Why do you have to spit out your gum before the extraction of dna?

The bacteria on the gum is the reason why. In the process of making gum, there are so many things that touch it that could mess up the results of the extraction. Even if it was machines that touched it, the ingredients from gum had to be touched by humans to create it.

economic impact of malaria is estimated to cost africa $12 billion every year. this figure factors in costs of health care, absenteeism, days lost in education, decreased productivity due to brain damage from cerebral malaria, and loss of investment and tourism.

this is math not biology xd