Swine Flu (H1N1/09)

Yes, it is a highly contagious infectious disease so it is possible. See the related questions below for information about the symptoms to watch for to see if you have the flu. After a certain length of time you can probably relax if you have not yet shown any symptoms. Here is information from the Centers for Disease Control and Prevention (CDC) about the incubation period of Novel H1N1:

"The estimated incubation period is unknown and could range from 1-7 days, and more likely 1-4 days.

"The typical incubation period for influenza is 1-4 days (average: 2 days). Adults shed influenza virus from the day before symptoms begin through 5-10 days after illness onset. However, the amount of virus shed, and presumably infectivity, decreases rapidly by 3-5 days after onset in an experimental human infection model. Young children also might shed virus several days before illness onset, and children can be infectious for 10 or more days after onset of symptoms. Severely immunocompromised persons can shed virus for weeks or months.

"Uncomplicated influenza illness typically resolves after 3-7 days for the majority of persons, although cough and malaise can persist for >2 weeks. However, influenza virus infections can cause primary influenza viral pneumonia; exacerbate underlying medical conditions (e.g., pulmonary or cardiac disease); lead to secondary bacterial pneumonia, sinusitis, or otitis media; or contribute to coinfections with other viral or bacterial pathogens."

According to the Centers for Disease Control and Prevention on 5/7/09:

7 May 2009 -- From transcripts of CDC Morning Press Briefing:

"We are reporting 1,823 probable and confirmed cases in 44 states. This is an increase of around 330. We are reporting 896 confirmed cases in 43 states, that's an increase of 254 cases and around 925 probable cases. Again, I want to reiterate that as soon as I say the numbers, they're wrong because ongoing testing is taking place at CDC, it takes place in every state. And so as you go to states, you will come up with [higher] numbers than are on our website. That is expected. The work continues. Median age remains 15. The range is one month to 87 years. 12 of the cases are under age one. So I do want to remind you that individuals of all ages can acquire this virus. Only about 10% of confirmed cases have a travel history from Mexico. This indicates as well ongoing transmission in communities. We would expect as this travels more around the country, that we're going to see that number go down further. So that while there may have been introduction from travel to Mexico, the spread that's ongoing does not require travel to Mexico. 58% of our confirmed cases are under 18 years of age. 5% have been hospitalized. That's 42 of the 896 confirmed cases. And two individuals died from this disease."

They are currently made exactly the same in the US with all the same ingredients, except the strain of the flu is the A-H1N1/09 strain in the H1N1 shot and the seasonal flu shot has three different types of seasonal flu. The strains of virus that are in the 2009 - 2010 seasonal flu shot in the US are:

• A/Brisbane/59/2007(H1N1)-like virus;
• A/Brisbane/10/2007 (H3N2)-like virus;
• B/Brisbane 60/2008-like antigens.

The 2009-10 seasonal influenza vaccine can protect you from getting sick from these three viruses, or it can make your illness milder if you get a related but different influenza virus strain. The H1N1/09 Swine Flu shot protects you from the Pandemic Swine Flu.

Most antiviral drugs must be started within 40 - 48 hours of the first signs of the flu for most efficacy. These drugs reduce the severity and duration of the symptoms, but do not actually "cure" the flu, that job must be done by your immune system.

There are two types of of antiviral agents, the first one is the adamantanes, such as amantadine (Symmetrel®) and rimantadine (Flumadine®). Adamantanes are useful only for influenza type A infections. The second type of antiviral agents are the neuraminidase inhibitors, such as zanamivir (Relenza®) and oseltamivir (Tamiflu®, 1999).

Approximately 80% of the circulating strains of flu viruses typical in a flu season are influenza type A virus H1N1. These types can be treated with adamantanes and zanamivir, but are resistant and cannot be treated with oseltamavir. Sometimes many of the circulating strains can be resistant to antivirals, but usually one type will work. The Centers for Disease Control and Prevention (CDC) provides information each year about the expected strains of flu coming in the next season and which antiviral drugs will be best to treat them.

Influenza type A virus H3N2 strains can be treated with oseltamavir and zanamivir, but are resistant to adamantanes.

