Rats, a genus of rodents that includes about 50 species, the most prevalent of which is the black rat, and its cousin the mouse, are seen as filthy, disease-spreading animals, because the rats' infestation to humans has caused the transmission of many very dangerous diseases, led by the plague, a bacterial disease transmitted From infected rodents to humans.

Correcting prejudice against city animals

Recently published in the well-established scientific journal Nature are two studies, the latest of which is reassuring and shows that rodents and other city-dwelling animals are less likely to cause the next epidemic than previously thought.

On the other hand, the other study - days before it - showed that climate change can increase the risk of new epidemics, and that global warming may provide new opportunities for viruses to jump between animals close to populated areas, and if the receiving host is close to humans, it must We are particularly concerned about that.

There's a massive scientific bias against rats and city pigeons (Pixabe).

According to a report by Agence France-Presse published on the Science Alert website, researchers at Georgetown University in the American capital studied data on nearly 3,000 mammals, and expected to discover that the mammals that are Living in urban environments has hosted more infectious viruses that humans can catch.

The researchers found that urban animals carry 10 times more types of diseases than wild animals only, compared to previous studies, which turned out to be more than 100 times!

And when the researchers corrected for this massive bias—a long-standing scientific preference for studying animals that accompany us in our cities, living under our feet rather than hiding in the rainforests—they were surprised to discover that rats were no more likely to be the source of a new human disease than other animals.

Researchers found that urban animals carry 10 times more diseases than wild (Shutterstock)

"Disease X"

Rats are larger animals than their mice relatives, weighing up to half a kilogram. Rats were a problem for the ancient Egyptians, as they infiltrated and spoiled grain silos, so the ancient Egyptian domesticated the cat because it chases and kills mice.

It is possible that rats in general pose the greatest danger to human life because of contamination of food and diseases.

Rats usually live in forests and fields, and most of them avoid approaching humans, but groups of them have been able to adapt with time to live next to humans in homes and in the fields.

"It's still a good idea to be very close to wildlife," Greg Albury, a pathology ecologist who led the study published May 2 in the Nature Ecology & Evolution Journal told AFP. in urban areas and amicably towards it".

"These urban animals are unlikely to be the source of the next 'Disease X', but they are often still the source of important and well-known diseases," he added.

"Disease X" is the name of an ingredient approved by the World Health Organization in February 2018 for any new, unknown pathogen that could cause a future epidemic.

Urban animals unlikely to be the source of the next 'Disease X' (Pixaby)

The next big threat

Albury gave an example of "leptospirosis", a bacterial disease commonly spread by rats. "Because we have been studying animals that live in cities for a long time, we know a lot about their parasites as there are relatively few unknowns there; While rural wildlife is more uncertain, it is likely to present us with the next big threat.”

Alberi explains that there are studies accusing city animals, such as pigeons and others, that they may contribute to spreading new epidemics, but he believes that this is also exaggerated due to the research bias of some researchers.

For his part, Jonathan Richardson, professor of urban ecology at the University of Richmond, said it was "still fair to describe mice as a sick sponge because humans are in constant contact with them."

Richardson emphasized that his research found that urban mice harbor more than 200 pathogens and parasites that can jump to humans, while nearly 80% of mice in some cities carry leptospirosis.

Climate change could increase the risk of new epidemics spreading through animals (Pixabe)

With climate change, we should be concerned

Alberi and his study partner, Colin Carlson, had published research - on April 28, last in the journal Nature - that showed that climate change could increase the risk of new epidemics.

They found that as animals such as bats escape to colder regions, they will mix with other species, creating new opportunities for diseases that can later infect humans.

Urban mammals could play a role in this process, Albury said.

"If a bat meets a mouse and transmits a new disease to it, then if that mouse has greater access to human areas, that provides an important pathway to humans," he added.

His research on global warming has also shown that new opportunities for viruses to jump between animals will now open up near populated areas, rather than in forests.

"The host-pathogen network is about to change dramatically, so what we now know about urban parasites is likely to become outdated quickly," Albury said.

"We need to improve monitoring of both urban and terrestrial animals so that we can determine when a pathogen jumps from one species to another, and if the receiving host is urban or close to humans, we should be particularly concerned."