Novel H1N1 Influenza (Swine Flu)  (Pandemic H1N1)

History:   Influenza is a highly contagious viral infection of the respiratory tract.  The name influenza comes from the Italian influenza, meaning “influence”.  (Wikipedia)  This name was assigned to the flu because many people in the 1700’s thought that certain astrological “influences” caused influenza infections.   We now know that it is a viral respiratory tract infection.


Description:   Influenza viruses are from the virus family of orthomyxoviruses of three different types (A, B, and C).   Influenza A causes most severe disease in humans.  The viruses are named based on two glyco-proteins named hemagglutinin (H) and neuraminidase (N) that are found on the cell coat of the virus.  These two different types of proteins form the basis of the H and N distinctions in naming different influenza organisms, for example, H1N1.  There are 16 H and 9 N subtypes known, but only H 1, 2 and 3, and N 1 and 2 are commonly found in humans. (Wikipedia)  Because influenza viruses have many subtypes and because the different influenza viruses can share genetic material, there is an unlimited number of different strains that can come into existence over time.  Each variation, or strain of the virus affects its host in different ways.  Some strains cause mild disease, while other strains can cause severe disease.

Influenza viruses infect humans and many other mammalian species including pigs.  They can also infect birds.  Influenza viruses that infect one species of animals typically will not cross into another species.  So, most cases of swine influenza will only be transmitted to other pigs.  The same is true of avian (bird) influenza.  Birds typically give bird influenza to other birds and pigs give pig influenza to other pigs.  For humans, cross species infection, a phenomenon called zoonosis, is known to occur, but it is rare.   In the rare event that cross species infection does occur, usually the influenza infection is not spread to other members of that species.  So, if a pig transmits influenza to a human, generally that human cannot spread the virus to another human.   The word “generally” is what is at issue at the present time, because a variant of swine flu is now infecting humans.

Genetic material in influenza viruses is known to slightly change, merge with other influenza virus genetic information, re-assort or even mutate periodically.  Because of this, people who have had the flu or the flu vaccine in the past can be susceptible to influenza infection with a type of influenza which has changed its genetic makeup.  This ability of the virus to change its genetic makeup causes the immune system of the body not to recognize the virus as an infection which the body has fought off in the past.  This ability of the virus to change leads to periodic epidemics.  This is reason that we have yearly flu shots.  Each year different strains of influenza are placed in the immunization.  This is to cover the expected influenza strains that will circulate each year.  The immunity of the flu shot is not lost each year.  You get a flu shot yearly, to protect against new strains of the flu that are included in the new vaccine for the year.

In the present case, unfortunately for us, a new influenza virus has emerged this past spring.  The official name of the virus was changed from “swine flu” to novel H1N1 a few months ago.  The names are interchangeable and refer to one virus.  The influenza virus that mutated contains genetic material from influenza viruses that cause disease in pigs, in birds (avian) and in humans.  The term “swine flu” has been labeled to this virus because part of its genetic code is from the influenza virus that infects pigs.  Because human influenza genetic material is also in this “swine flu” virus, human to human spread is possible, along with pig to human and pig to pig spread.

The primary problem with the emergence of this new strain is that there is very limited immunity in the population to this virus.  Only people who are over the age of 60 years have any immunity to the swine flu and then only 30% of those people have immunity.  Evidently, years ago, a flu strain that affected that generation now confers some immunity to this new strain.

So, why has the Centers for Disease Control (CDC) and the news media placed so much attention on this virus?  The answer to this question lies in history.  In March of 1918 a new strain of influenza began to spread across the world.  Unlike previous strains of the flu, this strain quickly became a worldwide health emergency because of the severity of infection.  This form of the flu caused many people, including healthy young adults, to develop bleeding problems in the lungs that in many cases were fatal.  In addition, other complications of the flu were present in this pandemic.  The “Spanish Flu” lasted from March 1918 to June 1920.  It is estimated that 50 to 100 million people were killed worldwide.  An estimated 500 million people, one third of the world’s population (approximately 1.6 billion at the time), became infected. (Wikipedia).  Ever since this “worst medical holocost” in history, physicians and health scientists have worried about when the next “superbug” would appear.

Although the current Swine Flu (H1N1) pandemic does pose some risk, it is not turning out to be anything like the 1918 disaster.  It appears to be about the same severity as our usual yearly seasonal influenza outbreaks.   What most people may not realize however, is that the seasonal flu infections we have each year cause many hospitalizations and deaths each year.  Typically 36,000 to 50,000 people may die of the flu each year.  In the US, more people die of influenza each year than all other infectious disease combined.  Therefore, when a new strain of the flu emerges, it is news because of the potential of so much harm as we have learned from history.

