A new study published in PLOS Neglected Tropical Diseases revealed that people may be able to contract Ebola and not even know it.

A team from a group called Partners In Health, which provided medical care to people during the recent Ebola outbreak, tested 187 people in a village of 900 called Sukudu, in Sierra Leone, in an effort to see if they had been infected with Ebola at some point, Time reported.

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Researchers found that 14 participants had Ebola-related antibodies in their blood, meaning that they’d been infected with the virus, but none of these 14 people were included in the original tally of 34 local residents who had contracted the virus. This suggests that health officials missed these people because they didn't show many signs of the disease, Time reported.

These study results suggest that people could be infected with Ebola and either show no symptoms, or have different symptoms than have previously been associated with Ebola, which could change how outbreaks of the virus are handled in the future.

Symptoms of Ebola typically appear between eight and 10 days after exposure to the virus. According to the Centers for Disease Control and Prevention, current symptoms include fever, severe headache, muscle pain, weakness, fatigue, diarrhea, vomiting, stomach pain, and unexplained bleeding or bruising.

Read: How Do You Get Ebola Virus? Ways You Can (And Can't) Contract The Deadly Disease

“Because minimally symptomatic individuals were not vomiting or having diarrhea, it is highly unlikely they were a source of significant viral transmission,” said study author Dr. Eugene Richardson, according to Time. “However, they still represent an instance where the health system failed to prevent human-to-human transmission of virus.”

Source: Richardson ET, Kelly JD, Barrie MB, Mesman AW, Karku S, Quiwa K, Marsh RH, et al. Minimally Symptomatic Infection in an Ebola ‘Hotspot’: A Cross-Sectional Serosurvey. PLOS Neglected Tropical Diseases. 2016.

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