Pandemic influenza and its implications for transplantation

Abstract

Influenza viruses are important infections in transplant recipients. They may lead to complications including viral pneumonia, secondary bacterial infections and graft dysfunction. There has been a recent widespread outbreak of highly pathogenic H5N1 avian influenza among domestic poultry and wild birds along with a number of human cases with severe disease and high mortality. Genetic changes in the H5N1 virus may lead to efficient human-to-human transmission, heralding the onset of the next influenza pandemic. Discussed are the implications that such a pandemic may have on transplant patients. Logical inferences can be made from data on influenza in transplant patients and from experience with other respiratory virus outbreaks. In the event of a pandemic, it is likely that transplant patients will have more severe disease and higher mortality as compared to the general population. Vaccination and antiviral strategies may be less effective in this population. Implications for transplant programs in general are also discussed.

Figure 1

Pandemic influenza virus may arise from one of two mechanisms: In Figure 1A , a co‐infection with an avian influenza virus and a human influenza virus occurs in a human host (or potentially in another species such as swine). A reassortment event results in a new pandemic influenza virus with genetic elements from both the avian and human viruses. In Figure 1B, an avian influenza virus infects a human host. Mutations in the virus occur, and result in a new pandemic virus capable of efficient human‐to‐human transmission.

Figure 2

The time‐line of different influenza pandemics is shown. Although outbreaks have undoubtedly occurred throughout history, only more recent pandemics have been well characterized.