On November 25, 2016, the Taiwan Centers for Disease Control (Taiwan CDC) announced the sixth indigenous dengue case confirmed since this summer. The case is a 56-year-old female who resides in Ruiguang Village, Nehihu District, Taipei City. On November 18, she sought medical attention at a clinic in her neighborhood after developing fever, muscle ache, and joint pain. When her symptoms continued to persist, she sought further medical attention at a clinic and a hospital respectively on November 20 and 21, and she was then hospitalized. On November 23, the case was reported to the authority as a suspected case by the hospital. On November 24, infection with dengue fever (DENV-1) was confirmed in the case by the Taiwan CDC laboratory. The number of days between her symptom onset date and the date of reporting her case to the health authority is 5. As of now, the case is still hospitalized for treatment. Although winter is upon us, the temperature in various parts of Taiwan can still facilitate mosquito growth. As a result, the public is urged to remain vigilant for dengue fever. At the same time, physicians are also advised to heighten vigilance for suspected cases and continue to reinforce case-reporting in order to prevent outbreaks.

According to the epidemiological investigation, the case has chronic medical conditions and had not recently traveled abroad during the incubation period.　The case’s primary areas of daily activities include places around her residence. In addition, prior to her symptom onset, she had recently went hiking. Therefore, it is determined that she acquired her infection locally. During the viremic period, the case had only visited healthcare facilities besides her own residence. So far, none of the 2 family members residing in the same household with the case have developed suspected symptoms. To prevent the further spread of the disease, the local health authority has implemented various prevention measures upon receiving the report of the case, including cleaning of vector breeding sites, investigating the mosquito population density around the case’s residence and workplace, monitoring and following up on the case’s close contacts, and providing the public with relevant health education. Further investigation identified an imported dengue case that was reported in Ruiguang Village, Neihu District, Taipei City on November 4 and the case’s residence is only 84 meters away from the sixth indigenous case’s residence. Both cases were infected with DENV-1. It was determined that the two cases are highly associated in terms of time and geography.

Since the beginning of this summer on May 1, 2016, a total of 6 indigenous dengue cases have been reported in Taiwan, including 2 cases respectively in Tainan City and Kaohsiung City and 1 case respectively in Pingtung County and Taipei City. Thus far this year, a cumulative total of 378 dengue cases have been reported in Taiwan.　In addition, as of November 24, 2016, a cumulative total of 331 imported dengue cases have been confirmed in Taiwan, which is a record high compared to the same period in the past years, and they were mostly from Southeast Asian countries, including Indonesia and the Philippines. Laos has recently reported a rather high level of dengue activity. On the other hand, Thailand, Singapore, Malaysia, Sri Lanka and China have all recently reported declining dengue activity.

As rain has recently continued to fall in all cities and counties in the nation, standing water following downpours can facilitate mosquito breeding. Hence, Taiwan CDC urges the public to attend to their environmental hygiene through voluntarily and promptly emptying and cleaning any standing water around their residence, including those on the rooftop and in the basement, and draining or removing any unused containers that collect standing water such as used tires, cans, canvas, plastic bottles, and plant pots in order to reduce the breeding of vector mosquitoes and prevent the transmission of dengue fever. Travelers planning to visit areas affected by dengue fever are urged to take precautions against mosquito bites. If symptoms such as fever, headache, retroorbital pain, myalgia, arthralgia, and rash develop, please seek immediate medical attention and inform the doctor of any relevant medical history, recent travel history and activity to facilitate prompt diagnosis and case reporting. For more information, please visit the Taiwan CDC website at http://www.cdc.gov.tw or call the toll-free Communicable Disease Reporting and Consultation Hotline, 1922 (or 0800-001922).