Epidemiologic and other studies indicate that risk factors for severe dengue include secondary infection with a heterologous serotype
, the strain of infecting virus, and age and genetic background of the host.
Several lines of evidence point toward secondary infection by a heterologous serotype
as one of the critical risk factors for DHF (1), underscoring the need to monitor circulating DENV serotypes and genotypes.
However, children approximately [greater than or equal to] 5 years of age have higher virus neutralization antibody titers than those 1-2 years of age (25), which suggests that reinfections may occur frequently, most likely with the viruses from the heterologous serotype