The document provides detailed information on swine flu (H1N1), an influenza A virus affecting pigs and humans, with historical data on outbreaks in India and symptoms associated with the disease. It discusses the epidemiology, transmission, complications, diagnostic methods, treatment options, and prevention measures, including vaccination recommendations. Key points include the significance of antiviral treatment within 48 hours of symptom onset and the recommendation for annual vaccination for high-risk groups.

1. UPDATES ON SWINE FLU
Dr. Jagdeep Singh -PGT 2
(General Medicine)

2. INTRODUCTION
• It is a type of influenza A virus
• Commonly infects pigs and causes respiratory tract infection in
pigs
• A new strain spread through airborne droplets from human to
human, possibly due to reassortment of viral ribonucleic acid
structure
• The average incubation period is 1-4 days (maximum 7 days)
• Close contact including hand shaking and hand to nose transmission

3. • Viral shedding begins the day prior to symptom onset and often to persist
for 5-7 days, sometimes even longer in children & immuno compromised
• Latest pandemic of swine flu was first noted in Mexico March 2009
• It spread worldwide affecting nearly 195 countries and it ended in
August 2010

4. • In India outbreak killed:
2009 - 981 2012 – 405
2010 – 1763 2013 - 699
2011 - 75 2014 - 218
• 2015 outbreak became wide spread throughout
India.
• 2009 pandemic strain is now responsible for the periodic seasonal outbreaks
of Influenza in India
EPIDEMIOLOGY

5. Number of swine flu [H1N1] cases and deaths in India :
YEAR CASES DEATHS
2012 5,044 405
2013 5,233 699
2014 937 218
2015 42,592 2,990
2016 17,86 265
2017 38,811 2,270
2018 15,266 1,128
2019 28,798 1,218
2020 2,752 44
2021 11,450 12
2022 13,202 410

8. • Every year new strains of influenza virus emerge as its genes undergo
point mutations over a period of time where subtype remains the same
leading to ‘Antigenic drift’
• This process helps the virus to evade host defense mechanism
• Infuenza A virus has 8 segmented genome with eight single stranded
RNA segments
• Sudden shift antigenicity resulting from recombination of genome of
two viral genome of two viral strain and reassortment of viral
genome and produce new subtype of different strain altogether-
,“Antigenic shift”
• 2009 viral strain had undergone triple reassortment and contain
genes from the avian, swine, and human viruses

10. ETIOPATHOGENESIS
ETIOLOGY :
Envelope proteins haemagglutinin and neuraminidase
Viral RNA polymerase
Martrix proteins
Non structural proteins essential for pathogenesis and replication

11. Cytokine storm of H1N1 Influenza :
There is excessively elevated levels of serum interferons, cytokines and chemokines
The pattern and diversity of immune dysregulation depend on severity of disease
Raised cytokines such as interferon gamma, IL6, IL1, TNF, IL-15, MCP-1(monocyte
chemoattractant protein), MIP-1(macrophage inflammatory protein), IL-8, GM-
CSF(granulocyte macrophage colony stimulating protein) are commonly observed.
It further results in multiorgan tissue damage and dysfunction

12. CLINICAL FEATURES
• The hallmark of influenza is the sudden, rapid onset of
symptoms
• Influenza symptoms may include rhinorrhea, shortness of
breath, fever with chills, body aches, sore throat, non-
productive cough, runny nose and headache
• Gastrointestinal symptoms and muscle inflammation occur
more often in young children
• Infants can present with a sepsis-like syndrome

13. COMPLICATIONS
In children :
• Sinus or ear infections
• Viral and bacterial pneumonia,
bronchiolitis,
• Croup
• Dehydration (with or without
diarrrhoea)
• Febrile seizures
• Sepsis-like syndrome
• Rhabdomyolysis
• Encephalopathy /encephalitis
• Cardiac complications
(Myocarditis and Pericarditis)
• Reye syndrome (with aspirin use)
• Toxic shock syndrome
• Sudden death (may be due to
cytokine dysregulation)

14. In Adults And Elderly :
• Exacerbation of chronic illness :
 Cardiac (congestive cardiac failure, coronary artery
disease)
 Chronic pulmonary disease (COPD)
• Respiratory complications include Bronchitis, Sinusitis,
Reactive airway disease and Pneumonia
• Invasive bacterial co-infection (sepsis, pneumonia),
mainly from Staphylococcus aureus [MRSA, MSSA],
Streptococcus pneumoniae, and Hemophilus influenza.

