Where does the world’s next Zika, West Nile or dengue come from?
The countries likely to be responsible for an outbreak of a contagious killer virus such as Zika or dengue fever have been revealed by scientists.
Researchers have created heatmaps to show viral hotspots around the world, by investigating which animals are most likely to spread diseases and where.
The maps show where existing flaviviruses – infectious viruses that usually spread through mosquitoes and ticks – or similar new ones are most likely to surface and spread in the future.
For example, Japanese encephalitis is most common in Western Europe, while the West Nile virus is a major threat in North America.
Information about thousands of bird species and mammals was involved in the study and researchers say it will help predict and monitor viruses around the world.
Scientists from the University of California, Davis, have investigated data on animal and bird species to find out where they think the following virus outbreaks could happen – they decided that the West Nile virus is likely North America, dengue fever South America, Japanese encephalitis affects Western Europe and yellow fever or Zika Southeast Asia
Researchers from the University of California, Davis, have mapped where they think future outbreaks of known viruses or similar strains will occur.
Viruses such as Zika, dengue fever and West Nile are usually transmitted to people – at least initially – from warm-blooded animals via mosquitoes.
Scientists have compared information about every known species of bird and mammal on Earth to find out what different types of viruses contain.
Finding out where animals are most likely to be affected by certain viruses can provide clues as to where they are likely to stick and spread to humans.
They discovered that Zika and yellow fever are most likely to break out in Southeast Asia, especially Indonesia and Malaysia, with other hot spots in Europe and Africa.
People are most at risk for the West Nile virus in the US, Mexico and southern Canada, with a lower but not absent risk in Europe and Russia.
The St Louis encephalitis and Usutu viruses are also likely to be found in the same areas, the study found.
Dengue, which is very common and can cause fever, vomiting and skin rashes, is likely to break out in South America in Brazil and the surrounding countries.
Yellow fever (YFV) and Zika (ZIKV) or similar viruses are most likely to break out in Southeast Asia (red and orange), with some risk areas in Africa, Europe and South America (yellow)
West Nile virus (WNV), St Louis encephalitis (SLEV) and Usutu (USUV) are, according to the study, probably most likely to affect North America, with some risk in Eastern Europe and Russia
Sign-borne encephalitis (TBEV), an infection that can damage people’s brains, is likely to emerge in Russia and Northern Europe, researchers showed
According to the study, Western Europe is most at risk for an outbreak of Japanese encephalitis, a brain infection in pigs that in severe cases can cause epileptic seizures, paralysis and even death in humans.
Sign-borne encephalitis, another brain infection, also breaks out most in Europe, although further east and in Russia.
When flaviviruses infect humans, they often cause fever, headache, fatigue and rash, muscle or joint pain, and some cause nausea or vomiting.
Most people only suffer from a mild illness and recover quickly, but complications can be life threatening.
Lesser known viruses Rio Bravo, Entebbe bat and Dakar bat – the latter both of which are carried by bats – are also most common in South America.
“If there is an outbreak tomorrow somewhere in the world, we now know which types of animals are most likely to be infected alongside humans,” said lead author Pranav Pandit.
Rio Bravo virus (RBV), Entebbe bat virus (ENTV) and Dakar bat virus (DBV) are probably all found in South America in Brazil and the surrounding countries, the study found
Dengue, an infection that is common in tropical countries, is also most likely to have broken out in South America, according to the study based on the types of animals that live there
Japanese encephalitis (JEV) is likely to spread among animals and birds in Northern and Western Europe, said the University of California scientists
WHAT IS THE MOST LIKELY TO CAUSE THE FOLLOWING EPIDEMY?
In February 2018, the World Health Organization released its annual list of deadly bugs that warned that there is an “urgent” need to speed up investigations.
Those who gave them priority were:
- Crimean Congo haemorrhagic fever
- Marburg virus disease
- Lassa fever
- Middle East respiratory syndrome coronavirus (MERS-CoV)
- Severe acute respiratory syndrome (SARS)
- Nipah and henipaviral diseases
- Rift Valley fever (RVF)
- Illness X
Approximately 10,400 bird species and 5,400 mammals were included in the study to determine which were most likely to have infectious diseases.
Some animals identified as potential carriers were first associated with viruses.
For example, 139 new hosts for dengue fever were discovered among the 173 species that the study predicted could carry the virus.
Researchers said the knowledge will be useful for monitoring the spread of viruses among animals, since testing for flaviviruses can be difficult.
If they focus on the right species, they can now test for diseases using non-invasive methods, such as taking saliva samples from primate-chewed sticks, for example.
Co-author, Professor Christine Kreuder Johnson, added: “We needed this modeling technique to help us understand the most likely hosts for these viruses in their natural habitat.
“That is important for both global health and the conservation of wildlife.”
The research is published in the journal Nature Communications.
WHAT IS THE ZIKA VIRUS?
The Zika virus is spread by mosquito bites, between people during unprotected sex and from pregnant mothers to their children.
It cannot be cured or prevented with medication. Although most adults do not get seriously ill from the infection, it can cause serious birth defects if pregnant women get it.
The brain of fetuses can be affected by the virus when it is transmitted by the mother and it can cause microcephaly.
Microcephaly is a condition in which baby’s heads are unusually small, which can lead to seizures, delayed development, and other disabilities.
The virus can also increase the risk of unborn children developing Guillain-Barre syndrome – an unusual disease where the immune system attacks the nerves and can cause muscle weakness and paralysis.
Zika is a tropical disease and is most common in Central and South America, Africa and Southeast Asia.
There was an outbreak of the virus in the capital of Brazil, Rio de Janeiro, in 2016 and there was a fear that the Olympic Games of the year would have to be canceled after more than 200 academics had warned the World Health Organization about this.
The virus is not often found in developed countries such as the UK, the US and Australia. But it is present on the Pacific islands such as Fiji and Tonga, where the pregnant Duchess of Sussex will visit her royal tour this month.