Final answer:
Compound 606, also known as Salvarsan, was the first drug available for use against parasitic infections. Since then, other drugs have been developed to treat different types of parasitic infections.
Step-by-step explanation:
The first drug available for use against parasitic infections was compound 606, also known as Salvarsan. It was developed by Paul Ehrlich and Shichiro Hata in the early 1900s to treat syphilis, caused by the bacterium Treponema pallidum. This marked the beginning of strategic drug discovery to combat infectious diseases.
Since then, several antiprotozoal and anthelminthic drugs have been developed to treat various parasitic infections. For example, atovaquone and proguanil are used to treat malaria, and praziquantel is used to treat parasitic tapeworms and liver flukes.
Overall, the development of drugs to treat parasitic infections has been an ongoing process, with new drugs constantly being discovered or repurposed for this purpose.