Nine viruses of concern to the World Health Organization

Nine viruses of concern to the World Health Organization

For infectious disease experts at the World Health Organization (WHO), the work is never done.

As the immediate dangers of the coronavirus appear to be more than three years after respiratory illness broke out in Wuhan, China and shut down around the world, epidemiologists must remain vigilant for the next virus that has the theoretical potential to explode into a public health emergency.

The organization has maintained a list of “priority pathogens” since 2017, which compiles the diseases that pose the greatest potential threat to humanity and on which we currently most need further research in order to ensure that we are in a position to fight them if they start to spread.

The list, used by governments and public health organizations to guide their planning, will soon be revised again after the WHO brought together 300 scientists in November to reassess the danger posed by 25 viruses and bacteria with a view to reprioritizing it.

“Targeting priority pathogens and virus families for research and development of countermeasures is essential for rapid and effective response to epidemics and pandemics,” said Dr. Michael Ryan, executive director of the WHO Health Emergencies Program.

“Without significant investments in R&D before the Covid-19 pandemic, it would not have been possible to develop safe and effective vaccines in record time.”

We can expect an update in the coming months.

The coronavirus tops the current list but aside from that since we all know it so well, here are the other eight viruses that are of most concern to WHO experts right now.

Crimean-Congo hemorrhagic fever

A common endemic disease in Africa, the Balkans, the Middle East and Asia, Crimean-Congo hemorrhagic fever is most often spread when people are bitten by infected ticks or encounter sick livestock.

The resulting condition can damage the internal organs of the body and the cardiovascular system and cause severe bleeding.

The disease has a mortality rate of 10-40% and a vaccine against it is licensed in Bulgaria but has not yet been approved anywhere else.

Ebola and Marburg

Bats and primates are carriers of these two diseases, which are part of the filovirus family, which also cause hemorrhagic fevers.

Once a human being has been infected, they usually transmit the viruses to others through their bodily fluids or through direct contact or through contact with contaminated surfaces in unsterilized environments.

They generally have a mortality rate of 50%, although this has varied from 25 to 90% in previous epidemics.

Vaccines have been used against Ebola in Guinea and the Democratic Republic of Congo, but are not widely approved.

Lassa fever

Endemic to West Africa, this disease is transmitted through the urine of rat and rodent faeces. Humans who contract it can then pass it on through their own feces or blood or through sexual contact.

Lassa fever is thought to pose a particular danger to expectant mothers during the third trimester of pregnancy and can also cause deafness in female patients.

The mortality rate is low at 1%, although it rises to 15% in cases where the condition of the sick is serious enough to require hospitalization. Ribavirin has been used to treat it but there is no vaccine.


Properly known as Middle East respiratory syndrome, this disease is equivalent to a deep infection of the respiratory tract and is native to the region, where it is carried by camels.

Once contracted by a human, it can be transmitted to others through close contact.

Its mortality rate is high at 35% and it has been diagnosed in 27 countries since 2012, according to the WHO, but there is still no vaccine.

Nipah virus

This is recurrent in Asia and carried by fruit bats, as well as domestic animals such as pigs, horses, cats and dogs, and can be transmitted to humans by these carriers, as well as from person to person. no one.

It can cause swelling of the brain (encephalitis), has a 40-70% mortality rate and is currently without a vaccine.

rift valley fever

A blood disease carried by mosquitoes, which transmit it by biting humans or livestock such as cows, sheep, goats, buffaloes and camels, Rift Valley fever has spread from Africa to Saudi Arabia and Yemen.

Although the mortality rate is less than 1% and the Rift Valley is mild for most people, about 8-10% of patients develop serious symptoms, including eye damage, encephalitis and hemorrhagic fever.

A vaccine has been developed but is not yet licensed anywhere.

Zika virus

Another disease spread by mosquito bites, which can infect the blood and be sexually transmitted, Zika is rarely fatal but can cause severe brain malformations in fetuses and is known to cause miscarriages and stillbirths.

There is currently no vaccine.

‘Disease X’

A place is reserved on the list for an as yet unknown virus that may arise in the future to cause us problems, as Covid demonstrated so well in the spring of 2020.

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