Confirmation of Japan’s first Zika infection since an outbreak erupted in Latin America last year has elevated concern about the disease.

The mosquito-borne virus was detected in a male high school student from Kawasaki days after he returned from a vacation in Brazil with his family.

While Zika has made headlines worldwide for its suspected link to birth defects in Brazil, experts say its symptoms tend to be mild. They also say a massive outbreak in Japan is unlikely at the moment because the mosquitoes are dormant.

Here are some basic questions and answers about the Zika virus.

What are the symptoms?

The most common symptoms are fever, rash, joint pain and red eyes, according to the United States Centers for Infectious Diseases and Prevention (CDC). The illness is usually mild, with symptoms lasting for several days to a week after infection from a mosquito bite. The disease has an incubation period of two to 12 days. People usually do not get sick enough to go to a hospital and Zika is rarely fatal. Those who are infected once are likely to build up immunity against future infections.

How is the virus transmitted?

The Zika virus is transmitted primarily through the bite of an infected Aedes mosquito, the insect that also spreads the dengue and chikungunya viruses.

In rare cases, a pregnant woman can pass the Zika virus to her fetus. In the ongoing outbreak in Latin America, babies with brains smaller than normal, a condition known as microcephaly, are being born from mothers who were infected with Zika while pregnant. Microcephaly can delay development and cause hearing loss and vision problems. Researchers are studying the presumed link between Zika and microcephaly.

To date, there are no reports of infants getting the virus through breast-feeding. But there have been a few confirmed cases of sexual transmission and about a dozen potential new ones are reportedly under examination. Blood transfusions, meanwhile, have been linked to multiple cases of transmission.

Is this the first case in Japan?

No, this is the fourth case. Three people were diagnosed with Zika infections in 2013 and 2014 after returning from Thailand and the French Polynesian island of Bora Bora. All were infected overseas.

Is there a cure for it?

No, and currently there is no vaccine to prevent or treat Zika.

The CDC recommends that patients drink fluids to prevent dehydration and take medicine such as Tylenol to relieve fever and pain but avoid aspirin and other non-steroidal anti-inflammatory drugs.

What can I do to prevent infection?

The best prevention is to prevent mosquito bites. When traveling to affected regions, use insect repellent, wear light-colored clothes that cover as much of the body as possible, and use physical barriers such as window screens, health authorities say.

Use repellent containing diethyltoluamide (DEET), or icaridin, both of which are available in Japan. To help prevent infection during sex, use a condom. If your partner is pregnant, either use condoms or abstain from sex during the pregnancy. A list of high-risk countries can be found at: www.cdc.gov/zika/geo/active-countries.html.

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