Lassa fever Flashcards
What is the Pathophysiology of lassa fever?
• Infectious dose appears to be low (1 - 10
viruses)
• Multiple portal of entry- oral, mucous
membrane, Parenteral, Inhalation, sex.
• Pantropism- virus affinity for α-receptor
present in most blood vessels thus making
most organs vulnerable to viral invasion
• Virus is taken up by antigen presenting cells-macrophages , dendritic cells in tissues
• The antigen particles are then presented to the Helper T cells(mostly TH1)
• The TH1 cells then releases IL-2 and IFN-γ which in turn activates macrophages to release IL-1 and TNF- α
• This results in endothelial activation, leukocyte recruitment and increase vascular permeability leading to the widespread clinical manifestations
seen in Lassa fever.
• Haemorrhagic manifestations therefore occur as a result of DIC, Liver failure, thrombocytopenia, severe platelet dysfunction accompanying the endothelial dysfunction.
• Increased vascular permeability is the primary defect and may result in facial flushing, periorbital edema and necrosis and haemoorhage in most body organs
• Down regulation of the humoral immune system is also believed to play a role in its pathogenesis.
• Patient who died from Lassa fever have
significantly lower titres of specific antibodies than survivors
• Another hypothesis is the ability of virus to inhibit and resist IFNs (anti viral) leading to unchecked multiplication of the virus in various tissues resulting in multi-organ damage, shock and death.
