Just three years ago, on January 30, 2020, the head of the World Health Organization made a historic statement: a “novel coronavirus” that was first identified in China had spread to such a degree that it became a ” public health emergency”. of International Interest (PHEIC).”
The virus now known as SARS-CoV-2, which causes the disease COVID-19, is still spreading. But for those who study infectious diseases, talking about possible next pandemics is a necessity.
That’s why the World Health Organization keeps a list of viruses and bacteria with pandemic potential. Jill Weatherhead of Baylor College of Medicine says the prioritization of diseases is generally based on two factors: their ability to spread and the ability of humans to cure them.
The list helps guide scientists, governments, and organizations in investing energy and funds to study the pathogens most likely to cause the greatest havoc to humans. WHO develops “blueprints” with strategic goals and research priorities for each disease on the list.
Here are the diseases in the current list. A revised list is expected in the coming months: at the end of 2022, the World Health Organization has convened more than 300 scientists to evaluate and update the list.
Note: The infrastructure for detecting diseases in different parts of the world varies, as does the fact that mild cases of a disease may not be known or reported. Death rates are based on the best data available.
Which animals carry it: fruit bats, including those called flying foxes, and pets such as pigs, horses, dogs and cats
How it spreads: Nipah virus can be transmitted to humans from contaminated food or animals. It can also be transmitted directly from human to human.
Its price: Mortality rate from 40% to 75%. The virus can also cause encephalitis or brain swelling.
Medical Toolbox: There is no vaccine available for either people or animals. Monoclonal antibody therapies are under development.
Pandemic Potential: Outbreaks occur nearly every year in parts of Asia, but there are known ways to prevent the virus from spreading. Prevention efforts include avoiding exposure to bats and sick animals, avoiding fruit that bats may have gnawed on, and not drinking some raw juices from fruits that bats eat. The risk of international transmission can be reduced by washing those fruits and fruit products thoroughly and peeling them before eating.
Crimean-Congo haemorrhagic fever
Which animals carry it: ticks, livestock
How it spreads: Humans usually get the virus from contact with infected ticks or livestock. Getting the virus from another person requires close contact with the blood or other bodily fluids of an infected person.
Its price: Mortality rate from 10% to 40%. The disease is endemic, meaning it occurs regularly, in Africa, the Balkans, the Middle East and Asia. The virus causes severe outbreaks of viral hemorrhagic fever, a condition that can damage the body’s organ systems and cardiovascular system and often includes severe bleeding.
Medical Toolbox: Although a vaccine is in use in Bulgaria, no research has been published on how it works and it is not licensed anywhere else. Other vaccines are in development, and an antiviral drug called ribavirin appears to help treat infections.
Pandemic Potential: It’s hard to tell when an animal is infected and should be avoided, and WHO says ticks carrying the virus are numerous and widespread. The threat could be reduced by trying to avoid tick bites and by wearing gloves and other protective clothing when near livestock.
Which animals carry it: rats and other rodents
How it spreads: The virus is endemic in parts of West Africa. Rats shed the virus and humans pick it up when exposed to rodent urine and feces, either through direct contact or by eating contaminated food. It can also be spread among humans through direct contact with an infected person’s secretions (blood, urine, feces), through sexual contact, and in medical settings through contaminated equipment.
Its price: 1%, but up to 15% in severe hospitalized cases. It can be fatal to people and fetuses in the third trimester of pregnancy. In addition to death, a common complication is deafness, which can be permanent.
Medical Toolbox: There is no vaccine, but ribavirin appears to help treat infections.
Pandemic Potential: Since the main method of transmission is exposure to a certain type of rat, the potential for spreading the disease is most likely limited to the countries where the rat lives.
Rift Valley fever
Which animals carry it: mosquitoes. Insects can transmit the virus to both humans and their offspring. Livestock such as cattle, sheep, goats, buffalo and camels can also become infected.
How it spreads: It spreads to people through contact with blood, other bodily fluids, or tissue from infected animals.
Its price: Although the fatality level is less than 1% and the disease is mild for most people, about 8-10% of infected people develop severe symptoms, including eye lesions, encephalitis, and haemorrhagic fever.
