Asymptomatic H5N1 Infected Chickens in Indonesia
Recombinomics Commentary
October 5, 2006
Head of the West Java Animal Husbandry Office, Rachmat Setiadi, said the warning was made following the discovery of healthy chickens that tested positive with H5N1 virus from a serology test conducted on 20 chickens around the house of two dead flu victims -- 23-year-old IJ and his 20-year-old brother -- in Kebonwaru area, Batunggal
The above comments indicate asymptomatic chickens can carry H5N1 bird flu. Although many H5N1 sequences from birds and people in Indonesia have been published, the link between H5N1 in dead poultry, and H5N1 in dead patients has not been established.
All reported sequences from human cases in 2006 on the island of Java have has a novel HA cleavage site. The novel cleavage site has only been detected in one duck on Java in Indramayu, and that sequence was similar to a few human sequences from late 2005 / early 2006 (in upper twig of lower branch of HA tree). The vast majority of human cases are on a separate twig of the lower branch, and these do not match any reported poultry isolates on Java. Matching sequences have been found in two chickens in central Sumatra, isolated in 2005.
The H5N1 asymptomatic chickens on Java are positive for antibodies. It is not clear if H5N1 sequences have been detected in the asymptomatic birds. These infections could represent a separate reservoir. There have also been repots on the recovery of suspect bird flu victims. However, these patients have been H5N1 negative, so it remains unclear if they are infected with H5N1, or if the H5N1 sequence from these recovered is different than the H5N1 fatal cases. Almost all H5N1 human sequences in Indonesia are from fatal cases.
Asymptomatic chickens in Vietnam have also been reported previously.
Clearly more surveillance and sequences from H5N1 infected people, birds, and other mammals are indicated.
Media Sources
Phylogenetic Trees