Burying dead pet rabbits in the garden is a sad, but consoling childhood ritual that many adults recall with fondness. No longer: rabbit owners are being warned that garden burials may be helping to spread a deadly virus across the UK’s rabbit and hare populations.

The first cases of rabbit viral haemorrhagic disease (RVHD2), which causes death by internal bleeding, were reported in the UK in 2013. It is believed to have spread among wild rabbits, and cases in wild hares have also appeared recently.

Infected rabbits often show no symptoms, which include fever, lethargy and even coma, all of which are also common in other less serious illnesses.

Pet rabbits can seem less at risk than the wild population, but vets are warning that the conditions in which they are kept mean they could come into contact with the virus without encountering an infected wild rabbit. The virus can be carried by birds and their droppings, on the soles of shoes or car tyres, through other pets, and can even be airborne.

Richard Saunders, a vet, told the Guardian: “It is everywhere. The virus is extremely good at surviving in the environment, up to eight months in ideal conditions, certainly weeks to months in cool temperatures, and spread quickly and easily. You only need to read the forums on Facebook and elsewhere to realise that it is killing pet rabbits all over the UK.”

It is hard to gauge how many pet rabbits may be infected because few are taken to the vet after dying. Garden burials may be comforting to the family, but offer no opportunity for the examination needed to establish the rabbit’s cause of death. Incorrect burial of an infected rabbit could allow the virus to be transmitted to others, particularly if the body is dug up by predators, warn experts.

If people cannot afford to take their pet to the vet to establish the cause of death, they are advised either to have the rabbit properly cremated or, if they choose a garden burial, to carefully wrap their pet in plastic first to reduce the risk of the virus spreading.

Owners are also advised to have their pets immunised against the disease. Of an estimated 1 million domestic rabbits in the UK, only about 14% have been vaccinated.

A Defra spokesperson said: “Rabbit haemorrhagic disease is a highly contagious disease among wild and kept rabbits and hares. Owners worried about their pet rabbits should speak to their vets for advice because a vaccine is available.”