BARCELONA (REUTERS) - Four lions at Barcelona Zoo have tested positive for Covid-19, veterinary authorities said, in one of just a handful of documented cases globally in which large felines have contracted coronavirus.

Three females named Zala, Nima and Run Run, and Kiumbe, a male, were tested after keepers noticed they showed slight symptoms of coronavirus.

Two staff at the zoo also tested positive for coronavirus, the authorities said on Tuesday (Dec 8), after the outbreak was first detected last month.

Officials are investigating how the lions became infected.

Keepers carried out PCR tests on the lions in the same way as humans are tested as the animals are accustomed to contact with the zoo staff.

The Veterinary Service of Barcelona contacted international experts and colleagues at the Bronx Zoo in New York, where four tigers and three lions tested positive for Covid-19 in April. All recovered.

In at least one other case involving large felines, a tiger tested positive for the virus and two more were presumed positive after briefly displaying symptoms at Zoo Knoxville in the US state of Tennessee in October, according to the zoo.

"The lions were given veterinary care for their mild clinical condition - similar to a very mild flu condition - through anti-inflammatory treatment and close monitoring, and the animals responded well," the authority in Barcelona said.

The four-year-old male and the females, who are all 16 years old, have had no contact with other animals at the zoo, which is open to visitors.