History of mosquito transmitted diseases
In the past, mosquito-borne disease presented a severe problem for early western colonizers. In the upper Midwest, in the late 1800's it was essential to employ two crews for every logging campsite, since it was not strange for half of the workforce to be out at any moment with malaria.
That mosquito-transmitted blood parasite sustained to be a trouble in many parts of the U.S. into the early 1950's, when it was brought under control by eliminating the human source of infection. Humans infected with the parasite are the only cause of malaria contamination, and with the appearance of efficient medicine, window screens and an improved understanding of mosquitoes and the infection, human malaria in the U. S. was eliminated.
Malaria is not the lone mosquito-borne disease that has caused troubles in the earlier period, even into the early 1940's hundreds of cases of equine encephalitis were accounted in the mid-west and west every year. It wasn't until the 1950's nevertheless that the first human cases of mosquito-borne encephalitis were acknowledged. Even nowadays human and equine cases of encephalitis are not unusual happenings.
For example, in Colorado in 1987, 45 horse and 30 human cases of Western Equine Encephalitis (WEE) were diagnosed. Also, in the same year 6 human cases of St. Louis Encephalitis (SLE) were accounted. In 1991, 1 human and 1 horse case of WEE was reported in the very same state. In 2002 everything changed, West Nile Virus arrived in Colorado.