Justin Bieber (Reuters files)

Justin Bieber fever looks like a full-on North American epidemic.

The teen sensation’s third studio album “Believe,” shot to the No. 1 spot in both Canada and the United States this week, giving the singer his strongest debut numbers yet.

In Canada, “Believe” sold an impressive 57,000 copies, according to Nielsen SoundScan figures. These numbers beat the 34,000 copies from his 2011 Christmas album and more than double the first-week sales of “My World 2.0” in 2010.

Legions of devoted fans picked up the disc south of border as well, making “Believe” the biggest U.S. debut of the year with sales of 374,000, according to Billboard.com.

In non-Bieber-related chart news, Neil Young and Crazy Horse’s “Americana” galloped up one to the second spot with another 18,000 in sales, beating out boy band One Direction’s “Up All Night” (6,000) in third place.

The Smashing Pumpkins’ concept album “Oceania” debuted in fourth place, just ahead of Kenny Chesney’s “Welcome to the Fishbowl” which entered the charts at No. 5.

Adele’s monster chart money maker “21” held steady in sixth spot ahead of Rush’s “Clockwork Angels” (last week’s No. 1) in seventh place. Ed Sheeran’s “+” dropped down three notches to land at No. 8.

Sitting at the bottom of the top ten this week was “Synthetica” by Metric at No. 9 , and the Rock of Ages movie soundtrack album at No. 10.

Stateside, it was Kenny Chesney (No. 2), Fiona Apple’s “The Idler Wheel Is Wiser…”(No. 3), The Smashing Pumpkins (No. 4) and The Rock of Ages soundtrack rounding out the top five.