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Dengue will ‘take off’ in southern Europe, US, Africa this decade, WHO scientist says

LONDON, Oct 6 (Reuters) – Dengue fever will become a major threat in the southern United States, southern Europe and new parts of Africa this decade, the WHO’s chief scientist said, as warmer temperatures create the conditions for the mosquitoes carrying the infection to spread.

The illness has long been a scourge in much of Asia and Latin America, causing an estimated 20,000 deaths each year. Rates of the disease have already risen eight-fold globally since 2000, driven largely by climate change as well as the increased movement of people and urbanization.

Many cases go unrecorded, but in 2022 4.2 million cases were reported worldwide and public health officials have warned that near-record levels of transmission are expected this year. Bangladesh is currently experiencing its worst-ever outbreak, with more than 1,000 deaths.

“We need to talk much more proactively about dengue,” Jeremy Farrar, an infectious diseases specialist who joined the World Health Organization in May this year, told Reuters.

Mosquito Biting Arm

Mosquito-borne diseases spreading in Europe due to climate crisis, says expert

Mosquito-borne diseases are spreading across the globe, particularly in Europe, due to climate breakdown, an expert has said.

The insects spread illnesses such as malaria and dengue fever, the prevalences of which have hugely increased over the past 80 years as global heating has given them the warmer, more humid conditions they thrive in.

Prof Rachel Lowe who leads the global health resilience group at the Barcelona Supercomputing Center in Spain, has warned that mosquito-borne disease outbreaks are set to spread across currently unaffected parts of northern Europe, Asia, North America and Australia over the next few decades.

She is due to give a presentation at the global congress of the European Society of Clinical Microbiology and Infectious Diseases in Barcelona to warn that the world must be prepared for a sharp uptick in these diseases.

“Global warming due to climate change means that the disease vectors that carry and spread malaria and dengue [fever] can find a home in more regions, with outbreaks occurring in areas where people are likely to be immunologically naive and public health systems unprepared,” Lowe said.

“The stark reality is that longer hot seasons will enlarge the seasonal window for the spread of mosquito-borne diseases and favour increasingly frequent outbreaks that are increasingly complex to deal with.”

Dengue used to be primarily found in tropical and subtropical regions, as freezing overnight temperatures kill the insect’s larvae and eggs. Longer hot seasons and less frequent frosts have meant it has become the fastest-spreading mosquito-borne viral disease in the world, and it is taking hold in Europe.

The Asian tiger mosquito (Aedes albopictus), carries dengue fever and has become established in 13 European countries as of 2023: Italy, France, Spain, Malta, Monaco, San Marino, Gibraltar, Liechtenstein, Switzerland, Germany, Austria, Greece and Portugal.

The insect is thriving; nine out of the 10 most hospitable years for transmission of the disease have occurred since 2000, and the number of dengue cases reported to the WHO has increased eightfold in the past two decades, from 500,000 in 2000 to more than 5m in 2019.

Lowe said climate breakdown would turbocharge this spread as droughts followed floods: “Droughts and floods linked to climate change can lead to greater transmission of the virus, with stored water providing additional mosquito breeding sites.

“Lessons from previous outbreaks underscore the importance of assessing future vector-borne disease risks and preparing contingencies for future outbreaks.”

She said that if the current trajectory of high carbon emissions and population growth continued, the number of people living in areas with mosquito-borne diseases would double to 4.7 billion by the end of the century.

Lowe added: “With climate change seeming so difficult to address, we can expect to see more cases and possibly deaths from diseases such as dengue and malaria across mainland Europe. We must anticipate outbreaks and move to intervene early to prevent diseases from happening in the first place.

“Efforts need to focus on enhancing surveillance with early warning and response systems similar to those seen in other parts of the world, to more effectively target finite resources to the most at-risk areas to control and prevent disease outbreaks and save lives.”

Climate breakdown is also amplifying the threat from antimicrobial resistance, a separate presentation at the conference will warn.

Prof Sabiha Essack, the head of the antimicrobial resistance unit at the University of KwaZulu-Natal in South Africa, said climate breakdown was a “threat multiplier” for antimicrobial resistance: “Climate change compromises the ecological and environmental integrity of living systems and enables pathogens to increasingly cause disease. The impact on water systems, food-producing animals and crops threatens global food supply.

“Human activities associated with population growth and transport, together with climate change, increase antibiotic resistance and the spread of waterborne and vector-borne diseases of humans, animals and plants.”


Why dengue in Europe could spell disaster for the rest of the world

Increased investment into previously neglected diseases could see poorer countries left behind.

In the early morning of the last day of August, Parisians experienced for the first time a practice normally confined to tropical regions — authorities fumigating the city against the tiger mosquito. The event was a tangible confirmation of what public health stats already showed: Dengue, the deadly mosquito-borne disease, had well and truly arrived in Europe. 

In 2022, Europe saw more cases of locally acquired dengue than in the whole of the previous decade. The rise marks both a public health threat and a corresponding market opportunity for dengue vaccines and treatments; news that should spur the pharma industry to boost investment into the neglected disease. 

On the face of it, this shift would appear to benefit not only countries like France but also nations like Bangladesh and the Philippines that have long battled dengue.

But that assumption could be fatally flawed, experts told POLITICO. 