Medical Toolbox: While a vaccine has been developed, it is not yet licensed or available.
Pandemic Potential: Rift Valley fever has spread from Africa to Saudi Arabia and Yemen. The floods appear to be contributing to increased Rift Valley fever because more virus-infected mosquitoes buzz after heavy rains. Rapid case detection, including timely laboratory testing of people with symptoms, has limited recent outbreaks.
Which animals carry it: mosquitoes
How it spreads: In addition to mosquito bites, the virus can spread from a pregnant person to a fetus. The disease can also be transmitted through sex and possibly through blood transfusions.
Its price: It is rarely fatal, but Zika can cause serious brain defects in fetuses, including microcephaly. It has also been linked to miscarriage, stillbirth, and other birth defects.
Medical Toolbox: No treatments or vaccines
Pandemic Potential: So far, it’s largely confined to areas where Zika-carrying mosquitoes live.
Ebola and Marburg virus disease
Which animals carry them: Bats and nonhuman primates are believed to carry the viruses, of the filovirus family, that cause these hemorrhagic fevers.
How they spread: Both viruses are believed to spread equally. After the initial spillover from an animal, humans have spread the viruses to other humans through direct contact with the blood or other bodily fluids of a person who is symptomatic or has died of the disease. Viruses can also spread through objects or surfaces contaminated by bodily fluids and through the semen of people who have recovered from the disease.
Their price: The average fatality rate is around 50%, although rates have varied from 25% to 90% in past outbreaks.
Medical Toolbox: Vaccines have been used for Ebola in Guinea and the Democratic Republic of the Congo. Monoclonal antibodies approved by the Food and Drug Administration in 2020 may also help in the treatment of Ebola. Vaccines for Marburg virus are under development.
Pandemic Potential: These viruses can spread rapidly in healthcare settings, especially when proper sterilization is not used. However, the disease only spreads when a person is symptomatic, making it easier to control.
MERS (Middle East Respiratory Syndrome)
Which animals carry it: camels
How it spreads: After the initial spillover event from camels to humans, this coronavirus can spread from person to person through close contact with an infected person.
Its price: The reported mortality rate, according to the WHO, is 35%.
Medical Toolbox: Several vaccines are under development, but none have been approved.
Pandemic Potential: 27 countries have reported infections since 2012. Unlike SARS-CoV-2, the coronavirus that causes MERS grows deep in the respiratory tract, making transmission through sneezing and coughing much less likely.
SARS (Severe Acute Respiratory Syndrome)
Which animals carry it: Palm civets were largely blamed for the 2003 outbreak. Bats and possibly other wildlife also carry it.
How it spreads: After the initial animal-to-human spillover event, SARS can spread from person to person through close contact with an infected person. It is thought to usually spread through droplets from coughs and sneezes and sometimes through surfaces touched by infected people.
Its price: less than 1% mortality
Medical Toolbox: No treatments or vaccines have been approved.
Pandemic Potential: Unlike SARS-CoV-2, which can spread before people know it is infectious, this SARS virus is usually only spread by those with known symptoms, making it much easier to contain through public health measures such as quarantine. The 2003 outbreak was contained after causing some 8,000 cases and 700 deaths in 29 countries.
WHO says it does not rank diseases in any order of potential threat, but recognizes the possibility that a yet unknown disease could cause a major pandemic.
In her work with bat viruses, for example, Cornell University’s Raina Plowright says that even in the small percentage of bat species that have been studied, the animals carry thousands of viruses “and we have no idea how many are at risk.” “. she says she. “We don’t have the technology to take a sequence and say for sure whether it can infect humans or transmit from human to human. We’re blind, really.”
Not to mention that variants pose a threat, he says. “Just the smallest genetic change can have a profound effect. What if we did [a pathogen] with a 50% fatality rate that it transmitted efficiently?”
Sheila Mulrooney Eldred is a freelance health journalist in Minneapolis. You have written about COVID-19 for many publications, including The New York TimesKaiser Health News, Medscape e The Washington Post. More sheilaeldred.pressfolios.com. On Twitter: @milepostmedia.