With millions of birds descending on Delaware Bay during migration, the propensity for bird flu (H5N1) to spread among flocks—and potentially among humans—has been a pressing concern. And as animals, from gray whales to monarch butterflies make epic treks of thousands of kilometers each year, the role of these travelers in spreading highly pathogenic diseases along the way has been a key question for ecologists and epidemiologists alike.
At first brush, a long-distance voyage might sound like an excellent opportunity for substantial disease spread. But perhaps unexpectedly animal migration might actually help keep super-pathogenic diseases in check, argued a team of researchers behind a new review paper.
“By placing disease in an ecological context, you not only see counterintuitive patterns but also understand the advantage of disease transmission,” John Gittleman, dean of University of Georgia’s Odum School of Ecology and who was not involved in the paper, said in a prepared statement.
Birds that migrate across continents tend to have a higher viral load than those that stay at home year round. But for some of those species, migrating might help to avoid the more virulent pathogens that can accumulate in one environment. Other animals might use this migratory escape method as well. For example, previous research has suggested that reindeer (Rangifer tarandus) shrug off pesky warble flies (Hypoderma tarandi) by finding new summer pastures away from where fly larvae have been shed in the spring.