Though many have argued that long-distance animal migration may lend to the spread of infectious diseases such as West Nile Virus, a recent paper published in the journal Science indicates that in some cases, the contrary may be true, according to the U.S. News and World Report.
Animals such as birds and insects travel thousands of miles every year and often encounter a wide variety of pathogens during their travels. As different species cross paths, the pathogens are often spread to other animals.
However, researchers also found that traveling long distances may help animals
in the long-run, as their movements often decrease the number of parasites or bacteria in a certain area. When the animals move on from a location, they sometimes decimate a pathogen's population so significantly that the disease dies off.
"Taken together, these findings tell us that migration is important for keeping monarch [butterflies] healthy- a result that could apply to many other migratory animal species," Sonia Altizer, a co-author of the study, told the news source.
Monarch butterflies typically travel 2,500 miles every year in order to find a warmer climate during the winter, according to Monarch-Butterfly.com.