Abstract
Opportunistic viral infections were investigated in 156 adult patients admitted over one year to a medical oncology service: 35% of the total group and 65% of those with acute leukaemia experienced viral infections, 79% of which were with viruses of the herpes group. Surprisingly few enteric viruses were recovered. Reactivation of herpes simplex virus in the brains of these immunosuppressed patients was suggested by the demonstration by nucleic acid hybridization of herpes simplex virus DNA sequences in neurones and endothelial cells in patients with evidence of past infection with virus. Acyclovir was effective in therapy and prophylaxis. Twenty-three strains from 7 patients were tested for sensitivity to this antiviral: in 3 instances clinical resistance was observed but the strains were fully sensitive in vitro, as were all other strains tested.