FAIRLEE — Camp Billings, a sleepaway summer camp on Lake Fairlee, is ending its season early due to a rapidly spreading gastrointestinal virus, camp administrators announced this week.

The camp, which serves children ages 8 to 15, informed families on Monday that the current session, will end on Wednesday — three days ahead of schedule. A viral infection, believed to be a norovirus, began spreading “at an exponential rate” last week through the camp, infecting both campers and employees, directors Sean and Anne Collins said in written statement.

Camp operators decided to end the camp session after discussions with the Vermont Department of Health and the camp’s nursing staff, the Collins said in a letter to families.

“While this is heartbreaking for everyone involved, it is clearly the best option for our Billings families,” they said in the statement.

Sean Collins declined to say how many children or adults had contracted the illness — which was also difficult to report because some children have already returned home. The current camp session, which began on Aug. 4, had 174 children and 74 staff, he said.

The short-lived viral symptoms — which last 12 to 24 hours — include nausea, fatigue, vomiting and occasional diarrhea, the directors said. No hospitalizations have been reported and affected campers have felt well enough to resume camp activities once the symptoms have subsided.

Campers affected by the illness were kept hydrated and directed to rest, nursing staff said in a letter to families. The camp increased efforts to sanitize surfaces of common areas and stressed regular hand washing and the use of sanitizers.

Eventually, however, camp administrators became concerned about their ability to continue operating the camp due as employees became fatigued, overworked and stressed while helping care for the large number of ill children, Collins said in a phone interview.

“When some staff began to contract the virus, it hit a point where we had to (discuss closing the camp),” Collins said.

Camp Billings, a nonprofit organization in its 118th year of operation, puts on four two-week camp sessions each summer. The tuition is $1,950 per session, according to the camp website.

The board of directors is currently discussing the matter of tuition reimbursement for the shortened session, Collins said.

Anne Sosin, of Thetford, said her 12-year-old daughter was one of the campers who contracted the virus last weekend. Her daughter has since recovered and has returned home.

“I know that outbreaks can be difficult to control in a congregate (setting) but it does raise questions about the camp’s preparedness to manage the outbreak and their response,” Sosin, a public health researcher at Dartmouth College, said in a phone interview.

Sosin said that the camp also had notified families of a similar virus outbreak that occurred during the previous camp session, which Sosin’s daughter had also attended. While her daughter did not get ill during the previous camp session, which ran from July 21 to Aug. 3, Sosin wondered whether the viral infection had carried over from the previous session — as many campers attended both.

While a similar virus occurred during the previous session, it did not spread a widely as the current outbreak and a fewer number of children were affected by it, Collins said.

“We can’t be sure it was the same strain (as now),” he said.

Brad Jordan, whose 14-year-old daughter attended Billings, said he was pleased with how the camp handled the outbreak — including care of his daughter, who contracted the virus this past weekend.

“My daughter had access to everything she needed (and we) were notified via email that she was sick (and) of the precautions they were taking and implementing to keep sick and non-sick campers safe,” Jordan, said in an email.

Camp administrators had consulted state health officials, including a gastroenterologist, to ensure that the camp was following the recommended protocol for patient care and infection containment, Collins said.

The Vermont Department of Health, which was notified of the illness by the camp on Sunday, helped to identify possible sources of transmission, recommended interventions to prevent further transmission and arranged testing of clinical specimens to confirm the pathogen, Sharon Muellers, a Department of Health spokesperson, said in an email.

“This is the first acute gastrointestinal outbreak reported by a camp this summer but similar outbreaks have been reported in previous years,” Muellers said. “Norovirus is the leading cause of vomiting and diarrhea in the United States. It is very contagious and spreads easily in group settings, especially if the groups are sharing small spaces and if handwashing stations are limited.”

Hand sanitizer, though effective against some germs, does not work well against norovirus, Muellers said.

The most effective prevention is thorough handwashing with soap and water, especially when eating, food-handling or using a lavatory.

Patrick Adrian may be reached at padrian@vnews.com or 603-727-3216.