People working in the field say the rise of dengue in the West could, in fact, make it harder to get lifesaving drugs to those who need them most, because pharma companies develop tools that are less effective in countries where the dengue burden is the highest or because wealthy nations end up hoarding these medicines and vaccines. 

“It might look like a good thing — and it is a good thing — that we’re getting more products developed, but does it then create a two-tier system where high-income populations get access to it and then we still have the access gap for low- and middle- income countries?” asked Lindsay Keir, director of the science and policy advisory team at think tank Policy Cures Research.

Killer invading mosquitoes

Climate change and migration mean the mosquitoes that transmit dengue, as well as other diseases such as chikungunya and Zika, are setting up shop in Europe. The most recent annual data from the European Centre for Disease Prevention and Control shows that, in 2022, Europe saw 71 cases of locally acquired dengue: 65 in France and six in Spain.

While dengue usually results in mild or no symptoms, it can also lead to high fever, severe headache and vomiting. Severe dengue can cause bleeding from the gums, abdominal pain and, in some cases, death.

So far, the mosquito has mostly been confined to Southern Europe but it’s a worry across the Continent. In Belgium, the national public health research institute Sciensano has even launched an app where members of the public can submit photos of any Asian tiger mosquitos they spot.


‘I felt pains all over my body’: Argentina battles dengue outbreak

Rising temperatures, dense urban populations and increasing poverty have contributed to more than a quarter of a million cases, and campaigners don’t think the government is doing enough about it

by Sylvia Colombo in Buenos Aires

Supported by

Open Society Foundations

About this contentFri 12 Apr 2024 14.00 BSTShare

On a particularly warm autumn afternoon in Buenos Aires, Michelly Natalí Barreto Sánchez, 22, began to feel unwell. As she served customers at La Boca, the bar she had opened in Villa 31, one of the capital’s largest slums, she suddenly started to experience severe headaches and dizziness.

She told her customers, who are among the 70,000 people who live in this densely populated area close to the city centre, that she would have to close the bar, and she headed home.

“It was a matter of hours before I felt pains all over my body,” she says. “My bones hurt. I tried to eat, and everything came back up, and in the following days, I couldn’t even swallow water. I vomited the medication I took and had to hold on to the walls to walk.”

Dengue in Argentina broke a record this year. In the first eight weeks of 2024, authorities reported 57,461 confirmed cases and 47 deaths, a 2,153% increase compared with the same period last year. Recent data from the health ministry indicates a new record was reached in March when cases rose to 233,000 and deaths to 161.

I waited 11 hours to be seen in a waiting room where people screamed in pain from their bones

Michelly Natalí Barreto Sánchez

The spike in cases occurred in the same year Argentina registered record temperatures, providing the conditions for the Aedes aegypti mosquito to thrive. An as-yet-unpublished report from the National Scientific and Technical Research Council (Conicet) associated with the University of Buenos Aires, two leading Argentine institutions, paints a picture of the current state of the epidemic in the country.


Latin America’s spike in dengue fever should serve as a warning

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The dengue-fever case counts now break regional records every year—and the structural reasons behind the spike suggest this sometimes-deadly virus will soon threaten more of the world. Breaches and security holes keep revealing how much of the internet’s innards are maintained by volunteers; we ask why (9:45). And the case for moving over, not up, at work (17:10). Runtime: 22 min


Global dengue

Global dengue risk reminder

Dengue is a virus spread by mosquitoes found in tropical and sub-tropical regions worldwide, including parts of Europe
Global dengue risk reminder

Dengue is a growing public health concern, with the World Health Organization (WHO) advising that approximately four billion people in 130 countries are at risk of infection. Since the beginning of 2023, the world has faced an unexpected rise in dengue cases and deaths in countries with an established risk of dengue (endemic) and dengue has spread into regions previously thought to be dengue free [1, 2].

As of April 2024, over five million dengue cases and over 2000 dengue-related deaths have been reported worldwide since the beginning of 2024 [3]. An increase in dengue cases has been reported in several regions, including Asia, Central and South America and across the Caribbean [2 – 6].

Dengue is not endemic in Europe. However, if environmental conditions are favourable in areas of Europe where mosquitoes that can carry dengue are found, travel-related cases may cause local dengue spread. Several European countries have previously reported locally acquired cases of dengue. In 2023, locally acquired cases have been reported in France, Italy and Spain [7, 8].

Dengue is caused by a virus (Flaviviridae virus family) and is spread by the bite of an infected mosquito (Aedes) which mainly feed during daytime hours. There are four different types of dengue virus: DENV- 1, DENV- 2, DENV- 3 and DENV- 4.

Most people infected with dengue remain symptom-free. If illness develops, it usually begins suddenly with a high fever, severe headache, muscle and joint pain, nausea, vomiting and a rash. Most infections are self-limiting, with a rapid recovery three to four days after the rash appears.

A small number of infected people develop a severe illness called severe dengue (previously sometimes known as dengue haemorrhagic fever). Symptoms include dangerously low blood pressure (shock), fluid build-up in the lungs and severe bleeding (haemorrhage). All four types of dengue virus infection can cause either dengue or severe dengue.

There is no specific drug treatment for severe dengue illness, but supportive treatment for shock and bleeding improves survival. Without this, severe dengue illness can be fatal.