Answer:
quinine; Cinchona.
Step-by-step explanation:
So, let us analyze this question one by one in order to get the answer correctly since we are not given options to make it easier for us. We will start from the symptoms that is the fever and chills and the few Health conditions relating to the symptoms are pneumonia, Flu, Hypothermia, Malaria and so on.
Then, the person has the symptoms after "passing through a swampy area" which narrows the health condition that it might probably be a mosquito bite leading to Malaria.
The Cinchona plant contains alkaloid such as quinine which can be extracted from the bark of the plant and this can be used for the treatment.
And this make a lot of sense since Quinine extraction was done in South America first.