Cases of dengue fever, a viral illness transmitted by mosquitoes, are increasing worldwide. This includes areas where the disease was previously unheard of, such as France, Italy, and Chad. Health officials in Pasadena, Calif., have reported the first locally transmitted case of dengue. The Aedes species of mosquitoes, particularly the Aedes aegypti, are responsible for spreading the virus. These mosquitoes have adapted to thrive in urban areas, breeding in small amounts of stagnant water in discarded items like tires and bottle caps. As more people move to urban areas, especially in developing countries with lower-quality housing, they become more vulnerable to the virus. Additionally, climate change is affecting mosquito habitats, extending their range. Symptoms of dengue fever can range from mild flu-like symptoms to severe cases with excruciating joint pain, vomiting, and high fever. Severe cases can cause organ failure and have a mortality rate of 2-5% when treated, but 15% when left untreated. Currently, about 40% of the global population lives in areas at risk for dengue infection, with tropical countries like Brazil being the most affected. Those living in housing without proper mosquito protection are most vulnerable to dengue. Factors such as screened windows, air-conditioning, and less social interaction can reduce exposure to mosquitoes. The United States is unlikely to face a serious problem with dengue as long as living conditions remain the same. However, dengue is expected to continue spreading due to climate change and rising rates of urbanization worldwide. There is currently no specific treatment for dengue, with patients only receiving symptom management. A vaccine called Dengvaxia was previously rolled out but later caused more severe cases in vaccinated individuals. The World Health Organization recommended the use of a new vaccine called QDENGA, but it is not available in the United States. Several countries have successfully controlled dengue through aggressive measures, such as Singapore’s inspection of breeding areas and high fines for violations. Brazil and Colombia have used a bacteria called Wolbachia to prevent the spread of dengue by infecting Aedes aegypti mosquitoes.