The latest:

Global cases top 80,000 with the vast majority of cases in China, where the health commission has reported 78,064 cases on the mainland with 2,715 deaths.

Not if but when: U.S. health officials say prepare for virus to start spreading at community level.

Iran reports 95 coronavirus cases and 15 deaths, disputes Qom lawmaker from Qom's claim of higher death toll.

Italy reports total of 260 cases, including first case south of Rome and three more deaths in northern Italy.

Two Italians are first reported cases in Austria; Croatia and Switzerland each report first case.

South Korea case numbers now at 1,146, government aims to test members of church at centre of outbreak in city of Daegu.

Read why the WHO doesn't yet consider the coronavirus outbreak a pandemic.

U.S. health officials told Americans Tuesday to begin preparing for coronavirus disease to spread within the country, as outbreaks in Iran, South Korea and Italy escalated.

Iran's coronavirus death toll rose to 16 on Tuesday, the most outside China, while Italy reported its 11th death.

Worsening infections in Iran, Italy and South Korea are of particular concern, world health officials said. South Korea and Italy stepped up emergency measures to help curb the virus' global spread.

Believed to have originated from wildlife in Wuhan city late last year, the flu-like disease has infected 80,000 people and killed more than 2,700 in China. But the World Health Organization (WHO) said the outbreak there has been declining since Feb. 2.

WATCH | Iran's deputy health minister, who tested positive for coronavirus:

Iran's deputy health minister Iraj Harirchi wiped his forehead several times during a news conference in Tehran, a day before he was diagnosed with coronavirus. He is now under quarantine. Iran is one of the worst-hit countries for COVID-19, a situation the World Health Organization calls "deeply concerning." 0:31

Dr. Nancy Messonnier, an official at the U.S. Centers for Disease Control and Prevention (CDC), told reporters Tuesday that data on the virus's spread over the past week had heightened the agency's expectations of transmission within the United States.

"Disruption to everyday life might be severe," she cautioned.

While saying the immediate risk from the coronavirus in the United States remained low, another top CDC official, Dr. Anne Schuchat, said it was no longer a question of whether the virus would become a global pandemic. "It's a question of when and how many people will be infected."

Dr. Theresa Tam, Canada's chief public health officer, reiterated Tuesday that the risk of spread of the virus within Canada remains low.

Several countries suspended flights to Iran, and some of its neighbours closed their borders, while Oman's Khasab port halted imports and exports with Iran.

"It is an uninvited and inauspicious visitor. God willing we will get through … this virus," Iranian President Hassan Rouhani said in a televised speech.

Iran's deputy health minister and a member of parliament were among those infected.

Afghanistan, Iraq, Kuwait Bahrain and Oman this week reported their first cases, all in people who had been to Iran. Bahrain said it now has 24 confirmed cases.

At a road block not far from Milan where police are stopping people from getting into the communities under quarantine. Some truck with permission are allowed through - there are dozens of places like this in the region with hundereds of officers <a href="https://twitter.com/hashtag/Coronavirius?src=hash&ref_src=twsrc%5Etfw">#Coronavirius</a> <a href="https://t.co/lMqFpRYl1G">pic.twitter.com/lMqFpRYl1G</a> —@rfilippone

Iran cancelled concerts and soccer matches nationwide, and schools and universities closed in many provinces. Many Iranians took to social media to accuse authorities of concealing facts.

Tehran says U.S. sanctions are hampering its response to the coronavirus by preventing imports of masks and medicines.

Get ready, WHO says

A top WHO expert urged countries to step up preparations.

"Think the virus is going to show up tomorrow," Bruce Aylward, a Canadian and head of the joint WHO-Chinese mission on the outbreak, told reporters on his return to Geneva. "If you don't think that way, you're not going to be ready."

WATCH | WHO doctor says the world can learn from China on fighting the outbreak:

The world is not ready to handle COVID-19 but it can get ready fast if people change their mindset, WHO doctor says. 4:14

In an interconnected world, the lesson from China's "extraordinary mobilization," Aylward said, showed how aggressive public health policy steps could curb the spread of the disease, but countries with outbreaks need to act quickly.

The response should include:

Find cases quickly, treat sick patients and isolate those they've been in contact with.

Gain community acceptance of quarantines where needed.

Have materials ready to support people.

In South Korea, which has the most coronavirus cases outside China with 1,146 infections and 11 deaths, authorities were testing all the estimated 215,000 members of the Shincheonji Church of Jesus.

The country's outbreak is believed to have begun in the city of Daegu with a 61-year-old woman who is a member of its congregation. Of the 169 new cases reported in South Korea, 134 were confirmed in Daegu.

There was misery, too, for 34 South Korean newlyweds whose honeymoons on the Indian Ocean island of Mauritius became a holiday from hell after they were put in isolation.

Tourism, sport and culture impacted

In Europe, Italy is the front line with more than 280 cases, as the outbreak is spreading from its origins in the northern regions of Lombardy and Veneto.

Italy's tourist industry, which accounts for about 13 per cent of its economy, fears a plunge amid travel warnings and restrictions on soccer matches, cinemas and theatres.

Truck drivers wait to cross into Iran, after Pakistan sealed its border with Iran as a preventive measure on Tuesday. (Naseer Ahmed/Reuters)

Italian Health Minister Roberto Speranza said neighbouring countries had agreed not to close their borders, calling such a step "disproportionate … at this time."

But airlines began restricting flights to Italy, prices of protective gear skyrocketed, a planned shoot in the country for Tom Cruise's seventh Mission: Impossible movie was postponed, Milan cathedral was closed and the Venice carnival cancelled.

Switzerland, Austria, and Romania reported their first cases, all in people who had been to Italy. Algeria and Croatia also recorded their first infections.

1/8 The <a href="https://twitter.com/hashtag/COVID19?src=hash&ref_src=twsrc%5Etfw">#COVID19</a> global risk situation is changing, with several countries now reporting sustained community spread. To date, <a href="https://twitter.com/hashtag/Canada?src=hash&ref_src=twsrc%5Etfw">#Canada</a> has been able to detect and manage sporadic cases, preventing spread in the community. <a href="https://twitter.com/hashtag/coronavirus?src=hash&ref_src=twsrc%5Etfw">#coronavirus</a> —@CPHO_Canada

Spain reported its first case on the mainland, a woman from Barcelona who had also visited northern Italy, while a four-star hotel on Tenerife was in lockdown after a couple tested positive there.

In China, a total of 406 new cases and 52 deaths were recorded on Tuesday, nearly all of them in hard-hit Hubei province, at the outbreak's epicentre.

Beijing said restrictions on travel and movement that have paralyzed activity in the world's second-largest economy should begin to be lifted.

In an example of the outbreak's global ripple effects, experts said travel restrictions introduced uncertainty in the timeline for Apple's introduction of new iPhone models later this year since engineers would normally be in Asia now ironing out assembly processes.