@Laotionne - Human bot flies are more common than you realize. You are more likely to have a problem with them in certain parts of the world where they are more common. One of the most popular ways the bot fly infects humans and other mammals is by attaching its eggs to mosquitoes.
Once the eggs are attached to the mosquito, the bot fly releases the mosquito and lets it go on its way. Of course, the mosquito goes in search of blood, and humans are one of its favorite feeding sites. When the mosquito bites and sucks blood, it releases the eggs and infects the person, horse or other animal it is feeding on.