Pathogenesis of dengue virus infection
Generally, when we get an infection, our bodies have an immune response for antigen clearance at that time and memory for the next infection resistance in the future.
Reversely,the immune response of dengue does not resist to the next infection, but promote the severity of the disease from dengue fever to dengue hemorrhagic fever.
However, not all dengue infection produces dengue hemorrhagic fever. There are 2 main factors affecting severity of dengue fever.
1. Dengue virus factors
– Viral load effect : the number of viruses directly have effect on target cells. The more dengue virus, the more target cell infection.
– Viral strain : Asia dengue viral strain is more virulent than American strain.
2. Patients factors
2.1 Personal factors
– Age : the disease in children is more severe than in adults.
– Gender : female tends to have more severe disease than male.
– Nutritional status : well-nutrition patients tend to have more severe disease than malnutrition patients.
– Nationality : the disease in yellow people is more severe than black people.
– Genetics : HLA class I genes relate to the severity of dengue fever.
2.2 Immunological role
– Humoral immunity/ Antibody
+Neutralizing antibody : this antibody can inhibit viral replication, activate T-cells and complement system for viral destroying. This type of antibody is often found in primary infection.
+Enhancing antibody : this antibody helps viruses entering and replicating in target cells. This type of antibody is found in secondary infection and described in pathogenesis of severe dengue fever like dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS).
– Cellular immunity
In the secondary infection with different dengue serotype, T-cell cannot inhibit viral infection completely. Viral elimination decreases, but the cytokine, especially proinflammatory cytokine e.g. TNF alpha, secretion increases. These cytokines have effect on vascular endothelium which means the severity of the disease.