Hostscan bediseasedfromlatencycondition by thedecreasingofhost's immunity and stimulation of condition, and soon , thenbecome a carrierandinfectioussource.
Immunity to dengue is low in Singapore's population because of the intensive dengue-carrier controls, "making the population vulnerable to outbreaks, " said Ng Lee Ching, director of the Environmental Health Institute at Singapore's National Environment Agency.