NEW YORK (Reuters) - Oil prices tumbled for a fifth day on Thursday to their lowest level in more than a year, as new reports of novel coronavirus cases outside China spurred investor fears that the rapidly spreading outbreak could slow the global economy.

Brent crude LCOc1 dropped $1.25, or 2.3%, to settle at $52.18 a barrel, off the session low of $50.97 a barrel, which was the lowest since December 2018. West Texas Intermediate (WTI) futures CLc1 sank $1.64, or 3.4%, to $47.09, after hitting their lowest level since January 2019.

Earlier this week, for the first time since the outbreak erupted, the number of new coronavirus infections reported outside China exceeded new Chinese cases.

Other risk markets also slumped on Thursday. The S&P 500 suffered its biggest one-day point loss since August 2011 and the Dow Jones Industrial Average marked its biggest-ever one-day point drop, as investors fled to the safety of assets like Treasury bonds and gold. The slump in global equities has wiped out more than $3 trillion in value this week.

The World Health Organization warned on Thursday that no country should make the mistake of assuming it will be spared from the virus, as governments from Iran to Australia raced to contain the epidemic’s spread.

“Oil is in freefall as the magnitude of global quarantine efforts will provide severe demand destruction for the next couple of quarters,” said Edward Moya, senior market analyst at OANDA in New York.

Roughly 1 million U.S. crude futures contracts changed hands on Thursday, the busiest day of trading since early January. The benchmark has dropped nearly 14% in the last five days of trading.

Trading in oil markets suggested investors expect a prolonged period of oversupply, with demand hurt as the virus has spread to large economies including South Korea, Japan and Italy.

The crude market is watching for a salve in the form of additional output cuts by the Organization of the Petroleum Exporting Countries and its allies including Russia, set to meet in Vienna on March 5-6. The group is currently reducing supply by roughly 1.2 million barrels per day to support prices.

Consultants Facts Global Energy forecast oil demand would grow by 60,000 barrels per day in 2020, a level it called “practically zero,” due to the outbreak.

U.S. gasoline futures RBc1 tumbled as much as 5.5% to $1.3742 a gallon, the lowest since late January 2019. Heating oil futures HOc1 dropped about 0.7% to settle at $1.4892 a gallon, after hitting the lowest since July 2017.

“It makes me think that the downside here now moves from crude to products should the virus continue to grow outside of China,” said Scott Shelton, energy broker with ICAP in Durham, North Carolina.

Margins for producing distillates HOc1-CLc1 - heating oil, diesel fuel and jet fuel - have hit their lowest levels since 2017 due to fears of reduced demand.

For both Brent and WTI, the spread between December 2020 futures and December 2021, a popular trade used as a barometer for supply expectations, fell firmly into negative territory. Both spreads CLZ0-Z1LCOZ0-Z1 hit the widest levels since January 2019, signaling that erosion in demand could lead to a glut through the end of this year.

Saudi Arabia, the world’s top oil exporter, is reducing crude supplies to China in March by at least 500,000 barrels per day due to slower refinery demand following the coronavirus outbreak, two sources with knowledge of the matter said.