As for influenza type B strains, they can be treated with oseltamavir, zanamivir; but are resistant, and cannot be treated with adamantanes.

In addition, for unvaccinated patients the recommended drug for influenza B exposure is oseltamivir, and the recommended drug for influenza A exposure or unknown subtype are zanamivir OR oseltamivir + rimantadine.

Most of the indications in clinical settings suggest that it is not significantly "airborne", according to the medical use of that word (see reference to one such research effort below). Airborne in that sense would mean that it is in the air and stays in the air to move on air currents.

The term airborne infectious disease in medical terminology refers to microbes or viruses that can float and stay in the air and are able to be transmitted from person to person carried by air currents and breezes. By that definition, the Novel H1N1 (2009 Swine Flu) is not airborne. However, it can be in the air and able to be inhaled for short time periods when carried on respiratory droplets from coughs and sneezes. These are heavier than true airborne particles and will fairly quickly fall to the ground or onto surfaces (or people) in only the immediate area of the source.

There is some debate on this (see also below), but the guidelines from the World Health Organization (WHO), Centers for Disease Control and Prevention (CDC), National Health Service (NHS) in the UK, and other infectious disease control and research organizations, for prevention of the spread of seasonal influenza and A-H1N1/09 (Swine Flu), include much more information concerned with the virus being spread by direct contact (e.g., on the hands) and from spread on respiratory droplets, instead of by a truly "airborne" route.

Coughing and sneezing by an infected person are the most common sources of the spread of influenza on respiratory droplets. Novel H1N1 (A-H1N1/09) can be on respiratory droplets for a short time in the air and then inhaled if you are within six feet of the person who coughed or sneezed. The droplets in the air carrying the virus will typically quickly fall to surfaces within that six foot radius. Once they are on the surfaces, they are easily picked up on hands and then from there transferred to another person or yourself (when the viruses from the surface come in contact with mucus membrane tissue in the nose, mouth, or eyes).

For the most effective protection against a direct transmission, it is recommended that you use good hygiene, and especially hand washing (or use hand sanitizers that are minimally 60% alcohol according to the product directions for use). In addition, the agencies mentioned above recommend that you maintain a distance of six feet from an infected person. This is far enough to be out of range of their sneezing or coughing (or otherwise producing respiratory droplets).

Avoid touching surfaces and items the infected person has touched. Whenever possible, avoid crowded places. Different time frames are found referenced about the length of time viruses can remain viable on surfaces outside a living host. For most environments, it is often quoted that they can "live" for 24 to 48 hours on nonporous environmental surfaces. They quote that they live less than 12 hours on porous surfaces, before becoming inert. (see related questions below)

Like the seasonal flu, H1N1/09 it is mainly transmitted person-to-person through direct skin-to-skin contact, or through the spread on respiratory droplets from coughing or sneezing by people infected with the influenza virus.

Are face or surgical masks helpful?

You can wear a "respirator" mask (a common type is known as N-95). These are worn on your face to filter the virus particles and prevent you from inhaling them. They must be fitted to your face according to specific medical fitting guidelines. They are not recommended for children or men with beards due to fitting difficulties which would allow the virus to enter around the sides of the N-95 mask. The plain surgical masks that are often seen being worn on the streets are not effective in filtering out the sub-microscopic virus. The virus will pass right through those masks or around the edges. The respirators can also be problematic for people with asthma, or others with respiratory disease, since they make it be difficult for some to breathe through them.

The surgical type of face masks are most effective as a means to cover the mouth and nose of infected people so that, like using a tissue, their coughs or sneezes will contained. These may also be effective for others to prevent respiratory droplets from being inhaled, such as health care workers, caregivers, or parents within that very close proximity to the ill person. Droplets may directly infect those within three feet of the ill person if no mask is used.

All types of face masks and respirators should be used only once and then carefully disposed of in trash containers, washing hands afterward. Some masks become ineffective when damp or after a period of use, and may need to be changed to remain effective (see guidelines for use with each device).

