Vancouver Sun

Mil­lions of viruses rain down on Earth ev­ery day: sci­en­tist

Univer­sity of B.C. vi­rol­o­gist a se­nior au­thor of study con­ducted in Spain

- KEVIN GRIF­FIN kev­in­grif­fin@post­media.com Biology · Bacteria · Science · Ecology · British Columbia · San Diego State University · San Diego · Spain · North America · United States of America · University of Granada · University of Granada · Granada

A sci­en­tific study has added a new vec­tor to the usual trans­porta­tion of viruses and bac­te­ria hor­i­zon­tally from per­son-to-per­son: They now can lit­er­ally fall on you from above.

Ev­ery day, more than 800 mil­lion viruses fall from the at­mos­phere and are de­posited per square me­tre at a height of 2,500-3,000 me­tres, the study found. That works out to about 25 viruses for ev­ery per­son in Canada, ac­cord­ing to Cur­tis Sut­tle, a vi­rol­o­gist at the Univer­sity of B.C. and one of the se­nior au­thors of the pa­per.

Closer to sea level, the num­bers would be even higher, Sut­tle said.

The viruses and bac­te­ria are swept up into the tro­po­sphere on dust from soil and spray from the ocean. They hitch a ride on air sys­tems mov­ing above weather, but be­low the flight paths of jet planes.

Yes, the mi­crobes are alive. But Sut­tle said they’re re­ally noth­ing to worry about.

“They’re fall­ing on us all the time,” he said in a phone in­ter­view. “For the most part, mi­crobes are our friends. We would be in­hal­ing tens of thou­sands of viruses a day.”

Viruses tend to be very spe­cific in the species they in­fect. Viruses that tar­get hu­mans would be pretty well non-ex­is­tent, he said.

“We wouldn’t need to worry about them,” Sut­tle said.

He com­pared it with go­ing swim­ming in the ocean. In a tea­spoon of wa­ter — the amount that you might swal­low dur­ing a swim — there are as many viruses as there are peo­ple in Canada. Un­less there are spe­cific con­tam­i­nants in a body of wa­ter, peo­ple gen­er­ally don’t get sick from swim­ming in the ocean.

“From our per­spec­tive, these viruses are ab­so­lutely be­nign,” he said.

The pa­per by Sut­tle and col­leagues from the Univer­sity of Granada and San Diego State Univer­sity was pub­lished in the In­ter­na­tional So­ci­ety for Mi­cro­bial Ecol­ogy Jour­nal. The data was pas­sively col­lected dur­ing the course of a year on round, slightly-small­erthan-din­ner-plate-sized col­lec­tors (each one had an ex­posed area of 667 cen­time­tres squared) in Spain’s Sierra Ne­vada moun­tains.

The study found that de­posit rates for viruses were nine to 461 times greater than for bac­te­ria.

Pre­vi­ous stud­ies, Sut­tle said, have shown that bac­te­ria col­lected in the same way will grow if added to wa­ter. Viruses are dif­fer­ent be­cause they need a spe­cific host to in­fect and grow.

Dur­ing rain and pe­ri­ods when dust from the Sa­hara was air­borne, de­posits of bac­te­ria were sig­nif­i­cantly higher than de­posits of viruses.

Sut­tle said what’s re­mark­able is that bac­te­ria and viruses orig­i­nat­ing in Europe could end up in North Amer­ica.

“One thing that has al­ways been puz­zling is that you find the same viruses and bac­te­ria ev­ery­where you look,” he said. “That’s not in­tu­itive be­cause they live in very spe­cific en­vi­ron­ments.”

The find­ings help ex­plain why ge­net­i­cally sim­i­lar mi­crobes are evenly dis­trib­uted around the planet.

One thing that has al­ways been puz­zling is that you find the same viruses and bac­te­ria ev­ery­where you look.

 ?? CANA­DIAN IN­STI­TUTE FOR AD­VANCED RE­SEARCH/FILES ?? UBC vi­rol­o­gist Cur­tis Sut­tle: “For the most part, mi­crobes are our friends.”
CANA­DIAN IN­STI­TUTE FOR AD­VANCED RE­SEARCH/FILES UBC vi­rol­o­gist Cur­tis Sut­tle: “For the most part, mi­crobes are our friends.”

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