Camel discovery explains pneumonia resistance

Camels' lungs are more resistant to deadly airborne viruses.

Thin membrane coating camels' lungs may be an effective shield against bacteria, viruses and deadly infections such as pneumonia.

ABU DHABI // A team of scientists working in the UAE and Canada believe they have discovered why camels tend to be less affected by pulmonary diseases such as pneumonia.

The key seems to lie in the thin membrane known as the visceral pleura, common in many animals and also humans, that surround the lungs.

Camels are unique in that the membrane is then covered by another layer, an array of cells dubbed the pleural curtain, believed to be capable of destroying harmful viruses and bacteria.

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Dr Ulrich Wernery, scientific director of the Dubai-based Central Veterinary Research Laboratory (CVRL), remembered first noticing the unusual tissue about 15 years ago as he dissected a dead camel. "I was wondering if this was a pathological or a physical feature," he said.

Although he noticed the tissue in several other camel dissections, he got absorbed in other work and forgot about it. He was reminded several years ago, when a giraffe arrived at the lab for a post-mortem study. Surprisingly, the giraffe had the same curtain at the edge of the lungs.

Dr Wernery and Dr Joerg Kinne, also from the CVRL, determined that aside from camels and giraffes, other members of the Bovidae family such as cows, goats, sheep, gazelles and oryx lacked the unusual feature.

The pleural curtain, although mentioned by two scientific papers, was not discussed at length in scientific journals.

At this point, the CVRL team approached Professor Gerald Buzzell, who was the chairman of the anatomy department at the faculty of medicine at United Arab Emirates University, to access light and electron microscopes that would enable them to examine the curtain's cell structure.

What the scientists found inside the curtain were fibrous threads - that in an adult camel can be up to 3.5 centimetres long and about 0.5cm thick - containing two to three layers of cells. The scientists identified about eight different types of cells, some of which they have yet to study in detail.

Some of them, however, appear to be known as phagocytising cells, similar to the ones living in the blood stream, Dr Wernery said. "When they hit bacteria, they get activated and start eating the bacteria."

It is these cells that may be key to the pleural curtain's function, explaining why camels rarely suffer from pneumonia.

"The curtain is like a windscreen sweeper," said Dr Wernery, explaining that as the animal inhales, the lungs increase in volume and the curtain reaches the edges of the insides of the ribs. "It wipes clean the pleura."

The team has also been able to ascertain that in addition to giraffes and dromedary camels, only Bactrian camels and llamas have the unique feature, said Prof Buzzell. "We have seen no other animal that has it," he said.

The team's research was published recently in The Anatomical Record, an American scientific journal.

Prof Buzzell has retired from his post in Al Ain and moved back to Canada, where he hopes to continue work on the issue, but admits it will be difficult to do so while away from the Emirates.

He said the research project showed how far collaborative work could go. "We had the facilities and they had the material, so we were able to do a very good collaborative project."

The cost of the study was not more than Dh500, which was spent on chemicals and film for the microscope, he said. "It was very inexpensive for such interesting results."