Expert Perspective/Influenza A, H1N1 (Swine Flu) May, 2,2009
It came out of nowhere . . . well, probably Kansas. By the time it was over, the Spanish Flu Pandemic (influenza virus A, H1N1) of 1918 caused 50 – 100 million deaths out of 1 billion-estimated infected worldwide over a year, in several tsunami-like waves of increasing biological mayhem. More died than in 100 years of the Black Death (bubonic plague) in Europe. Twice as many died as from World War I.
Most shockingly, death was often rapid, sometimes only hours after illness onset. And, it was directly from the flu virus, rather than secondary bacterial infections as with usual flu viruses; and the highest death rates were in prime years, teens to 50’s. In those times, many would have said only the Wrath of God could be at work. The current Swine Flu virus is influenza A, H1N1. Can we expect the same in the months ahead? That is the reason for the hour-to-hour worldwide public health alert actions.
To gain a reasoned understanding of where we are and where we are most likely to go, there is no getting around understanding some basic epidemiological, infectious diseases discipline terms and concepts.
Epidemic/Pandemic: A statistically significant increase above baseline activity of an infectious agent in a population. Pandemic is worldwide pervasion (multiple, concurrent epidemics) of the agent throughout humankind. This term does not imply anything with regard to individual case infection severity or risk of death.
Virulence: The ability to cause damage and disease in the host organism.
Mutation: A genetic change that may affect fundamental virus properties in how the infectious agent interacts with a host – especially virulence and/or transmissibility. Any mutation may make these properties better or worse, singly or in combination, or in opposite directions.
Transmissibility : The ability of an infectious agent to move from one host to another.
How is the current situation similar to 1918?
- This H1N1 flu virus is a biological cousin of the Spanish Flu agent.
- Epidemic disease activity spiked up in a non-seasonal flu pattern.
- Transmissibility appears to be high.
- Infection epicenter Mexican deaths, so far, have been mostly in those 20 – 50 yrs-old.
- Epidemic onset and rampant spread occurred in a “developing country”, which 21st title would be aptly applied to all countries, medically, in 1918.
How is it different?
- So far, there have been no conclusive reports that the deaths to date have been from influenza virus per se, in an overwhelming host-virus biological cataclysm, causing virtual multi-organ dissolution in a matter of hours to days, as with Spanish Flu.
- Many secondary cases are now located in entirely different social and healthcare system “laboratories” as the virus has been transported to industrialized nations. It will be interesting to see if the epidemic nature and individual case outcomes change in this new model, providing the virus does not mutate in a way that affects virulence and transmissibility.One difference in even today’s “developing country” model and that of 1918 is that back then there were no antibiotics or high-tech inpatient services (IV medication or fluids, intensive care methods or equipment).
- There was no rapid, across-the-globe coordination and communication system that approached anything like the real-time international informational “nervous system” that exchanges information real-time, multinationally, as well as down to local communities.
Next, what is known?
- Transmission: Just the number of cases both confirmed and suspected suggest at least a standard influenza virus’ communicability. The rapid spread internationally is related to our world’s travelling connectivity. It is likely that in weeks ahead we will find that the H1N1 virus has caused much more subclinical disease in many more Mexican citizens (which will lower the mortality figures, as a percentage of the total numbers infected, and so the perception of the virulence and danger of the virus).
- Virulence: Our usual, annual flu epidemics cause an average of 35,000 – 40,000 U.S. deaths. As this H1N1 virus spreads, there will be deaths. The mark of virulence will be whether total deaths exceed the usual 0.1% (1 per 1,000 illnesses). The Spanish Flu mortality rate was estimated at between 2 – 20 % (or 20 to 200-fold that of “routine” flu), and, again, it was in the healthiest, fittest of the society.
- Vaccine: We have none for this H1N1 virus. But, since the H1N1 swine flu aborted epidemic of 1976, and the alarm it caused because of a perceived similar onset story to the Spanish Flu, the annual flu vaccines used in the U.S. have contained H1N1 virus components. We all may have some “immunological memory” that allows U.S. citizens to experience relatively minor illness if they catch this flu.So far, U.S. cases of the Swine Flu have been relatively usual, from a clinical point of view. But, be clear, the Spanish Flu Pandemic started with relatively few deaths in the February/March, 1918, but with viral passage through the human species it adapted and became an efficient killing machine by August, when severe illness and death of the infected became expected and usual.The Mexico experience, again, is complexly different, and perhaps of limited use in inferring implications for more developed nations. The availability of over-the-counter antibiotics, as well as many other medications, along with a public/governmental healthcare system that is problematic (from their citizens’ viewpoint) in terms of timely access to effective expertise, impels individuals to self-diagnose, self-medicate, and present late in illness, affecting the ultimate outcome, and so the statistics that may fan fear and panic.Parenthetically, the available water quality, nutritional health, and underlying usual medical conditions in a society can have a dramatic effect on both individual infection cases and so the perceived behavior of an infection across a society. Tuberculosis and HIV/AIDS in the developing versus industrialized world come to mind.
