Tokyo, Jan 11
The number of influenza patients reported at designated medical institutions across Japan in the final week of December hit the highest level since the current record-keeping began in 1999, according to the Ministry of Health, Labour and Welfare.

In the week through December 29,317,812 flu patients were reported across roughly 5,000 institutions, averaging 64.39 people per facility and surpassing the warning level of 30, the ministry said.

The record figure jumped from 42.66 the week before, marking the 10th consecutive week of increase.

All the country's 47 prefectures reported an increase from a week earlier, with 43 topping the warning level, according to the ministry.

"The fact that people expanded their range of movement as they entered the holidays could be a contributing factor," a ministry official said.

Oita Prefecture in southwestern Japan had the highest figure, averaging 104.84 cases per clinic, followed by other prefectures in the Kyushu region. Major metropolitan areas were also hit, with Osaka averaging 67.53 people per facility and Tokyo 56.52.

As numbers continue to rise, ministry officials urged people to wear masks and thoroughly wash their hands to prevent infections, Xinhua news agency reported.

Influenza (flu) is a very contagious viral infection that affects the air passages of the lungs. It causes a high fever, body aches, a cough, and other symptoms. It's one of the most severe and common viral illnesses of the winter season. Most children are ill with the flu for less than a week. But some children have a more serious illness and may need to be treated in the hospital. The flu may also lead to lung infection (pneumonia) or death.

The flu is one of the most common infectious diseases. Every flu season, about 20 to 40 million people in the US catch the flu.

The flu and the common cold can have similar symptoms, like runny nose and cough. But cold symptoms are usually mild and flu symptoms can be severe and lead to serious complications. Different viruses cause colds and the flu.

Japan reports record-high flu cases since 1999