Clinical

Interferon may treat flavivirus-induced encephalitis

Last Updated: 2004-09-10 12:07:30 -0400 (Reuters Health)

By Megan Rauscher

NEW YORK (Reuters Health) - The results of a pilot study suggest that early initiation of interferon (IFN)-alfa2b may reduce the severity and duration of neurologic complications of meningoencephalitis due to St. Louis encephalitis (SLE) virus.

IFN-alfa2b has demonstrated in vitro activity against at least three members of the Flaviviridae family: hepatitis C virus, Japanese encephalitis virus, and West Nile virus, Dr. James J. Rahal from New York Hospital Queens in Flushing and colleagues note in the September 15th issue of The Journal of Infectious Diseases. These viruses are structurally and genetically related to SLE virus.

During an outbreak of severe SLE viral meningoencephalitis in Louisiana in the summer of 2001, Dr. Rahal's team treated 15 patients with confirmed SLE virus infection with IFN-alfa2b. They compared the clinical course and laboratory results of these patients with that of 17 infected untreated patients.

Treated patients initially received 3 million units of IFN-alfa2b intravenously, followed by 3 million units administered subcutaneously 12 hours later and then every 24 hours for 14 days.

After the first week of hospitalization, significantly fewer treated than untreated patients had persistent quadriplegia, quadriparesis, or respiratory insufficiency (2 of 15 treated vs 11 of 17 untreated patients).

After the second week of hospitalization, these complications were present in only 1 of the 15 treated patients compared with 5 of the 17 untreated patients.

In this pilot study, IFN-alfa2b therapy for CNS infection due to SLE was well tolerated, except for the development of transient neutropenia and/or mild hepatitis noted in 11 patients.

"There are currently no effective treatments for St. Louis or West Nile encephalitis," Dr. Rahal told Reuters Health. "Our results suggest that interferon is a possible treatment for [these] infections and we are now doing a more definitive double-blinded trial this year against West Nile virus," he added.

J Infect Dis 2004;190:1084-1087.