Dr. Chin-Hui Yang (Taiwan Centers for Disease Control): tackling dengue in Taiwan
Dr. Chin-Hui Yang is Director of the Division of Acute Infectious Diseases at the Taiwan Centers for Disease Control. After several decades of Taiwan being overall dengue-free, the disease is now making a resurgence. In this interview, the ISNTD speaks with Dr. Chin-Hui Yang about the reasons behind this, the national response to dengue prevention and outbreak management, and why establishing an annual World Dengue Day would offer an essential rallying point for the numerous and multidisiciplinary global movements tackling this rapidly growing threat.
From 1942 to the 1981 Taiwan was relatively dengue free - what in your opinion caused the re-emergence of dengue and what were the lessons if any learnt in the dengue free years?
We are unclear of the exact reason for the dengue re-emergence in Taiwan. However, we know that the vectors, Aedes aegypti and Aedes albopictus, are present throughout the island. Frequent travels between Taiwan and neighboring countries with endemic dengue fever is usually how the disease is introduced into Taiwan, causing subsequent outbreaks. With the re-emergence of dengue, we realized that surveillance of dengue is needed as long as the vector is present. The disease could be brought into the country at any time. Good surveillance may allow us to identify cases and implement subsequent intervention early to prevent large outbreaks.
Tainan, Kaohsiung, and Pingtong are high risk areas for dengue in southern Taiwan. Tainan and Kaohsiung had large dengue outbreaks in 2007 and 2002, respectively. During 2014–2015, we experienced the largest outbreaks in southern Taiwan. In 2014, Kaohsiung had 15,000 cases of dengue, and in 2015, Tainan and Kaohsiung each had about 20,000 cases of dengue. In 2007 and 2014, the circulating dengue virus was type 1 dengue. In 2015, it was type 2 dengue. With fewer people having immunity to type 2 dengue, and many people having atypical presentations such as vomiting and diarrhea, instead of fever, musculoskeletal pain, doctors had difficulty in diagnosing the disease early.
For the last 20 years, Taiwan has been working hard in preventing dengue outbreaks even when the outbreaks were small. During outbreaks, our main strategy is to eliminate mosquito breeding sites through community mobilization. The organizational structure for community mobilization has been in place for many years, which allowed us to move quickly through communities with risks for outbreaks when dengue cases are identified. Having gone through the outbreak of 2015, Taiwan is now even more prepared and could be more precise in implementing control measures. In addition to breeding site elimination, we now also implement strategies to diagnose disease early, improve clinical care quality, and initiate control measures early. Our goals are to decrease the number of severe dengue cases and decrease deaths associated with dengue infections.
After the 2015 Dengue outbreaks in Tainan, Kaohsiung and Pingtung what changes have taken place in national response to dengue prevention and outbreak management?
Taiwan had the most severe dengue outbreaks in 2014 and 2015, each causing more than 10,000 cases. In 2014, over 95% of the cases lived in Kaohsiung, but the 2015 outbreak, Kaohsiung had only about 45% of the cases, and Tainan had about 52% of the cases. Because of the large outbreak, “Dengue Response Central Command Center” was established by the Central Government in September 2015. With the Command Center established, we were able to expedite responses, including providing education to frontline doctors at clinics, procuring NS1 rapid test kits, simplifying disease reporting system, and providing public health announcements for the general public to seek medical assistance early. All these measures helped in containing diseases and decrease deaths associated with dengue. Furthermore, we coordinated the use of material and human resources, and worked with local health departments to set up health education through multiple channels, to remind our residents to vigilant of the disease and work with the government in preventing dengue infections. After action of the 2015 dengue response was done, and the current strategies for dengue prevention and containment include early detection, early prevention, and early diagnosis.
What has been the dengue situation in the last 3 years? How are communities being mobilized to help in this effort?
We’ve seen a dramatic decrease of dengue cases since the 2015 outbreak. In 2016 and 2017, we had 381 and 10 cases of locally-acquired dengue cases, respectively. This year, by September 7, we’ve found 86 cases. Both the central and local governments agree that breeding site elimination is the most important measure in preventing the spread of dengue. To ensure that dengue prevention concepts take root in the daily lives of residents, local governments implemented programs in community mobilization that include training volunteers and communities leaders, and help them in establishing mosquito elimination teams. Because these volunteers are familiar with the area where they live and work, they take the dengue prevention messages right into the communities, and help residents to incorporate mosquito-bite prevention efforts into their daily lives. Because the 2015 dengue outbreak did cause disruption to the lives of the residents and result in economic losses, residents have been more willing to work with community volunteers in breeding site elimination. Their efforts have helped with disease containment.
We are advocating for a World Dengue Day - in your opinion why do we need this day of recognition?
Dengue fever cases have risen rapidly over the last 20 years. Currently, over 2/5 of the world population live in areas at risk for dengue outbreaks. In addition to Southeast Asia and the Western Pacific regions, which had been affect the most, dengue is now found in ever expanding regions of the world. With the increase of international travel, dengue fever is no longer a disease of a single country, or a disease of a single region. All countries and regions must work together to prevent this disease from its continual spread. Having a World Dengue Day will give us the opportunity to increase awareness of the disease throughout the world. It is important to have this day of recognition in an effort to contain the disease worldwide.