Browsing by Author "Ferreira, Janca"

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    A prospective study investigating the role of respiratory viral infections in Sudden Unexpected Death in Infancy (SUDI) at Tygerberg Medico-legal Mortuary
    (Stellenbosch : Stellenbosch University., 2020-03) Ferreira, Janca; De Beer, Corena; Dempers, Johan; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Pathology. Medical Virology.
    ENGLISH ABSTRACT: Background: The current South African infant mortality rate is 22.1 per 1 000 live births with respiratory infections, pneumonia, influenza and interstitial lung infections being responsible for most infant deaths. Sudden Unexpected Death in Infancy (SUDI) includes all infant deaths between the age of 7 days and 1 year without an apparent cause before any investigation has occurred. However, cases that remain unexplained following thorough investigation are classified as Sudden Infant Death Syndrome (SIDS). SIDS is regarded as a disease in search of a cause with several interlinking risk factors. Numerous respiratory viruses have been detected from SUDI autopsy specimens, therefore, viral infections could contribute to some SUDI cases as an exogenous trigger on a vulnerable infant during a specific developmental stage. This might be due to the infants’ vulnerability to infections due to immaturities of their immune systems. Nonetheless, the exact contribution of respiratory viruses preceding death still needs further investigation. Objectives: The primary aim of this study was to investigate the role of major respiratory viruses, found in the lungs and trachea as either single or co-infections of all SUDI cases admitted to Tygerberg Medico-legal Mortuary (MLM) over a 1-year period. The secondary aim entailed collecting all the epidemiological information and other relevant laboratory data from the retrospective cases from the Tygerberg MLM (2015-2016) to assess any trends or differences between the 2 studies and to evaluate how risk factors associated with SUDI cases at the Tygerberg MLM might have differed or remained constant over 2 study periods. Finally, laboratory results from all infants aged between 7 days and 1 year admitted to Tygerberg Hospital (TBH) due to respiratory infections during the study period were retrieved in order to identify if similar single and multiple viruses were circulating in both populations. Methods: Between March 2018 and March 2019 samples were collected from 173 SUDI cases admitted to Tygerberg MLM. As part of the mandatory routine investigations into SUDI cases bacterial culture swabs were collected from the lower left and right lung lobes at autopsy to investigate the role of single and co-infections of viruses associated with SUDI. The Seegene AllplexTM RV Essential Assay one-step multiplex, real-time Polymerase Chain reaction (PCR) assay was used for the detection of 6 ribonucleic acid (RNA) respiratory viruses, Influenza A (Flu A), Influenza B (Flu B), Human Metapneumovirus (HMPV), Human Parainfluenza virus (HPIV), Respiratory syncytial virus A and B (RSVA/B) and Human Rhinovirus (HRV) from RNA extracted from lower left and right lung lobe and tracheal swabs. Tissue sections from the lower left and right lung lobes were also assessed for histology signs of infection. TIBCO Statistica® version 13.5.0 was used to identify any similarities or differences between the current prospective study and retrospective study, as well as the comparison group of infants admitted to TBH. Results: During this study multiple known demographic risk factors for SUDI, such as age (12.1 ± 9.8 weeks), male predominance, prematurity, low birthweight, cold season, bedsharing, prone sleeping position and ventilation were observed. With the AllplexTM RV Essential real-time PCR assay between 1 and 5 viruses were detected in 90.2% (156/173) of cases. RSV A/B (31.7%) and HRV (24.8%) were the most commonly detected viruses. The majority of PCR-positive cases were detected in the cold season, with a statistical significance observed for Flu A (p = 0.04), Flu B (p = 0.04), HPIV (p = 0.03) and RSV (p = 0.02) and cold season. The most frequently detected co-infection was between RSVA/B and HRV. Thirty-three cases had 2 viruses detected, 5 had 3 viruses and 1 case had 5 different viruses (Flu A - Flu B - HMPV - RSV A/B - HRV). The majority of cases had a cause of death (COD) of Infection. Furthermore, Flu A was significantly associated with the COD Infection and Flu B with SIDS. In 4 SIDS cases with positive histology, positive viral PCR results were observed leading to a change in COD to Infection. Major differences between the prospective and retrospective studies included female predominance, COD of SIDS, HRV being the most frequently detected virus and co-infection only being observed in 3 cases (Flu A - HRV, Flu B - HRV; HPIV - HRV - RSV A/B). The same viruses were circulating in SUDI cases and the comparison group. Conclusion: In cases that had a COD of SIDS, the PCR viruses detected cannot be ignored, especially when it is supported by histological signs of infection as seen during this study Therefore, the use of real-time PCR could alter a COD Classification from SIDS to Infection. However, the role of single or co-infection with respiratory viruses in SUDI cases wherein no histological sign of infection was observed requires further investigation. Future research is needed to determine the exact role of co-infections in those who succumb to SUDI, more specifically how viral interactions play a role in disease progression and severity in a vulnerable infant. Finally, research should be aimed at determining the effect of PCR-positive viral results in the absence of histology to identify the true cause of vulnerability in infants.