[1] He is an internationally recognized expert in infectious disease research, with a focus on fungal and bacterial pathogenesis and basic immunology of antibody structure-function.

[6] In March 2015, Casadevall was named a Bloomberg Distinguished Professor at Johns Hopkins University for his accomplishments as an interdisciplinary researcher and excellence in teaching.

[11][12] He also serves as the Alfred and Jill Sommer Professor and Chair of the W. Harry Feinstone Department of Molecular Microbiology and Immunology at the Bloomberg School of Public Health in 2015.

Casadevall is passionate about improving the doctoral curriculum, stating that he wants to "develop a program of putting the 'Ph' [philosophy] back into 'PhD' [...] Hopkins reformed medical education 100 years ago, and now we can experiment with creating better ways of training scientists.

[14] Epstein posits that Casadevall's early life experiences, including working odd jobs unrelated to medicine, contributed to his later success.

[3] Casadevall's groundbreaking work in the field of infectious diseases has been recognized by many, including the National Institutes of Health, which presented him with a Merit Award in 2007.

"[5][15] ASM also notes that Casadevall was the first Hispanic Department Chair at the Albert Einstein College of Medicine, and has "provided exemplary training and mentoring to a significant number of minority scientists, and himself served as a role model of success.

His lab has studied host-microbe interactions with Cryptococcus neoformans, Mycobacterium tuberculosis, and Bacillus anthracis, with a focus on microbial pathogenesis and mechanisms of antibody action.

Together with Liise-anne Pirofski, he proposed the 'Damage-Response Framework' of microbial pathogenesis, a new synthesis that shifted the emphasis away from focusing on microbes as pathogens, commensals, opportunists to the outcome of host-pathogen interactions.

[30][31][32][33] The damage-response framework was the first theory of microbial pathogenesis to incorporate the contributions of both the host and the pathogen and refocused attention into the outcome of the interaction.

[34] In addition, Casadevall, in collaboration with Dr. Ferric C. Fang, has been constructive in shaping the nations approach to science, scientific misconduct,[35][36] and promotion of women and underrepresented minorities.

[44] In response to the COVID-19 pandemic, Casadevall was part of a national effort to investigate and expand the use of convalescent plasma, antibody-containing blood serum collected from patients who have recovered from the virus, as a measure to help until a COVID-19 vaccine becomes available.

[54] Casadevall has suggested that global warming could result in the emergence of new fungal diseases as natural selection could slowly increase heat tolerance in fungi to the point where they may be able to survive in human hosts.

[55] He has published more than 1,000 papers and 33 book chapters, largely in the fields of immunology and microbiology, genetics and molecular biology, biochemistry, and medicine, and more recently scientific culture and competition.