I understand you point, but you would have a very, very hard time doing this in Brazil. Protecting someone who is biking through multiple regions in a country like Brazil would be very hard to do with pesticides.
By the way, I'm not saying that pesticides aren't useful, and I understand entirely your point, its just that in a country like that with people scattered all over the place - including the rainforest, it's hard to eradicate the risk with just pesticides.
I agree...that isn’t going to happen. But you can reduce the incidences down to very, very low levels.
Before DDT was banned, I believe there were countries that had a 50-90% decrease in reported cases using the same kind of approaches pioneered in the fight against Yellow Fever, but using DDT spraying instead of simply draining standing water or spraying oil on it.