A tiger cub – the third and last of the litter reared with the help of a “dummy toy tigress mother” – died in Madhya Pradesh’s Bandhavgarh Tiger Reserve on Wednesday. “Though no laboratory has confirmed the [viral] infection yet, the symptoms appear to be that of parvovirus-strain 2,” Field Director Mridul Pathak told The Times of India.

The two other cubs of the litter had died after being infected with the same virus, which reduces platelet count.

A two-member team from the National Tiger Conservation Authority has reached the reserve forest to investigate the circumstances under which the cubs died, reported Hindustan Times. Pathak told the daily that the cubs had very low immunity because they did not get their mother’s milk. Their blood samples have been preserved for investigation and preventive measures, according to The Times of India.

The three tiger cubs had been brought to Bandhavgarh after poachers killed their mother in Sanjay Tiger Reserve on January 14. The weak and dehydrated cubs were kept in an isolation room and given time to acclimatise to their new environment. The stuffed toy was even fitted with artificial nipples and milk bottle for the cubs to feed on. They were later put on a diet of crushed meat, reported CNN-News18.

With 85 adult tigers and more than 40 cubs, the Bandhavgarh Tiger Reserve has one of the highest densities of the big cat in the country. However, man-animal conflict has been on the rise for the past few years. In 2017 alone, the state lost five tigers and 41 in the past 14 months.