Fresh outbreak of Ebola in Uganda
Updated at 9:11 pm on 16 November 2012
Canadian scientists have demonstrated that the Ebola virus is transmitted from pigs to monkeys without any direct contact between them.
The researchers say they believe that limited airborne transmission might be contributing to the spread of the disease in some parts of Africa.
The BBC reports there is no known cure for Ebola. The virus causes death in 90% of human cases.
The Canadian scientists are concerned that pigs might be a natural host for the lethal infection.
Ebola viruses cause fatal haemorrhagic fevers in humans and many other species of non human primates.
Details of the research were published in the journal Scientific Reports.
According to the World Health Organisation (WHO), the infection gets into humans through close contact with the blood, secretions, organs and other bodily fluids from a number of species including chimpanzees, gorillas and forest antelope.
A growing body of experimental evidence suggests that pigs, both wild and domestic, could be a hidden source of Ebola Zaire - the most deadly form of the virus.
Now, researchers from the Canadian Food Inspection Agency and the country's Public Health Agency have shown that pigs infected with this form of Ebola can pass the disease on to macaques without any direct contact between the species.
In their experiments, the pigs carrying the virus were housed in pens with the monkeys in close proximity but separated by a wire barrier. After eight days, some of the macaques were showing clinical signs typical of ebola and were euthanised.
Aerosol droplets carry virus
One possibility is that the monkeys became infected by inhaling large aerosol droplets produced from the respiratory tracts of the pigs.
One of the scientists involved is Dr Gary Kobinger from the National Microbiology Laboratory at the Public Health Agency of Canada. He told BBC News this was the most likely route of the infection.
"What we suspect is happening is large droplets - they can stay in the air, but not long, they don't go far," he explained.
"But they can be absorbed in the airway and this is how the infection starts, and this is what we think, because we saw a lot of evidence in the lungs of the non-human primates that the virus got in that way."
Dr Kobinger stresses that the transmission in the air is not similar to influenza or other infections. He points to the experience of most human outbreaks in Africa.
"The reality is that they are contained and they remain local, if it was really an airborne virus like influenza is it would spread all over the place, and that's not happening."
The authors believe that more work needs to be done to clarify the role of wild and domestic pigs in spreading the virus.
Three die in new outbreak
Meanwhile, a fresh outbreak of the deadly Ebola virus in Uganda has killed three people.
Meanwhile Uganda's Health Minister Christine Ondoa says a fresh outbreak of the deadly Ebola virus in Uganda has killed three people - including two from the same family.
She also says two other people are in an isolation unit at Mulago hospital in Kampala.
Dr Ondoa says conclusive evidence of Ebola has been found in Luweero, about 60km from the capital.
An estimated 17 people died in western Uganda during an outbreak in July.
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