Fears about the fallout from a potential Ebola outbreak hammered stocks in the travel and leisure sectors on Tuesday with UK-listed airlines and tour operators dropped sharply.In contrast, supermarket and mining stocks were bucking the trend with the two sectors, which have both bore the brunt of the selling pressure over recent weeks, the only categories to trade in positive territory in afternoon trade in London.News that a Madrid nurse has caught Ebola spooked investors across Europe on Tuesday, given that she is the first to contract the deadly virus outside West Africa.Anglo-Spanish airline conglomerate IAG was among the worst performers in London, down nearly 6% on fears on how any potential contagion could affect business.Other airlines were also flying firm lower, such as Easyjet, Ryanair and even Fastjet despite reporting record passenger numbers for September. All three stocks were down at least 4.1%.Travel tour operators TUI Travel and Thomas Cook were down 3.4% and 4.5%, respectively, while hotel group IHG fell 2.6%.Leading the upside were grocery stocks as they continued to claw their way back after a string of profit warnings and an accounting scandal at Tesco hammered sentiment last month.Shares in the UK's largest retailer were trading nearly 5% higher after the news that the company has asked another senior manager to step down as it attempts to rebuild confidence and repair trust among its shareholders.The stock had lost 25% of its value in the two weeks following after 22 September when Tesco revealed that first-half profit guidance was overstated by £250m.The reported departure of Kevin Grace, commercial director, will bring the total of senior executives leaving the company to five.As for the miners, the revelation that Glencore had approached Rio Tinto about a "possible combination" in the summer gave the sector a boost, even though the latter turned the offer down.The deal, which Rio claimed "was not in the best interests" of its shareholders, would have created the biggest mining company in the world with a market value estimated to be $160bn, surpassing that of BHP Billiton ($154bn).Others in the sector, such as Anglo American, Randgold Resources, Lonmin, Kazakhmys and Centamin, were also performing well.Top performing sectors so far todayFood & Drug Retailers 2,582.68 +2.86%Industrial Metals & Mining 1,297.88 +2.45%Mining 15,863.98 +1.55%Bottom performing sectors so far todayOil Equipment, Services & Distribution 21,262.24 -2.27%Travel & Leisure 7,079.99 -2.08%Technology Hardware & Equipment 1,051.57 -1.92%Aerospace and Defence 4,702.79 -1.64%Forestry & Paper 10,669.03 -1.54%