High CFR in High Fever Illness in Eastern China
Recombinomics Commentary
September 9, 2006
Since the middle of July 2006, an unknown pig disease has occurred in the neighboring provinces of Anhui, Jiangsu, Jiangxi, Hunan and Henan, and other areas. Already 40 percent of pigs have died from infection. As of mid-August this disease had already spread to parts of Hubei. Conditions are relatively serious. According to reports, the pig disease is characterized by high fever, sudden onset, rapid transmission, and high mortality rate.
Pig "high fever illness" is appearing in all areas in our province [Zhejiang] other than Zhoushan City. There are more than 66 000 ill pigs and already more than 11 000 have died. Since July, pig "high fever illness" has appeared in one village after the other in Jiangshan. Symptoms are elevated body temperature, redness on the body surface, and cough. Ears turn light blue in a minority of pigs. The mortality rate among sucklings and weaned pigs is especially high.
I hope that the Chinese authorities are carefully considering the possibility of Swine Influenza usually caused by H1N1, H1N2, or H3N2 in Asia. Although Swine Influenza does not normally cause very high mortality (i.e. only 2-3 percent die when the disease is endemic), a new influenza strain could cause high mortality in swine, just as it would in humans. Therefore, it is important we find out exactly what is causing this undefined, undiagnosed disease over large areas of China. - Mod.PC]
The above excerpts from the latest Promed report on the swine outbreak in China, as well as the final comment, are cause for concern. The failure to diagnose this widespread and fatal illness is curious. As noted in the commentary, the symptoms certainly do not exclude swine influenza, and the description of the light blue ears sounds remarkably like combs turning blue in H5N1 infected poultry. Although H5N1 is not directly mentioned in the commentary, there is data out of China supporting “a new influenza strain.”
H5N1 in swine in China has been reported previously. Initial reports were on isolates from Fujian ands Shenzhen provinces. These isolates were most closely related to “older” H5N1 isolates from China which were not associated with human cases. Similarly, the H5N1 infections were not linked to a high mortality or easy transmission.
However, more recent isolates from Guangdong and Anhui provinces are more diverse and also have a curious history. The sequences from all 8 gene sequences were placed on deposit at GenBank on April 1, 2006. A month later all 40 sequences were “removed at the submitter’s request because the sequence could not be confirmed”. However, the sequences can still be accessed (see links below) and they have evidence of recombination, especially the Anhui sequences, with wild bird H5N1 sequences in China (tree sparrows in Henan amd migratory ducks in Jiangxi). These wild bird sequences are more closely related to the H5N1 found in human cases.
The interaction between H5N1 in swine and H5N1 in migratory birds is cause for concern. The Qinghai strain has PB2 E627K and has been isolated from human cases in Turkey, Azerbaijan, Egypt, Iraq, and Djibouti. Infection of swine can lead to the accumulation of mammalian polymorphisms, which can lead to more efficient infection in swine and humans.
The most recent H5N1 sequences from swine in China are the retracted sequences from 2003/2004. Information on 2006 sequences and more detail on diagnosing the “high fever illness”, would be useful.
A/swine/Anhui/2004(H5N1)
A/swine/Fujian/1/2003(H5N1)
A/swine/Fujian/F1/2001(H5N1)
A/swine/Guangdong/1/2003(H5N1)
A/swine/Guangdong/2/2003(H5N1)
A/swine/Guangdong/4/2003(H5N1)
A/swine/Guangdong/5/2003(H5N1)
A/swine/Shandong/2/03(H5N1)
Media Sources
Phylogenetic Trees