Medical Microbiology

436 8 VirusesasHumanPathogen

— Coxsackievirus,groupB,withsixserotypes.

— Echoviruswith 34 serotypes.

— Enterovirusesnumbers 68 – 71.

ThegenusParechovirusincludesthespeciesparechovirustypes 1 and2.

Pathogenesisandclinicalpictures.Theenterovirusesandparechoviruses

aretransmittedperosandreplicateatfirstinthelymphoidtissueofthepha-

ryngealspace,latermainlyintheintestinalwall.Theythenreachtheir“target

organs”viathebloodstream(e.g.,CNS,muscles,heart,liver),followedby

manifestorganinfection,which,however,onlydevelopsinasmallpercen-

tageofcases.Mostinfectionsrunanasymptomaticcourse.Viremiaisalways

present,sothatevenasymptomaticenterovirusandparechovirusinfections

confereffectiveimmunity.Thecasesofmanifestinfectionfrequentlyrun

atypicalcourseswithmildclinicalsymptoms.Thesameviraltypecancause

differentsymptomsandseveraldifferentviraltypescancauseagivenclinical

symptom.Recently,severecomplicationshavebeendescribed,mainlyasa

sequeltohand,foot,andmouthdisease(HFMD,Table8. 2 )inSoutheastAsia.

Thefollowingclinicalpictureshavebeendescribedforenterovirusesand

parechoviruses(Table8. 2 ):

Diagnosis.TheavailablelaboratorydiagnostictoolsincludePCRorisolation

ofthevirusfromcerebrospinalfluid,pharyngealsmear,orlavage,withthe

bestchancesofsuccessfromstool.Serodiagnosisplaysonlyaminorrole.

Epidemiologyandprevention.Humansarethereservoiroftheentero-

viruses.Transmissioniseitherdirect(smearinfection)orinfoodandwater.

Table8. 2 EnterovirusesandParechoviruses:ClinicalSyndromes

Virustype Importantsyndromes

Polioviruses Poliomyelitis,paralysis,asepticmeningitis,encephalitis

CoxsackievirusesA&B,

echoviruses,

enterovirus 68 – 70

Meningitis,paralysis,pharyngitis(herpangina),pneu-

monia,hepatitis,maculousandvesicularexanthems,

includinghand,foot,andmouthdisease(HFMD)

CoxsackievirusB Inadditiontotheabove:myalgia,pleurodynia

(Bornholmdisease),pericarditisandmyocarditis,

pancreatitis,diabetes

Enterovirus 71 Acutehemorrhagicconjunctivitis,HFMD

Parechovirus 1 and 2 Respiratoryandgastrointestinal(“summerdiarrhea”)

infections

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Kayser, Medical Microbiology © 2005 Thieme