How Taiwan Can Prepare for the Next Dengue Fever CrisisTaiwan can no longer count on cold winters to eradicate Dengue-bearing mosquitoes and must therefore supplement its traditional response tools
There’s finally some good news on Dengue fever. On Jan. 8, 2016, the Taiwan Central Epidemic Command Center (CECC) responsible for Dengue response was deactivated. This was a welcome development because it signaled that the disease was waning to the point that the CECC was no longer needed. However, the good news is tainted by the fact that the human cost to Taiwan from the 2015 outbreak has far exceeded that of any other Dengue outbreak in its history. By the time the CECC ended operations, more than 44,000 people had been infected and 209 had died (as of Dec. 23) from the disease. Furthermore, there is every expectation that Dengue will return — with added severity — in spring 2016. Taiwan must fully engage in preparations to handle the expected spring outbreak.
Dengue Fever is a tropical viral disease carried by mosquitoes. Symptoms range from a rash to fever, headaches and muscle and joint pains. In severe cases, Dengue Hemorrhagic Fever causes fever, abdominal pain, vomiting, bleeding, difficulties breathing and potentially, death. The mortality rate for Dengue fever is typically under 1%. The mortality rate for Dengue Hemorrhagic Fever ranges from 2-5%, though if untreated the rate can rise to as much as 50%. To date there exists no vaccine or other medication to treat the disease other than hydration, fever/pain alleviation (e.g. acetaminophen) and rest.
Following a nationwide epidemic that struck in 1942, Taiwan had a break from Dengue that lasted until 1981. In that year Dengue returned. Subsequently, Dengue began recurring fairly regularly during the rainy and warm months, usually starting in early summer then peaking in October before declining with the arrival of cold weather.
Why has Dengue fever returned to Taiwan?
As the World Health Organization has noted, ongoing trends including global warming, urbanization, population growth and increased international travel have contributed to Dengue’s spread. Over the past 50 years worldwide incidence of Dengue fever has risen 30-fold. Today, 2.5 billion people are at risk of infection while 390 million fall ill each year. Taiwan is not exempt from these trends.
TaiwanTaiwan is densely populated and heavily urban with a well-traveled population. It provides an increasingly comfortable (warm and often wet) environment for the principal carrier (vector) of the disease, the Aedes mosquito, in particular Aedes aegypti. As a result, whereas in past Dengue in Taiwan was seasonal, it now seems to have become endemic and active over a longer stretch of the year. Between 2000 and 2014, the total number of Dengue cases in Taiwan grew from 139 to 15,702. And while 15,702 represents a historically large number of cases, as noted earlier, the number of cases in 2015 dwarfed even this. Regionally, the most dramatic increase occurred in Taiwan’s south, particularly in Tainan, Kaohsiung and Pingtung.
Add to this the impacts of El Niño. In an El Niño year Taiwan can expect unusually warm and wet weather, excellent conditions for mosquitoes. And of course, this year’s El Niño is proving to be remarkably strong. As a result, Taiwan public health officials are predicting that 2016 will set another record for the number of Dengue cases.
Not unreasonably, the public expects the Taiwanese government to manage the Dengue outbreaks effectively. The Taiwan Centers for Disease Control (TCDC) has responded to the steady increase in Dengue cases by enhancing past efforts while exploring new means to tackle the disease. Since no cure currently exists, the TCDC has primarily focused on traditional prevention methods, concentrating on disease surveillance, public education about the disease, and working with the public on eradicating mosquito breeding grounds. However, with expectations for a larger outbreak this year, the TCDC has moved beyond these traditional approaches to explore new options.
One option is to develop a Dengue vaccine. Taiwan’s National Institute of Infectious Disease and Vaccinology has joined the global effort to develop such a vaccine. While encouraging results have been achieved, a vaccine will not be available in time for the upcoming Dengue season.
An additional, highly innovative option for Dengue control involves infecting mosquitoes that carry Dengue with the Wolbachia bacteria. Wolbachia, which occurs naturally in the wild, does not naturally infect Dengue carrying mosquitoes. However, mosquitoes infected with Wolbachia are less able to become infected with Dengue and are therefore less likely to transmit Dengue to humans. In pilot tests in Australia (2011) and Vietnam (2013), mosquitoes artificially infected with the bacteria were released in the wild. The results were encouraging, with no, or reduced transmissions in areas where Wolbachia infected mosquitoes inter-bred with the wild mosquito population. This relatively new approach to Dengue control has been expanded and scaled up in Indonesia, Brazil and Colombia. Taiwan is also considering a trial.
Perhaps the most straightforward option to supplement traditional Dengue response efforts relies on already existing infrastructure and would thus be relatively easy to implement. In this case, Taiwan would be following WHO and World Bank recommendations to strengthen state-community engagement. This can be accomplished by developing a cooperative relationship with Taiwan’s Li Chang (sometimes described in English as the neighborhood warden).
The Li Chang functions between the state and society, working and cooperating with both. In effect, the Li Chang straddles the line between society and the state, connected to the state, but arising from within society and not part of the state bureaucracy. Since all people in Taiwan live in one of the approximately 7,800 Li (neighborhoods), they can all be reached by the Li Chang either directly or through one of his/her appointed assistants, the Lin Chang (in English: Block Captains). Each Li Chang appoints an average of 20 Lin Chang. Together they provide a range of services including those relating to public health. For example, Li Chang may provide information from the government to the public regarding public health matters while also supporting public health officials who visit their neighborhoods. Li Chang may organize volunteer groups to disinfect their neighborhood, dispense masks and cleaning agents, identify and clear mosquito breeding grounds and provide support for people requiring home care.
Turning to Li and Lin Chang may also contribute to overcoming the public’s general distrust of government. The Li and Lin Chang are normally long-term members of the community, trusted (and in the case of Li Chang, elected) by community members. They live within their communities and work closely with community members over an extended time, building familiarity and trust through close interactions.
Successful Dengue response requires intensive cooperation to eradicate existing and prevent future threats of spread while also treating those infected as quickly and effectively as possible. Clearly, the Li and Lin Chang are well situated to assist in this effort. Moreover, according to Taiwan’s CDC director, Dr. Steve H.S. Kuo (郭旭崧), over 90% of Taiwan’s Dengue 2015 cases occurred in only 300 Li. Assuming that these same neighborhoods are likely to suffer the brunt of the potential 2016 Dengue outbreak, it would be sensible to concentrate attention and resources on these Li in particular. The focus on community engagement through the Li Chang enjoys an additional, noteworthy benefit. The Li Chang infrastructure is already in place and can be immediately engaged.
According to Director Kuo, the Taiwan CDC has recently requested an additional NT$400 million (US$11.88 million) from the interim Cabinet to combat Dengue. If approved, the funds will be used to expand traditional Dengue control efforts while also supporting vaccine development and new approaches such as releases into nature of Wolbachia-infected mosquitoes and enhance cooperation with Li Chang.
As the planet warms Dengue fever is spreading. And, whereas in the past Taiwan could count on cold winters to eradicate Dengue bearing mosquitoes, this is no longer the case. Taiwan must therefore supplement its traditional Dengue response tools. To do so, the Taiwanese government should approve the additional funding requested by the TCDC. It should support vaccine development and potentially revolutionary technologies like Wolbachia. However, since we can expect this spring to bring a renewed outbreak in Taiwan, the most easily and quickly implementable option may be the best near-term option: Engaging the community in cooperation with the Li Chang. Such efforts should begin immediately, long before the weather warms and Dengue returns.
Jonathan Schwartz is Professor of Political Science, Director Asian Studies, State University of New York, New Paltz.