Yale epidemiologist Jordi Casals-Ariet, who studied and classified viruses such as rabies, Eastern equine encephalitis, and the Lassa virus, died in Manhattan Feb. 10 at the age of 92.

Casals-Ariet was born in Spain and served in the Spanish army. He studied at the University of Barcelona, where he served as an intern before joining Manhattan’s Rockefeller Institute of Medical Research and eventually coming to Yale.

Casals-Ariet returned to Manhattan to work at the Mount Sinai School of Medicine after he retired from Yale in 1981. His final scientific paper was published in 1998.

Durland Fish, a professor of epidemiology and public health at Yale, said he was impressed with the wide range of Casals-Ariet’s expertise.

“His accomplishments were pretty broad in the field of virology,” Fish said. “He knew a lot about a large variety of viruses. He was kind of a walking encyclopedia in that respect. There aren’t a lot of people with that kind of knowledge anymore.”

Fish said Casals-Ariet made substantial contributions to both Yale and the field of virology, especially in the 1960s and 1970s.

“He left kind of a legacy for Yale and in terms of discovery,” Fish said. “It was state-of-the-art researching, and he was right on the cutting edge.”

Charles H. Calisher, a professor of microbiology at Colorado State University, said Casals-Ariet worked meticulously to create a viral classification system. He said Casals-Ariet was an “artist” in the field of creating schemes for rapid identification, classification and diagnosis of diseases.

“Now, everything’s done with genetic sequencing,” Calisher said. “But that wasn’t possible in 1938. He used very crude techniques like complement fixation and the hemoglobin initiation test, and slowly but surely he built up what we would now call a database.” Casals-Ariet’s technique of classification evolved into the modern system of genetically dictated taxonomies.

Calisher said Casals-Ariet was not just a skilled researcher but also a humble person.

“He was a gentleman,” Calisher said. “He was hard-working and didn’t wave his own flag. He just went about his work and didn’t seem to want to get famous — although it turned out he did. He made fundamental findings, but because he didn’t toot his own horn, there may have been other people who thought he was a plodder. In fact, he was quietly leading the way.”

Casals-Ariet sometimes worked under dangerous conditions in search of information. While in Nigeria with his Yale research team in 1969, Casals-Ariet and his colleagues discovered the Lassa virus, which causes hemorrhaging and fever. The disease claimed the lives of two nurses during the research, and a third nurse and Casals-Ariet became infected. His life was saved when he received an antibody-containing plasma injection from Lily Pinneo, the infected nurse.

Calisher said Casals-Ariet’s research helped pave the way for deeper investigation into viruses.

“I worked at the [Centers for Disease Control] for 27 years,” Calisher said. “I did the kinds of things he did, but I would never have been able to do them unless he had forged the way.”

Casals-Ariet is survived by his wife, Ellen, and his daughter, Christina.