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Foscarnet prophylaxis reduces severity but does not prevent HHV-6 encephalitis

In All, Encephalitis & Encephalopathy, Transplant Complications, Treatments - Antiviral by Kristin Loomis

A Japanese trial of foscarnet prophylaxis in cord blood transplant patients was successful in reducing severity and mortality as well as suppressing high viral loads, but it failed to prevent encephalitis. The authors note that the blood brain barrier must be inflamed to allow effective penetration of the drug into the central nervous system and speculate that the prophylaxis may have protected the meninges.

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HHV-6B reactivates first, proceeds to end organ disease faster in transplant patients

In All, Gastrointestinal, Transplant Complications by Kristin Loomis

Investigators at Fred Hutch Cancer Research Center found that HHV-6B is the first DNA virus to reactivate at a median of 3 weeks, compared to CMV, EBV and Adenovirus at 5-6 weeks. HHV-6B also peaked rapidly, unlike other DNA viruses that took 3-6 weeks to reach peak viral load. HHV-6B reactivation resulted in increased mortality after 100 days.

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Inherited ciHHV-6 increases risk of developing acute GVHD and CMV in transplant patients

In All, Cancer, ciHHV-6, Transplant Complications by Kristin Loomis

A higher prevalence of inherited virus was found in patients

Investigators at Fred Hutchinson Cancer Center determined that transplant patients with inherited ciHHV-6 were twice as likely to develop acute graft vs host disease and three times more likely to develop high level CMV viremia. Transplant patients were also significantly more likely to have inherited ciHHV-6 than donors.

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HHV-6 reactivation, monocytes and B cells are unusually elevated in cord blood transplant patients

In All, Transplant Complications by Kristin Loomis

CD8+ T cells recover but CD4+ T cells remain low

Investigators in France discovered that monocytes and B lymphocytes recover quickly and become abnormally elevated by day 75 in cord blood patients, while they remain below normal or normal in stem cell patients. Although CD8 T cells recover, CD4+ T cells remain below normal levels for six months in both groups.

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Multiple viral infections and HHV-6B increase risk of mortality in HSCT

In All, Transplant Complications by Kristin Loomis

A retrospective study of allogeneic hematopoietic stem cell transplant patients at University of Washington found that reactivation of several double stranded DNA viruses significantly increased the risk of overall mortality, as did an increased quantitative burden of viral exposure. HHV-6B conferred a significantly increased risk for overall mortality.

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HHV-6 induced amnesia after rituximab therapy for autoimmune disease

In All, CNS Dysfunction, Encephalitis & Encephalopathy, Transplant Complications by Kristin Loomis

A young woman on rituximab and two other immunomodulatory agents for the treatment of dermatomyositis developed encephalitis with severe anterograde amnesia. As the use of biologic treatments for refractory autoimmune disease has been increasing, physicians are advised to consider HHV-6 and offer prompt antiviral therapy to limit irreversible morbidity.