Herpes simplex virus encephalitis in pediatrics: diagnosis by detection of antibodies and DNA in cerebrospinal fluid.

Between 1983 and 1991, 16 cases of herpes simplex encephalitis were diagnosed at the Royal Children's Hospital, Melbourne by virus isolation from the brain or cerebrospinal fluid (CSF) (2 cases), by detection of herpes simplex virus-specific IgM, IgA or IgG by enzyme immunoassay (12 cases) or by polymerase chain reaction (PCR) and herpes simplex virus-specific antibodies (2 cases). Specific antibody was detected in 4 of 13 CSF samples taken on Days 1 to 4 after onset of neurologic symptoms compared with 15 of 17 samples taken after the fourth day of illness. PCR was retrospectively applied to 20 stored CSF samples from 11 patients; 5 of 8 samples taken less than 4 days after onset of symptoms were positive compared with 2 of 12 taken after Day 4. In contrast all 5 fresh unfrozen CSF samples taken from Days 2 to 21 were positive by PCR. These results indicate that PCR is more sensitive for early diagnosis of herpes simplex encephalitis than detection of specific antibody in CSF which is most useful after the fourth day of illness.

Respiratory syncytial virus and heart block--cause and effect?

A child aged 3 years who developed a respiratory syncytial virus infection is described. His admission was complicated by the development of an irregular pulse. He initially had a variable first or second degree heart block with transient electrocardiographic evidence suggestive of pericarditis and/or myocarditis and later developed complete heart block. He has remained asymptomatic for the past four years. A search for other causes of the heart block proved negative. It is tempting to suggest an association between the acute RSV infection and the development of the heart block but such an association at this stage remains speculative.

Respiratory viruses and sudden infant death.

Viruses were shown to be present in the respiratory tract in 200 of 763 cases of the sudden infant death syndrome studied in the nine years 1974-82. Epidemiological and pathological evidence suggested that the distribution of viruses in the sudden infant death syndrome differs between infants aged 3 months or less and those aged over 3 months: the incidence of detection of virus was 14% in the younger group compared with 39% in the older group. The distribution of the viruses in these two groups was compared with that in 1341 live infants with respiratory virus infections. Adenovirus, influenza virus, parainfluenza virus, and rhinovirus had similar distribution among the victims of the sudden infant death syndrome and live controls. The incidence of detection of respiratory syncytial virus was increased in the older infants dying of the sudden infant death syndrome (90% of the cases detected) compared with the older group of live infants (53%). Antibody studies, detection of virus, and epidemiological data suggest that respiratory syncytial virus may be a precipitating factor of sudden death in older infants.

Association of respiratory virus infections with sudden infant death syndrome.

From September, 1974, to September, 1979, 488 cases of sudden infant death syndrome (SIDS) in Melbourne were studied for evidence of viral infection. One hundred and eighty-eight infants (39%) yielded one or more viruses, with respiratory viruses being detected in 102 cases (21%). Further evidence of a respiratory virus association with SIDS was obtained by comparing the monthy respiratory virus isolation rates at the Royal Children's Hospital from 1973 to 1979 with the incidence of SIDS in the same period. A highly significant correlation was obtained between these isolation rates and the incidence of SIDS, which suggests that respiratory viruses play a role in SIDS in Melbourne.