Japan is becoming a center of concern as the coronavirus spreads globally, with the country's official infection tally suspected to be the tip of the iceberg of a much wider outbreak.

As of Monday afternoon, Japan had 263 confirmed cases of the pneumonia-causing virus, excluding those from the Diamond Princess cruise ship quarantined for weeks in Yokohama bay. In neighboring South Korea, however, infections have swelled rapidly, reaching more than 4,000 after the government tested tens of thousands of people to get a clearer picture of the deadly outbreak.

That divergence has experts — and members of the public — concerned about Japan's approach to diagnosis.