DSS is nearly always associated with secondary antibody response. This response is one elicited to a repeat stimulation with antigenetically related antibodies, most likely other dengue serotypes. The primary infection which might even be asymptomatic sets the stage for an allergic response from a subsequent infection that may be very serious. In cities, migrants and other poor people without piped water and good garbage disposal are much more often infected than better intergrated social neighborhoods. Old tires and discarded containers as mosquito breeding grounds are notorious.