de Beer, M

Dewar, J

Elliot, E

Monaisa, P

Semenya, D

Steele, A

South African Medical Journal (SAMJ)

July 2005, Vol. 95, No. 7  SAMJSCIENTIFIC LETTERTo the Editor: Acute diarrhoeal diseases are a major publichealth problem leading to high morbidity in both developedand developing countries, with the additional burden of highmortality in the latter.  Worldwide, rotavirus infection is themost common cause of severe diarrhoea in young children,1accounting for 20 - 25% of diarrhoeal deaths in any 1 year.2   It isestimated that rotavirus infection annually causes 111 millionepisodes of gastroenteritis requiring home care, 25 millionclinic visits, 2 million hospitalisations and approximately 600 000 deaths in children under 5 years of age.3Rotavirusvaccine development and introduction is a priority in the fightto reduce rotavirus-associated mortality in the developingworld.  In South Africa, accurate rotavirus surveillance iscritical for the rotavirus vaccine trials currently underway inthis country.   Against this background of morbidity andmortality there is a need for rapid and sensitive rotavirusdetection methods in routine diagnostic laboratories, many ofwhich perform rotavirus group antigen detection using eitherenzyme immunoassay (EIA) or latex agglutination assay(LAA).4Dipstick rotavirus immunochromatographic tests(ICT) provide comparable or better sensitivity than LAA.5,6These dipstick assays make use of monoclonal antibodiesattached to a nitrocellulose solid phase and colloidal gold asindicator.  We set out to compare the sensitivity and specificity ofassays used routinely in pathology laboratories for thedetection of rotaviruses.  LAA and ICT results were comparedwith the enzyme-linked immunosorbent assay (ELISA) as goldstandard.  During May and early June 2004 a commercialpathology laboratory based in Johannesburg screened 90 stoolspecimens for rotavirus using the Diarlex LAA (OrionDiagnostica, Finland). These specimens were re-screened at theMedical Research Council (MRC)/MEDUNSA DiarrhoealPathogens Research Unit, University of Limpopo, for rotavirususing the IDEIA ELISA kit (DAKO, Denmark) and the CorisRotaStrip ICT (Coris BioConcept, Belgium).Table I shows the results obtained after screening thesespecimens with the LAA, ICT and ELISA.  We noted that of the90 specimens tested, 83% (75/90) were rotavirus-positive whenusing the ELISA.  The Diarlex LAA showed a very poorsensitivity of 57% (43/75) and a specificity of 93%, while theCoris ICT indicated an improved sensitivity of 88% (66/75) anda specificity of 100% compared with the ELISA.Pathology laboratories that routinely use LAA kits forrotavirus diagnosis should view the results of this study withconcern.  While LAA provides a rapid result, requires nospecialised equipment and is useful for testing singlespecimens, the Diarlex LAA appeared to be relativelyinsensitive when compared with the Coris ICT (57% v. 88%).The Coris ICT is a convenient, cost-effective assay with anequivalent turnaround time that could be adopted for routine,rapid rotavirus detection.  It requires no additional equipmentand is simple to perform, with easy-to-read results.It is appropriate that laboratory personnel regularly monitoravailable kits to find the most sensitive assay. Accurate andrapid diagnosis of (rota)viral infections should reduceunnecessary use of antibiotics in patients infected only with(rota)virus.  This would improve treatment – overall costswould be lowered and inappropriate use of antibiotics andresulting antibiotic resistance would be reduced.  