What is swine flu (H1N1 infection)? Can spread of H1N1 virus be controlled?

what is swine flu or h1n1 infection

What is swine flu or H1N1 infection?

Swine flu is an acute respiratory disease caused due to H1N1 viral infection. It became a household term in 2009 when it was first discovered to cause infection in human beings. In August 2010, the World Health Organization (WHO) declared Swine flu as a pandemic as it spreads from person to person across the world covering large geographies simultaneously.

How is swine flu caused? How does H1N1 virus spread?

Swine flu is caused by a strain of influenza virus with genes very similar to influenza viruses usually occurring in swine (pigs) in North America, hence the name “Swine flu”. The virus strain causing swine flu is relatively new, known as the H1N1. The virus has now acquired the form of a regular human flu virus that spreads seasonally like other strains of the flu. Unlike many other diseases like typhus, that can be transmitted to humans from animals i.e. by ticks, in case of swine flu, the disease is usually transmitted from one person to another and not from an animal to person. However, in the case of veterinarians and pig farmers, there are chances of animal to human transmission. Further, swine flu can’t be contracted from pork products when cooked properly.

Swine flu is highly contagious. The disease is spread through saliva and mucus particles from person to person in some of the following ways:

  • By breathing in air droplets containing virus when an infected person coughs or sneezes.
  • An uninfected person touches inanimate surfaces like door handles contaminated with the flu virus from another person and then touches their nose, mouth, eyes etc.
  • When a person comes in contact with body fluids like saliva of another person for example while taking care of an infected child or adult.

What are the risk factors for swine flu? Who are at higher risk for H1N1 infection?

There is no significant difference in the risk factors for getting swine flu and any other type of flu. The highest risk of getting infected with H1N1 virus is from being in close proximity to an individual/s suffering from swine flu.

What are the risk factors for swine flu? Who are at higher risk?

Who are at higher risk?

However, some categories of individuals are at a higher risk for serious illness after infection with H1N1 because their immune systems are compromised. These categories include:

  • Senior citizens or elderly over age 65 years, because their immune system may be compromised and are unable to effectively fight off infection.
  • Children below 5 years of age because the immune systems are not fully developed
  • Immuno-compromised individuals with diseases like AIDS, malignancies or those on chronic medications, chemotherapy etc.
  • Pregnant women due to changes in the abilities of their immune system to ward-off infections making them vulnerable to severe illnesses.
  • Individuals with serious medical conditions and chronic diseases like diabetes mellitus, cardiac diseases etc.

What are the symptoms of swine flu?

The signs and symptoms of swine flu are similar to that of common influenza. Some of these include:

What are the symptoms of swine flu?

signs and symptoms of swine flu

  • Body ache
  • Headache
  • Chills
  • Cough
  • Diarrhoea
  • Fatigue
  • Fever
  • Nausea and vomiting
  • Stuffy or running nose
  • Sore throat

What are the complications of swine flu? Is swine flu always fatal?

High-risk categories can suffer from more serious effects of swine flu, some of which include:

Infections of the ear: Children are more prone to ear infections that can arise due to inflammation of the throat and inner ear or direct attack on the inner ear by the H1N1 virus. Persistent sneezing, running nose and coughing cause fluid accumulation and thus provide a conducive environment for bacterial infections.

Sinusitis: Similar to ear infections, flu can have an effect on the sinuses too by attacking them directly or indirectly causing infection. 

Worsening of pre-existing asthma: H1N1 viruses exacerbate pre-existing asthma by causing swollen respiratory airways & increased sensitivity to allergens.

Pneumonia: It is a common complication of swine flu, especially in high-risk categories and flu can be deadly. Fluid build-up due to inflammation within the tissues of the lungs reduces their oxygen supply and that to other tissues of the body.

Febrile Seizures: Swine flu can cause neurological complications in children when associated with a fever causing “febrile seizures”. These seizures can result in convulsions or sudden jerking movements. A temperature of 102 degrees Fahrenheit or higher can cause seizures however usually there is no long-lasting damage.

Pregnancy-related complications: Some of the complications associated with swine flu in pregnant women include:

  • Low birth weight
  • Neural tube birth defects (defects of the brain and spine).
  • Pneumonia
  • Preterm birth
  • Respiratory infections
  • Death of fetus/ mother or both

Death: Swine flu-related complications may cause death depending on the severity of the complications and delay in seeking medical care, especially in the case of high-risk categories. 

