The World Health Organization’s chief scientist Jeremy Farrar has warned dengue fever could soon “take off” and become a constant presence in the United States, one of many emerging health threats driven by the climate crisis as rising temperatures make new parts of the world hospitable to vectors of disease.
KEY FACTS
Dengue—often called “breakbone fever” on account of the excruciating pain it can cause—is caused by a virus spread through the bites of infected female mosquitoes, primarily the invasive Aedes aegypti.
Dengue is common in warmer climates where the mosquitoes that spread it thrive, including parts of South America, South Asia and the Philippines. There are four related viruses that cause dengue and around 400 million people are infected every year, though experts believe this number is likely much higher as most people will not have any symptoms.
Around a quarter of people with dengue will get sick and experience flu-like symptoms such as fever, headache, rash, aches and pains and vomiting that typically begin a few days after infection and last a week or two.
Dengue can become a medical emergency within a matter of hours, however, with around 1 in 20 of infected people who get sick developing serious symptoms like severe pain, shock and internal bleeding that can lead to death, and around 40,000 die from severe dengue each year. There is no specific medicine to treat dengue and the focus in most cases is on treating pain and providing supportive care, with severe dengue often requiring hospitalization.
Preventing mosquito bites through guards like screens, netting, repellent and environmental management is the primary way of preventing infection with dengue, though a vaccine for those who haven’t been infected previously is now available, albeit not universally. (The company withdrew its application to be authorized in the U.S.)
NEWS PEG
Farrar, who joined the WHO from the Wellcome Trust in May, told Reuters in an interview that the world needs “to talk much more proactively about dengue” and that many countries need to prepare themselves for the added pressure coming their way. Parts of the U.S., Europe and Africa—all areas where local transmission of dengue have been documented in the past—are particularly susceptible runways from which the virus can “take off” and become endemic, he said, meaning the virus will be a continued presence.
KEY BACKGROUND
Climate change—in addition to increased city living and global movement of people—is a key driver of dengue as it expands the areas hospitable to Aedes aegypti and other mosquitoes like Aedes albopictus that can transmit the virus. These typically live in warmer environments and estimates suggest climate change will soon make large parts—or even all—of the U.S. suitable habitat for the insects, increasing the risk of dengue and other diseases the same mosquitoes carry like Zika, yellow fever and chikungunya.
There have already been outbreaks of dengue with local transmission reported in Florida, Hawaii, Texas and Arizona, though most U.S. cases are linked to travelers and previous outbreaks have been small, the Centers for Disease Control and Prevention said. With the vector mosquitoes present, it would only take one infected person to be bitten to kick start a local chain of transmission. Such fears have sparked insecticide campaigns in places like Paris, where officials worried two people who contracted the virus abroad could start an outbreak given the more extreme conditions and heat that have allowed the mosquitoes to thrive in the city. Extreme weather, set to get worse with climate change, is also being blamed for the severity of an ongoing dengue outbreak in Bangladesh, where more than 1,000 people have already died.
SURPRISING FACT
Infection with one type of dengue virus does not grant immunity against other kinds of dengue, and a person can be infected multiple times over the course of their lives. Unlike many infections—which often convey a degree of protection, or are at least neutral, against related viruses—repeat infections with dengue come with a greater risk of severe disease. The issue was a contentious and debated topic among scientists for years but it is now believed that antibodies developed following the first round of infection actually assist the virus if contracted again later.
Source: Forbes
