and jaundice to neurologic disease with meningitis, encephalitis, or cranial nerve dysfunction. Cases have occurred in both immunocompetent and immunocompromised individuals.

Usutu virus disease can be similar to and possibly mistaken for West Nile virus disease.

Diagnosis

Testing for Usutu virus disease can be performed at CDC. There are no commercially available tests for Usutu virus disease in the United States.

Please contact your state or local health department if you have a patient with an acute illness and epidemiologic risk factors that might be compatible with Usutu virus disease. They can assist you with determining if samples should be sent to the CDC Arbovirus Diagnostic Laboratory for further testing. Specimens should be submitted to CDC through state health departments. All results will be sent from CDC to the appropriate state health department.

Treatment and Prevention

There is no specific treatment for Usutu virus disease; clinical management is supportive. Patients with severe meningeal symptoms often require pain control for headaches and antiemetic therapy and rehydration for associated nausea and vomiting. Patients with encephalitis require close monitoring for the development of elevated intracranial pressure, seizures, and inability to protect their airway.

No Usutu virus vaccines are available for use in humans. In the absence of a vaccine, prevention of Usutu virus disease depends on personal protective measures to decrease exposure to infected mosquitoes. This includes using insect repellent, wearing long-sleeved shirts and pants, and treating clothing and gear with 0.5% permethrin. Travelers should choose a hotel or lodging with air conditioning or screens on windows and doors or use mosquito nets.

More information about preventing mosquito bites is available at: Preventing Mosquito Bites | Mosquitoes | CDC and preventing mosquito bites while traveling at: Preventing Mosquito Bites While Traveling | Mosquitoes | CDC].

Although transfusion-transmitted Usutu virus infection has not been reported, the virus has been identified in blood donors and could potentially be transmitted by this route. People with confirmed Usutu virus infections should not donate blood for 120 days (4 months) after their illness. Usutu virus infections temporally associated with blood transfusion should be reported promptly to the appropriate state health department.