Fear of human-to-human transmission
Direct spread of avian influenza from poultry to humans resulting in a high fatality rate is of course a major concern. What worries scientists and public health officials more, however, is the increasing risk of person-to-person transmission as a result of a change in the viral genome. Genomic variation could occur if avian virus genetic material mixes with that of a human virus in an intermediate host such as the pig or in a patient infected simultaneously with both avian and human influenza strains; or it could occur with spontaneous mutation of an avian virus. A recent report provided strong evidence of avian influenza that spread from the index patient to her mother and aunt (both the 11-year old girl and her mother died). No further spread occurred, suggesting the infection resulted from a purely avian virus with no human virus involved.5
How effective will preventive measures be?
The current danger to people from avian influenza has been recognized sooner than the threats that preceded previous influenza pandemics, which burst upon the world with little warning. Lessons from the severe acute respiratory syndrome (SARS) epidemic in 2003, advances in science and public health surveillance, and cooperation among countries and organizations such as the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) have allowed us to observe the emergence of avian influenza in rural Asia and consider its wider implications. CDC’s response has focused on enhanced surveillance and laboratory testing for human and avian influenza in the US and Asia and work on vaccine development with WHO and the National Institutes of Health (TABLE 2). CDC has not recommended avoiding travel to any of the involved countries, but has released guidelines for travel to affected areas (TABLE 3).6
In the event of an avian flu outbreak in humans, there will be questions about the best public health response, the use of antiviral agents, and infection control in health care settings. The SARS outbreak was substantially controlled through the use of the traditional public health measures of isolation (separating ill or infected people from others) and quarantine (separating people exposed to infected people from others in order to prevent the further spread of the infection). Whether such measures would be successful with a highly contagious viral infection like influenza is debatable. Stohr of WHO has outlined a research agenda that includes study of hospital infection control practices, vaccine clinical immunogenicity, early interventions such as use of antivirals or vaccine to slow the spread of an emerging pandemic virus, the role of animal and bird species in influenza virus development, and risk assessment.7
TABLE 2
CDC response to avian influenza
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TABLE 3
General precautions for travel to countries with avian influenza outbreaks*
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| * As of February 4, 2005 this was directed at travelers to Vietnam only; see reference #6 for complete details. |
Awareness the best defense now
If avian influenza makes the leap to person-to-person transmission, family physicians across the globe will be at the forefront of diagnosis and treatment. Though no immediate actions are necessary, we all must follow developments and support the work of health departments at improving their ability to monitor emerging outbreaks. The interconnectedness of global health is well exemplified in the concern about avian flu and the efforts to prevent an influenza pandemic.
Correspondence
Eric A. Henley, MD, MPH, Department of Family and Community Medicine, University of Illinois College of Medicine at Rockford, 1601 Parkview Avenue, Rockford, IL 61107-1897. E-mail: ehenley@uic.edu