(This information is not intended to be a substitute for the advice of a doctor or a recommendation for any particular treatment plan. Like any printed material, it may become out of date over time. It is important that you rely on the advice of a doctor for your specific condition.)


Human influenza viruses can be divided into: A, B and C. Types B and C are usually only found in humans and cause milder symptoms than type A, which can be found in both humans and animals such as birds, pigs, horses, whales and seals.

Influenza A viruses are further classified into subtypes on the basis of two surface proteins: hemagglutinin (H) and neuraminidase (N). Both influenza A and B viruses undergo continual minor antigenic change (i.e., drift), but influenza B viruses evolve more slowly and are not divided into subtypes. Only influenza A viruses can undergo the major antigenic changes (i.e., shift) so that the H or both the H and N are replaced and a new influenza A virus with pandemic potential can result. Influenza type C infections cause a mild respiratory illness and are not thought to cause epidemics.

The influenza season in temperate climates extends from October through March in the northern hemisphere and from April through September in the southern hemisphere. Every year, the composition of influenza vaccines is modified separately for the northern and southern hemispheres. Since the antigenic changes in circulating influenza viruses can occur abruptly and at different times of the year, there may be significant differences between prevailing influenza strains in the northern and southern hemispheres. The internationally available vaccines contain three inactivated viral strains, the composition of which is modified every 6 months to ensure protection against the strains prevailing in each influenza season. The composition of vaccines is therefore adjusted for the hemisphere in which the vaccine will be used:
• The "flu shot"— an inactivated vaccine (containing killed virus). Booster is needed every year.
• The “nasal-spray” flu vaccine — a vaccine made with live, weakened flu viruses, sometimes called LAIV for “live attenuated influenza vaccine”. Booster is needed every year.

This seasonal influenza vaccine does neither provide protection against avian H5N1 - H7N9 influenza nor swine H1N1 influenza viruses; but since 2010 the seasonal influenza vaccine includes the swine H1N1 influenza strain.

Antiviral chemoprophylaxis with a neuraminidase inhibitor medication (oseltamivir or zanamivir) is not a substitute for influenza vaccination, but should be considered for persons who are at high risk of developing complications from influenza for whom influenza vaccination is contraindicated, unavailable, or expected to have low effectiveness (e.g., persons who are significantly immunocompromised). The most recent avian H5N1 & swine H1N1 influenza viruses isolated from humans are fully resistant to the M2 inhibitors (amantadine and rimantadine).

Avian Influenza (H5N1 & H7N9)

The Avian influenza viruses occur naturally among birds. Wild birds worldwide may carry the viruses in their intestines, but usually do not get sick from them. Avian influenza is very contagious among birds and can make some domesticated birds, such as chickens, ducks, and turkeys, very sick and kill them within 2 days. Infected birds shed influenza virus in their saliva, nasal secretions, and feces.

Most cases of avian influenza infection in humans have resulted from contact with infected poultry such as domesticated chickens, ducks, and turkeys, or surfaces contaminated with secretion from infected birds. About 50% of infected people died from the infection.

The time between infection of a person with the flu virus and the appearance of symptoms, the incubation period, can range from one to five days. The symptoms of avian influenza vary in severity depending on which virus caused the infection. Symptoms of avian influenza in humans are similar to typical human influenza-like symptoms: Fever, Cough, Sore throat, Muscle aches and Eye infections. Pneumonia or severe lung infections and other severe respiratory diseases can occur. This could lead to life-threatening complications that may necessitate hospitalization and use of a respirator.

There currently is no commercially available vaccine to protect humans against the H5N1& H7N9 virus, and no known medications that treat an avian influenza infection specifically. Flu treatments that should work for avian flu include rest, medications to bring down high fevers, and drinking plenty of water. If complications occur and the patient becomes very sick, then hospitalization may be necessary with administration of oxygen or the use of a respirator.

The following tips will help you prevent flu infections such as the common flu and Avian flu:
• Wash your hands frequently with soap and water, particularly before eating and after sneezing or coughing.
• Use NIOSH-approved disposable masks rated N95 or higher and that fit tightly over your nose and mouth.
• Cover your mouth and nose with tissue when you cough or sneeze. Put used tissues in a wastebasket. If you don’t have a tissue, cough or sneeze into your upper sleeve.
• Stay at home if you are sick and stay away from others if they are sick.
• Eat only cooked meat and poultry.

The N95 surgical face mask has been recommended by USA experts as the best protection from virus. The mask has a >99% Bacterial Filtration Efficiency. The N95 is the USA equivalent of the European P2 and P3 masks with the P3 offering the higher protection. The N95 mask has a Particle Filtration Efficiency of >95% at 0.3 micron. Masks are intended for use in infection control practices.

Swine Influenza (H1N1)

H1N1 Flu Infections Influenza viruses happen naturally among pigs, hogs, and boars. Swine influenza is very contagious among swine. It can make some domesticated pigs very sick. It is unusual for humans to catch swine flu viruses, but occasionally cases happen, usually in people who have contact with infected pigs. Swine flu viruses have also been reported to spread from person to person in the past, but previous episodes of transmission were very limited.

Droplets from a cough or sneeze of an infected person move through the air. Germs can be spread when a person touches something that is contaminated with germs such as a table, door knob, or desk and then touches his or her eyes, nose, or mouth before washing their hands. Frequent hand washing will help you reduce the chance of getting contaminated from these common surfaces. Infected people may be able to infect others beginning one day before symptoms develop and up to seven or more days after becoming sick.

The most common symptoms of H1N1 influenza in humans are similar to typical human flu and include: Fever, Cough, Sore throat, Body aches, Chills and Fatigue. Some people have reported diarrhea and vomiting associated with H1N1 flu. People who have chronic conditions such as asthma, diabetes, congestive heart failure, etc. may notice a worsening of their medical conditions. You should seek medical care if you develop any of the “emergency warning signs”. Some of the “emergency warning signs” that require urgent medical attention are: Difficulty breathing or shortness of breath, Pain or pressure in the chest or abdomen, Sudden dizziness, Near-fainting or fainting, Confusion, Severe or persistent vomiting, and High or prolonged fever.

Antiviral medications are currently recommended only for those patients with moderate or severe illness from H1N1 flu. Most people get better without antiviral medicines. Antiviral medications must be taken within 48 hours after symptoms appear. They may diminish your symptoms, but they may not make your symptoms go away entirely. Other flu treatments that should work for H1N1 flu include rest, medications to bring down a high fever, and drinking plenty of water. If complications happen and you become very sick, hospitalization may be needed. Hospitalized patients may be given oxygen or use a respirator.

If you get sick with the flu, here are some tips to avoid spreading the disease to others:
• Stay at home and avoid contact with other people.
• Cover your nose and mouth with a tissue when you cough or sneeze. Put used tissues in a waste basket. If you don’t have a tissue, cough or sneeze into your upper sleeve.
• Wash your hands every time you cough or sneeze. Alcohol-based hand cleaners are also effective.

(Source:  WHO, U.S. Centers for Disease Control and Prevention & U. S. National Library of Medicine - National Institute of Health)