The spread of malaria is like a two-way street.The disease is spread to humans through the bite of mosquitoes infected with malaria parasites，the most dangerous of these being plasmodium falciparum.Uninfected mosquitoes become infected with the parasite by biting infected animals.In sub-Saharan Africa and parts of Asia an estimated 300million people are infected every year，more than one million of them are children，many of whom die.Years of attempting to cure the disease with antibiotics and quinine drugs have caused the parasite to become resistant to treatment.Scientists are trying to come up with novel strategies for conquering malaria.One idea that has been around for a number of years is the creation of genetically altered mosquitoes that could be released into the environment.

What lead to the resistance to treatment of the parasite?（）