AsianScientist (Mar. 31, 2011) – Duck porridge, salted duck eggs, roasted duck: the Chinese love duck dishes, and so last spring, when Chinese farmers noticed their prized birds were dying from a mysterious illness, it was a cause for national worry.
In some flocks, egg production was down by as much as 90 percent, and the ducks showed a drop in coordination and appetite. Some died within days.
By the end of the year, an estimated 4.4 million ducks in the eastern provinces of Fujian, Shandong, and Zhejiang had caught the illness. The outbreak quickly spread to six other provinces, along with rural areas outlying Beijing.
Then came Microbiologist George Gao and colleagues from the Chinese Academy of Sciences in Beijing. Armed with tissue and serum samples from animals in affected flocks, they tested the samples and found the cause of the affliction to be an aggressive new flavivirus, a class of viruses that includes yellow and dengue fevers.
As detailed in a paper published this month in PLoS ONE, the team first ruled out avian flu by testing serum samples from the animals for antibodies against the virus. Then, working with brain and ovary tissue from ducks that had died within 6 hours of infection, they isolated the virus and named it the BYD virus.
They injected healthy ducks with the virus – the BYD ducks soon fell ill.
Gao and colleagues say the BYD virus is closely related to the Tembusu virus, a flavivirus found in Southeast Asia. Like that other virus, they suggest that BYD could be spread by mosquitoes.
Ernest Gould, a virologist and visiting scholar at the Université de la Méditerranée in Aix-Marseille, France, noted that the ducks started falling ill in the cool weather of early spring, when mosquito populations were presumably low, which is inconsistent with a mosquito-borne flavivirus. However, he pointed out that a rapidly spreading Chinese flavivirus could mean a global problem.
The BYD virus is the first flavivirus ever identified in ducks. According to Gao, most flaviviruses are zoonotic meaning they can be transmitted from animals to people. Because of the pervasiveness of duck farming in China, Gao and colleagues stress that the disease should be closely monitored.
The next step, they say, is to develop a BYD vaccine.
The full paper can be found here at: Su J. et al. (2011) Duck Egg-Drop Syndrome Caused by BYD Virus, a New Tembusu-Related Flavivirus.
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Source: ScienceNow.
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