Butterflies and Bats Reveal Clues about Spread of Infectious Disease – Science Nation

Butterflies and Bats Reveal Clues about Spread of Infectious Disease – Science Nation


SONIA ALTIZER: It amazes me that
insects that weigh a half a gram can live so long and travel so
far. MILES O’BRIEN: Up to two billion
monarch butterflies migrate every year to winter in Mexico.
That’s where ecologist Sonia Altizer goes to get a good look
at them. SONIA ALTIZER: Male, 51.55. MILES O’BRIEN: With support from
the National Science Foundation, Altizer and her team study how
long-distance migration in flying animals affects the
spread and evolution of infectious disease. In monarchs,
they study a parasite. SONIA ALTIZER: So adult
butterflies that are really heavily infected will look like
this one. This is a protozone parasite called ophryocystis
elektroscirrha, OE for short. MILES O’BRIEN: This flying
treadmill in her lab at the University of Georgia tracks
speed and stamina. SONIA ALTIZER: On average,
infected monarchs fly about 20 percent less well than healthy
butterflies. MILES O’BRIEN: We all know human
diseases can spread quickly. It only takes one infected person
hopping on an airplane, but for insects and birds, long-distance
travel often means lower infection rates. Perhaps only
the strong survive? SONIA ALTIZER: If we had to run
a marathon with the flu, we probably wouldn’t do very well.
The animals that are the most heavily infected simply drop out
of this migration en route to their wintering sites, and they
simply can’t make a long-distance journey. MILES O’BRIEN: But human
activities like habitat destruction and herbicide use
are disrupting some of these long-standing migration
patterns. SONIA ALTIZER: If we take the
migration away, and we’re left with the smaller remnant
populations that don’t migrate, we could actually see infections
build up in those populations, and that could possibly increase
the risk of pathogens jumping over into people and their
domesticated animals. MILES O’BRIEN: In Peru,
Altizer’s team studies vampire bats. Their populations have
exploded as ranchers have introduced livestock into the
Andes and the Amazon. And more bloodthirsty bats might mean
more rabies. DANIEL STREICKER: One of the
main goals we have is to try to understand what determines the
frequency and intensity of rabies outbreaks and what
can we do about it. MILES O’BRIEN: Altizer also
analyzes data and parasite samples sent in from citizen
scientists around the world. Her aim is to piece together the big
picture of how pathogens spread when their hosts take wing. For “Science Nation,” I’m Miles
O’Brien.

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