What is H1N1 influenza A?
The current H1N1 influenza is a respiratory disease caused by the influenza virus. This virus has occurred in clusters of cases, indicating that it is spread within communities. This strain first appeared in Mexico in March. The first case in the United States appeared April 17.
How is it spread?
H1N1 appears to spread in the same way that seasonal flu spreads, mainly from person to person through coughing or sneezing. Sometimes people may become infected by touching something with flu viruses on it and then touching their mouths or noses.
What is the incubation period from exposure to sickness?
Normal incubation - time from exposure to symptoms - is from one to four days.
How long does the illness last?
Influenza usually lasts seven to 10 days.
How many cases have been confirmed?
There have been 4,379 cases of confirmed influenza A (H1N1) infection in 29 countries by May 10, including 2,532 cases in the United States by the morning of May 10. Missouri has 14 confirmed or probable cases, in Platte and Howard counties and the Kansas City and St. Louis areas. Additional possible cases are under study.
How severe have the cases been?
Most U.S. cases have not been severe and are comparable in severity to seasonal influenza. It has been rare in elderly persons. There have been 45 deaths among the 1,626 confirmed cases in Mexico, far less than the mortality level originally reported. There have been five reported deaths among the 2,703 documented cases outside of Mexico. Three of the deaths were in the United States, and all five cases apparently had prior predisposing illness.
Less than two percent of cases and none of the deaths have been in people over age 60. Since this age group is usually the most susceptible, it seems they may have prior immunity from exposure to a similar virus in the past. So far, 104 of the cases in the United States have required hospitalization, and many of these have had predisposing conditions. The virus is now known to lack two key virulence genes found in the 1918 pandemic strains and in recent Asian H5N1 strains.
What will happen next?
Influenza is never totally predictable. Usually, influenza leaves the world's northern hemisphere in spring and appears in the southern hemisphere as winter begins there. We will soon know if that will happen with new H1N1 virus.
What are signs and symptoms of H1N1 influenza?
Like regular seasonal influenza, onset is often abrupt. Symptoms include fever, cough, sore throat, body aches, headache, chills and fatigue. Like seasonal flu, H1N1 may be more severe in people with underlying chronic medical conditions.
In children, emergency warning signs that need urgent medical attention include:
- Fast breathing or trouble breathing
- Bluish skin color
- Not drinking enough fluids
- Not waking up or not interacting
- Being so irritable that the child does not want to be held
- Symptoms that improve but then return with fever and worse cough
- Fever with a rash
In adults, emergency warning signs that need urgent medical attention include:
- Difficulty breathing or shortness of breath
- Pain or pressure in the chest or abdomen
- Sudden dizziness
- Severe or persistent vomiting
What if I have influenza symptoms now (May 12)?
Similar to responding to flu symptoms under ordinary conditions, follow good hand hygiene, including using hand sanitizer gels and washing your hands. Cough or sneeze into a tissue or your sleeve, avoid crowds and immune compromised persons, stay home if possible and seek medical help only as symptoms warrant it.
People who have returned from Mexico or have had known contact with an H1N1 case within seven days of symptom onset may be tested with a standard rapid flu test and a specialized H1N1 influenza test, which are available at the MU Student Health Center and all MU Health Care clinics.
Avoid crowds and people with compromised immune systems, and stay home if possible. Seek medical attention only as symptoms warrant it. People who have returned from Mexico or have had known contact with a person with H1N1 flu within seven days of the onset of symptoms may be tested with a standard rapid flu test and a specialized H1N1 flu test. Tests are available at MU's Student Health Center and all MU Health Care clinics.
What medications are available to treat H1N1 influenza infections in humans?
There are two anti-viral medications available to treat this strain of influenza, oseltamivir (Tamiflu, taken by mouth) and zanamivir (Relenza, taken by inhalation). MU Health Care facilities have supplies plus ready access to the emergency state stockpile.
Is MU Health Care monitoring the situation?
Yes, University Hospital infection control experts and emergency preparedness officials on campus are monitoring the situation and planning strategies to counter any cases of H1N1 influenza that may occur in central Missouri.
If you've been vaccinated for influenza this year (fall/winter 2008-early 2009), will it offer any protection against H1N1 influenza?
Although this is under further study, the CDC has advised that current flu vaccines do not offer protection against H1N1 influenza.
How can you avoid getting H1N1 influenza?
Practicing good hygiene and avoiding exposure are the best preventive methods.
- Sneeze or cough into your sleeve, rather than your hand, if you do not have a tissue. If you do have a tissue, cover your nose and mouth with it when you cough or sneeze. Place, rather than throw, the tissue in the trash after you use it.
- Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hand cleaners are also effective.
- Avoid touching your eyes, nose or mouth. Germs spread that way.
- If you get sick, the CDC recommends that you stay home from work or school and limit contact with others to keep from infecting them
Can I get H1N1 influenza from eating or preparing pork products?
No. Influenza is not spread by food. In fact, even though it has swine influenza genes, this particular strain has rarely infected pigs. You cannot get H1N1 influenza from eating pork or pork products. Eating properly handled and cooked pork products is safe.
For up-to-date state and national information and guidelines, please visit http://www.dhss.mo.gov/BT_Response/_SwineFlu09.html and http://pandemicflu.gov/. E-mails are welcome to Michael Cooperstock, MD, MPH, chief of the Division of Pediatric Infectious Disease and medical director of the MU Health Care Infection Control Department, at firstname.lastname@example.org.