How can we be so certain that diseases-carrying mosquitoes are bound to certain places and won’t cause a mass epidemic? How about people that come and go from countries stricken by malaria, dengue fever, etc.? Don’t they risk becoming infected and bringing the disease overseas worth them?
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Mosquitoes have a lifespan of about three weeks and can only fly at top speeds of one to one and a half miles per hour, so that naturally limits the distance they’re realistically capable of traveling.
For people traveling, most nations have vaccination requirements for entering and leaving the country — particularly in regions that are prone to such diseases.
Most diseases can’t be spread by mosquitos. Of the diseases that can be spread, almost all of them are dependent on the precise species of mosquito. So for instance Malaria can only be spread by Anopheles mosquitos. So to get a mosquito borne disease, you need to be in an area where both the disease and the right kind of mosquito are together.
So if someone with the disease goes to a new place, it is very unlikely that they get bitten by the right kind of mosquito to pass it on to someone else.
Take a look at [this map](https://apps.who.int/malaria/maps/threats/#/maps?theme=prevention&mapType=prevention%3A0&bounds=%5B%5B9.845902666780262%2C27.71913582964153%5D%2C%5B43.01310477155744%2C61.41787666916832%5D%5D&insecticideClass=PYRETHROIDS&insecticideTypes=&assayTypes=MOLECULAR_ASSAY%2CBIOCHEMICAL_ASSAY%2CSYNERGIST-INSECTICIDE_BIOASSAY&synergistTypes=&species=&vectorSpecies=&surveyTypes=&mmType=1&excludeLowerPatients=false&excludeLowerSamples=false&endemicity=false&storyMode=false&storyModeStep=0&years=2010%2C2023) showing malaria risk around the world. Notice how the risk of malara pretty much disappears above and below a certain latitude? North and south of these regions, the temperatures are too low for mosquitoes to survive year-round or for malaria to complete its lifecycle. As a result, there isn’t much opportunity for viruses like malaria to be passed from generation to generation.
Viruses like West Nile Virus are a little different, because they can pass from mosquitoes to birds then back to mosquitoes, but this risk is not as high for diseases like malaria or dengue.
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