Dengue fever - Common initial symptoms are high fever and headaches

Tsunehiro Ando, Japanese Red Cross Medical Center

Last year, the first domestic dengue fever infection in Japan in 69 years was confirmed. Japan sees 50–200 imported cases of dengue fever each year, mostly from tourists who catch it while traveling abroad, so diagnosing the disease was nothing new to infectious disease experts. But domestic infection was new. The source of the infection was traced to mosquitoes carrying the dengue virus in Yoyogi Park and other places in Japan. Fifteen infected people were treated at Japanese Red Cross Medical Center in Hiroo.

With more people and products flowing freely over borders, there is a good chance that mosquitoes carrying the virus will be brought into Japan again this year.

The signs and symptoms of dengue fever include flu-like symptoms such as high fever (over 38°C) and headaches that last about a week. A cough, runny nose, and sore throat are not among them, but hives might also develop 4–5 days after fever onset. An infection can develop into dengue hemorrhagic fever, which causes dehydration due to an imbalance of body fluids as well as bleeding due to thrombocytopenia. Children and the elderly are at higher risk as they are more susceptible to dehydration.

Dengue fever usually occurs after an incubation period of 5–7 days following the bite of an infected mosquito. If you develop high fever and headaches after being bitten by a mosquito a week before the symptoms started, go see a doctor to check for dengue fever. Since there is no vaccine or specific medication for the disease, victims are typically hospitalized and treated with supportive measures including administration of antipyretics and intravenous drips and told to rest well until they feel better.

Protecting yourself from mosquito bites by reducing the amount of exposed skin is the most effective preventive measure. Long-sleeved clothing and mosquito repellents are the most viable options.