15. • Uncomplicated influenza: ILI (Influenza-like illness) may
present with fever, cough, sore throat, coryza, headache,
malaise, myalgia, arthralgia and sometimes gastrointestinal
symptoms, but without any features of complicated
influenza.
• Complicated/severe influenza: Influenza requiring hospital
admission and/or with symptoms and signs of lower respiratory
tract infection (hypoxaemia, dyspnoea, tacchypnoea, lower chest
wall indrawing and inability to feed), central nervous system
involvement and/or a significant exacerbation of an underlying
medical condition.

17. Lab Diagnosis
• Routine hematological, Biochemical, Radiological investigations
• Confirmation of seasonal influenza (including HI N 1) infection is
through:
• • Real time RTPCR or gene-xpert
• • Isolation of the virus in culture or
• • Four-fold rise in virus specific neutralizing antibodies.
Laboratory testing of uncomplicated illness is NOT routinely
recommended, as it provides no advantage in the management
of individual patients.
• Testing can be considered for the patients: who meet the criteria
for complicated or severe influenza, where a laboratory diagnosis
will assist in patient management should undergo.

18. • In line with WHO recommendations, molecular diagnostics
(real-time multiplex PCR for influenza A and B virus or Gene
expert for influenza A and B virus) are currently the method of
choice for influenza virus detection.
• A negative Rapid Influenza Diagnostic Test (RIDT) result
does NOT exclude influenza and should not preclude
starting empiric antiviral treatment where sound
indications exist.

19. Specimen collection, storage and transportation
• Combined nasopharyngeal and oropharyngeal swabs in universal
transport medium (UTM) are preferred specimen.
• Flocked swabs should be used to collect specimens for a better
yield on PCR].
• Dacron or rayon swabs may be used if flocked swabs are not
available.
• Cotton wool budded swabs are not recommended.
• Once collected, these samples should be transported on ice to the
testing laboratory.
• The specimens must be refrigerated at 4°C if transport is expected
to be delayed.
• If the specimen(s) cannot be shipped within 72 hours of collection,
they should be kept frozen at -20°C. Avoid repeated freezing and
thawing of specimens.

20. TREATMENT
Antiviral agents :
Neuraminidase inhibitors – Oseltamivir(orally) and Zanamivir(inhalation)
Matrix protein inhibitors – Amantadine and Rimantadine
Antiviral drugs are most affective if they are started within first 48 hours after clinical
signs begin although they may also be used in severe or high risk cases first seen after
this time
Resistance to all IAV antiviral drugs is possible through accumulation of escape
mutants

21. Adamantanes (amantadine and rimantadine) not recommended
for use due to high levels of resistance

22. Supportive therapy
Paracetamol or ibuprofen is prescribed for fever, myalgia and headache.
Patient is advised to drink plenty of fluids
Smokers should avoid smoking
Salicylate / aspirin is strictly contra-indicated in any influenza patient due to
its potential to cause Reye's syndrome
Patient with sign of distress, severe pneumonia and oxygen saturation <90%
should be supplemented with oxygen therapy/ ventilatory support
• Antibiotics for secondary bacterial infection
• Vasopressors for shock
• Low dose corticosteroids may be useful in persisting septic shock

23. Prevention of influenza(Vaccine)
WHO recommends vaccination of high risk groups with
seasonal influenza vaccination
WHO recommends 2019-20 quadrivalent vaccine to contain
following strains of viruses :
• A/Brisbane/02/2018(H1N1)like virus
• A/Kansas/14/2017(H3N2)like virus
• A B/Colorado/06/2017 like virus
• A B/Phuket/3073/2013 like virus
For trivalent vaccines, WHO recommend use of
B/Colorado/06/2017 like virus along with two strains of IAV

24. Vaccines licensed for use in india :
Agrippal – Inactivated surface antigen(trivalent) 0.5ml S/C
Fluarix – Inactivated quadrivalent vaccine 0.5ml S/C
Influgen – Inactivated(fixed virus) 0.5ml I/M or S/C
Influvac – Inactivated surface antigen(trivalent) 0.5ml I/M or S/C
Nasovac – Inactivated freeze dried 0.5ml inhalational

25. Chemoprophylaxis
• Annual influenza vaccination is the best way to prevent
influenza.
• Antiviral chemoprophylaxis is currently NOT recommended.
However, WHO guidelines state that individuals at high risk
of severe disease who have been exposed to a patient with
influenza may benefit from presumptive treatment with a
full twice-daily 5-day course of antivirals, even if they do
not show signs and symptoms of infection.
• Alternatively, such patients can be monitored closely for
early signs of possible influenza infection, and given
antiviral treatment if they occur.

26. Thank you