Emerging infectious diseases are diseases that are new, re-emerging, or drug-resistant and whose incidence in humans has increased over the past two decades or whose incidence threatens to increase in the near future. Factors contributing to the emergence of new infectious diseases are microbial adaptation and change, widespread use of antibiotics, economic development and land use, international travel and trade, demographics, and human behavior , technology and industry. An emerging infectious disease that is re-emerging is West Nile virus. Disease and PathologyWest Nile virus is an emerging infectious disease because it continues to re-emerge; showing an increase in incidence and has spread to different geographical areas thanks to modern means of transport. This virus was first identified in 1937 in Uganda, Africa and has existed in Africa and the Middle East for decades, if not centuries. But in 1999, it landed in Queens, New York, via an unknown route. The infection then continued to move across the country and has since spread to 48 states, Canada, Mexico and many other countries. Encephalitis is a serious symptom and the most common symptom in hospitalized West Nile virus patients, affecting 50% to 84% of patients. of patients; manifests itself with behavioral or personality changes such as irritability, confusion or disorientation that can progress to stupor and even coma, with changes in mental status that persist for up to several weeks. Although very serious symptoms rarely occur in infected people, about 20% of infected people have milder symptoms, which include fever, headache, muscle pain, nausea, vomiting, and sometimes swollen lymph nodes. Most (80%) infected people have no symptoms. Symptoms of W......middle of paper......previous years. In 2010 the virus was most widespread in Greece, the Russian Federation and Romania. Works Cited1. Arabi, Jamal. "Symptoms of West Nile Virus". AutoFly spray systems. 2011. 10 April 2011. .2. Dugdale, David C. West Nile Virus. March 18, 2011. .3. "Flavivirus." Wikipedia. April 14, 2011. .4. “Flavivirus Fact Sheet.” North Dakota Department of Health. April 11, 2011. .5. Torture, Gerard, Berdell Funke and Christine Case. Microbiology. Benjamin Cummings, 2009.6. “West Nile Virus Home Page.” Center for Disease Control and Prevention. March 17. 2011. .