Trichinella spiralis is the smallest known nematode parasite of humans. The males measure about 1.4 mm to 1.6 mm in length and the females are twice the size of ...AnimalDiversityWebUniversityofMichiganMuseumofZoologyUniversityofMichiganHomeAboutUsAboutAnimalNamesEducationalResourcesSpecialCollectionsGlossaryBrowseAnimaliaMoreInformationAdditionalInformationEncyclopediaofLifeTrichinellaspiralisFacebookTwitterByGingerHartwellGeographicRangeHabitatPhysicalDescriptionDevelopmentReproductionBehaviorCommunicationandPerceptionFoodHabitsPredationEcosystemRolesEconomicImportanceforHumans:PositiveEconomicImportanceforHumans:NegativeOtherCommentsContributorsReferencesGeographicRangeTrichinellaspiralisisprevalentinMexico,thenorthernhemisphere,partsofsouthernAsia,Africa,SouthAmerica,andtheMiddleEast.Thespeciesisalsofoundinothertropicalregions.(Olsen,1974;RobertsandJanvoy,1996)BiogeographicRegionsnearcticpalearcticorientalethiopianneotropicalHabitatTrichinellaspiralishasanextremelybroadhostrange;almostanyspeciesofmammalcanbecomeinfected.Adultwormslivearoundthecolumnarepithelialcellsofthesmallintestineandthelarvaeliveinstriatedmusclecellsofthesamemammal.Therearethreedifferentecologicaltypesoflifecycles,theurbancycle,thesylvaticcycle,andthemarinecycle.Intheurbancycle,ratsandpigsserveashostsandreservoirsoftheparasite.Humanscanbecomeinfectedwiththewormbyeatingporkthatisnotcookedthoroughly.Inthesylvaticcycle,predatorsandscavengersarehoststoT.spiralis.Seals,walruses,whales,andpolarbearsareallhostsinthemarinecycle.(Lapage,1957;;Olsen,1974;RobertsandJanvoy,1996;Wassom,1988)HabitatRegionstemperatetropicalpolarterrestrialTerrestrialBiomestundrataigadesertordunesavannaorgrasslandchaparralforestrainforestscrubforestmountainsOtherHabitatFeaturesurbansuburbanagriculturalPhysicalDescriptionTrichinellaspiralisisthesmallestknownnematodeparasiteofhumans.Themalesmeasureabout1.4mmto1.6mminlengthandthefemalesaretwicethesizeofthemales.Thebodyofthewormismoreslenderattheanteriorthenattheposteriorend.In