Japanese encephalitis (JE) is a serious viral infection of the brain caused by the *Japanese encephalitis virus* (JEV). It primarily affects children and is the leading cause of viral encephalitis in many parts of Asia. The virus is transmitted to humans through mosquito bites. Track Japanese encephalitis activity and outbreaks specific to Oregon.
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Japanese encephalitis was first recognized as a distinct clinical entity in Japan in the 1870s, and the causative virus was isolated in 1935. It became a major public health concern across Asia due to recurrent large-scale outbreaks. The development and widespread use of effective vaccines in the mid-20th century significantly reduced its burden in many endemic regions.
Japanese encephalitis is transmitted to humans through the bites of infected *Culex* mosquitoes, primarily *Culex tritaeniorhynchus*. These mosquitoes acquire the virus by feeding on infected birds (such as herons and egrets) and pigs, which act as amplifying hosts. Humans are dead-end hosts, meaning they do not transmit the virus to mosquitoes or other humans.
Contagious Period: Varies by disease
Local health department information and state-specific prevention guidance
Our AI-powered surveillance continuously monitors Japanese encephalitis activity across Oregon. We track data from state health departments, local hospitals, CDC reports, and 50+ global health sources to provide early warning of emerging threats.
Get instant push notifications when Japanese encephalitis activity increases in Oregon or your specific county.
For official state health alerts, vaccination locations, and public health guidance specific to Oregon, visit your state health department's website.
Whether you live in Oregon, are traveling there, or have family in the state, understanding Japanese encephalitis prevention is essential. Follow these evidence-based prevention measures:
If you experience symptoms of Japanese encephalitis in Oregon, contact your healthcare provider immediately. Early diagnosis and treatment improve outcomes significantly.
Emergency symptoms: If you experience severe symptoms, difficulty breathing, or signs of dehydration, call 911 or go to your nearest emergency room.
Trusted information from leading health organizations
Global disease surveillance and guidelines from the World Health Organization
View WHO Resources →Disease information on Virus Watcher is reviewed by our Chief Epidemiologist, a former CDC lead analyst for FluSight forecasting. Outbreak data is aggregated from verified sources including BEACON, ProMED, WHO, CDC, and 50+ national health agencies. This information is for educational purposes and should not replace professional medical advice.
Last reviewed: 2026-06-03
No confirmed cases reported in Oregon yet. Here are the latest Japanese encephalitis reports from our global surveillance network.
The first case of Japanese encephalitis this year has been reported, prompting authorities to urge the public to follow safety guidelines. This emphasizes the need for immediate preventive measures against this serious mosquito-borne disease. <!-- hash:4e0d80ec19caae01192ceb9c83…
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