3)      Brisk growth of cities in tropical countries has directed to congestion, urban decay, and substandard sanitation, permitting more mosquitoes to live nearer to more people.     4)      The amplification in non-biodegradable plastic packaging and redundant tires is generating new breeding sites for mosquitoes.      5)      Augmented jet air travel is serving people dirty with dengue viruses to move easily from city to city.      6)      Dengue hemorrhagic fever is as well on the upsurge. Persons who have been contaminated with one or more variety of dengue virus are at larger risk for the more harsh disease. With the rise in all types of virus, the rate of dengue hemorrhagic fever becomes more expected.