Commodities and shares in meat producers were among the first on the block as investors purged portfolios of assets potentially affected by the growing swine flu outbreak.
With the virus now found in Spain and the US, besides killing more than 100 people at its epicentre in Mexico, investors mulled an estimate from the World Bank last year that a flu pandemic could cost $3,000bn, reducing global economic growth by more than 5%.
The Asia Pacific region's 2003 Sars outbreak, which claimed 775 lives, is estimated to have cost $40bn in lost output.
The oil market, a bellwether for other commodities, went sharply into reverse on Monday morning, with New York crude down 5.1% at $48.91 a barrel at 11:00 GMT and Brent crude losing 6.6% to $49.27 a barrel.
Agricultural commodities could but follow, hurt both by the general prospect of economic downturn and the particular hit a slump in pig farming could do to demand for animal feed, despite reassurances from US officials that swine flu cannot be transmitted from eating pork.
Soybeans, which had been supported this month by Chinese demand for livestock feed, was amongst the worst hit. Chicago's May contract wiped out three weeks' gains to stand 4.5% lower at $9.94 a bushel.
Corn, an important source of biofuels as well as animal feed, was 3.8% down at $3.62 ¾ a bushel for Chicago's May contract, with wheat off 2.6% at $5.18 ¼ a bushel.
European contracts fared only marginally better, with London wheat for May down £1.50 at £109.00 a tonne and Paris wheat down E2.75 at E138.75 a tonne. Paris rapeseed, an alternative for soybean products in many functions, such as vegetable oil, slumped E7.50 to E293.00.
"Agri markets are getting stuffed by swine fever," a London-based trader told Agrimoney.com.
Traders also sniped at shares in potentially vulnerable equities. Shares in Hunan New Wellful, a Chinese pork producer, slumped 10% to RMB7.21.
Nonetheless, prices of pigs themselves were relatively resilient, at least in Germany, where Hanover's June contract was 5.5 cents lower at E1.50 a kilo.