Pet tarantulas pose risk to owners' eyes, say doctors

The owner of a tarantula spider has suffered severe eye inflammation from cleaning out his pet's cage, doctors have reported.

They say the man had no idea his pet was the problem when he came to their clinic for treatment.

When they told him they could see tiny hairs sticking out of his eyeball he remembered his pet spider sending out a mist of hairs which hit his face.

The doctors say anyone working with spiders should wear eye protection.

Dr Zia Carrim, of St James's University Hospital in Leeds, writing in the Lancet, says the man came to his clinic in February, having had a red, watery and light sensitive eye for three weeks.

I advise anybody keeping such tarantulas as pets to be aware of the danger David Field, Zoological Society of London

It was when he was examined under a high magnification lens, that hair-like projections were spotted at various depths within the cornea.

When these findings were described to the patient, he immediately recalled an incident that had preceded the onset of his symptoms.

Cleaning

Three weeks earlier, he had been cleaning the glass tank (terrarium) of his pet, a Chilean Rose tarantula.

While his attention was focused on a stubborn stain, he sensed movement in the terrarium.

He turned his head and found that the tarantula, which was in close proximity, had released "a mist of hairs" which hit his eyes and face.

TARANTULAS New World tarantulas from North and South America have urticating hairs as their first line of defense All have a venomous bite but it is not deadly to humans Because other proteins are injected into the victim along with the venom some humans may experience a severe allergic reaction to their bites

Dr Carrim said: "It was very obvious that the course of the inflammation was driven by these tiny hairs.

"We attempted removal of corneal hairs for our patient under the operating microscope but even with the smallest pair of forceps it was impossible. "

The Chilean Rose tarantula ( Grammostala rosea) is one of the most commonly imported tarantulas.

It is believed to be hardy and docile, but it is venomous and has urticating hairs, which can cause a stinging pain, over the back end of its abdomen.

As a defence mechanism, the tarantula will rub its hind legs against its abdomen to dislodge these hairs into the air.

The authors said the spider was about 15 to 20 cm from his eye.

The hairs have multiple barbs that allow them to migrate through the eye tissue to various depths.

Patient's inflamed eye

Their patient had both surface irritation and evidence that some had migrated through to the innermost endothelial layer of the eyeball provoking inflammation in the interior of the eye.

"He was treated with steroids to dampen down the response" Dr Carrim said.

"And he will remain on long-term treatment with steroids at a very low dose."

Keepers at Whipsnade Zoo estimate that thousands of people in the UK are keeping tarantulas as pets.

David Field, director of the Zoological Society of London, said: "I advise anybody keeping such tarantulas as pets to be aware of the danger."

Tasmanian devil facial cancer origins 'identified'

Researchers believe they have identified the source of fatal tumours that threaten to wipe out the wild population of Tasmanian devils.

Writing in Science, an international team of scientists suggest cells that protect nerves are the likely origin of devil facial tumour disease (DFTD).

The disease is a transmissible cancer that is spread by physical contact, and quickly kills the animals.

DFTD has caused the devil population to collapse by 60% in the past decade.

"To look more closely at the tumours' origin, we sequenced the genes that are expressed in this devil cancer and compared them with other genes that are expressed in other devil tissues," explained lead author Elizabeth Murchison, from the Australian National University in Canberra.

She told the Science podcast the team's findings delivered surprising results.

"We found that the tumours expressed genes that were normally only expressed by Schwann cells, which are cells that are found in the peripheral nervous system that protect nerves."

'Genetically distinct'

The researchers sampled 25 different tumours from all over Tasmania, the only place on the planet where the world's largest carnivorous marsupials are found.

DEVILS IN DETAIL Scientific name: Sarcophilus harrisii Devils were given their common name by early settlers, who were haunted by "demonic growls" Largest living carnivorous marsupial Now only found in Tasmania Can live up to five years in wild Weight: male 10-12kg; female 6-8kg They favour habitats where they can shelter by day and scavenge by night

They found that the growths were genetically distinct from their hosts, but were identical to one another.

Dr Murchison, who is also a researcher at Cold Spring Harbor Laboratory, US, said the teams findings had a number of positive outcomes: "Most importantly, this has led to the development of a diagnostic test for the disease.

"Devils are susceptible to a number of different types of cancer. Just like humans, they can get breast cancer, leukaemia, etc - especially in their old age.

"Sometimes it can be difficult to tell the difference between these types of cancer and the transmissible disease.

"Now that we know that these very specific Schwann genes are expressed in the cancer, we can use these genes as diagnostic markers."

DFTD was first described in the mid-1990s, when devils with large facial tumours were photographed in north-eastern Tasmania.

By the end of 2008, the disease - which kills infected animals within nine weeks - had been confirmed at 64 locations, covering more than 60% of the Australian island state's mainland.

Experts warn that without intervention, the disease could wipe out the wild population of the world's largest carnivorous marsupial within decades.

Dr Murchison hoped identifying the catalogue of genes associated with DFTD would lead to the development of vaccines, or possibly therapies.

The disease usually kills infected devils within nine weeks

"As yet, unfortunately, there is nothing we can do to help the devils that have the disease," she said.

"This devil facial cancer is very unusual as it is an infection cancer; it is a little bit like an organ transplant," she said.

"In an organ transplant, you have an organ that is transplanted into an unrelated individual. In the case of the devil cancer, you have a cancer that is transplanted into another unrelated devil through biting.

"One of the big questions about this cancer is why it is not being rejected or being recognised as a foreign graft.

"If we could understand that... we could perhaps use this data to develop a vaccine that could help the devils' immune system reject the cancer before it takes hold."