US Confirms First Human Case of Avian Influenza with No Known Animal Contact
On 22 August, an adult patient tested positive for avian influenza (AI) at a hospital in the state of Missouri, USA, where previously only domestic and wild birds had tested positive for the H5N1 strain of the virus. What makes this case remarkable is that public health officials do not know how this individual contracted the disease, as they had no known contact with animals, although it is possible they may have been exposed to an infected animal without their knowledge.
Fortunately, the patient recovered; however, this represents the 14th person to fall ill from AI in the US this year, and the first patient with no “known immediate exposure to animals”, according to the Centers for Disease Control and Prevention (CDC).
All previous human cases occurred among workers who had contracted the virus from infected animals on poultry or dairy farms. This new case presents a mystery that the CDC is working to resolve.
CDC officials are now sequencing the viral genome from this recent human case in order to better understand the origin of the pathogen and how it may have adapted to infect mammals, including humans.
The patient in Missouri has not transmitted the virus to any close contacts, and with no known cases of person-to-person transmission to date, the CDC still rates the threat of avian influenza to the general public as “low”.
“The risk of sustained transmission or infection among the general public remains low”, confirmed the Missouri Department of Health and Senior Services. However, the fact that this patient required hospitalisation is a concerning sign; it is currently unknown whether their severe symptoms were attributable to the virus itself or to underlying medical conditions.
According to CDC Deputy Director Nirav Shah, his team is closely monitoring any increase in AI severity in humans, as this could indicate that the virus is mutating in a manner that may pose a risk to public health.