The emergence of the coronavirus, and the global pandemic it caused more than three years ago, prompted scientists to be more vigilant about the next virus that might trigger a new global health emergency.

The World Health Organization has issued a list of "priority pathogens" since 2017, which includes diseases that represent the greatest expected threat to humanity and for which we currently urgently need more research to ensure we are in a position to control and treat them if they begin to spread.

Coronavirus tops the current list, and here are the other eight viruses that currently concern WHO experts.

Crimean-Congo Hemorrhagic Fever

Crimean-Congo Hemorrhagic Fever is continuously spread in Africa, the Balkans, the Middle East, and Asia, and occurs when people are bitten by infected ticks or encounter sick livestock.

Ebola and Marburg

Bats and monkeys carry both of these diseases, which are members of the filovirus family, which also causes hemorrhagic fever.

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

Lassa Fever

This disease spreads in West Africa through the urine and feces of rats and rodents, and infected humans can transmit it through their secretions, blood, or sexual contact.

Lassa fever poses a special risk to pregnant women in the last three months of pregnancy, can also cause deafness in patients, and Ribavirin has been used to treat it, but there is no vaccine.

Middle East Respiratory Syndrome

The disease is known as MERS or camel flu, it is a deep viral infection in the respiratory system, and once a person is infected, it may be transmitted to others through close contact.

The disease first appeared in Saudi Arabia in 2012 and again in South Korea in 2015.

Nipah Virus

This virus is commonly found in Asia and is carried by fruit bats, as well as pets such as pigs, horses, cats, and dogs, and is transmitted to humans through these carriers and from person to person.

Rift Valley Fever

Mosquitoes carry this disease and transmit it by biting humans or livestock such as cattle, sheep, goats, buffaloes, and camels, and the disease spreads from Africa to Saudi Arabia and Yemen.

A vaccine has been developed for this disease but has not yet been licensed anywhere.

Zika Virus

Another disease transmitted through mosquito bites, which can infect the blood and be transmitted sexually, and Zika is rarely fatal but may cause severe brain defects in fetuses, is known to cause miscarriage and stillbirth, and currently there is no vaccine for the disease.

"Disease X"

A space has been reserved on the list for a virus unknown so far that may emerge in the future and cause us problems, as the coronavirus did.