Encephalitis is an inflammation of the brain that is often caused by a viral infection. The arboviruses cause encephalitis and are passed on to people and animals by insects.
There have been outbreaks in recent years in the U.S. of several types of encephalitis, such as West Nile encephalitis and St. Louis encephalitis. Travelers abroad are most at risk for Japanese encephalitis and tick-borne encephalitis.
Japanese encephalitis is mosquito-borne and occurs mainly in:
Japanese encephalitis also occurs less often in Republic of China (Taiwan), Singapore, and Hong Kong. In all of these areas, Japanese encephalitis is mainly a rural disease.
On average, among people who are infected by a mosquito bite, very few will develop an illness. Most people who are infected develop only mild or no symptoms. But among people who develop encephalitis, the results are serious.
Tick-borne encephalitis is a viral infection of the central nervous system passed on by bites of certain ticks. The disease occurs in:
People can be infected by the bite of infected Ixodes ricinus ticks. This usually happens in people who visit or work in forests, fields, or pastures. You can also get the infection by consuming unpasteurized dairy products from infected cows, goats, or sheep.
The risk of getting the disease is greatest from April through August. This is when ticks are most active.
The arboviruses that cause encephalitis are passed on to people and animals by insects. In rural areas, arboviruses that are carried by mosquitoes or ticks are the most common cause of arboviral infection. The infection is often mild, but it can progress to encephalitis.
The following are the most common symptoms of encephalitis caused by arboviruses:
The symptoms of arbovirus encephalitis may look like other health conditions or problems. Always see your doctor for a diagnosis.
Healthcare providers will use blood tests and tests of cerebrospinal fluid to find the virus.
Because this is a viral disease, antibiotics will not help. There are no effective antiviral medicines at this time. There is no specific treatment for encephalitis. The main goal is to ease symptoms and keep the person's breathing and circulation working well while the infection runs its course. Your healthcare provider will determine the best treatment for you based on:
A vaccine for Japanese encephalitis is currently available in the U.S. through most travelers' clinics. The CDC generally recommends the vaccine only for people who will travel in rural areas for 4 weeks or more. It is also recommended where there is a known outbreak of Japanese encephalitis.
As a traveler, take steps to prevent insect bites, including the following:
If you are traveling to rural areas, bring a portable bed net. Use permethrin, a mosquito repellent/insecticide, on both the bed net and clothing.
Another way to prevent encephalitis is with mosquito control. In many emergency cases, the best method is with aerial spraying. Many states may use aerial spraying to control mosquitoes. They can also spray in areas where the virus is active.
To protect yourself against tick-borne encephalitis, follow these recommendations:
Call your healthcare provider if you have the following symptoms:
Tips to help you get the most from a visit to your healthcare provider:
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