Researchers from Arizona State University and Ethiopia have found that adenoviruses are common among baby gelada monkeys in the Ethiopian highlands, with patterns of infection resembling those seen in human children at day care centers.
The study focused on geladas, a primate species living in large social groups. The team discovered that adenovirus infections were most prevalent in infants under 6 months old who spend much of their time close to their mothers rather than playing with other young monkeys. “This is kind of that melting pot thing you see in a day care,” said India Schneider-Crease, assistant professor at ASU’s School of Human Evolution and Social Change and core faculty member at the Center for Evolution and Medicine.
Gelada babies typically ride on their mothers during daily activities, exposing them to viruses as their mothers groom and interact with other monkeys. By the time these infants begin playing more independently, they often have already developed some immunity due to earlier exposures.
The research was conducted at a long-term field site in Simien Mountains National Park, Ethiopia, where individual geladas have been tracked since 2006. Researchers collected 248 fecal samples from 43 identified monkeys to analyze adenovirus presence throughout infant development. DNA was extracted from the samples, genomes were assembled, and positive cases for various adenoviruses were identified.
The team produced 10 complete adenovirus genomes representing seven distinct lineages; four of these lineages are considered new species. These new viral genomes have been deposited into public databases for further scientific use.
Maya Saroff, first author of the study and former undergraduate at Barrett, The Honors College at ASU, worked on this project as part of her honors thesis under Schneider-Crease’s mentorship. “I picked adenoviruses and did a literature review,” Saroff said about starting her research. She contributed to genome annotation work in Professor Arvind Varsani’s lab and helped interpret results within the context of gelada behavior alongside Schneider-Crease.
Contrary to initial expectations that infections would peak when infants began social play around six months old, the highest rates occurred earlier while infants were still closely attached to their mothers. Adult infection rates remained low during this period.
Saroff noted that “the youngest infants also had the highest number of different adenoviruses at once.” One sample from an infant just days old contained three different types of adenoviruses simultaneously. This co-infection suggests young geladas are particularly vulnerable but also points toward early exposure being important for immune system development.
Seasonal trends were observed as well: higher numbers of viruses appeared when temperatures rose. In cooler wet seasons when food is abundant, geladas stay together more often—providing more opportunities for babies to play together—while drier seasons lead groups to spread out in search of food.
Wild primates offer insight into how our own immune systems may have evolved because they mature faster than humans do; studying them allows researchers to observe virus dynamics over shorter periods than possible with human populations alone. According to Schneider-Crease: “Studying these types of natural dynamics can provide that context for us.”
Noninvasive collection methods such as fecal sampling enable scientists to gather data without disturbing animal behavior or welfare. Discovering new virus species highlights gaps in knowledge about global viral diversity and supports arguments for ongoing wildlife surveillance efforts.
For parents navigating cold and flu season, this research reinforces that infants are naturally susceptible but benefit immunologically from early exposures—whether through maternal contact or safe vaccination strategies later on. As Saroff described working with wild monkeys: “beyond cool for so many reasons.”
Arizona State University has been recognized for its innovative approaches across disciplines; it was named number one in innovation by U.S. News & World Report for eight consecutive years (https://news.asu.edu/20220911-university-news-asu-no-1-innovation-us-news-world-report-eighth-year?utm_source=twitter&utm_medium=asu&utm_campaign=ASURankings&utm_term=USNWR).
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