The Thiruvananthapuram Zoo has barred the entry of visitors for a week following the outbreak of foot-and-mouth disease.
The zoo has reportedly lost its entire stock of Indian gaur (Bos Gaurus) -- a lookalike of the Indian bison - and 12 blackbucks in the week gone by.
It was confirmed last Friday that the foot-and-mouth virus -- strain 'O' - had caused the death of animals.
The zoo was being sanitized and visitors are being disallowed from entering the premises as a precaution.
"We are applying chemicals in the field near the cages. We are also cleaning up the whole campus. We have closed the zoo because it's a highly contagious disease. Even people passing in front of the cages can get it," said Elcey George, the zoo director.
Animal rights activists have accused the zoo authorities of failing to protect the animals.
Jayasimhan, an activist of the People for Ethical Treatment of Animals (PETA), said it was the government's responsibility to look often the animals.
The zoo should follow Central Zoo Authority guidelines, Jayasimhan added.
At least a million people visit the scenic 56-acre zoo which houses 72 species of animals.
India had not previously confirmed the presence of the highly contagious disease, which causes severe weight loss in cloven-hoofed animals such as cattle and hogs.