If you mean long ago, they didn't have antibiotics or vaccines so they had to treat the symptoms. This means to give something to bring down the fever, etc. Both malaria and yellow fever are carried by mosquitoes. That meant protecting people from them by draining standing water and using mosquito nets. Now there are vaccines for yellow fever and malaria.
William C. Gorgas
You have breakdown of red blood cells in malaria. your kidney produces the hormone called as erythropoitin. This helps in formation of red blood cells. This way kidney helps in fighting malaria for longer period.
I don't know what the Spanish SPECIFICALLY brought to the Americas, but I think it's a mixture of these diseases (some of them might be from the French and Anglo-Americans too, so beware) : chicken pox, smallpox, measles, STD's, diphtheria, mumps, typhus, influenza, cholera, tuberculosis, whooping cough, and malaria.
B. Malaria
Research on how to cure yellow fever was conducted by many independent doctors including my ancestor Dr. Samuel A. Mudd. Though one of the most famous doctors known for researching Yellow Fever was a Cuban doctor named Carlos Finlay. Now for your question, William Gorgas, a physician was most well known for helping fight yellow fever in Panama.
Fight Fever happened in 1994.
Fight Fever was created in 1994.
Basically, the conflict is the yellow fever virus. The virus is tearing apart cities, families, and sanity. It is a fight it stay alive, and the thing that is the killer is the virus.
Quinine.
Internal conflicts in Fever 1793 include protagonist Matilda's struggle to adapt to the changing circumstances caused by the yellow fever epidemic and her desire for independence. External conflicts arise from the epidemic itself, such as the danger and chaos in the city, the impact on the characters' relationships, and their fight for survival.
quinine
They fight against diseases
They fight bacterial infections.