Malaria

"Bringing to his work the utmost vitality of a strong race and the highest aspirations for economic property, albeit attained through a Homeric struggle, man in the Amazon (...) will quite soon regret his own daring, upon the destruction of all his accumulated energies. Entire waves of people from Ceará, valiant people who exemplify our national resistance and tenacity, are decimated by malaria in a short space of time! Those who do not perish, those whose uncertain fate was less brutal, these return, bearing the remains of their sickness in the form of permanent organic lesions."

"Malaria is a focal disease whose distribution is influenced by literally dozens of factors related both to human, mosquito, and parasite populations and to the environment."

"I have failed in finding parasites in mosquitoes fed on malaria patients, but perhaps I am not using the proper kind of mosquito."

"This day relenting God Hath placed within my hand A wondrous thing; and God Be praised. At His command, Seeking His secret deeds With tears and toiling breath, I find thy cunning seeds, O million-murdering Death. I know this little thing A myriad men will save. O Death, where is thy sting? Thy victory, O Grave? [Poem he wrote following the discovery that the malaria parasite was carried by the amopheline mosquito]"

"I can think of a few microorganisms, possibly the tubercle bacillus, the syphilis spirochete, the malarial parasite, and a few others, that have a selective advantage in their ability to infect human beings, but there is nothing to be gained, in an evolutionary sense, by the capacity to cause illness or death. Pathogenicity may be something of a disadvantage for most microbes."