The BBC Film 'Return to Asthma Island', first broadcast December 2008, documents Dr Noe Zamel's work with Tristan islanders to track track down the genes that cause asthma.

Asthma Island

The BBC first broadcast a programme in the Horizon series on BBC2 at 9pm on Tuesday 9th December 2008 entitled 'Allergy Planet' featuring film made on Tristan da Cunha. Immediately afterwards, on BBC 4 a second 30 minute companion programme 'Asthma Island' showcased extended coverage of Tristan da Cunha, much shown during the earlier programme.

This page provides the background to the programme and will also provide a review.

Horizon: 'Allergy Planet' and the related programme 'The Story of Asthma Island'

The Horizon programme dealt with a wide range of allergies from many locations. We only seek here to report on the Tristan da Cunha content of the main programme, and that of the companion programme 'The Story of Asthma Island'.

The film was made by a Horizon team in May 2008. The team travelled out on MV Edinburgh, expecting to spend a week on the island, but, due to typical winter weather, were 'stranded' for three weeks from 1st - 21st May, and so extended thier fillming to allow the second specialist tristan programme to be made, though all the Tristan Horizon footage is repeated and extended. The Horizon team, including Rebecca Harrison was accompanied by the Asthma expert Dr Noe Zamel from University of Toronto, Canada.

Dr Zamel first recognised this phenomenon when he met the islanders after they were evacuated to Britain in 1961, when the island's volcano erupted. Studying for his PhD at the time, Dr Zamel was part of the team of scientists assembled to learn everything they could about this unique population. "I was in charge of doing the pulmonary function tests and I was amazed that every second Tristanian that I tested had evidence of airway obstruction caused by asthma" said Dr Zamel.

After the volcano calmed, the islanders returned home, followed eventually in 1993 by Dr Zamel. His quest was to discover what was behind the asthma pandemic.Dr Zamel knew the island was pristine. "From the air pollution point of view, Tristan da Cunha is the safest place in the planet. There is basically no industry and the winds are so strong that the air here is as pure as it can be. "

So the answer, Dr Zamel deduced, must lie in their genes. With only seven surnames amongst the entire island, the population has a very homogenous gene pool. "So with the smaller sample size we could achieve what would be required with thousands and thousands of other populations," he said.

By analysing the islanders' genes Dr Zamel achieved what would have been impossible with any other population - the isolation of one particular gene - known as ESE3. This gene is involved with the deposition of collagen in the airways. If the gene is faulty then the airway walls are thickened and constricted, making it more difficult to breathe.

The people of Tristan da Cunha are only part of the jigsaw that is the global allergy explosion.It is hoped that with the discovery of the gene that contributes to asthma, medications will be developed to target the disease worldwide. With Dr Zamel's latest visit to the island, accompanied by the Horizon team, he collected more DNA samples to further his studies.

Asthma is brought on by the overreaction of the body’s immune system to everyday substances. The fascinating research from Tristan da Cunha suggests that genetic factors are 30-40 % responsible. But as has been discovered elsewhere in the world, polluted air has its part to play, as does well-scrubbed skin, apparently, and homes filled with comforts such as carpets and upholstered furniture.