, ▁and ▁treatment ▁would ▁be ▁developed ▁to ▁help ▁patients ▁with ▁the ▁in fection . ▁In ▁the ▁United ▁States , ▁Cy clos por a ▁in fection ▁must ▁be ▁reported ▁to ▁the ▁Center ▁for ▁D ise ase ▁Control ▁according ▁to ▁the ▁CD C ' s ▁Report able ▁D ise ase ▁Chart ▁ ▁Pres ent ▁day ▁discover ies ▁ ▁The ▁process ▁of ▁ident ifying ▁new ▁inf ect ious ▁agents ▁continues . ▁One ▁study ▁has ▁suggested ▁there ▁are ▁a ▁large ▁number ▁of ▁path og ens ▁already ▁causing ▁ill ness ▁in ▁the ▁population , ▁but ▁they ▁have ▁not ▁yet ▁been ▁properly ▁identified . ▁ ▁Gast ro int est inal ▁path og ens ▁ ▁Many ▁recently ▁emer ged ▁path og ens ▁inf ect ▁the ▁g astro int est inal ▁tract . ▁For ▁example , ▁there ▁are ▁three ▁g astro int est inal ▁proto zo al ▁in fe ctions ▁which ▁must ▁be ▁reported ▁to ▁the ▁Center ▁for ▁D ise ase ▁Control . ▁They ▁are ▁Gi ard ia , ▁Cy clos por a ▁and ▁C rypt os por id ium , ▁and ▁none ▁of ▁them ▁were ▁known ▁to ▁be ▁significant ▁path og ens ▁in ▁the ▁ 1 9 7 0 s . ▁ ▁Figure ▁ 1 ▁shows ▁the ▁pre val ence ▁of ▁g astro int est inal ▁proto zo a ▁in ▁studies ▁from ▁the ▁United ▁States ▁and ▁Canada . ▁The ▁most ▁pre val ent ▁proto zo a ▁in ▁these ▁studies ▁are ▁considered ▁emer ging ▁inf ect ious ▁dise ases ▁by ▁some ▁research ers , ▁because ▁a ▁cons ensus ▁does ▁not ▁yet