Medical Microbiology

&Otherspeciesinfectinghumans

Brachiola(formerlyNosema)connori(disseminatedininternalorgans),No-

semaocularum(cornea),Microsporidiumafricanum,M.ceylonensis(cornea),

Vittaformacorneae(formerlyNosemacorneum)(cornea),Pleistophorasp.

(skeletalmuscle),Trachipleistophorahominis(skeletalmuscle,nasalmucosa),

andTrachipleistophoraanthropophthera(cardiacandskeletalmuscle,liver,

brain).

Epidemiology.LittleisknownabouttheepidemiologyoftheMicrospora.

Theirsporescanremainviableoutsideofahostforseveralweeks,arerela-

tivelyheat-resistant,andarekilledby 70 %ethanolin 10 minutes.E.cuniculi

hasareservoirinanimals;isolatesofthisspeciesfromrabbitsandhumans

aremorphologically,immunologically,andgeneticallyidentical.Pigs,dogs,

andcatscanfunctionascarriersandexcretersofE.bieneusi,butthegeno-

typesofanimaloriginareoflittle—ifany—significanceforhumans.

Diagnosis.DirectdetectionoftheMicrosporaandidentificationtakinginto

accountspecies-specificcharacteristics(seeFigs.9. 11 g, 9.20c).Encephalito-

zoonandNosemaspeciescanbegrownandconcentratedinculturesinvar-

iouscelltypes.Materialobtainedinthiswaycanthenbeusedtoidentify

speciesorstrainsusingantigenorDNAanalysis.InvitroculturingofEnte-

rocytozoonhasnotsucceededyet.Serologicalantibodyassaymethodsare

stillbeingevaluatedanddonotcurrentlyplayasignificantroleindiagnostic

practice.

Therapyandprevention.Accordingtocasereports,treatmentwithalbenda-

zoleisclinicallyandparasitologicallybeneficialinenteralandsystemicin-

fectionswithEncephalitozoonspecies;thesubstanceis,however,lesseffec-

tiveagainstEnterocytozoonbieneusi.Nitazoxanidewasreportedtobeeffec-

tiveinsinglecasesagainstthislatterspecies.

Balantidiumcoli

Causativeagentofbalantidiosis

Balantidiumcoliisaworldwidedistributedciliateofhighlyvariablesize(30– 150 lm

long).Itisfrequentlyfoundasaninhabitantofthelargeintestineofmonkeys,rats,

andinparticularpigs.Itisalsofound,morerarely,inhumans,inwhomitoccasion-

allycausesintestinalnecrosisandinflammationwithulceration.Thediseaseistrans-

mittedthroughsphericalcysts(40– 60 lm)fromhosttohostonthefecal-oralroute.

Diagnosisinvolvesdetectionofcystsorvegetativeformsinfecalsamples.Drugs

recommendedfortreatmentaretetracyclinesandmetronidazole.

542 9 Protozoa

9

Kayser, Medical Microbiology © 2005 Thieme