Büyükada, the biggest of Istanbul’s Princes’ Islands and home to a large cat population, is fighting a feline disease pandemic, animal rights activists say. They counted some 700 cats among the victims in the past four months, while others struggle for their lives.

The cats are suffering from feline infectious peritonitis (FIP), according to initial findings, a viral infection caused by strains of a virus, also known as feline coronavirus. Volunteers have made efforts to place stray cats in quarantine.

Neslihan Sipahioğlu, a volunteer caring for the cats on the island, says she was caring for 210 cats in one area of the island she was "responsible" for and their number dropped to 50. Celal Karabulut, a vet checking the cats, adds FIP is a deadly disease for cats.

The infectious disease without a known cure prompted animal lovers to build makeshift quarantine rooms for cats. Those with severe symptoms are cared for in abandoned, unused buildings on the island.

Sipahioğlu told Demirören News Agency (DHA) on Friday that they were "picking up dead bodies" off the streets and personally witnessed eight cats dying. "It is a desperate situation. There is medication for them, but it is very expensive and not easily accessible. I paid for expensive treatment for three cats but not all treatment, medication options produce results for all cats," she said. Sipahioğlu added that the infections had appeared to reach their peak, while the volunteers continued to do "all we can."

Metin Türkmenoğlu, another volunteer who has been recording the number of cats dying on the island since 2013, says every year up to 500 cats died since then for various reasons but this year, the situation was "dire." "Between January and May, some 700 cats died. In the past, they used to die of wounds from dog attacks or after they were hit by vehicles. This time, the majority of deaths stem from FIP. Roughly seven out of every 10 cats die of FIP," he said, urging authorities to take measures to protect the felines.

Karabulut says there was no alternative therapy for infected cats and the disease affected even kittens while they were still in the womb of infected mothers. On the root cause of infections, he pointed out that it may have spread due to cats’ habit of eating together or in areas they collectively use for defecation.