When to seek emergency care if you suspect you have swine flu?

If you or someone you know are having flu, please seek emergency care if any of the following is noticed:

  • Bluish or grey discoloration of skin
  • Confusion
  • Dehydration: lethargy, dryness of mouth, decreased urine output, dark yellow urine or decreased output, decreased energy etc.
  • Difficulty in breathing
  • Dizziness
  • High fever that does not come down even after administering  medications
  • Pressure or pain in the chest or abdomen
  • Seizures
  • Vomiting- severe or persistent

How is swine flu or H1N1 infection diagnosed?

The diagnosis of swine flu can be made by your doctor on the basis of your medical history, exposure to the H1N1 virus through an infected person and physical examination. Confirmatory tests include:

  • Throat/ nasopharyngeal swab test
  • Blood test for the H1N1 antibodies

How is swine flu treated? Can H1N1 infectiion be cured without medicine?

Similar to other forms of flu, swine flu is treated symptomatically (symptom relief). Consultation from a doctor may be warranted mostly in case of the high-risk category of individuals who are prone to developing medical complications from the flu. In routine cases, the focus should be on symptomatic relief and preventing the spread of the H1N1 infection to other people.

Treatment with oral antiviral medicines is often reserved for people at high risk for complications from the flu. This so because the virus undergoes mutagenic changes, as a result, it becomes resistant to the drug very fast. Healthy individuals contracting swine flu have inherent ability to fight the infection.

What are the home remedies to manage swine flu?

Symptomatic management of swine flu is similar to that of regular flu. Following tips helps the body to fight swine flu better:

  • Adequate rest gives an opportunity to the body’s immune system to focus on fighting the infection.
  • Dehydration should be prevented by drinking enough water and other liquids. Fluid replenishment with soups and clear juices help in restoring lost nutrients.
  • Over-the-counter painkillers may be taken to manage symptoms such as sore throat, body ache, headache etc.

What is the incubation period for H1N1 virus infection?

The incubation period, i.e. the period between infection and appearance of symptoms of swine flu ranges from approximately one to four days, two days being average.

The contagious period for swine flu, i.e. the period in which it is highly infectious usually begins a day prior to the appearance of symptoms and lasts for about five to seven days. However, in individuals who are at high risk or have a weak immune system and children may remain contagious for a prolonged duration of as long as 10 to 14 days.

How long does the swine flu last?

Like other seasonal influenza virus, uncomplicated cases of swine flu infection typically begin to recover within three to seven days. However, generalized cough and malaise may persist for a longer duration, sometimes up to two weeks or more in certain cases. Complicated cases of swine flu or those with underlying medical problems or those at high risk may require hospitalization that may prolong the total length of time of infection to as long as 10 days.

How can swine flu be prevented?

Flu season may vary from year to year. In India, it usually peaks in June and may run till December, though it’s possible to get the flu any time of year.

How can swine flu be prevented?

A yearly shot of flu vaccination is considered to be an effective way of preventing swine flu. In addition other preventive and precautionary measures that can be taken include:

Frequent hand washing using soap or hand sanitizer

  • Avoid touching your mouth, nose or eyes, especially after touching inanimate objects like doorknobs etc. in unfamiliar surroundings.
  • Avoid visiting public places, work or school if you’re ill
  • Avoid attending large gatherings during swine flu season, especially if you belong to high-risk category.

Follow the recommendations issued by governmental public health institutions from time to time.

Can swine flu be prevented by wearing a mask?

The effectiveness of wearing a mask for prevention of the spread of flu virus wasn’t something of which scientists were sure of till sometime back. However, studies in the recent past are suggestive of their utility and effectiveness.

Many scientific studies have concluded that masks can prove to be highly effective in preventing spread when used correctly. It has been demonstrated in these studies that proper use of mask reduced the likelihood of spread by as much as 70-80 % in family members of children who were infected with swine flu. However, another important fact in these studies was that the use of a surgical face mask was effective only when it was used in conjunction with proper hand washing.

What type of masks can be used in H1N1 infection?

