Avian influenza in humans - an update
Summary
Reports of human cases of avian influenza have been reported worldwide, following bird to human transmission. How great is the risk that this virus could mutate further and form the next human flu pandemic? Prof Kwok-yung Yuen reviews the evidence.
Key Points
- Avian influenza and SARS are two zoonotic (spread directly from animal to humans) viral infections capable of causing epidemics or pandemics with serious mortality.
- The influenza viruses (A,B,C) have an RNA genome and belong to the Orthomyxoviridae family of viruses. The largest natural reservoir of influenza A virus is in aquatic birds and these viruses are the avian influenza viruses.
- Influenza viruses readily undergo antigenic change making the effectiveness of vaccines short-lived.
- Most outbreaks of human infection have occurred in South East Asia, but an outbreak has also occurred in the Netherlands.
- Early recognition of avian influenza is important, but there are no specific features of the illness other than a history of contact with infected birds. Anyone with an unexplained temperature above 37.50C, respiratory symptoms, or systemic symptoms such as aching muscles, should be regarded as having an influenza-like illness.
- Avian influenza viruses do not yet pass readily from one human to another, but this may not always be the case and WHO recommendations should be followed.
Declaration of interests: No conflict of interests declared
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