The Honolulu Zoo’s only male lion, Ekundu, who fathered three cubs in 2012, has died after testing positive for the coronavirus, the city announced Friday.

Zoo officials said they are awaiting pathology results for the exact cause of death and to determine the extent the viral infection may have played in his death Monday.

Ekundu’s mate, Moxy, 12, the only other lion at the Waikiki zoo, also tested positive for SARS-CoV-2, but her symptoms quickly diminished and she is expected to make a full recovery. They are the first animals to test positive for the virus at the zoo.

Honolulu Zoo veterinarian Jill Yoshicedo said it is possible the 13-year-old male, who had been treated for epilepsy for more than five years, died from an underlying condition.

“Both cats got infected,” she said. “One got very sick, and the other seems to have recovered.”

If the virus did indeed kill Ekundu, “it’s very rare, probably one of the first reported cases of SARS-CoV-2 causing a fatality in the U.S.,” Yoshicedo said.

On Oct. 7 a 2-1/2-year-old snow leopard with a respiratory illness may have died from COVID-19 at the Great Plains Zoo in South Dakota, according to an Associated Press report. Yoshicedo said she believes Ekundu is the first lion to have possibly died from the virus.

“Most cases of the SARS-CoV-2 infections in large, nondomestic cats have been mild illnesses that respond to supportive care,” she said. “Ekundu was unfortunately one of the newer cases where COVID seems to be linked to severe pneumonia and tragic loss of life in these species.”

However, earlier this summer, two lions died in India and possibly two tigers, according to Yoshicedo.

On Oct. 4 both Ekundu and Moxy began showing signs of upper respiratory illness, including some coughing, the city said in a news release. Samples were immediately taken to test for SARS-CoV-2 and came back positive from mainland laboratories, but only after Ekundu had died.

The pair had tested negative earlier in the year.

As Ekundu grew sicker and stopped eating, he was unable to take medication through his food. Veterinary and animal care teams decided to anesthetize him so they could administer antibiotics, fluid therapy and other medications to make him feel better, the release said.

The treatments helped resolve the upper respiratory symptoms, but the lion then experienced difficulty breathing, a sign of lower respiratory disease, over the next few days.

Ekundu died exactly one week after his symptoms began.

Born Nov. 2, 2007, the animal was just three weeks shy of his 14th birthday. African lions typically live 15 to 25 years in captivity.

The source of the lions’ infection remains a mystery.

In many cases of SARS-CoV-2 at zoos, big cats have contracted the virus from an asymptomatic keeper, Honolulu Zoo Director Linda Santos said. That was the case in a Bronx Zoo tiger’s illness early in the pandemic.

Santos said the select crew of three to four people who work closely with the lions at the Honolulu Zoo had been vaccinated and are tested regularly for COVID-19 — all testing negative for the disease.

They were in compliance with the city’s employee vaccination policy, as are zoo staff members who prepare the food, who also tested negative.

As for the public being the source, Santos said thick, laminated glass at exhibit viewing points make it impossible for visitors to get close to the animals.

However, as it is an open-air exhibit, “we cannot rule out someone tossing something into the exhibit,” she said.

The zoo is working with the Centers for Disease Control and Prevention along with the U.S. Department of Agriculture to investigate the lion’s death.

“We can’t rule anything out, so we don’t know at this point,” Santos said.

“Ekundu was beloved and iconic. The zoo ohana is very saddened with his passing, and are working together to remain focused on the health and welfare of Moxy, and the care for the rest of our animals in the zoo.”

When Ekundu arrived in 2010, Santos unloaded him and got him to his sleeping quarters.

“He was a very calm, mellow male lion, and he liked the attention of his keepers,” she said. “He was very cooperative for training most of the time, and I think his keepers will miss him greatly because he was very special.”

Ekundu and Moxy raised their three cubs born Dec. 15, 2012. The offspring went into breeding programs and have been transferred to other zoos as part of the Association of Zoos and Aquarium’s Species Survival Plan.

The zoo will be looking for another lion down the road, Santos said, although Moxy, at age 12, is past the recommended age for breeding.

The zoo has signage in high-risk areas, asking visitors to wear masks and social-distance from animals primarily near the primates and cat and canine species, both to protect the animals and to protect themselves, “given the zoonotic aspect of the disease,” Santos said.

While rare, humans have transferred SARS-CoV-2 to their pets, and there have been two documented cases of animal transmission to pets on mink farms, although the risk is low.

The Honolulu Zoo’s other cats include a Sumatran tiger, three cheetahs and one serval.