An ongoing outbreak of Cyclospora, a parasitic infection that causes severe gastrointestinal distress, has affected more than 18,000 people across 45 states and led to over 400 hospitalizations since May. While the exact source of the outbreak remains unidentified, public health experts are discussing an unlikely but theoretically possible mode of transmission: person-to-person spread via contaminated surfaces.
Cyclospora typically spreads through the fecal-oral route, meaning individuals become infected by consuming food or water contaminated with human feces. The parasite requires one to two weeks to mature in the environment after excretion before it becomes infectious. This maturation period is a key reason why direct person-to-person transmission is generally considered unlikely by health authorities, including the Centers for Disease Control and Prevention (CDC).
However, experts speaking to the Daily Mail have outlined a scenario where fomite transmission, or transmission via contaminated objects, could occur. This would involve an infected individual not washing their hands adequately after using the restroom and subsequently touching a surface, such as a handrail on public transport. If the parasite's eggs remain on the surface long enough to mature into their infectious form, another person could pick them up on their hands and become infected by touching their mouth. "Theoretically, yes – if the parasite survives and ends up in someone's mouth," said Dr. Kelley Steury, a public health specialist. Dr. Omer Awan, a physician and public health contributor, added that while "a lot of things would have to go right for that to occur," transmission is "biologically possible."
This theoretical transmission route is reminiscent of early concerns during the COVID-19 pandemic, when surface transmission was a significant focus. However, subsequent evidence indicated that airborne transmission was the primary mode of infection for the coronavirus.
Cyclospora parasites are known for their durability and ability to survive in various environmental conditions for weeks. This resilience, coupled with their environmental maturation period, allows them to persist before becoming infectious. Dr. Brian Labus, an infectious disease epidemiologist, noted that if indirect person-to-person spread were confirmed, it would challenge current understandings of the organism's biology, which is based on a cycle requiring external maturation. "If it didn't do that, we would see a lot of cases of this every single year — way more than what we're seeing in this outbreak," he explained.
Despite the alarming theoretical possibility, experts emphasize that this mode of transmission is not a cause for widespread panic. "It appears scary, but I think we can all get through this," Dr. Awan stated, urging against alarm while acknowledging the ongoing investigation into the outbreak's origins.