Influenza virus and neurological diseases

Area of Science:

• Neurology
• Virology
• Immunology

Background:

• Influenza viruses infrequently lead to acute encephalopathy.
• Post-influenzal encephalitis, occurring weeks after infection, is hypothesized as an autoimmune response involving demyelination and vasculopathy.
• Historical associations suggest links between influenza A (Spanish flu) and Economo lethargic encephalitis, potentially leading to postencephalitic Parkinsonism.

Purpose of the Study:

• To review the neurological complications associated with influenza virus infections.
• To discuss the proposed autoimmune mechanisms underlying post-influenzal neurological disorders.
• To examine the potential role of influenza in chronic neurodegenerative diseases.

Main Methods:

• Literature review of studies on influenza and neurological complications.
• Analysis of proposed etiological mechanisms, including autoimmune responses and molecular mimicry.
• Discussion of historical and contemporary observations linking influenza to neurological conditions.

Main Results:

• The incidence of Reye's syndrome has significantly declined due to avoiding salicylates during influenza and varicella treatment.
• Inactivated influenza vaccines have been implicated in Guillain-Barré syndrome via molecular mimicry, triggering autoimmune reactions.
• The hypothesis that persistent influenza virus genes in neural cells cause chronic central nervous system degenerative diseases by inducing apoptosis remains unproven.

Conclusions:

• Influenza virus infections can trigger rare but serious neurological complications, primarily through autoimmune pathways.
• Preventive measures like avoiding salicylates and understanding vaccine-related risks are crucial.
• Further research is needed to elucidate the long-term neurological impact of influenza virus persistence in neural cells.