Dengue fever is now the fastest spreading insect-borne virus in the
world and has reached “epidemic potential,” the World Health
Organization said Wednesday.
Indeed, Dr. Scott Halstead, a leading dengue expert who has studied
the virus for more than 50 years, goes even further: he believes the
pandemic has already arrived.
“We’re in it. We’re in the pandemic,” said Halstead, a senior scientific adviser to the Dengue Vaccine Initiative.
“We have more dengue in more countries, and in more places and
involving more people, than any other time in history. It’s reached a
huge geographic expanse and now we’re stuck with it.”
While Halstead and the WHO may differ on the precise definition of
what constitutes a “pandemic,” they both agree dengue has reached
alarming levels since “breakbone fever” began to spread just after the
Second World War.
In 1955, only three countries reported dengue cases, according to the
WHO, which released its second report on neglected tropical diseases
Wednesday. Today, dengue fever is found in over 125 countries and nearly
half the world’s population is now at risk of infection.
A patient talks on her mobile phone under a
mosquito net at a dengue fever ward in Villa Elisa, Paraguay. The health
ministry declared an epidemic alert for the entire country after some
400 new cases of dengue were reported in 24 hours, totalling more than
6,000 confirmed cases and 70 deaths in the past three months.
Currently, there are several dengue outbreaks. One on Portugal’s
Madeira Island marks Europe’s first sustained transmission of the virus
in nine decades. Paraguay is in the midst of a nationwide epidemic.
There have been more than 6,000 confirmed cases and 70 deaths in the
past three months, according to Reuters.
“In 2012, dengue ranked as the fastest spreading vector-borne viral
disease … registering a 30-fold increase in disease incidence over the
past 50 years,” the UN health agency said in a news release. “The world
needs to change its reactive approach and implement sustainable
preventive measures.”
Dengue is transmitted by mosquitos — primarily the female Aedes aegypti,
which also spreads yellow fever — and typically causes flu-like
symptoms, headache and skin rash. The disease is incredibly painful and
debilitating.
“I’ve met many, many adults who have had dengue, mostly in Asia, and
what they say is almost the same words: ‘That is the worst disease I’ve
ever had,’ ” he said.
The disease can develop in a severe form known as dengue hemorrhagic
fever or dengue shock syndrome, which can be fatal. About 2.5 per cent
of people affected die, according to the WHO.
There is no treatment for severe dengue other than hospitalization
and fluid management, which can make dengue an expensive disease to
treat, Halstead said.
What makes finding a dengue vaccine particularly challenging is that
there are four strains of the virus. An infected person will develop
lifelong immunity to one particular strain, but he or she is at
increased risk of getting severe dengue if infected later with one of
the three other strains.
According to Dr. Raman Velayudhan, a WHO scientist specializing in
neglected tropical diseases, two main factors have contributed to
dengue’s rapid rise: urbanization and the spread of mosquitoes, aided by
spreading transportation networks.
“The mosquitoes are spreading all over silently,” Velayudhan said.
“They are there in many places and just waiting for an infected human to
come by.”
Both he and Halstead agree it is unlikely that the tropical disease
will ever become established in Canada — but that doesn’t mean Canadians
shouldn’t worry about it.
According to the Public Health Agency of Canada, about 200 to 300
Canadian tourists get dengue every year. A nasty bout of breakbone fever
is just a plane ride away.
“I don’t think there’s any tropical country you can visit that
doesn’t have dengue,” Halstead said. “These are all global problems that
have an enormous impact on the health and the financial stability and
prosperity of countries in the world. Dengue is a drain.”
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