Herald Café: What is the influenza A (H1N1) virus?
Dr Chitralekha Nayak: There are 4 types of seasonal influenza viruses: types A, B, C
and D. Influenza A and B viruses circulate and cause seasonal epidemics of
disease.
Influenza A viruses
are classified into subtypes. Currently circulating in humans are subtype A
(H1N1) and A (H3N2) influenza viruses. The A (H1N1) is also written as A (H1N1)
pdm09 as it caused the pandemic in 2009 and subsequently replaced the seasonal
influenza A (H1N1) virus, which had circulated prior to 2009. Only influenza
type A viruses are known to have caused pandemics.
The present influenza
A (H1N1)v virus is a new virus subtype of influenza affecting humans, which
contains segments of genes from pig, bird and human influenza viruses.
HC: Is seasonal influenza
linked to pandemic flu?
Dr CN: Seasonal influenza
outbreaks are caused by small changes in viruses that have already circulated,
and to which many people have some immunity. A pandemic occurs when an
influenza virus emerges that most people do not have immunity from because it
is different from any previous strain in humans. This enables the strain to
spread easily between people. Seasonal influenza viruses may contribute to the
emergence of a pandemic virus; and once a pandemic virus has been established,
as with the pandemic A (H1N1) in 2009, it can become a seasonal virus.
HC: How do people become
infected with influenza A (H1N1)v?
Dr CN: This can happen
through the air via droplets from an infected person who is sneezing or
coughing in a face-to-face situation, through direct (skin) contact by hand,
contaminated by an infected droplet, touching the mouth or through indirect
(skin) contact through any material (eg door handle) contaminated by an
infected droplet, touched by the hand that then touches the mouth.
HC: What are the
symptoms of swine flu?
Dr CN: Important clinical
features of swine influenza include fever, and upper respiratory symptoms such
as cough, running nose and sore throat. Headache, body ache, fatigue, diarrhoea
and vomiting have also been observed.
HC: What tests should we
do to confirm swine flu?
Dr CN: Throat swab from the
suspected patient is collected and sent for testing of swine flu. If it
confirms H1N1, then we label this patient as confirmed case of swine flu.
HC: Can H1N1 virus cause
complications?
Dr CN: Yes. It can cause
complications like pneumonia, respiratory failure, worsening of chronic
conditions, such as heart disease and asthma, neurological signs and symptoms,
ranging from confusion to seizures.
HC: How long does the
germ live on surfaces, like on my desk if someone sneezes in my office?
Dr CN: Influenza virus
survives only minutes on inanimate objects or hands, so these are very
inefficient ways to spread the illness. Influenza is most easily spread by
droplets that come into contact with our mucus membranes such as when someone
coughs or sneezes in our face. If we shake hands with an infected person, who
has just wiped their nose and then we rather quickly rub our nose or eyes with
our own hand, then we could get the flu. So, good hand washing plays a role in
preventing the spread of the disease.
HC: How long are infected
persons contagious?
Dr CN: An adult is usually
contagious as long as they have symptoms – usually up to 7 days following the
beginning of the illness. The ‘shedding stage’ of the virus is during the first
4-5 days of illness. Children can be considered contagious longer, up to 10
days.
HC: Can I catch it from
pigs?
Dr CN: No, you can only
catch this strain from other humans. It is a mutated pig virus.
HC: Can I catch it from
eating pork meat and pork products?
Dr CN: No. Swine flu is not
transmitted by the food you consume – it is not a food borne illness. All pork
food products are safe to consume, as long as they are prepared properly. Swine
flu is transmitted in the same way normal flu is – through airborne droplets
form a sick person’s cough or sneeze.
HC: How is H1N1 influenza
(swine flu) treated?
Dr CN: Treatment is largely
supportive and consists of bed rest, increased fluid consumption, cough
suppressants, and paracetamol for fever and myalgia. Severe cases may require
intravenous hydration and other supportive measures. Antiviral agents may also
be considered for treatment.
HC: Are antiviral tablets
required for all patients with flu?
Dr CN: No. Patients with
mild fever plus cough / sore throat with or without body ache, headache,
diarrhoea and vomiting do not require testing nor antiviral agents. Antiviral
agents are required for high risk groups and patients with severe complications
like breathlessness, drowsiness, fall in blood pressure.
HC: Which high risk
groups are most likely to suffer severe illness if become infected?
Dr CN: People of all ages
with chronic underlying conditions such as diabetes, heart disease, kidney and
liver diseases, cancer, asthma, extreme obesity; pregnant women; and young
children (especially those under two years of age) and people older than 65
years of age.
HC: If I am infected, how
can I stop others from becoming infected?
Dr CN: Limit your contact
with other people. Do not go to work or school. When you cough or sneeze, cover
your mouth with a tissue. If you do not have a tissue, cover your mouth and
nose. Wash your hands and face regularly. Keep all surfaces you have touched
clean. Follow your doctor’s instructions. All suspected cases need to be
notified to the Directorate of Health Services.
HC: Other than hand
washing, what can I do to take care of myself and others?
Dr CN: If you are ill, stay
home. Cover the nose/mouth with a handkerchief/ tissue paper when coughing or
sneezing. Use tissues to contain respiratory secretions and dispose of them in
the nearest waste receptacle after use. If you cough into your hand, remember
the virus could be live on your hand for at least a few minutes, so wash your
hands before touching anyone else. If you get symptoms suggesting the flu,
consult your doctor, who can prescribe medication to treat the flu.
HC: Is there a need for
influenza vaccine to prevent H1N1?
Dr CN: Government of India recommends vaccination
of High Risk Groups with Seasonal Influenza Vaccine. Health care workers,
working in hospital settings (doctors, nurses, paramedics) with likelihood of
exposure to Influenza virus should be vaccinated. Persons and children with
chronic illnesses such as Bronchial Asthma, Heart disease, Liver and Kidney
disease, Blood disorders, Diabetes, Cancer and immunocompromised patients
should also be vaccinated.
