Mon, Sep 28, 2015 page3

• Ex-CDC head urges governments over dengue

  With more than 10,000 dengue fever cases in southern Taiwan, former Centers for Disease Control (CDC) director and dengue fever expert Su Yi-jen told staff reporter Jennifer Huang in an interview with the ‘Liberty Times’ (the sister newspaper of the ‘Taipei Times’) that if the government does not establish a nationwide dengue research and prevention center, and come up with medium to long-term plans for prevention of the disease, it might become an epidemic that spreads to the nation’s northern areas within the decade

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  Liberty Times (LT): Why has the dengue fever situation worsened dramatically this year? Do you foresee that it will be worse than last year?

  Su (蘇益仁): Southeast Asian nations such as Vietnam and Thailand, having first seen signs of dengue fever in the 1970s, now have reports of the disease — all four sub-types — all year long, showing that the disease has become an epidemic.

  Although the dengue fever baseline outbreak has not reached such proportions in Taiwan, rising temperatures in March directly contributed to the growth of Aedes albopictus and Aedes aegypti mosquito populations in the north and south respectively. Human carriers of the disease arriving from southeast Asia have also contributed to the outbreak.

  

  Former Centers for Disease Control director Su Yi-jen gestures during an interview on Sept. 6.

  Photo: Wang Chun-chung, Taipei Times

  The nation usually records upward of 1,000 patients, with last year’s total being 15,000 — the highest number ever recorded in Taiwan — due to Kaohsiung failing to pay attention to disease prevention because of the gas pipeline explosions in the municipality.

  Dengue fever cases last year before August totaled 1,500, but from last month onward, the number exceeded 4,000 each month, with September seeing more than 5,000 cases. It is an indicator that this year’s outbreak will be worse than last year’s.

  The severity of the outbreak in Tainan is mainly due to the plum rain season in May and the large amount of rainfall brought by typhoons.

  However, given that in past years Tainan has seen only about 100 cases, it seems that the municipal government has not paid attention to cleaning out potential mosquito breeding sites.

  There are many records being set by this outbreak. The first patients with dengue fever in northern Tainan were reported in May — in communities that have been around for a number of years and are densely populated.

  From there, the situation snowballed to 4,000 patients within two weeks, with one day bringing 400 new cases.

  From past experience, September, October and November are peak periods for outbreaks, often seeing two to three times the number of patients.

  Both the public and the government should make preparations for the worst and be on heightened alert over the next three months.

  LT: Experience indicates that southern Taiwan is usually the hardest hit by the disease, but experts [including you] are warning that there are signs of the disease spreading northward. Please give us your thoughts on this.

  Su: A aegypti, the most common carrier of the disease, usually thrives south of the Tropic of Cancer, which is why dengue fever is more prevalent in Southeast Asia, Central and South America and southern parts of Africa.

  Dengue fever in Taiwan stems from people arriving from southeast Asia, as CDC records show. While imported cases are not confined to southern Taiwan, A albopictus, the main carrier of the disease in the north, does not bite people as much as A aegypti and thus transmission is limited.

  Communities in southern Taiwan are exposed more frequently to A aegypti, which means more people contract the disease.

  From statistics obtained by the WHO, only nine nations reported dengue fever cases in 1970, but global warming and international travel is seeing the disease move slowly northward.

  According to statistics, at least 100 nations reported endemic cases of dengue fever, including Japan, which is in relatively high latitudes. The spread of dengue fever might well cross the Tropic of Cancer in a decade or two. Taiwan would not be exempt from this trend and the entire nation, instead of just the south, could be affected.

  In addition, convenient travel along the length of the nation coupled with high temperatures and frequent rain might also be encouraging the northward spread, as well as the advent of an endemic strain, an outcome that needs to be watched for closely.

  LT: The number of cases this year is still growing. Do you think this is due to lack of preventive measures?

  Su: During my tenure as CDC director, every time southern Taiwan reported from 300 to 600 dengue fever cases, we would dispatch teams from the central government to the local governments to help prevent further spread of the disease.

  Disease prevention and control are the result of multiple fields of professional knowledge — the distribution of disease carriers, the density of carriers, which kind of mosquitos have which virus and whether the mosquitos have developed immunity to countermeasures — which requires experts from separate fields to work as a team.

  In fact, some experts from the National Taiwan University said while I was CDC director that many of the countermeasures we were using to combat dengue fever were outdated. This means that local disease control bureaus — which might have less than 10 people each — cannot handle a major event by themselves.

  From my own observation of the distribution of patients in Tainan, from how there were many new cases in the city’s northern areas three weeks after pesticide was sprayed there, it is evident that pesticide is not an effective control and prevention method.

  The central government must intervene and establish a command center for the containment of the disease so more professionals and resources can be put to use in the area, such as the establishment of GPS data for infected areas, a database of all patients, population densities and environmental concerns.

  Such measures would allow experts to analyze the data and potentially provide solutions with a more scientific approach.

  LT: What are your suggestions for disease prevention and control with dengue fever becoming an annual problem and the risk that it could spread northward?

  Su: The incubation period of dengue fever, including the time for the mosquito to reach the adult phase of its lifecycle, is more than one month. In essence, people who exhibit dengue fever symptoms today might have been bitten as early as June, with the mosquito possibly reaching the adult phase with rain brought on by the plum rain in May.

  With such a long period of incubation, the best time to begin prevention and control efforts is in March, when temperatures begin to rise.

  I would suggest that the government establish and fund a standing dengue fever research and prevention center in southern Taiwan similar to what it has done for malaria.

  Judging by how malaria has been eradicated in Taiwan, the center would enable professional research into dengue fever prevention.

  It is sad to see that academics that the government helped fund during that era have found little to no desire to pass on their knowledge.

  The National Health Insurance would need billions of New Taiwan dollars to treat the thousands of dengue fever cases, while the expenses necessary to maintain disease prevention equipment and human resources also weighs heavily on local governments.

  Research into disease carriers, management of residences, placing more emphasis on preventative measures and border controls, as well as establishing a systematic medical response to outbreaks are the measures that could be taken to stem the northward spread of dengue fever, not to mention continuing research into dengue vaccines.

  More importantly, the government needs to establish a mid to long-term disease prevention policy that would at least aim to find solutions to potential epidemics a decade from now.

  Taiwan is an island nation with a subtropical climate; it cannot afford to overlook the threat posed to its people by diseases such as dengue fever.

  Translated by Jake Chung
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