Role of respiratory viral infection in SIDS: detection of viral nucleic acid by in situ hybridization.

There is considerable evidence suggesting that respiratory viral infection is involved in the genesis of the sudden infant death syndrome (SIDS), with rates of about 20 per cent of SIDS victims compared to about 13 per cent of controls. Since the techniques used previously are prone to under-reporting from autopsy material, non-isotopic in situ hybridization (NISH) has been used to detect viral nucleic acid in lung in SIDS. Forty-five SIDS cases (30 males) were examined (age range 3 weeks-14 months, mean age 3.9 months). Thirty non-SIDS cases (15 males) were also examined (age range 5 weeks-24 months, mean age 9.0 months). Eleven of 45 (24.4 per cent) SIDS cases were positive by NISH compared to 1 of 30 (3.3 per cent) non-SIDS cases (P = 0.012). There were eight cases of adenovirus type 5, two cases of respiratory syncytial virus (RSV), and one case of parainfluenza virus type 2. The one positive control case was adenovirus type 5. Only lung parenchyma was examined here. Additional examination of the upper respiratory tract may increase the number of positive cases.