- Swine A, H1N1 (2009): This virus, though closely related to Spanish Flu H1N1, is also genetically significantly different, which can mean everything in terms of transmissibility and virulence. House cats and tigers are both biologically related felines.
- Antiviral Drugs: There were none in the early 1900s. We have several drugs which are highly effective, if started within 48 hours of illness onset.
What is not known?
- Swine Flu A, H1N1 Virulence: This will become more evident as the virus moves through sophisticated healthcare systems that can calculate overall virus prevalence (asymptomatic and illness cases) against total deaths. Likewise, post-mortem exams (autopsies) will demonstrate biological similarity, or lack of it, to routine flu viruses in the manner of death, a direct reflection of viral virulence.
- Background Immunologic Memory: Many U.S. citizens and those in many other countries should have some antibodies from prior flu vaccinations that will provide some H1N1 virus defense. It is speculated that one reason the elderly did not suffer extraordinarily high death rates with the 1918 influenza A, H1N1 was that they still had some residual immunity from exposure in the 1889 Russian flu epidemic.
- Transmissibility: Without broad-based sampling of an entire population to ascertain how many asymptomatic infections had occurred, it is impossible to know how easily an agent infects and passes between hosts. At this point, it appears that the virus is readily transmitted between people since institutional outbreaks have occurred. This will likely be better detailed in upcoming months.
What can we conclude?
- There will be deaths. If people drive cars, there will be deaths. The question is what is the nature (speed, character, and age-group) of such deaths, as well as the mortality rate compared to usual flu?
- It is premature to make major public health restrictive or quarantine policies if it is being done in response to perceived serious disease jeopardy.The proper rationale for any such moves, with what we know, is to foreshorten new outbreaks of this virus, to minimize deleterious social and economic impact of the infection, as well as to protect those at unusually high-risk from any flu agent: less than 5 yrs-old, over 60 yrs-old, pregnant, underlying medical conditions.
- Swine Flu A, H1N1 will spread. How much of this has to do with the nature of the virus and how much has to do with the way we live and move across our country and our world are probably equally important. Activity should pick up in South America as winter commences there now, with increasing cases in North America in the Fall.It is likely that this virus, without prohibitive public health restrictions in businesses, school, and communities will play out, in waves, for the rest of this year.
What can we do?
- Be attentive. Take in everything stated hear and remain calm and informed as information develops. This is not a panic situation. But, it is not a time for intellectual recumbency, either. Specifically, be alert for expert opinions on how similar Swine Flu virus is acting like usual flu or like Spanish Flu, 1918, as reflected in the character of deaths and the speed and pattern of spread.
- Wash your hands frequently after contact with others, especially out there in your life.
- Do not fly or attend public events or social venues (restaurants, shopping) if you have had a respiratory illness (especially with fever) in the past week, until all this is over. The same applies to visiting any of the aforementioned unusually high-risk group people or going to long-term care facilities and hospitals.
- Travel – Do not do it at all (every means of travel, except a bike, implies closed, shared air-space) if ill, as in #3 above.Avoid travel to areas of extraordinary disease activity, such as the epidemic epicenter, Mexico. If you must go, consider taking along an N-95 respiratory mask, Tamiflu or Relenza, and other medications of use in weathering the flu and its unusual complications if you will be at your destination for more than several days (especially if such medication may be hard to get there). Those at high-risk for flu illness or its complications, as previously defined, can consider taking Tamiflu or Relenza on an ongoing, preventive treatment schedule (see guidelines at CDC.gov/swineflu) while in areas of exposure.
- If you become ill with flu-like symptoms, obtain expert medical advice immediately, the anti-viral mediations must be started right away (and proper testing will confirm the diagnosis in several to 24 hours).
Finally, the 1918 Spanish Flu Epidemic was a “perfect storm” – the confluence of a newly mutant virus crossing from the animal kingdom to humans, an infectious agent with high transmissibility and virulence properties, a vast number of entirely immunologically naïve people, a primitive healthcare system, no directly effective medications, a rudimentary public healthcare apparatus (locally and internationally), and worldwide movement of humans across oceans and borders waging a World War. This is said not to say that it cannot happen again. Rather, we need to bring perspective and balance to what is happening now and in the months ahead.
Of final interest is whether this epidemic/pandemic will bring the U.S. populace to engage more actively in assessing the value of an highly expert, accessible, and effective medical care system. As this issue is front and center in our political dialogue, perhaps the way this healthcare crisis plays out and affects peoples’ lives will provoke reconsiderations of the value and priority our citizens place on the medical care available to them and the degree to which they have taken it for granted. The confluence of these two issues as well as a test-run of our response to a future virulent pandemic may be enduring benefits of what now is only appreciated as a negative.
Edward R. Rensimer, MD, FACP
Infectious Diseases/Tropical Medicine
Director, International Medicine Center
Houston, TX USA