29 October 2005
Africa and the Threat of Avian and Pandemic Flu: The US Should Act Now
In a candid “Risk assessment for Africa” the World Health Organization (WHO) October 28th made explicit what can be anticipated if and when H5N1 avian influenza, and its attendant human pandemic threat, arrives in Africa. The time for the US and other nations to act to prevent, or at least mitigate, the following readily predictable avian influenza events in Africa is now, even though not so stated by the WHO. Such preemptive action by the USA would be both the right thing to do from a humanitarian perspective and from a national self-interest perspective. HHS Secretary Leavitt returned this month from an admirable five-nation tour of H5N1-affected nations in SE Asia. A similar tour is warranted within the next few months to nations in North and East Africa that can be predicted to be affected soon by H5N1 by virtue of migratory bird flyways from Europe and Asia.
Key avian influenza-related issues the WHO noted with regard to Africa include:
1. Large numbers of households keep backyard flocks of poultry, as in parts of Asia, affording many opportunities for transmission of avian influenza via close contact with humans, including children.
2. Surveillance for avian influenza is, with few exceptions, non-existent. Moreover, mortality of nutrition-poor birds is high at baseline, therefore missing the initial outbreak of bird flu easily occur.
3. Farmers are unlikely to be adequately compensated by economically challenged governments for culling of avian-flu infected poultry, thus discouraging compliance with reporting and culling requirements.
4. Late diagnosis of avian flu outbreaks increases the probability that viruses like H5N1 will become endemic in parts of Africa, as this virus has in parts of Asia.
5. A critical source of nutritional protein for human populations of Africa will be removed if large numbers of poultry are killed by avian flu and subsequent culling in an attempt to limit its spread.
6. Avian-to-human infection with H5N1 virus in Africa is likely to occur as it has in Asia, partly due to similar traditional culinary practices.
7. Human infections with H5N1 virus would be an immense superimposed burden on the health care system of Africa already overwhelmed by HIV/AIDS/SIDA, TB, malaria, parasitic and other diseases,
8. Adequate resources are not generally available for the rapid diagnosis of H5N1 virus, a non-specific mimic of other respiratory and influenza-like-illness, nor are large stockpiles of affordable and effective antiviral drugs for H5N1 therapy.
9. Infection control to prevent spread to other patients and health care providers would be difficult to sustain in most hospitals. How would the needed large amounts of personal protective equipment become available?
10. Surveillance for clusters of human disease due to H5N1 and related viruses in Africa would be difficult. The excellent reference laboratories in Africa could be overburdened by a surge in demands for testing. Early warning signs of a nascent human pandemic in Africa could be readily missed. Thus, there is a national and international self-interest in preventing and mitigating H5N1 influenza in Africa, in addition to the immense humanitarian value.
11. Indeed, on October 28th the WHO also posted online the information that “the H5 hemagglutinins (HA) genes of viruses from birds in China, Indonesia, Japan, Mongolia, Russia, South Korea, and Turkey, as well as 3 viruses from humans in Indonesia are genetically distinguishable from the prototype strains selected last year for influenza pandemic vaccine development. There is also evidence of antigenic variation among the HA of recent viruses. However, their geographical spread and pathogenicity in human populations remain unclear.”
12. Thus, “for vaccine research purposes, the WHO H5 Reference Laboratory Network, which undertakes the tasks of selecting and developing the pandemic vaccine strains, has initiated the development of experimental H5N1 vaccine prototype strains from the recent viruses.”
13. At the same time “WHO does not recommend changing the previously selected H5N1 prototype strains for ongoing pandemic vaccine development.
In my opinion, the predictable future H5N1 viruses that will occur in Africa will need to be analyzed ASAP, as do those now in Europe and Asia, to understand and act on their evolving antigenic relationships. Significant changes in how the human immune system perceives these evolving H5N1 viruses (ie, “antigenic relationships”) could have a direct and immediate impact on the probability that current pre-pandemic prototypic human vaccines against H5N1 will even partially protect humans if an H5N1-related virus triggers the next human influenza pandemic.
Daniel R. Lucey, MD, MPH
Director, Center for Biologic Counterterrorism and Emerging Diseases
ER One Institutes, Washington Hospital Center
Co-Director, Master of Science (MS) Graduate Program in
“Biohazardous Threat Agents and Emerging Diseases”
Georgetown University School of Medicine, Washington, DC