The epidemiology of dengue and West Nile virus (WNV) is based on mosquito models and their interaction with humans. Dengue has affected almost every continent and continues to represent a serious public health problem. WNV, on the other hand, is a relatively new public health problem, especially in the United States. It may be possible to model successful control efforts against globally distributed dengue into West Nile virus control right here in the United States. I was in high school when WNV hit my home state of Colorado, and I saw firsthand the impact of this epidemic and wanted to look at it retrospectively with a public health perspective. The epidemiology and natural history of these viruses begins with their close relationship. Dengue and WNV are both members of the Flaviviridae family, which includes other human pathogens such as Japanese encephalitis and yellow fever virus.13 Dengue is a positive-sense, single-stranded RNA virus, while WNV is a enveloped single-stranded RNA virus. 11, 18 An estimated 40% of the world's population is at risk of dengue and it is considered the most important mosquito-borne viral disease in the world today, with incidence increasing 30-fold over the past 50 years.11 West Nile is a more recent human disease, but is experiencing similar increases in incidence. A total of 37,000 human cases were reported between 1999 and 2013, and WNV is now the leading cause of mosquito-borne encephalitis in the United States and Canada.20 50-100 million cases of dengue occur each year.9 The WNV is more difficult to estimate because approximately 80 percent of infected people will show no symptoms.13 A new formal modeling framework has estimated that the actual global burden of dengue could be closer to 390 million infections (more than 3 times the WHO estimate... half of the document...) ....it is important to continue supporting funding. Preventive education also remains an important factor in communities affected by these diseases. I think public awareness messages and training of health workers should be a priority especially during high-risk transmission. Environmental changes (e.g. global warming) also have a major effect on mosquito and bird populations, so it is necessary find a model to predict vector fluctuations and transmission rates. Medical research priorities should be: a vaccine against dengue, a sensitive vaccine. used diagnostic testing for WNV and care beyond supportive treatment for patients. However, so far it appears that a vaccine or drug may be expensive and far from mass distribution. For all these reasons, I believe that awareness and prevention continue to be our best defenses against dengue and West Nile virus.