By ELAINE KURTENBACH and MARK STEVENSON

MITO, Japan (AP) — The number of coronavirus cases all over the world topped 20 million on Tuesday, more than half of them from the U.S., India and Brazil.
Health officials believe the actual number is much higher than that tally kept by Johns Hopkins University, given testing limitations and the fact that as many as 40% of those who are infected have no symptoms.
It took six months or so to get to 10 million cases after the virus first appeared in central China late last year. It took just over six weeks for that number to double.
An AP analysis of data through Aug. 9 showed the U.S., India and Brazil together accounted for nearly two-thirds of all reported infections since the world hit 15 million coronavirus cases on July 22.
The number of new daily cases has continued to rise in India, hitting a rolling seven-day average of 58,768. In the U.S., which has more than 5 million cases, the average has decreased since July 22nd, but remains high at 53,813 new cases a day.
In the 45 days it took reported infections to double to 20 million, the number of reported virus deaths climbed to 736,191 from 499,506, according to the Johns Hopkins count. That’s 236,685 new deaths, an average of more than 5,200 a day.
About one-fifth of reported deaths, or more than 163,000, have been in the U.S., the highest in the world.
Caseloads are still rising quickly in many other countries, including Indonesia and Japan.
In Mexico, President Andrés Manuel López Obrador, like Brazil’s Jair Bolsonaro and President Donald Trump, seldom wears a mask and has resisted calls for a strict lockdowns, saying Mexicans should be convinced to observe social distancing, not forced to do so by police or fines.
With nearly 500,000 cases and more than 50,300 deaths, Mexico has struggled with how to curb outbreaks given that just over half its people work off the books with no benefits or unemployment insurance.
A full lockdown would prove too costly for people with little savings and tenuous daily incomes, said Assistant Health Secretary Hugo López-Gatell, the president’s point man on the epidemic, noting “we do not want a solution that would, in social terms, be more costly than the disease itself.”
Mexico’s relatively high death rate results partly from the country having one of the world’s highest rates of obesity and diabetes. There has also been relatively little testing. Of all tests done, 47% are positive, suggesting that only seriously ill people are getting tests. That has hindered contract tracing.