Probable first case of H7N9 human-to-human transmission, researchers report

avian influenza h7n9 (Danumurthi Mahendra

Since the novel avian influenza A (H7N9) virus was identified in Eastern China earlier this year, researchers have been worried about the possibility of human-to-human transmission. So far, fortunately all sources of human infection seem to be from infected poultry or a contaminated environment. However, researchers at the Jiangsu Province Centre for Disease Control and Prevention investigated the case of two family members infected with the virus and say that the first case of human-to-human transmission has probably occurred – albeit limited and not sustained.

The patients in question are a 60 year old man and his 32 year old daughter. The man was first to become ill, and the daughter developed symptoms a few days later. While the man probably contracted the virus from his recent exposure to live poultry, the daughter had no such exposure and had not visited the markets recently.

However, the daughter did spend long periods of time, with no personal protective equipment, at her sick father's bedside. Furthermore, the two strains of virus isolated from the individuals were almost genetically identical.

Human-to-human transmission of the virus therefore looks probable in this case. The researchers write: "To our best knowledge, this is the first report of probable transmissibility of the H7N9 virus from person to person with detailed epidemiological, clinical, and virological data".

However, the transmission was limited and not sustained. None of the 43 close contacts of the two patients test positive for infection – and the virus does not appear to have gained the ability for sustained transmission from human to human. What this study does do however is reinforce the notion that the H7N9 virus possesses the potential for pandemic spread. As James Rudge and Richard Coker write in a BMJ commentary, while H7N9 might not be closer to delivering the next pandemic, and limited human to human transmission is not surprising, it does act as a reminder that "the threat posed by H7N9 has by no means passed."

There are a variety of H7N9 vaccine in development, but none are available yet. Vaccines from Inovio Pharmaceuticals, Novavax, Medicago and Vaxart are all in the mix. Read more about H7N9 vaccine development here.

Read the BMJ article >

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