Rapidrotavirus diagnostic capacity with a quick turnaround timewould facilitate containment of infected patients, improvinginfection control and preventing nosocomial outbreaks.We suggest that more assay validation should be routinelyand regularly performed and that the results of the validation494Medical Research Council Diarrhoeal Pathogens Research Unit, MedicalUniversity of Southern Africa, Pretoria.J DewarM de BeerD Semenya A Steele Du Buisson, Bruinette and Kramer Inc (Ampath), Johannesburg.E Elliott P MonaisaCorresponding author: johndewar_2000@yahoo.co.ukTable I. Sensitivity and specificity of the Diarlex LAA and theCoris RotaStrip when tested against ELISADako ELISAPositive Negative TotalDiarlex Latex test*Positive 43 1 44Negative 32 14 46Total 75 15 90Coris RotaStrip†Positive 66 0 66Negative 9 15 24Total 75 15 90*Specificity 93%, sensitivity 57%.†Specificity 100%, sensitivity 88%. Rapid detection of rotaviruses – are laboratoriesunderestimating infection in infants?J Dewar, M de Beer, E Elliott, P Monaisa, D Semenya, A Steelepg 494-495  6/24/05  4:11 PM  Page 494495July 2005, Vol. 95, No. 7  SAMJSCIENTIFIC LETTERprocess should, in turn, be translated into the rapid adoption ofassays providing the most sensitive assay results at that time.In addition, protocols to assess the competency of laboratorystaff may demonstrate competence but fail to discloseincompetence.7We therefore suggest that alternative and newtechnologies should continue to be investigated for adoptionby South African laboratories as they strive to improve theirservice.    We would like to thank the Medical Research Council of SouthAfrica, the World Health Organization and the Norwegian Councilfor Higher Education (NUFU) for financial assistance.  The authorsdeclare no association with the products that may constituteconflict of interest.1. Kapikian AZ, Chanock RM. Rotaviruses. In: Fields BN, Knipe DM, Howley PM, et al., eds.Fields Virology. 3rd ed. Philadelphia: Lippincott-Raven, 1996:  1657-1708.2. Cunliffe N, Kilgore P, Bresee J, et al. Epidemiology of rotavirus diarrhoea in Africa: a reviewto assess the need for rotavirus immunization. Bull World Health Organ 1998; 76: 525-537.3. Parashar U, Hummelman E, Bresee J, Miller M, Glass R. Global illness and deaths caused byrotavirus disease in children. Emerg Infect Dis 2003; 9: 565-572.4. Mitchell D, Jiang X, Matson D. Gastrointestinal infections.  In: Storch GA, ed.  Essentials ofDiagnostic Virology. New York: Churchill Livingstone, 2000: 83.5. Fernandez D, Valle I, Llamos R, Guerra M, Sorell L, Gavilondo J. Rapid detection of rotavirusin faeces using a dipstick system with monoclonal antibodies and colloidal gold as marker. JVirol Methods 1994; 48: 315-323.6. Wilhelmi I, Colomina J, Martin-Rodrigo D, Roman E, Sanchez-Fauquier A. Newimmunochromatographic method for rapid detection of rotaviruses in stool samplescompared with standard enzyme immunoassay and latex agglutination techniques. Eur J ClinMicrobiol Infect Dis 2001; 20: 741-743.7. Sharp S, Elder B. Competence assessment in the clinical microbiology laboratory. ClinMicrobiol Rev 2004; 17: 681-694.ICD-10International Statistical Classification of Diseases andRelated Health Problems Volume 1, 2 and 3ICD-10 code source books are available from the South African Medical Association’s (SAMA) Healthand Medical Publishing Group (HMPG) at very reasonable rates.HMPG is a recognised distribution agent of the World Health Organisation who publishes this com-prehensive set of ICD-10 codes.We have obtained a special discounted rate on this set, only available to South African doctors.The three-volume set contains all the codes and a tutorial on how to use the codes correctly.Thisbook set is a user-friendly quick reference guide that will help you gain the most benefit from thecodes.To take advantage of this offer, contact HMPG’s Book Department at Tel: (021) 530 6520  •  Fax: (021) 531 4126 Or e-mail:books@samedical.orgVolume 1: Members: R535.00;Non-members: R590.00Volume 2: Members: R179.00; Non-members: R199.00Volume 3: Members: R535.00; Non-members: R590.00pg 494-495  6/24/05  4:11 PM  Page 495

Rapid detection of rotaviruses - are laboratories underestimating infection in infants?

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Rapid detection of rotaviruses - are laboratories underestimating infection in infants?

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