Scientists propose a “more effective” way to detect and prevent epidemics

Most pathogens come from animals and the theory of spread is the basis of many surveillance and prevention studies.

But for epidemiologist Gregory Gray, of the University of Texas in the US, dedicating so many resources to this idea is like “looking for a needle in a haystack”.

According to the scientist, “spread occurs all the time, and a few of them turn into epidemics.”

Gray and other experts propose an alternative method for monitoring and preventing epidemics—one that in some ways challenges our thinking about their origins and how we deal with them.

These scientists assume that searching for thousands of viruses in animals is expensive and often ineffective.

“It’s very interesting from a scientific point of view, but I don’t really think it’s possible to predict which of them will become epidemics,” biologist Stephen Goldstein, from the University of Utah in the US, tells BBC News Mundo, the BBC’s Spanish-language service.

Like Gray, Goldstein insists that fallout happens all the time. “But most of them don’t get past the first recipient,” he said.

This is because although the virus is able to adapt to humans, it usually takes time — often years — and for another variant to emerge that spreads efficiently, turning into a pandemic. And it is in this period of time that we should focus, according to these scholars.

“If we observe and study people who have frequent contact with animals, such as agricultural workers or live animal dealers, especially when they are sick, we can identify pathogens,” Goldstein explains.

He continues, “Instead of looking for thousands of viruses in animals, we look at what is actually circulating here.” “We are facing viruses of concern because we already know they can infect people.”

“That’s the basis of our argument,” says Gray. “Reducing data and detecting pathogens in their early stages, when they have already caused disease. From there, we can create intervention measures against the most threatening ones.”

There haven’t been many studies in the past few decades that have looked at cases of overexertion in people to determine how common it is.

When patients with mysterious pneumonia come into the emergency room, doctors look for known pathogens. They cannot detect viruses that are not detected. And this is the kind of case that scientists are asking for further study.

In a video conference, Gray shows in a graph the viruses that have caused the most deaths in the past century.

Most are respiratory viruses. Some examples are the Spanish flu in 1918, SARS in 2003, H1N1 virus in 2009, and SARS-CoV-2 in 2020.

So Gray believes we can close the loop around the most threatening viruses by focusing more research on respiratory viruses.

“It often spreads without symptoms and we can’t control it very well,” says the scientist. “They are transmitted before we can isolate patients.”

“When human-animal interaction cannot be monitored, an effective option is to monitor novel respiratory viruses in pneumonia patients in areas of frequent contact with animals,” Gray says in his study. “If they are detected, their risk to humans can be assessed and, if necessary, combat strategies can be initiated.”

Gray argues that the massive study of animals was not able to predict the Covid-19 pandemic, nor influenza A in 2009. When the variants that spread around the world appeared, it was too late.

But there are studies suggesting that SARS-Cov-2 may have waited decades in an animal’s body, before the deadly variant emerged.

Research published in Nature in 2020 suggests that the strain that gave rise to SARS-CoV-2 may have been circulating among bats since around 1969, undetected.

“If that’s true, it took a long time for it to become so transmissible in humans,” says Gray.

Some virologists would say that among the thousands of coronaviruses, only a few seem to be transmissible to humans. But if we monitor humans’ exposure to animals and find new viruses, we can do something, based on their biological evolution, before they invade emergency care,” the specialist insists.

Gray realizes that the theory he advocates has risks, too.

“If we put all the resources into respiratory viruses, we can ignore other threats,” he explains. “This is why we also advocate the development of other technologies, such as parallel mass sequencing.”

Epidemiologist David Heymann, of the London School of Hygiene and Tropical Medicine, agrees that the databases created in connection with the study of animal viruses are not very effective in predicting epidemics.

But, he notes, “if a new virus emerges, you can compare its sequence to this database, identify which animals carry that virus, and possibly make a list of the animals where it may have originated.”

Goldstein of the University of Utah also warns of challenges to the theory he advocates if it is implemented too often.

“You still need the resources, they are very expensive and require logistical and global coordination,” he explains. “And if you discover viruses circulating, it’s not easy to decide what to do about it.”

Finally, it will be necessary to manufacture vaccines for infections whose prevalence will remain a matter of hypothesis.

“To make vaccines, you need clinical trials in humans, and it’s difficult to do those trials on viruses that haven’t caused epidemics, although it’s troubling,” says Goldstein.

On the other hand, biologist Constance Wells, of Swansea University in the UK, warns that it is equally important to assess how human behaviors and different interactions between humans and animals contribute to animal virus infection in different contexts.

“For example, tourists or urban residents may be exposed to bats differently than hunters or guano gatherers. [as fezes dos animais]. It is still important to note how these differences in environments and interactions affect the circulation of the virus,” Wells explains.

Without detracting from the need for research efforts on the most threatening viruses, Wells highlights the complexity of these interactions. For him, “it is equally important to work on identifying so-called ‘blind spots’: unknown species and environments that can facilitate the spread of pathogens.”

Wells concludes that any disease-causing emergency “needs to be evaluated from many different perspectives.”