Generally, two types of masks can be considered to prevent the spread of swine flu virus:

Surgical face masks: Disposable surgical masks often used by dentists, doctors and healthcare staff during patient treatment are available over the counter. These masks are protective against the bigger droplets of bodily fluids that may get dispersed from the nose and mouth and may carry the virus. Splashes or sprays released during coughing and sneezing may also get prevented by surgical facemasks. However, the disadvantage of these masks is that they are unable to prevent the inhalation of airborne contaminants of a smaller nature.

What type of masks can be used in swine flu?

Respirator N95 mask

Respirators: Respirator masks or N95 masks are protective against the smaller contaminant particles that may be inhaled from the air. As per the American Centre of Disease Control, these masks have the capability to filter 95 percent of airborne particles, hence the name N95. These masks also find use while handling potentially toxic materials or chemicals. Generally, respirators are to be selected depending on the user’s face size so that they can form a tight  seal to prevent any gaps for the passage of particles. N95 respirators have a protective effect against both small and larger sized particles.

Even though respirators are considered to be more effective for the prevention of the flu virus scientific studies have demonstrated the benefits of both types of masks when used properly, especially when combined with hand hygiene. 

Who should definitely get the vaccine to prevent swine flu?

Even though some public health organizations recommend that everyone above 6 months of age should take the flu shot, certain high-risk categories of individuals should definitely take it. These categories include the high-risk individuals as mentioned earlier. In addition, workers employed in public settings are at a higher level of exposure to the disease, hence it is important for them to receive a vaccination. Personnel who are in constant contact with at-risk individuals include: 

  • School teachers
  • Employees of day-care centers
  • Hospital and healthcare staff
  • Public health and sanitation workers
  • Home healthcare providers
  • Disaster and emergency response personnel
  • Public employees like bus drivers etc.
  • Family members of high-risk individuals and people in abovementioned professions.

Who should definitely get vaccine to prevent swine flu?

Influenza (Flu) Vaccine

In what conditions is a flu shot contraindicated? Who should not get a flu shot?

Some categories of individuals are generally recommended not to have a flu shot. These conditions include.

Previous history of reaction: Individuals who have had a bad reaction to the flu vaccine previously, should not get a flu shot.

Allergy to eggs: In case you have a known and severe allergy to eggs, it is recommended that you should avoid vaccination. In case of a mild known allergy, do inform your doctor as you still may qualify for the vaccine.

Allergy to Mercury: Some types of flu vaccines may contain trace amounts of mercury. Thus if you have any known history of allergy to mercury, do inform your doctor.

Guillain-Barre syndrome (GBS): A rare side effect of the flu vaccine can be temporary paralysis or GBS. If you already have GBS or had an incidence of GBS in the past, keep your doctor informed.

Fever: On the day of vaccination if you have a fever, a flu shot will be temporarily contraindicated. You should wait for the fever to subside before receiving the shot.


Swine flu caused by the H1N1 virus is a highly contagious infection that can rapidly spread from person to person. Coughing and sneezing can release thousands of particles that can spread through the air. If the person is infected, the virus too gets dispersed and can linger on inanimate surfaces like table-tops, door knobs etc. and can be picked up by others easily. Hence, the best strategy to deal with swine flu is to prevent it.

Hand sanitization is an important way to stop the spread of the virus. Avoiding direct contact with infected individuals can help in reducing person-to-person transmission.

The single best way to protect at-risk individuals against the flu is the annual flu shot. You can schedule an appointment with your doctor to receive a flu shot for self and family if you are at high risk of the infection or its complications. 

  • Mayo Clinic. Swine Flu (H1N1 Flu). Available at:https://www.mayoclinic.org/diseases-conditions/swine-flu/diagnosis-treatment/drc-20378106. Accessed on 20 October, 2018
  • Swine Flu: General Information. Available at: https://www.cdc.gov/h1n1flu/general_info.htm. Accessed on 20 October, 2018
  • Ministry of Health and Family Welfare Directorate General of Health Services. Seasonal Influenza: Guidelines for Vaccination with Influenza Vaccine. Available at: https://mohfw.gov.in/sites/default/files/30580390001493710612.pdf. Accessed on 20 October, 2018
  • John Hopkins Medicine. Influenza (Flu).Available at: https://www.hopkinsmedicine.org/healthlibrary/conditions/infectious_diseases/influenza_flu_85,P00625. Accessed on 20 October, 2018
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