Think you know who has the flu? Thing again: a new study finds that three-quarters of people infected with seasonal flu and swine flu in recent years showed no symptoms.
Sunday, March 16, 2014 (National Institutes of Health)
Researchers analyzed data gathered in England during the winter flu seasons between 2006 and 2011, including the 2009 H1N1 "swine flu" pandemic.
Overall, about 18 percent of unvaccinated people became infected with an influenza virus, but only 23 percent of them went on to develop flu symptoms, the researchers reported March 16 in The Lancet Respiratory Medicine.
What’s more, only about 17 percent of infected people became ill enough to see a doctor, the British study found. And compared with some the seasonal flu strains, the 2009 swine flu strain actually caused much milder symptoms.
The findings suggest that relying on data about flu-related visits to primary care doctors underestimates the extent of flu infections and illnesses, the researchers said.
Overall, the infection rate for the winter flu seasons as calculated in the study were an average of 22 times higher than the rates recorded by standard methods.
"Reported cases of influenza represent the tip of a large clinical and subclinical iceberg that is mainly invisible to national surveillance systems that only record cases seeking medical attention," study lead author Dr. Andrew Hayward, of University College London, said in a journal new release.
"Most people don’t go to the doctor when they have the flu" he added. "Even when they do consult they are often not recognized as having influenza. Surveillance based on patients who consult greatly underestimates the number of community cases, which in turn can lead to overestimates of the proportion of cases who end up in the hospital or die."
An important question that needs to be answered is whether people who have the flu but have only mild or no symptoms can still easily pass on the virus, Dr. Peter William Horby from the Oxford University Clinical research Unit in Vietnam, wrote in an accompanying editorial.
Even if only mildly infectious, a large number of these people could play a major role in spreading flu each season, he suggested.
The symptoms associated with the flu are the result of the body’s immune response rather than the presence of the virus itself. Some of the more dangerous forms of influenza, like the Spanish Flu and its descendant H1N1 can be fatal only because the immune system reacts so violently to the infection, the infiltration of WBCs (white blood cells) into the lungs literally drowns the host. That’s why these flu epidemics kill young healthy adults rather than the very young and very old who have little immune response to challenge the virus.
Autoimmune diseases, like MS, Crohn’s Disease, and Rheumatoid Arthritis, are also a result of an overactive immune system and thought to be triggered by viral infections and other foreign bodies that find their way into the blood stream. Eighty-five percent of emerging disease is autoimmune in nature. I fear that the rapid spread of viral infections in our global population, along with the high mutation rates of viral infections is the driving force behind much of autoimmune disease.
THE BOTTOM LINE:
If someone around has the flu, you are probably infected as well, even if you never develop any symptoms. To protect against colds and flues, a daily dose of Echinacea is recommended. It takes two weeks for Echinacea to reach its’ full potential in the immune system. Then it acts as a modulator rather than just stimulating the immune system. It can protect against an overt over active immune response to H1N1 as well as stimulate a response to a more passive virus. Eighty percent of the Echinacea sold in the US is not Echinacea or is made from the wrong plant species or wrong plant parts. Fortunately, good Echinacea will make your tongue “tingle” within a minute or so of placing it on the tongue. That’s an easy test to see if you are taking the real thing.