[1][2] Wirth is one of the world's leading malariologists, dealing with how the genus Plasmodium has evolved in terms of population biology, drug resistance, and antigenicity.

[4] Wirth's lab identified the cytochrome B gene of the avian malaria species Plasmodium gallinaceum in 1989, as genetic study of the parasite was in its early days.

[5] In 1993 the labs of Wirth and Kamini Nirmala Mendis published the first successful use of the electroporation method to insert new DNA sequence into a malaria cell (also Plasmodium gallinaceum).

[6] Wirth was awarded the American Society of Tropical Medicine and Hygiene's Bailey K. Ashford Medal, given for distinguished work in tropical medicine, in 1995, and the Joseph Augustin LePrince Medal, for contributions to malariology, in 2015.

[8] In 2021 she was awarded the American Society of Tropical Medicine and Hygiene's Walter Reed Medal.