Climate change and Asia’s deadly dengue fever outbreaks

September 20, 2019

A woman and child in one of the slums of Dhaka, Bangladesh. This year, Bangladesh experienced the worst outbreak of dengue fever in its history.

It has been difficult to scroll through my newsfeed on social media for the past couple of months without feeling alarmed. In Bangladesh, the situation with dengue fever was dire, with people urgently seeking blood, information on which hospitals had available beds, complaining about the rising prices of mosquito repellants and general panic. On one single day in August, nearly 2,500 dengue patients were admitted in hospitals in the country, breaking all records. It has been the worst outbreak in the history of the country.

Globally, a 30-fold increase in the number of dengue cases over the past 50 years has been recorded. Among an estimated 2.5 billion people at risk for dengue, 70 percent of them reside in the Asia-Pacific.

The numbers are telling:

  • Philippines declared an epidemic last month, with 622 deaths, and dengue affecting a staggering 146,000.
  • In Thailand this year, the numbers doubled compared to last year, to 20,000 cases, with children being the most affected.
  • From January to August this year, 200,000 people in Sri Lanka contracted dengue, with over a 100 deaths.

Dengue is a mosquito-borne viral infection with symptoms similar to the common flu, but can cause lethal complications especially among vulnerable groups such as children, the elderly and pregnant women.

There is no specific treatment for dengue, but early detection and access to proper medical care can lower mortality to below 1 percent.

Changing patterns of rainfall, humidity and temperature – linked to climate change, are leading to longer breeding spells for the mosquito species that carries the virus, and shortening disease incubation times.

This is causing dengue epidemics to become much more unpredictable in terms of when and where they occur, and their scale, overwhelming health systems.

Rapid and unplanned urbanization, living conditions for the urban poor and lack of sanitation are all contributing to a surge in numbers of people affected by vector-borne diseases such as dengue.

Governments are responding to these outbreaks the best they can. Effective vector control, mass media campaigns for public awareness, and strengthening health systems to deal with the increasing numbers of patients is important.

However, preparedness is key, and early warning systems are essential to increase our ability to predict, detect early and respond to outbreaks.

Viet Nam is pioneering a dengue early warning system that can serve as an innovation for other countries to consider. The country is using satellite data on precipitation and atmospheric pressure combined with health and water availability information to produce a dengue-forecasting model designed for this new reality.

The initiative is supported by the UN Development Programme in Viet Nam, the World Health Organization, the UK Space Agency, HR Wallingford, the London School for Hygiene and Tropical Medicines, the UK Met Office and Oxford Policy Management.

The innovative approach looks at dengue and the health effects of climate change as an interaction between the environment and public health.

When complete, beneficiaries will be able to receive alerts for dengue outbreaks, and policy-makers will be able to look at assessments of vector-borne disease risk under future climate and land-use change scenarios.

A recent study estimated that an additional 2 billion people globally could be affected by dengue by the year 2080, and that increase largely comes from population growth in areas already at risk.

The world can learn from Viet Nam. The time to act is now.