MENUAparasiteisdefinedasananimalorplantthatderivessustenanceand/orprotectionbylivinginoronanotheranimalorplantcalledthehost.Intestinalandtrachealparasitesofpoultryarecommonlyreferredtoas"worms,"althoughthistermistechnicallynotcorrect.Theseparasitescancausechickensinaflocktoappearunthrifty,whichoftenleadstosecondarycomplications.Insomecases,theparasitescancausemortalityintheflock.Frequentinspectionoftheflockforsignsofillnessisthebestmanagementtoolforidentifyingwhentheseparasitesareaproblem.RoundwormsRoundworms,alsocalledascarids,arethemostcommonintestinalparasitefoundinpoultry.Thesewormsarespecies-specific,sothereislittlechanceofcrossinfectionamongpoultryspeciesorfrompoultrytopetsorhumans.LifeCycleandPathogenesisThelifecycleofroundwormsisrelativelysimpleandmaytakeaslittleas35daystocomplete.Adultfemalewormslayeggsthatpassoutofthehost'sintestinaltractwiththefeces.Whileinthelitterofthehouse,theseeggsdeveloptothelarvalstage.Optimumtemperaturefordevelopmentoftheroundwormeggis90°F–93°F.Anewhostingeststhedevelopedeggsintheinfectedlitter.Thelarvaearereleasedfromtheeggandthenmaketheirwaytotheintestinaltractwheretheydevelopintheintestine'smucosallining.Larvaereturntothelumenoftheintestinewheretheybecomeadults.Wormsaresexuallymature35daysafterhatching,andtheybegintolayeggsoftheirown,thusperpetuatingthecycle.Youngpoultryareparticularlysusceptibletoinfestationbyroundworms.Birdswilltypicallydevelopimmunityfromlow-levelexposurebythetimethattheyare2–3monthsold.Birdsthatarenotimmuneandareinfestedwithsignificantnumbersofroundwormsbecomeunthriftybecausethedamagetotheintestinalliningreducesthebirds'digestiveandabsorptivecapabilities.Iftheinfestationissevere,theremayevenbeintestinalblockageduetoalargequantityofworms.DiagnosisandControlDiagnosisisbasedonnecropsyofsuspectbirdsandfindingsignificantnumbersofwormsalongwithdamagetotheintestinalliningandlossofbodycondition.Examiningfecesandfindingalargenumberofascarideggsinunthriftychickensalsosuggestsaninfestation.Simplyfindingsmallnumbersofwo