So, what do we make of all this?  Thus far, the swine flu virus infections we have seen in our country (and what I have seen in the office) is no worse than our usual seasonal flu outbreaks we see each winter.   The illness makes people feel really sick with high fevers, chills, fatigue, malaise, muscle aches, headache, congestion, vomiting, diarrhea and cough.  The vast majority of people who catch the swine flu will completely recover with no sequellae (longlasting complications).  The notable difference between swine flu and seasonal flu is that we are seeing swine flu (H1N1) in August.  We anticipate that we will also see the seasonal flu strains that normally circulate each year as well.  You might say that we anticipate a double dose of the flu this year with twice as many people getting sick and probably twice as many people dying of the flu as both the swine flu and the seasonal flu viruses go through our communities.   Therefore, if 90,000 people die of influenza infection this year and the US population is 304,059,724, you have a 1 in 3,378 chance of dying from the flu this year.   Therefore, although some risk for mortality is present from the flu, the risk is low.

Signs and Symptoms:After an incubation period of 1 to 3 days, an Influenza illness is generally characterized by the abrupt, sudden onset of high fever, frequently with chills or rigors, headache, feelings of tiredness, muscle aches, and a dry cough.  103 to 105 F degrees of fever are common with influenza.  Then, the respiratory signs of sore throat, nasal congestion, and cough become more prominent.  Less commonly, eye redness and watery discharge, abdominal pain, nausea, vomiting and diarrhea can also be present with the “flu”.  In some children, influenza can have the appearance of a simple “cold virus” or it can appear as a fever illness with few respiratory signs.  In newborn babies and very young infants, influenza can produce a variety of symptoms which can be more serious.  The infection can look like sepsis in a young infant (a severe, generalized bacterial infection) requiring several tests to investigate this possibility.  Besides the above routine symptoms of the flu, it can occasionally cause croup, apnea, or pneumonia in these infants.

Some older children with the flu can have a tendency to develop tenderness of the calf portion of the leg and refuse to walk.  This symptom of the flu may develop several days into the influenza illness.  This is especially prone to happen with Influenza type B infections.  Reye syndrome, a severe disease producing inflammation of the brain and liver with the development of coma, has been associated primarily with influenza B, but also with influenza A infection.  The development of Reye syndrome in people infected with the flu has been associated with the consumption of aspirin.  Obviously you should not take aspirin if you have the flu to avoid this potential complication.

How It Is Spread:  Generally, Influenza is spread from person to person by direct contact, large droplet infection (as from a sneeze), or from articles recently contaminated by nasal secretions.  Specifically, Swine flu spreads in the same way that other flu viruses do, through the air when a person who has the virus sneezes, coughs, or speaks. People also can catch the virus after touching a contaminated object that someone with the virus sneezed or coughed on.  Influenza organisms can live on surfaces for several hours (4 to 8 hours).  Therefore, cleaning of surfaces and discarding used tissues are very important during flu outbreaks, especially in schools.

During an outbreak of influenza, the highest attack rates occur in school-age children.  Secondary spread to adults and other children within the family is very common.  The attack rates depend in part on the immunity developed by previous experience (either by natural disease or immunization) with the particular strain of the virus which is encountered.  In Arkansas, our flu epidemics usually occur during the winter months, and peak within 2 weeks of onset of the epidemic and last 4 to 8 weeks or longer.  In recent years, activity of two or three types of influenza virus has been common and associated with a prolongation of the influenza season to 3 months or more.  With the recent development of the swine flu this summer, the flu season could easily go for many months into 2010.

Influenza is highly contagious, especially among institutionalized populations.  People with the flu are most infectious in the 24 hours before the onset of symptoms and during the period of peak symptoms.  They usually remain contagious until 5 to 7 days from the onset of illness have past.  However, the contagiousness of the flu can last longer in young children and immunodeficient patients.

Duration:  After five days, fever and other symptoms have usually disappeared.  But a cough and weakness may persist for several more days. All symptoms are usually gone within seven to 14 days.  Pneumonia, sinusitis, and ear infections are occasional complications of the flu.

Treatment: Because the flu is a viral illness, antibiotics don’t help.  There are flu medications which can shorten the duration and diminish the severity of the illness if begun within 24 to 48 hours of the onset of the illness.  Should you become ill with the flu,  and desire to be treated by a flu medication, you should contact your physician early in the illness to obtain appropriate treatment.  However, the CDC and the Arkansas state department of health are recommending that most people not be treated with the flu medications because of the mild nature of most infections and because of the possibility of influenza developing resistance.  Some resistance patterns of the influenza organisms have already emerged.  This resistance pattern has made the choice of anti-viral medications complicated this year.  There are tables available from the CDC with the recommended medications for different influenza organisms.

