Breakbone Fever Goes Global – The Terrifying Spread of Dengue to Unlikely Climates.

At some point during the fourth or fifth day of dengue fever, the pain begins to feel like punishment rather than illness. All of them protest together. Sharp signals are sent to the brain when the backbone is pressed against something as commonplace as a mattress. In December 2015, a journalist who had the illness in Bangkok reported that his gums began to bleed on their own, as if he had been struck in the face without any pain. You remember that picture. In a way that medical descriptions seldom are, it is strangely accurate.

Dengue has always been known as “breakbone fever,” and people outside of the tropics have mostly heard about it as an exotic background noise that occurs in distant locations with different mosquitoes and climates. It’s becoming more difficult to maintain that assumption.

2015 saw 140,000 dengue infections in Thailand, the highest number since a significant outbreak in 1987 that reached 170,000 cases. Not only is the number impressive, but the timing is as well. In December, the journalist from Bangkok contracted the infection. Thrisadee “Por” Sahawong, a popular Thai TV personality, became ill in November. Traditionally, dengue was thought to be a disease that only occurred during hot, rainy seasons. Even at lower volumes, the fact that it is circulating in the winter indicates that the regulations are changing. Perhaps no one has really understood how quickly.

An opportunist is the Aedes aegypti mosquito. It grows well in crowded urban areas and reproduces in still water, such as flower pots, clogged drains, and abandoned tires. Its habitat has greatly expanded due to Southeast Asia’s rapid urbanization. The surrounding countryside is colder than the cities. They fill a thousand tiny containers with water. They concentrate human populations in ways that facilitate effective transmission. When you observe a growing city like Dhaka or Colombo from above, you are essentially witnessing the construction of dengue infrastructure.

Everything is becoming more complicated due to climate change. Rising temperatures are predicted by the Intergovernmental Panel on Climate Change to extend dengue transmission seasons and spread the disease to new areas. Aedes populations were once thought to be too cold in parts of the southern United States, southern Europe, and higher-altitude regions of South Asia. The buffer is getting smaller. An increasing amount of research indicates that dengue may become endemic in regions where there are currently only sporadic imported cases.

During the same period in 2015 that devastated Thailand, record dengue numbers were reported in Bangladesh and India. That’s three sizable, geographically separate nations going through simultaneous surges, which is not a coincidence to be written off. Although every outbreak has a unique local story, it is difficult to ignore the broader trend. Even though the exact nature of it is still unknown, something systemic is taking place.

Beyond the bone pain and bleeding, the behavior of second infections is what makes dengue especially unsettling. There are four serotypes of the virus. The immune system may be primed to overreact when a different serotype emerges, making subsequent infections more severe. However, surviving one does not protect against the others. Thinking back on his own serious case, the journalist from Bangkok questioned whether he had previously contracted an undetected infection that made him more susceptible. It’s the kind of lingering thought.

A universal vaccine does not yet exist. Dengue is one of the most neglected tropical diseases according to the World Health Organization, which is a quietly concerning label for a disease that affects hundreds of millions of people each year. Until you consider the scale, one percent mortality seems insignificant. It’s not reassuring to run the numbers.

It’s difficult to avoid the impression that, while the majority of the world is oblivious, the geography of dengue is being subtly redrawn in real time. A passport is not necessary for the mosquito. All it needs is a city to relocate to and a warmer winter.