A school district in Colorado has closed more than 40 schools for the next two days after a virus outbreak spread quickly through the student population.

The affected school district was the Mesa County Valley School District 51. It's the first time the school district has been obligated to close all schools due to an illness, said the district on Wednesday in its announcement.

According to the announcement by the Superintendent of Schools, Dr. Diana Sirko, the Mesa County Valle School District 51 will be closed Thursday and Friday, Nov 21-22. Classes will resume as scheduled following the Thanksgiving break.

Nursing Coordinator Tanya Marvin said in the statement that they "are taking this highly unusual action because this virus is extremely contagious and spreading quickly across our schools."

The illness reports increased in recent weeks after more than a dozen schools in the state's 14th largest district reported sudden increases in absences due to illness. There were also several reports of incidences of vomiting in public areas of the school, according to the Mesa County Public Health Department.

Soon after, a second, related virus began to affect students as well. "The combination of the two has created an unprecedented spread of illness", stated the district. "Onset of symptoms for both types of viruses, including vomiting, is incredibly fast. The second version also causes fever in several cases," the district statement said.

Both viruses have not yet been identified but the health department is working to do so, stating the illness acts like a norovirus, which lasts between 12-24 hours. Norovirus, commonly known as the "stomach bug" is easily spread through direct contact, touching contaminated surfaces or objects and then putting your hands in your mouth or through consuming contaminated food or water.

Mesa County Public Health Executive Director, Jeff Kuhr, stated: "the decision to close is the right move".

"Past experience with these types of viruses tell us having a period of time away from close person-to-person contact can be instrumental in these illnesses running their course," said Kuhr.

The closing period will allow time to give the school areas to disinfect and start fresh after the Thanksgiving holiday.

The Health Department has instructed parents and concerned individuals to visit their website for more information on the symptoms and the contagious illness.