There are some who believe that the influenza virus also poses a threat as an airborne particle under specific environmental conditions, and who recommend filtration and purification systems for use with HVAC systems in buildings and homes. (See the discussion section for more.) The necessity of these for use in non-clinical public settings, and residential settings is questioned by other researchers. WHO, CDC, and others do not specify use of these in their prevention recommendations.

Modes of Transmission

In an August 21, 2009 document on Swine Flu Infection Control Considerations from the Center for Infectious Disease Research & Policy (CIDRAP) at the University of Minnesota (see links section below), they stated:

"Influenza viruses potentially can be transmitted through droplet, contact, and airborne modes. Although existing data are limited regarding the contribution of each mode of transmission, a recent review concluded that influenza virus transmission occurs at close range rather than over long distances (see References: Brankston 2007)."

"Droplet transmission

• Influenza viruses are predominantly transmitted by large droplets (ie, >5 mcm).

• Droplets are expelled by coughing and sneezing and generally travel through the air no more than 3 feet from the infected person.

• Transmission via large droplets requires close contact between the source and recipient persons, permitting droplets, which do not remain suspended in the air, to come into direct contact with oral, nasal, or ocular mucosa.

• Special air handling and ventilation systems are not required to prevent droplet transmission."

"Airborne transmission

• Airborne transmission of influenza viruses (i.e., transmission via droplet nuclei [<5 mcm], which remain suspended in the air and have the potential to travel farther than several feet) has been suggested in several reports, although evidence to conclusively support airborne transmission of influenza virus is limited (see references, Bridges 2003)."

• Available data suggest that airborne transmission does not play a major role in the spread of influenza viruses. . .However, airborne transmission of influenza viruses may occur, at least over short distances, and further study is needed to determine the importance of this mode of transmission in healthcare or other settings.

• There is no evidence to date that droplet nuclei containing influenza viruses can travel through ventilation systems or across long distances, such as can occur with tuberculosis and certain other viral agents."

In a research paper, published in 2003 in the Chicago Journals, Transmission of Influenza: Implications for Control in Health Care Settings, by Carolyn Buxton Bridges, et al, (see link below) the following excerpts were found:

"Airborne transmission entails the production of infectious droplet nuclei, generally <5 μm in diameter, which, in contrast to droplets, can remain suspended in the air and be disseminated by air currents in a room or through a facility to be inhaled by a susceptible host. Preventing the spread of droplet nuclei requires the use of special air‐handling and ventilation procedures."

"Evidence exists to support the transmission of influenza viruses by direct and indirect contact and by droplet and droplet nuclei (i.e., airborne) transmission. However, experimental studies involving humans are limited, and the relative

contribution of each mode of transmission remains unclear. Furthermore, the relative importance of airborne transmission in a setting of normal air exchange is unknown."

Transmission of influenza A in Human Beings, by Gabrielle Brankston MHSc, et al, published in 2007 in The Lancet (see link below) gave further information about the airborne transmission of Influenza viruses. This excerpt is from that paper:

"Despite vast clinical experience in human beings, there continues to be much debate about how influenza is transmitted. We have done a systematic review of the English language experimental and epidemiological literature on this subject to better inform infection control planning efforts. We have found that the existing data are limited with respect to the identification of specific modes of transmission in the natural setting. However, we are able to conclude that transmission occurs at close range rather than over long distances, suggesting that airborne transmission, as traditionally defined, is unlikely to be of significance in most clinical settings. Further research is required to better define conditions under which the influenza virus may transmit via the airborne route."

For more information on how to protect yourself from microbes and influenza, such as the A-H1N1/09 swine flu virus, see the related questions below.

It is not known exactly where the virus originated. Analyses in scientific journals have suggested that the H1N1 strain responsible for the 2009 pandemic probably first evolved in September 2008, and circulated among humans for several months before being identified as a new strain of flu in Mexico. It is speculated that it may have actually first started in the US in pigs, moved to Mexico where it began spreading to humans and was identified as a new strain of influenza not seen before. See the related question below for more details of what caused the new 2009 H1N1 swine flu.

