Inprenataldiagnostics,PCRisseeingincreasingusefordirectdetection
ofpathogensintheamnioticfluid.DetectionofToxoplasmaDNAwiththis
methodisareliablesignoffetalinfectionanddemandsachemotherapeutic
orotherresponseaccordingly.Diagnosisofprenataltoxoplasmosisinneo-
natesisdifficult,buthighlyimportant.SinceIgGantibodiesaretransmitted
frommothertochilddiaplacentally,detectionoftheminthechildcannot
serveasadefinitivediagnosticindicator.IgMisonlypresentinabout 50 %
ofprenatallyinfectedchildren.Insuspectedcases,thebloodorcerebrospinal
fluidshouldbyexaminedusingthePCR.
Therapy.Thefollowingcasesrequiretreatment:acuteorsubacute,sympto-
maticinfectionsinchildrenandadultsaswellassymptomaticorasympto-
maticprimaryinfectionsinpregnantwomen.Inanacuteprimaryinfection
duringpregnancy,theriskofinfectionforthedevelopingfetuscanbeelimi-
natedbystartingchemotherapyimmediately.Severaldifferenttherapeutic
schemesarerecommendedforthisindication.Forexample,spiramycindaily
forfourweeksfromdiagnosistotheendofthe 15 thweekofgravidity,andin
theperiodbeginningwiththe 16 thweekofgraviditypyrimethaminedailyfor
fourweekstogetherwithsulfadiazineandfolicacid.Therecommendations
alsovaryfortreatmentoftoxoplasmosisinAIDScases,e.g.,pyrimethamine/
sulfadiazineorpyrimethamine/clindamycin.
Epidemiologyandprevention.Humansbecomeinfectedbyperoralinges-
tionofrawmeatcontainingcystsorbyuptakeofsporulatedoocysts.T.gondii
isalsotransmitteddiaplacentallyandbytransplantationofinfectedorgansto
uninfectedrecipients.
InEuropeabout 1 – 6 %ofdomesticcatsareoocystexcreters.Sheepand
goatsarefrequentlyinfectedwithtoxoplasmas;infectionprevalencesof
pigshavedecreasedsignificantlyinpigfarmswithhighhygienicstandards
asdemonstratedinrecentstudies.Cattlehavealwaysbeenconsideredrare
carriers,butrecentlyinSwitzerlandToxoplasmaDNAwasfoundusingPCRin
1 – 6 %oftheanimalsexamined(n=350).Theepidemiologicalsignificanceof
thesefindingshasnotyetbeenclarified.Certainwildanimalspecies(e.g.,
wildboars)arerelativelyfrequentlyinfected,notsohorsesandchickens.
Milkandeggsarenotconsideredsourcesofinfection.
Toxoplasmacystsremainviableandinfectiousinmeatforuptothree
weeksat 48 C.Deep-freezingto–20 8 Ckillsbradyzoiteswithinthreedays,
heatingto 708 Cislethaltothemwithinafewminutes.Toxoplasmaoocysts
showconsiderableenvironmentalresistance,butcanbekilledrapidlyby
heat(7 08 C).
Pregnantwomenshouldeatonlymeatthathasbeenthoroughlyheated
ordeep-frozen.Closecontactwithcatsshouldbeavoided.Catlitterboxesin
thehouseshouldbecleanedoutdailyandflushedwithboilingwater(wear
rubbergloves!).Catscanbefedcanned(boiled)meattoprotectthemfrom514 9 Protozoa9
Kayser, Medical Microbiology © 2005 Thieme