Tf feem ntau muaj nyob rau hauv plasma, cov ntsiab lus nruab nrab yog li 1.20 ~ 3.25g / L. Hauv cov neeg noj qab haus huv faeces, yuav luag tsis muaj nyob. Thaum lub plab zom mov los ntshav, Tf hauv cov ntshav ntws mus rau hauv plab hnyuv thiab tawm nrog cov quav, nws muaj ntau hauv cov neeg mob plab los ntshav. Yog li ntawd, fecal Tf ua si lub luag haujlwm tseem ceeb thiab tseem ceeb rau kev tshawb pom ntawm plab hnyuv los ntshav. Cov khoom siv yog qhov yooj yim, qhov pom kev zoo uas kuaj pom Tf hauv tib neeg lub plab, nws muaj kev tshawb pom siab thiab muaj zog tshwj xeeb. Qhov kev ntsuam xyuas raws li qhov tshwj xeeb ntawm ob chav tshuaj tiv thaiv kab mob Sandwich cov ntsiab lus thiab cov txheej txheem ntsuas kub immunochromatographic tshuaj ntsuam xyuas, nws tuaj yeem muab qhov tshwm sim hauv 15 feeb.