Coronavirus cases in China topped 81,000 on Wednesday, as the outbreak of the flu-like illness hits its ninth week. But in just six days, coronavirus cases outside of China have increased significantly, more than doubling since Friday. On Wednesday, more new cases were reported outside of China than inside the country for the first time since global health officials began tracking the virus. The spike in cases outside of China has caused investigators and researchers to fear that the infection is on the verge of becoming a pandemic.

At a Monday press conference, officials from the World Health Organization stopped short of calling the outbreak a pandemic — but they cautioned that it had the potential to become one, if the outbreaks outside of China continue to grow.

Here are the six places that have had the most coronavirus cases so far, according to the World Health Organization.

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South Korea: At least 1,261 cases, 12 deaths

South Korea is currently facing the largest outbreak outside of China and one of the fastest rates of new cases. There are now six times as many confirmed cases in the country as there were last Friday.

The majority of South Korea's cases have been reported in the city of Daegu and the surrounding area. More than 500 of the country's cases have been linked to a branch of the Shincheonji church in Daegu, according to the Korea Centers for Disease Control and Prevention. The first patient in Daegu was a member of the church, The Associated Press reported Monday.

To combat this rise, South Korean officials increased the country's virus threat rating to its highest level, granting government officials the power to implement stricter containment measures and travel restrictions. A spokesperson for the Shincheonji church has also said all 1,100 of its local churches have been shuttered, according to the AP. On Tuesday, organizers announced that Seoul Fashion Week, scheduled for next month, is canceled.

Locations such as Hong Kong and Mongolia are limiting the acceptance of South Korean nationals. The U.S. CDC has increased the travel advisory for the country to level 3, warning travelers to avoid nonessential travel.

Diamond Princess cruise ship: At least 691 cases, 3 deaths

Until this week, the Diamond Princess cruise ship had the highest number of confirmed cases outside of China. The cruise ship confirmed its first case more than three weeks ago, when a passenger tested positive for the virus after he disembarked in Hong Kong at the end of January. The ship stopped in Yokohama on February 4, and has remained there while Japanese health officials tried to quarantine healthy passengers. Nearly 700 people who were on board have since tested positive.

As the number of confirmed cases on the ship topped 500, Japanese officials faced international criticism over the effectiveness of the quarantine. In a since deleted video, a Japanese infectious disease professor reported seeing guests moving freely throughout the ship, according to the BBC. But a Japanese health official told CBS News most of the transmission occurred before the quarantine began.

The situation grew so dire that some countries, including the United States, evacuated citizens out of Japan. At least 40 of the American passengers evacuated from the ship tested positive for the coronavirus, according to the CDC.

Beginning last Wednesday, the ship began to disembark passengers that completed the 14-day quarantine and tested negative for the virus. There are no longer any passengers on board.

According to a spokesperson for Diamond Princess, less than 1,000 crew members remain on the ship. The company also implemented its own passenger restrictions for other cruises, saying that passengers who had traveled to mainland China, Hong Kong or Macau within 14 days of the start of the cruise would not be permitted to board.

Italy: At least 322 cases, 11 deaths

For more than two weeks, Italy had only three confirmed cases of coronavirus in the country. But that number began to increase exponentially at the end of last week — and now, there have been more than 300 confirmed cases and 11 deaths, according to the WHO. The Italian Ministry of Health, which is reporting more cases in real-time, has confirmed 400 cases and 12 deaths. The epicenter of the cases is in the northern region of Lombardy, home to Milan, where three-quarters of the country's total cases are located.

It's not yet clear what caused the uptick in cases. To try and stop the spread of the virus, regions with at least one confirmed case are facing increased containment measures. Soccer matches have been cancelled, and classes are suspended. In Venice, where the larger Veneto region has seen more than 30 confirmed cases, the annual festival Carnival has been cut short.

Japan: At least 164 cases, 1 death

It has been nearly six weeks since Japan reported their first confirmed case from Wuhan, China — and until this weekend, the number of total cases remained under 100. But like Korea, the number of cases spiked over the weekend and now are more than twice as high as they were a week ago. The severity of the situation in mainland Japan has been overshadowed in recent weeks, as cases began to mount on the Diamond Princess cruise ship.

The Japanese government has taken extended steps to limit public events and mass gatherings, especially in recent days as the virus has spread. The famed Ghibli Museum is closed until at least the middle of March, and a week ago, the Tokyo Marathon restricted participation to only elite runners, cutting the field of runners from tens of thousands to hundreds.

These measures pale in comparison to what looms ahead as Tokyo and national authorities prepare to host the 2020 Olympics in July. In an interview with the AP, Dick Pound, the longest-serving member of the International Olympic Committee, said there is a three-month window to decide if the Olympics will continue.

Iran: At least 139 cases, 19 deaths

The first confirmed cases in Iran were reported last week. But on Wednesday, global health officials confirmed 19 deaths from the virus — the highest number of fatalities outside China.

According to State media, that number could be much higher. On Monday, one outlet reported the death toll could be as high as 50, citing a state lawmaker from Qom, the center of the country's outbreak. Iran's health ministry has disputed this report.

In response to the outbreak, Iran has shut down schools and cultural events around the country. In the capital city of Tehran, officials are sanitizing metro stations, according to the AP. President Hassan Rouhani has also established a national headquarters to help fight the virus.

Update: The World Health Organization's daily situation report, which is the source for the remainder of this article, listed 95 confirmed cases and 15 deaths in Iran. But the Eastern Mediterranean branch of the organization released the higher numbers on Twitter, and the WHO told CBS News that the updated numbers are accurate.

Singapore: At least 91 cases, 0 deaths

Singapore reported its first coronavirus case a month ago, and the rise in reported cases has been steady since, averaging almost three new cases a day. While it's avoided the significant spikes seen in neighboring countries, its early infections brought its national total to nearly 100 cases. But there has been a positive trend in the nation, as 58 of the 91 patients have been discharged from the hospital. Only seven remain in the hospital in critical condition.

Singapore has postponed hosting an annual rugby competition until October and has enacted travel restrictions to other locations, including mainland China and most recently Daegu, the epicenter of the virus in South Korea, according to the Ministry of Health. The country is also asking Singapore nationals returning from mainland China to self-quarantine for 14 days.