Profiling the approach to the investigation of viral infections in cases of sudden unexpected death in infancy in the Western Cape Province, South Africa.

Background: Sudden unexpected death in infancy is one of the main contributory factors to high infant mortality rates world-wide. Several risk factors, including viral infection, have been implicated in SUDI cases, but no single factor has been confirmed as the main cause of death. At the Tygerberg Medico-legal Laboratory, Cape Town, South Africa, investigation of lung tissue for viral infection forms part of an institutional protocol for the examination of cases of sudden unexpected death in infancy.

Methods: Lung tissue from 82 cases of sudden unexpected death in infancy was collected over a 10 month period. Routine shell vial cultures and histological examination of the tissue were performed according to the standard institutional protocol on fresh and formalin-fixed tissue, respectively. In addition, real-time polymerase chain reactions and immunohistochemical staining for adenovirus, cytomegalovirus and respiratory syncytial virus were done on fresh and formalin-fixed lung tissue, respectively.

Results: Huge variation was found in the number of positive cases confirmed by shell vial culture, real-time polymerase chain reaction and immunohistochemistry (0, 2 and 0 for adenovirus; 3, 29 and 2 for cytomegalovirus; and 0, 0 and 4 for respiratory syncytial virus, respectively).

Conclusions: In the absence of a National Protocol for investigation of sudden unexpected death in infancy, we conclude that the selection of viruses and routine diagnostic technique included in the institutional investigation protocol might be suboptimal and should be re-evaluated.