As with other viruses, fever control is unnecessary and if done will prolong and worsen the illness.  Fever is a God given defense mechanism of the body that helps your immune system know that it is supposed to fight.  Fever is present in a person for very good reasons.  It is a physiologic signal from the brain to the immune system that an infection exists in the body.  White blood cells in the body respond to fever by increasing their surveillance, increasing their activity and reducing their threshold to release their biological attacks on the invading organisms.  Kids with fever generally lay in bed with a blanket, because so much energy is going into fighting the infection.  The net result of letting the body fight off the infection with fever is that the child will be sick a shorter amount of time with less complications.  Therefore, I recommend that you don’t routinely use ibuprofen or acetaminophen for the flu unless your child is just too uncomfortable to bear the fever.  A dose of Tylenol (acetaminophen) at bedtime to help a child sleep won’t hurt too much.  Children with seizures should have their fevers treated because seizures can be made worse with fever.  Children who began to hallucinate (seeing scary things that aren’t there) with the fever of influenza should also have their fevers treated because their brain is not tolerating the fever well.  Have your child take lots of liquids and eat nutritious, carbohydrate rich foods.

Kids with any of these symptoms need immediate medical attention:

  • fast breathing, trouble breathing or wheezing
  • bluish skin color
  • not drinking enough fluids (the signs of dehydration are a dry mouth and poor urine output, less than three times per day)
  • very sleepy or lethargic
  • in babies, severe irritability with not wanting to be held
  • fever with a rash
  • flu-like symptoms improve, then return with fever and a worse cough (this is a sign of pneumonia)

Prevention:  It is better to prevent swine flu than to treat it.  A vaccine against swine flu (H1N1) is currently in trials and should be available in the fall.  The Centers for Disease Control and Prevention (CDC) specifically recommends the swine flu vaccine for:

  • pregnant women
  • people who live with (or care for) children younger than 6 months old
  • children and young people between the ages of 6 months and 24 years old  (that means all school children)
  • people ages 25 to 64 with chronic health conditions or compromised immune systems
  • health care and emergency services personnel

Please know that the swine flu vaccine does not protect against seasonal flu, so it’s also important to also get the seasonal flu vaccine this year.   Seasonal flu vaccination is recommended for all children between the ages of 6 months and 19 years.  Both vaccines may be administered on the same day.  In our office we have already begun to give flu vaccines this year.  A nasal flu vaccination called FluMist is available along with the old standby, the flu shot.  So, get you and your family a flu shot as soon as possible.

High Risk Groups:  As with other types of flu, kids with chronic medical conditions (like diabetes, heart disease, or asthma or other lung problems) can have more problems coping with the illness. They might get sicker and need more medical support including anti-flu anti-viral medications and in some cases, hospitalization.  Pregnant women who catch the flu also are more likely to get sicker.  Having the flu can increase the risk for complications during pregnancy, labor, and delivery.   If you are pregnant and you catch the flu or have been exposed to someone who has the flu, see a doctor right away. You may need to take antiviral medications as a precaution for yourself and your baby.  In infants, the flu can be life threatening and requires immediate medical attention.  If your child has a chronic condition, like asthma, make sure to check with your doctor to help ensure the condition is under control. Kids without chronic health conditions usually tolerate infection with flu viruses fairly well. In fact, most children with swine flu get better on their own without any medical treatment.

Tips for avoiding the flu

  • avoid touching your eyes, nose, and mouth.  This is how the flu is spread, into your mouth or nose.
  • teach your child to wash their hands often.
  • get plenty of sleep and rest to keep your immune system healthy.
  • get both of your flu shots this year.

Tips for managing the flu

These tips can help you cope with the flu:

  • drink lots of fluids to prevent dehydration
  • cover your nose and mouth with a tissue when you sneeze or cough and put used tissues in the trash.
  • If you don’t have a tissue, cough or sneeze into your upper sleeve, not your hands.
  • clean your hands after coughing or sneezing — wash with soap and water or use alcohol-based hand cleaner.
  • get plenty of sleep and rest.
  • take acetaminophen or ibuprofen to relieve fever and aches if you must, but remember that fever helps the flu go away faster if it is not treated.
  • do not give aspirin if you have the flu.  This is to prevent Reye’s syndrome.
  • wear layers, since the flu often makes a person cold one minute and hot the next (wearing layers — like a T-shirt, sweatshirt, and robe — makes it easy to add or subtract clothes as needed)
  • call a doctor if your child seems to get better but then feels worse, develops a high fever, has any trouble breathing, or seems confused.  These can be a signal complications of the flu.
  • keep sick kids home from childcare or school and limit their contact with others; kids should stay home 7 to 10 days after the onset of illness.
  • if your child becomes ill with a flu like illness consult your child’s physician.
  • remember that God is in control of your life, not the swine flu.  “Don’t be anxious about your life”

The monograph was prepared from the following “Recommendations for prevention and control of influenza in children, 2009-2010”Wikipedia, influenza, swine fluSeptember 10, 2009, Dr. Jerry Byrum