All about Dengue, the sometimes fatal illness plaguing Africa and Asia

The world is witnessing a metamorphosis in dengue behaviour, raising questions about its evolution and implications.

Dengue fever, often simply referred to as dengue, is a mosquito-borne viral infection that can lead to a range of symptoms, including high fever, severe joint and muscle pain, bleeding, and even death in severe cases.

It is caused by the dengue virus, which is transmitted to humans through the bites of infected female Aedes mosquitoes, primarily the Aedes aegypti mosquito.

Recent developments are turning this narrative on its head.

Not only are new dengue infections steadily surging worldwide, but the outbreaks are growing larger and less predictable.

Associate Professor at the Faculty of Health at Anglia Ruskin University, Simon Bishop, investigates recent patterns with the disease and how increasingly worrying its spread has become.

He cites 2019 for instance when the highest number of dengue fever cases ever were recorded, nearly doubling the previous year's figures. He also highlights a record number of deaths attributed to dengue in Bangladesh in July 2023.

Symptoms and causes of dengue

The typical dengue victim endures a barrage of flu-like symptoms, ranging from the mildly unpleasant to the agonizing, often featuring fever, headaches, and joint pain. In more severe cases, the virus's attack on blood vessels leads to internal bleeding, bruising, and haemorrhaging from the nose and gums.

These dire circumstances can ultimately culminate in organ failure and, tragically, death as the body plunges into shock.

The primary vector for dengue transmission is the Aedes aegypti mosquito, known as the Asian Tiger mosquito. Its cousin, Aedes albopictus, can also serve as a vector. While Aedes aegypti is predominantly a tropical mosquito, it has proven itself to be an adaptable creature.

Why the growing numbers?

Associate Professor at the Faculty of Health at Anglia Ruskin University, Simon Bishop, has cited climate change as a possible reason for the increasing number of dengue cases.

According to him, the early arrival of rains, coupled with unusual temperature and humidity spikes, caused mosquito numbers to surge in Bangladesh this year.

Bangladesh's population often resides outdoors, and their simple dwellings offer easy access to mosquitoes, which facilitated dengue's rapid spread and explosive outbreak.

The precise factors driving the increase and volatility of dengue remain elusive, but climate change looms as a potential accomplice. As the world warms and experiences increased precipitation, these conditions may foster dengue's expansion, he further noted.

Nonetheless, a recent report from the World Health Organization's chief scientist suggests that dengue could establish itself in parts of Europe, the United States, and Africa where it was previously absent.

A repeating pattern akin to Bangladesh could unfold in middle- and low-income countries, where the convergence of mosquitoes and people is more frequent, Prof Simon Bishop stated.

The remedy he says may lie in an affordable and effective vaccine. The WHO has recently recommended the Qdenga vaccine for children in areas where the disease poses a significant public health risk.

Yet, dengue is not the sole mosquito-borne threat. Aedes aegypti also carries a host of other deadly infections, including chikungunya, yellow fever, and the Zika virus.

As the world grows warmer, wetter, and less predictable, the stage is set for more frequent and erratic mosquito-borne disease outbreaks and the tragic loss of lives. Alas, it is the marginalized communities in the global tropics who bear the brunt of this burden once again.