Rats have been seen as disease-spreaders since the time of the plague, but new research shows that rodents and other city-dwelling animals are less likely to cause the next epidemic than previously thought.
Researchers at Georgetown University in Washington DC studied data on nearly 3,000 mammals and expected to find that they hosted more viruses that could be caught by humans, because they were in such close contact.
They found that urban animals carry 10 times as many diseases as rural animals, and that more than 100 studies had been published about them.
The researchers were surprised to find that rats were not more likely to be cuttling under our feet than hiding in rainforests.
Greg Albery, a disease ecologist who led the study, said it was still not a good idea to get too close to urban wildlife.
These urban animals are unlikely to be the source of the next disease, but they are still often a source of important diseases.
The pigeon threat was exaggerated due to research bias, he said.
Because we have been studying animals in cities for so long, we know so much about their parasites that there are relatively few unknowns in rural areas.
Jonathan Richardson, a professor of urban ecology at the University ofRichmond, said it was an important study because the authors highlight the over-representation of data coming from urban mammal research.
He told Agence France-Presse that rats are still considered to be disease sponges because humans are in such regular contact with them.
According to Richardson, urban rats have more than 200 pathogens and parasites that can jump over to humans, while nearly 80 percent of rats in some cities carry the disease leptospirosis.
Last week, Albery and Colin Carlson published research showing that climate change could increase the risk of new epidemics.
They found that as bats migrate to cooler areas, they will mingle with other species for the first time and create new opportunities for diseases that could be passed on to humans.
Albery said urban mammals could play a role.
If a bat meets a rat and gives it a novel disease, and if that rat has greater access to human areas, that provides an important pathway into humans.
Global warming research showed that new opportunities for viruses to jump between animals would now take place closer to populated areas than in forests.
Albery said that the host-pathogen network is about to change so what we know about urban parasites is likely to become outdated quickly.
We need to better watch wild and urban animals so that we can identify when a pathogen jumps from one species to another, and if the receiving host is urban or in close proximity to humans, we should get particularly concerned.
Agence France-Presse
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