Medical Microbiology

Nematoda(Roundworms) 579

tlingandprominenceofperibronchialregionsinradiographs(Lo ̈fflersyn-

drome).Bloodeosinophiliaisoftenconcurrentlyobserved.Thissyndrome

maybeaccompaniedbycoughing,dyspnea,andmildfever.Duringthe

intestinalphaseoftheinfection,onlysomepatients developdistinct

clinical symptoms:abdominaldiscomfortwithnausea,vomiting,pains,

anddiarrhea.Ascaridssometimesalsomigrateintothestomach,thepan-

creaticductorthebileductsandcausesymptomsaccordingly.Infection

orfrequentcontactwithvolatileAscarisantigens(laboratorystaff!)cancause

allergies.

Diagnosis.Aninfectionwithsexuallymatureroundwormscanbediagnosed

byfindingeggsinthestool(Figs 1 0. 1 and 1 0. 13 ).MigratingAscarislarvaecan

beindirectlydetectedbymeansofserologicalantibodydetection(especially

specificIgE),butthistechniqueisseldomusedinpractice.

Therapyandcontrol.Pyrantel,mebendazole,albendazole,andnitazoxanide

arehighlyeffectiveagainsttheintestinalstagesofAscaris.Migratorystages

arenotaffectedbynormaldosagelevels.Duetothepossibilityofreinvasion

oftheintestinebylarvaemigratinginthebody,thetreatmentshouldbe

repeatedaftertwotothreeweeks.Preventivemeasuresincludesewage

disposal,improvementofsanitation,goodfoodhygienepractices(washing

fruitsandvegetables,cookingfoods,etc.)andregularanthelminthictreat-

mentofinfectedpersonsinendemicareas(seealsofilariosis,p.593).

Trichuristrichiura(Whipworm)

Causativeagentoftrichuriosis

Occurrence.Trichuristrichiuraoccursinhumansandmonkeys.Althoughthis

parasitehasaworldwidedistribution,itisfoundmostfrequently,likeAscaris

lumbricoides,inmoist,warmareaswithlowhygienicstandards(prevalence

around 2 – 90 %).Thenumberofinfectedpersonsworldwideisestimatedat

onebillion(WHO, 199 8).

Parasite,lifecycle,andepidemiology(Fig. 1 0. 13 ).Thenamewhipwormchar-

acterizestheformofthis 3 – 5 cmlongnematodewithaverythinanteriorpart

reminiscentofawhiplashandathickerposterior“handle.”Theadultnema-

todesliveinthelargeintestine,mainlyinthececum.Thefemaleslay 2000 –

14000 thick-shelled,yellow-browneggsperday.Theeggsareabout 50 –

55 lmlongandarereadilyidentifiedbytheirlemonlikeshapeandhyaline

polarplugs(Fig. 1 0. 1 ,p. 54 4).Aninfectivelarvadevelopsintheeggwithina

fewweeks.Inmoistsurroundings,Trichuriseggsremainviableformonthsor

evenyears.

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Kayser, Medical Microbiology © 2005 Thieme