Profiling the approach to the investigation of viral infections in cases of Sudden Unexpected Death in Infancy (SUDI) in the Western Cape Province

Burger, Marilize Cornelle (2011-03)

Thesis (MScMedSc)--University of Stellenbosch, 2011.


ENGLISH ABSTRACT: Sudden Unexpected Death in Infancy (SUDI) refers to any such sudden demise in a child. If the child dies while asleep within the first year of life, and if no conclusive cause of death can be ascertained by means of complete autopsy and investigation into the circumstances surrounding death, including visit of the death scene, such a case is classified as one of Sudden Infant Death Syndrome (SIDS). By South African law, a full medico-legal autopsy is mandated in cases where the cause of death is not evident – including cases of possible SIDS. There can be little doubt that viral infection can be a cause of death in cases of supposed SUDI. At the Tygerberg medico-legal (forensic) laboratory, the evaluation of lung tissue for the presence of fatal viral lung infections forms part of the institutional protocol for the examination of SUDI cases. Lung samples of these SUDI cases are routinely tested for the presence of Cytomegalovirus (CMV), adenovirus and respiratory syncytial virus (RSV) by means of shell vial cultures. In a retrospective pilot study of 366 SUDI case files from Tygerberg Hospital, Western Cape, from 2004 – 2006, it was evident that in only 13.9% of possible SIDS cases, positive results for one or more of the aforementioned viruses were obtained. We hypothesise that the current method of virus detection, together with other factors such as the interval between death and post mortem examination, transport time of the specimens to the laboratory etc. might not be optimal to give a realistic picture of death in infancy caused by viral pulmonary infection. As other test modalities exist for the diagnosis of pulmonary viral infections, these methods were compared in terms of positive yield and association with viral pneumonitis, keeping the cost and time needed for each assay in mind. A total of 82 samples were collected over an 8 month period and routine shell vial cultures were done, followed by real-time Polymerase Chain Reaction (PCR) and immunohistochemical (IHC) staining of the lung sections with consensus pathology opinion. As expected, the real-time PCR method was much more better suited for identifying positive samples than shell vials (35% vs. 3.7% respectively). IHC staining also aided the pathologist in diagnosing viral infections microscopically. We expect the findings to be instrumental in streamlining not only our institutional SIDS investigation protocol, but also the development of a standardised national SIDS investigation protocol.

AFRIKAANSE OPSOMMING: “Sudden Unexpected Death in Infancy” (SUDI) verwys na enige skielike sterfte van ‘n kind. Indien die kind sterf tydens sy/haar slaap periode en geen oortuigende oorsaak van dood bepaal kan word deur middel van ’n volledige nadoodse ondersoek en ondersoek na die omstandighede tydens die dood, insluitend ’n besoek aan die doodstoneel nie, word so ’n geval as Wiegiedood (SIDS) geklassifiseer. SuidAfrikaanse wetgewing vereis ’n volledige medies-geregtelike nadoodse ondersoek in gevalle waar die oorsaak van dood onbekend is – insluitend gevalle van moontlike Wiegiedood. Daar is min twyfel dat virusinfeksie ‘n oorsaak van, of bydraende faktor tot dood kan wees in gevalle van moontlike SUDI. By die Tygerberg forensiese laboratorium vorm die evaluasie van long weefsel vir die teenwoordigheid van dodelike virusinfeksies deel van die institusionele protokol vir die ondersoek van SUDI gevalle. Long monsters van hierdie SUDI gevalle ondergaan roetine toetse vir die teenwoordigheid van sitomegaalvirus, respiratoriese sinsitialevirus en adenovirus deur middel van selkulture (“shell vial cultures”). In ‘n retrospektiewe steekproef van 366 SUDI gevalle by Tygerberg Hospitaal, Wes-Kaap van 2004 – 2006, is bevind dat in slegs 13.9% van moontlike SUDI gevalle die teenwoordigheid van een of meer van bogenoemde virusse bevestig kon word. Ons hipotese is dat hierdie metode van virus deteksie, tesame met ander faktore soos die tydsinterval tussen dood en nadoodse ondersoek, tyd om monsters na die laboratorium te vervoer ens. moontlik nie optimaal is om ‘n realistiese beeld van dood in babas as gevolg van pulmonale virusinfeksie te gee nie. Aangesien ander toets modaliteite bestaan vir die diagnose van pulmonale virusinfeksies, is hierdie metodes vergelyk in terme van positiewe opbrengs en assosiasie met virale pneumonitis, teen ’n agtergrond van die koste en tyd benodig per toets. ’n Totaal van 82 monsters is oor ‘n 8 maande periode versamel en roetine selkulture is gedoen, gevolg deur “real-time” Polimerase Ketting Reaksie (PKR), asook immunohistochemiese (IHC) kleuring van long snitte met patologiese verslae. Soos vermoed, is gevind dat die real-time PKR metode baie meer akkuraat is om positiewe monsters te identifiseer as roetine selkulture (35% vs 3.7% onderskeidelik). IHC kleuring het ook mikroskopiese diagnose van virale infeksies deur die patoloog vergemaklik. Ons verwag dat hierdie bevindinge grootliks kan bydra in die vaartbelyning van ons institusionele SIDS ondersoek protokol, asook in die ontwikkeling van ’n gestandaardiseerde nasionale SIDS ondersoek protokol.

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