Italy has the largest number of coronavirus cases outside China, where the outbreak started. Here are some of the factors that might have contributed to that.

How bad is the situation in Italy? 

Italy recorded 168 deaths today from the novel coronavirus, its highest single-day toll to date, pushing the number of fatalities outside China to more than 1,000.

Overall in Italy, 631 people have died from Covid-19 disease caused by the virus and 10,149 have been infected in just over two weeks.

Today's toll raised the total number of deaths outside China to 1,115, according an AFP tally.

Did the virus go undetected? 

The first person to test positive in the north of Italy who had not been to China was confirmed to have coronavirus on 21 February. 

By that stage the 38-year-old man had already infected his wife and several doctors, nurses and patients at the hospital where he had attended with flu-like symptoms three days earlier. 

Experts now think the virus may have been present and spreading in northern Italy since at least the second half of January.

Does Italy have an old population? 

Dr Giovanni Rezza, head of infectious disease at the National Institutes of Health, has attributed Italy's high death rate to the fact that the country has the world's oldest population after Japan.

Most of those who have died are elderly with previous health issues.

For that very reason the high death rate is not surprising, said Professor Marina Della Giusta from the department of economics at the University of Reading. 

"The little we know so far of this virus is that it has much higher mortality rates for older people, at least that's what the Chinese data suggests so far. 

"Italy is the oldest country in Europe probably so that won't be surprising. The demographic affected is way bigger than it would be in lots of other places." 

Could Italy's sociable, outdoor culture be a factor? 

Italians generally enjoy the great outdoors and have a tactile culture, said Prof Della Giusta. 

She said: "The interpersonal physical space in Italy is a lot shorter than it is in [the UK or Ireland]. 

"Their habit is to kiss each other when you say hello. 

"There is higher physical contact anyway around the Mediterranean between people and people are outdoors more at this time of year than they are in other parts of Europe, where it's still a bit colder." 

Did movement not stop when schools were shut? 

Professor Della Giusta, who is originally from the Piedmont region in the northwest of the country, said many people did not take self-isolation measures very seriously when schools were first closed in northern regions a few weeks ago. 

"When schools got shut in Lombardy a lot of people just took their kids and went off on holiday to their holiday homes in the mountains and at the seaside in the other regions. 

"They thought they were making their kids safe by taking them away, but this kind of behaviour is really very damaging." 

Will the latest, more extreme measures work? 

Some experts have described the country-wide lockdown as not only unprecedented, but also unsustainable. 

Professor John Edmunds from the London School of Hygiene and Tropical Medicine said it will probably only have a short-term impact. 

"If they can't be sustained for the long term, all they are likely to do is delay the epidemic for a while," he said. 

But Prof Della Giusta said Italy's current measures are "excellent" and "entirely appropriate". She said the government had reacted too slowly initially.