The summer 2020 Olympic and Paralympic games in Tokyo may be hit with dengue fever, scientists warn.

Concerns have been raised after the Japanese capital experienced an unexpected outbreak of the killer infection in 2014.

This shows the city has the climate and mosquitoes to support the virus returning, Harvard University researchers argue.

Researchers have now said Japan needs to step up its preparations ahead of the games in order to prevent an outbreak. 

The summer 2020 Olympic and Paralympic games in Tokyo may be hit by dengue fever, scientists warn. Concerns were raised after the capital experienced an unexpected outbreak in 2014, which shows the city has mosquitoes that can carry the virus (stock)

The summer 2020 Olympic and Paralympic games in Tokyo may be hit by dengue fever, scientists warn. Concerns were raised after the capital experienced an unexpected outbreak in 2014, which shows the city has mosquitoes that can carry the virus (stock)

Dengue is treatable but up to a fifth of patients with a severe case of the mosquito-borne infection die without drugs. Most patients have no symptoms. 

Scientists led by Dr Naoki Yanagisawa reviewed the preparedness of existing health services in Japan to cope with outbreaks. 

Fears of an outbreak of the mosquito-borne virus in Tokyo are particularly high due to the Olympics taking place during the summer.

Prior to the city’s 2014 outbreak, up to 200 cases of dengue occurred every year in Tokyo, all of which were brought in from abroad.

During this time, the number of tourists who visited the city rose from 5.2 million in 2003 to 24 million in 2016, the year of the last Olympics.

But this is set to increase further due to Japan working to attract 40 million visitors from all over the world by 2020.

WHAT IS DENGUE? 

Dengue is a viral infection spread by mosquitoes that can be deadly. 

It is found in southeast Asia, the Caribbean, the Indian subcontinent, South and Central America, Africa, the Pacific Islands and Australia. 

More than 40 per cent of the world’s population in over 100 countries are at risk of dengue infection.  

Cases found elsewhere occur in people who have recently traveled to an area where the virus is common. 

Most dengue cases are mild and pass within a week or so.

Symptoms usually develop suddenly between four and 10 days after a person was infected. 

Mild symptoms can include:

  • Fever that reaches over 40C
  • Severe headache
  • Pain behind the eyes
  • Muscle and joint pain
  • Nausea and vomiting
  • Widespread rash
  • Loss of appetite

In up to five per cent of patients, dengue becomes severe, which is sometimes known as dengue fever. 

People with suspected severe dengue should go to hospital immediately.

There is no specific treatment or widely available vaccine for the infection. 

People should therefore try and avoid being bitten by using insect repellent, wearing loose but protective clothing and sleeping under a mosquito net.

Most infected people can usually look after themselves at home via painkillers, plenty of rest and staying hydrated.  

Source: NHS  

Infection control teams in the Asian country are normally ‘robust’ at preventing outbreaks, according to the researchers.

However, they said concerns are always raised when international visitors gather for ‘special events’. 

Dr Yanagisawa admitted it is ‘virtually impossible to prevent any pathogen from entering a country just by enhancing border control’.

Writing in a report, the team said: ‘Given dengue was introduced, chikungunya and Zika could be problematic as well.

‘Although an outbreak has not been recognized in Japan to date, there is always the possibility that these infections would cause an outbreak.

‘Participants and spectators of international sporting events such as the Olympics are at risk of acquiring imported and locally endemic infectious diseases.’

Dr Yanagisawa and colleagues identified 20 critical points to prevent a dengue outbreak in the journal PLOS Neglected Tropical Diseases.  

They included recommendations that Japanese doctors are trained on how to manage tropical diseases. 

While they also said provisions should be made to ensure adequate communication between medical staff and foreign patients. 

Hotel workers should also be trained in managing tropical diseases and have a plan in place if they suspect a traveler is infected. 

The study follows the norovirus outbreak that occurred at the Winter Olympics in PyeongChang, South Korea, earlier this year.

A flu outbreak also struck the 2002 Winter Olympics in Salt Lake City, while measles was recorded at the games eight years later in Vancouver. 

Officials even considered cancelling the 2016 Olympic games in Rio after the Zika outbreak. 

The World Health Organization declared, however, there was no public health concern to justify stopping the event. 

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