Thousands of people in Catalonia in northeastern Spain have been infected by norovirus. Local health officials said the infection was caused by the consumption of contaminated bottled water.

According to the health department of the regional government of Catalonia, around 4,146 people were infected by norovirus after drinking water from office water coolers. The water was contaminated with human faecal matter, The Guardian reported.

Albert Bosch, a microbiology professor at the University of Barcelona, who was tasked with the analysis of the contaminated water samples, reportedly said this was the first time that bottled water had been infected by norovirus, which otherwise usually contaminates tap water. He added that they are clueless as to how feacal water can mix up with bottled water.

"The way this usually happens with tap water is because somehow faecal water got mixed up with drinking water. But in this case we are talking of bottled water, there is a process and we don't know at what point it happened," Bosch was quoted by the UK daily as saying.

The Eden Springs bottled water company, which had supplied the contaminated water, said it bottled the water in Andorra, which is a small mountainous principality located between Spain and France. As a precautionary measure following the outbreak, the company has recalled more than 6,150 bottles of water it supplied to 925 companies.

Those infected were treated in Barcelona and Tarragona after they complained of nausea, vomiting and fever. Six required hospitalisation.

Norovirus, which mostly causes stomach infection or gastroenteritis, is caused by the consumption of food and water contaminated with faecal matter. It is a highly contagious virus that spreads by coming in contact of contaminated surfaces.

After no new case of norovirus was detected in Catalonia in the past week, health officials have reportedly declared the outbreak to be over.