Christopher H. Coulter, MD, MPH
Chief Medical Officer
Update (4/30/09):
The World Organization for Animal Health reminds people that "there is no evidence of infection in pigs, nor of humans acquiring infection directly from pigs." Pork is still safe to eat.
On Wednesday, WHO (World Health Organization) raised the pandemic flu alert to phase 5, but said there were no current indications that would prompt them to raise the alert further (phase 6 would indicate evidence of big outbreaks in at least two world regions and that pandemic is on the way). There was an increase in cases in Mexico, but scientists believe that increase is from a back-up of specimens waiting to be tested. There has been one death in the U.S., but most of the 100+ cases here have not required hospitalization. WHO is preparing to distribute additional treatments of the antiviral drug Tamiflu to areas in need.
For more information, please visit one of the websites listed at the end of this alert.
With the rapid spread of the swine flu outbreak and the anxiety that many people are feeling regarding the possibility of becoming infected, good information about the illness and its prevention is critical. Here is a quick overview of the important questions:
What is swine flu?
Influenza is a common illness, but even ordinary “flu” can be fatal – 35,000 Americans die each year from the illness, mostly the very young, the very old, and those with serious medical problems. The virus that causes influenza comes in many different varieties, and each variety can behave differently. Some influenza viruses don’t infect humans, but instead infect other mammals or birds. The swine flu virus is believed to have started in birds, but then spread to pigs, which is why it is called “swine” flu. It has occasionally spread from infected pigs to humans in the past in small outbreaks.
There is evidence that the current strain may have been “reassembled” from more than one virus infecting a pig, making the new form that is more infectious to humans. It is also harder to predict its behavior, since in many ways it is a brand new virus. It is not clear yet whether it is primarily spread by respiratory (coughing and sneezing sheds viruses into the air) or contact (infected secretions spread from hand-to-hand and then ingested) routes, or both. The speed of its spread suggests that it is much more infectious than swine flu strains of the past.
What are the symptoms of swine flu?
Influenza has symptoms of general illness, respiratory symptoms, and sometimes gastrointestinal, and swine flu symptoms are no different from those of other influenza viruses that you may have had in the past. Symptoms begin with a fever, lack of energy, and perhaps a general achiness. There may be gastrointestinal symptoms like nausea, diarrhea, and vomiting. There may also be respiratory symptoms like sneezing, sore throat, and cough. These symptoms resolve on their own, but people get into problems if they become dehydrated or get pneumonia.
A person is contagious after infection one day before symptoms begin, but that person is most contagious when the symptoms are worst and can continue to spread the virus for up to a week after becoming ill.
Who is at risk?
It is not yet clear who is at greatest risk for infection or most vulnerable to serious cases. The 65 cases documented in the U.S. to date have generally been mild, although there is one reported death. This is in marked contrast to Mexico, where more than 150 deaths have been reported. It is unclear at this point why the virus has behaved so differently in these locations, and why the virus could have greater mortality than in the past.
Because few humans have been infected with swine flu in the past, there is little natural immunity in our population. There may be some cross-immunity with other strains of influenza, but the flu shots that many people had last fall are not likely to offer strong protection, since the vaccine was directed against different varieties of flu virus.
Pork products are safe, when properly handled and cooked. The flu virus is killed very effectively at the temperature of 160º achieved in cooking pork.
How do I protect myself and my family?
Swine flu virus is spread by contact with infected individuals, and by far the best protection is to avoid exposure to the virus in the first place. General measures to prevent illness are equally effective for swine flu – wash your hands well after contact with others and with surfaces that others frequently touch. Avoid people who are ill and encourage them to go home from a workplace or school.
There is no vaccine yet available that is effective against the current swine flu virus and no indication whether those who had the recent flu vaccine are provided any protection.
There are antiviral medications that may offer some protection to those exposed to active cases of swine flu. It is not yet clear whether Tamiflu and Relenza are active against the current strain. Even if they are today, flu viruses can develop rapid resistance, so their effectiveness is unclear over longer periods.
Also, if you or a family member has symptoms that may be the flu, do not go to work or school and expose others. Resting, staying hydrated, and taking aspirin or Tylenol for fever and aches will take care of the problem for most people infected.
Why is there so much concern and what is being done?
Influenza in the past has spread as an epidemic, even going global as a “pandemic.” The current outbreak of swine flu has been localized to Mexico, the U.S., and a few other countries, and at this point there is no clear indication that it will become a global epidemic. The concern arises because of the lack of natural immunity and the high mortality rate in Mexico – a global outbreak could be serious. Millions died worldwide in flu pandemics during the 1950s and 1960s, leading us to take significant precautions today.
For these reasons an active pandemic watch is underway. As the risk of a pandemic rises, countries will take progressive steps to prevent further spread. Travel may be restricted, schools closed, and public events restricted as there is more evidence of a pandemic and preventing its spread becomes more important. You will see this process unfold if the “alert level” goes up. Currently it is at level four, and level six is when the most restrictive physical proximity restrictions take effect.
Where can I learn more?
The best and latest information comes from the Centers for Disease Control:
http://www.cdc.gov/swineflu/
The World Health Organization addresses the issues relating to global spread and pandemics:
http://www.who.int/topics/influenza/en/
WebMD is also a good source for the latest information:
http://blogs.webmd.com/breaking-news/
Photo credit: shibuya246
