Ebola 'could be spread by birds'

Ebola has killed hundreds of people in central Africa

There are fears that birds could spread the deadly Ebola virus.

The shell of the human pathogen is similar to viruses that attack birds, suggesting it could have jumped from birds to humans.

It is possible that there is a bird host, possibly a migratory bird, and that is consistent with the epidemiology of the disease

David Sanders

If this is the case, Ebola could be being carried long distances on the wing, with obvious health implications.

The theory has not been proven, but researchers say it should be borne in mind by health agencies.

The warning comes from US researchers who have studied the biochemical structure of Ebola.

Quarantined children during the 1995 outbreak

David Sanders of Purdue University in West Lafayette, Indiana, said biochemical analysis revealed the protein shell of Ebola was close to that of certain bird retroviruses.

A genetic similarity between Ebola and several bird viruses has already been noted.

Taken together, it suggests Ebola was once a bird virus and could now be being spread by birds.

"We knew these viruses were inwardly similar, and now we see their outer similarity as well," he said.

"While bird transmission of Ebola is by no means certain, the resemblance among all these viruses should encourage health officials to be on guard for it."

Migratory birds

Ebola, which was discovered in 1976, is known to infect humans and monkeys.

It has lead to hundreds of deaths in central Africa, and it is fatal in 50 to 90% of cases.

Traces of the virus have also been discovered in small mammals, suggesting they may help spread the disease although they cannot catch it.

Health officials are keen to find out how Ebola gets to people, to help in the fight against the deadly disease.

"It is possible that there is a bird host, possibly a migratory bird, and that is consistent with the epidemiology of the disease," Professor Sanders told BBC News Online.

"We haven't found any birds infected by the Ebola virus yet," he added. "But birds haven't been examined."

Gene therapy

The Purdue research is reported in the Journal of Virology.

The scientists reveal in the same journal that they have been able to redesign the shell of the virus to transform it from killer to healer.

They say the modified virus could be used as a vehicle for gene therapy.

It has been developed into a form that could be inhaled rather than injected, which may one day be helpful in treating lung diseases such as cystic fibrosis.