features of co-infected patients” Comment on “Viral acute gastroenteritis: clinical andepidemiological INFECTIOUS DISEASES

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braz j infect dis.2013;17(1):112–113

The Brazilian Journal of

INFECTIOUS DISEASES

w w w .e l s e v i e r . c o m / l o c a t e / b j i d

Letter to the Editor

Comment on “Viral acute gastroenteritis: clinical and epidemiological features of co-infected patients”

DearEditor,

I read with interest Ferreira et al.¹ evaluation of enteric virusesco-infectionsinhospitalizedpediatricpatientswith acutegastroenteritis(AGE),andtheassessmentofclinicaland epidemiologicalcharacteristicsofthesepatients.Thisstudy wouldbevaluabletoformulatefutureplanstoimprovethe diagnosticroutineofviralAGEinhospitalsettings.Neverthe- less,Iwouldliketoshareparticularapprehensions,andclarify sometopicsinordertocontributetotheknowledgeofviral AGEco-infectionsinBrazil.

Thedetectionofpositiverotavirus(RV)sampleswascon- ducted usingmixed methodologies(enzyme immunoassay, latex agglutination and PAGE)with distinct sensitivity and specificityvalues.Theevaluationofthesemethodologiesper- formance islargely described inliterature, and the results oftenshowpoorcorrelationduetodistincttargetsandinher- entproblems.²Consideringtheabove-mentionedfinding,the largecollectionperiod(9 years),andthe limitednumberof stoolsamples, didthe authors test all sampleswith these threedifferentmethodologies?AssuranceofRVpositivityis acriticalissue,onceitisthecentralbaseofthestudy.Still regarding RV positivity, and considering the fact that the authorsusedthesensitiveandspecificmethodsofRT-PCRand PCR(standardtestsforviraldiagnosis)fornorovirus(NoV), astrovirus(AstV),andhumanadenovirus(HAdV)detection, whydidtheauthorsnotuseRT-PCRforRVdetectionorcon- firmation?

Anotherconcern isthe use ofgenericprimers toHAdV detection. Virtuallyall HAdVserotypes havebeen foundto beshed throughthe fecesand a varietyofserotypes have beendetectedinstoolsamples.Thusfar,howeveronlytwo serotypes,HAdV-40andHAdV-41(membersofvirusspecies HAdV-F) have been provenas acausative agent ofAGE.³ I understandthattheauthors conductedtheclinicalevalua- tion ofthe patientsinorder toeliminate acuterespiratory orurinaryinfectionsduetoHAdV,neverthelessthemethod described byAvéllon et al.⁴ isabletodetected47different types of HAdV. Therefore there is no guarantee that only enteric HAdV-40 and -41 were detected. In addition, sev- eral reports have described the detection of enteric HAdV

infectionsusingspeciﬁcsetofprimersforHAdV-40and-41, includinginBrazil.³

Thestudyalsoobservedasigniﬁcantdifference(p=0.03) inthe medianageofthe childrenbetweenthemono- and co-infectedgroups.Itisknownthatbreast-feedingplaysan importantroleinreduceviralgastrointestinalinfections,and could preventRVinfectioninchildrenduringtheﬁrst year oflife.Thehigherfrequencyofviral-co-infectionsobserved inolderchildrencouldberelatedtobreast-feeding.Didthe authors have access to such information in the medical recordsarchived?

Theevaluationofdiseaseseveritybetweenco-infectedand mono-infectedpatientsisaninterestingpointofthestudy.

I amvery curiousaboutthe causes ofdeaththat occurred among casesofnosocomial infection.Did the patients die duetoseveredehydration?Itispossiblethatthesynergetic actionofmorethanoneenteropathogenicvirusincreasesthe clinicalsignificanceofdiarrhealdisease.However,theresults ofastudyapplyingaclinicalseverityscoreindicatethatthe severityofdiarrhealillnessisnotreflectedintheproportion ofmixedinfections.⁵Anotherquestioncanberaised:didthe patientshavesometypeofco-morbidity,immunosuppression orimmunodeficiencythatcouldcontributetothefatality?It ispossiblethatthepresenceofco-infectionsinsuchdebilitate patientscouldaggravatethediarrhealillness.

AsstatedbyFerreiraetal.,¹fewreportsconcerningenteric virusesco-infectionsinhospitalizedchildrenareavailablein Brazil.SurveillancestudiesofAGEareimportanttodetermine theprevalenceandvarietyofviralpathogens,toinitiatetar- getedpreventivemeasures,suchasvaccineprograms,andto monitoritsimpact.

Conﬂict of interest

Authordeclaretohavenoconﬂictofinterest.

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AdrianaLuchs InstitutoAdolfoLutz,VirologyCenter,EntericDiseasesLaboratory,

SãoPaulo,SP,Brazil E-mailaddress:[email protected] Received16July2012 Accepted22July2012 Availableonline15January2013

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http://dx.doi.org/10.1016/j.bjid.2012.07.016