The outbreak in Mexico was thought to have been an ongoing epidemic for months before it was officially recognized as such. The Mexican government soon closed most of Mexico City's public and private offices and facilities to contain the spread of the virus. As the virus quickly spread globally, clinics were overwhelmed by testing and treating patients, and the WHO and the U. S. Centers for Disease Control and Prevention (CDC) eventually stopped counting all cases and focused instead on tracking major outbreaks.

In early June 2009, the World Health Organization (WHO) declared the outbreak to be a pandemic, but also noted that most of the illnesses were of moderate severity. It eventually reached all corners of the world as a true pandemic. See the related questions about the numbers of infections and deaths during the pandemic.

The initial outbreak was called the "H1N1 influenza". The CDC began also referring to it as "Novel Influenza A (H1N1)". In the Netherlands, it was originally called "pig flu", but is now called "Mexican flu" by the national health institute and in the media. South Korea and Israel briefly considered calling it the "Mexican virus". Later, the South Korean press used "SI", short for "swine influenza". Taiwan suggested the names "H1N1 flu" or "new flu", which most local media adopted. The World Organization for Animal Health proposed the name "North American influenza". The European Commission adopted the term "novel flu virus". See more about the naming of this new virus in the related question below.

Unlikely, unless you are in one of the high risk groups (see related question below).

The US Centers for Disease Control and Prevention (CDC) has estimated that, as of 2/12/10, since the beginning of the pandemic, the US has had approximately 57 million cases of A-H1N1/09 Pandemic Swine Flu and approximately 11,690 resulting deaths. Based upon this, an estimate of the mortality rate in the US from the pandemic is 0.02%.

In comparison, the CDC and World Health Organization (WHO) have estimated that with seasonal flu, "we see over 30 million cases in the United States. We see 200,000 hospitalizations and, on average, 36,000 deaths." (During the entire fall and winter flu season.) Based upon this, the average mortality rate of seasonal flu in the US would be 0.12 %.

The statistics of this mortality rate variation and other information gathered during the pandemic are under study by epidemiologists. It may be attributable to the fact that the especially vulnerable demographic group of the elderly (age 65 and older) suffers the majority of the cases and deaths from seasonal flu (because their weakened immune systems are unable to fight it off before their frail bodies must attempt to deal with the symptoms caused by another new strain of virus). In contrast, the majority of cases of the pandemic swine flu are among the younger and healthier demographic groups, so that, except for the very young and those with underlying medical conditions, most are able to survive the disease. It is not fully understood yet why the elderly do not contract this virus subtype as easily as the typical seasonal viruses, but speculation is that they may have acquired immunity through prior exposure to a similar virus strain.

As mentioned above and explained in the related question below, the risk increases if you are in the high risk groups: pregnant, have asthma, are young, or if you are suffering from an underlying illness at the time (for the full list see the related question).

Wash your hands, take vitamins, get the flu shot, and contact your doctor if you have a fever.

It can be a serious sign in children with the swine flu. The symptoms of swine flu are similar to the standard seasonal flu symptoms:

1. Coughing
2. Headaches
3. Body Aches
4. Vomiting
5. Diarrhea
6. Sneezing
7. Runny Nose
8. Fever

According to the Centers for Disease Control and Prevention, if you have symptoms of the flu, you should seek medical attention for emergency care if you experience any of the following warning signs:

In children emergency warning signs that need urgent medical attention include:

* Fever with a rash

* 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

* Flu-like symptoms improve but then return with fever and worse cough

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

* Confusion

* Severe or persistent vomiting"

If you think you have the swine flu and, especially if you also live in an area where 2009 swine flu has been confirmed, you should seek medical attention. For the anti-viral medications that could lessen or stop your symptoms more quickly to be effective, they must be given within two days of the first symptoms.

Anecdotal account from a contributor:

I started to feel ill with flu 7 days ago. The day after this I had to go abroad for 4 days, and when I got home was told 3 of my close workmates have been diagnosed with swine flu. I cannot get tested as I cannot get to surgery, but it almost certainly is swine flu. Symptoms are dizziness, aching bones especially back and base of skull, sore throat, headaches, bad cough runny nose, eyes etc. Today I developed a rash on my lower legs - red raised spots which look a little like blisters. I have never seen anything like this before. I am 51 years old.