Researchers from the University of Arizona and the University of Cambridge claim to have traced Human Immunodeficiency Virus to its origin within the United States, clearing the name of the so-called “Patient Zero,” who was previously blamed with bringing the disease into the country. HIV was first reported in the United States in 1981, when five young and previously healthy gay men in Los Angeles became afflicted with cases of a rare lung infection. It was soon evident that their immune systems were not functioning as they should be. Two of the men died by the time a study was published in the same year. After the study was published, more cases of an autoimmune disorder were reported in gay male communities in California and New York, marking the beginning of the AIDS epidemic.
To trace the true origin of HIV across the United States, the researchers of the University of Arizona and University of Cambridge study had to analyze reconstructed RNA sequence samples from eight gay men who were unknowingly infected with HIV in the late 1970s. Through the methods of “RNA jackhammering,” the scientists were able to break apart degraded HIV genomes and recombine them into working RNA sequences.
Through these RNA sequences, the researchers were able to conduct a phylogenetic analysis—a process that uses the known rate of mutations in DNA or RNA and works backward in order to find a common ancestor. Using this process, researchers were able to determine that HIV entered the United States around 1970, traveling from the Caribbean to New York. From there, the virus went undetected for a decade, spreading from the East Coast to San Francisco and diversifying across the United States.
Michael Worobey, the lead author of the study, asserted in a press conference that while the RNA samples did originate from the late 1970’s, there appeared to be too much genetic diversity within them for the samples to not have been present much earlier than that in the United States. With HIV’s characteristic of remaining latent for years before progressing into AIDS, the virus’ spread was difficult to discover and ripe to spread in epidemic-level proportions.
This study clears the name of “Patient Zero,” a French-Canadian flight attendant who is often blamed as the source of HIV in the United States. Researchers were able to analyze his RNA from blood samples and found that his strain of the disease was newer than some of the other strains, meaning he was not the one to introduce HIV into the country. In fact, “Patient Zero” is not entirely accurate, reports the study. Originally referred to as “Patient 057,” he was the 57th case to be reported to the Center of Disease Control and Prevention, with the “0” being the letter “O” to denote that he was from outside of California.
Richard McKay, a co-author of the study, warns that focusing on a single patient as the cause of an epidemic can obscure larger mechanisms that are at work. The study outlines that detailed research and historical context can work in tandem to draw a fuller picture than either element would by itself.