SWINE FLU

SIDDHARTHMEDICINE PG

INTRODUCTION•It is caused by Influenza virus (H1N1)•It is usually a mild and self limited

respiratory illness•It has potential to cause significant

morbidity and mortality •2009 pandemic influenza A (H1N1) virus

is continued to co-circulate following years along with seasonal influenza A and it cased significant mortality among young people

EPIDEMIOLOGY•Latest pandemic of swine flu was first

noted in Mexico in march 2009•It spread worldwide affected nearly 195

countries and it ended in August 2010•In India outbreak killed: 2009 - 981 2012 - 405 2010 - 1763 2013 - 699 2011 - 75

•2015 outbreak became wide spread throughout

India. Gujarat & Rajasthan were the worst affected states

•2009 pandemic strain is now responsible for the periodic seasonal outbreaks of Influenza in India

•The average incubation period is 1-3 days (maximum 7 days)

•Transmission through contact with large particle respiratory droplets

•Other body fluids and fomites also play a role in transmission

•Viral shedding begins the day prior to symptom onset and often to persist for 5-7 days, sometimes even longer in children & immuno compromised

RISK GROUPS•Age < 5 years & > 65 years•Obese individuals•Pregnancy•Persons with Asthma/ COPD or other

chronic pulmonary diseases•Immuno compromised and ppl receiving

Immuno suppressive therapy•Sickle cell anemia and other

Hemoglobinopathies

•Long term aspirin therapy•CKD•Metabolic disease such as diabetes

mellitus•Persons with Neuromuscular disorders,

seizure disorders, cognitive dysfunction•People working in Health care institutions

ETIOLOGICAL AGENT

•It’s a RNA virus belonging to the family of Orthomyxoviridae

•Three main genera - Influenza A, Influenza B, Influenza C

•Influenza A is further sub-typed into 16 distinct H types & 9 distinct N types based on Hemagglutinin & Neuroaminidase antigens on the surface of the virus

•Every year new strains of influenza virus emerge as its genes undergo point mutations leading to ‘Antigenic drift’

•This process helps the virus to evade host defense mechanism

•Infuenza A virus has a 8 segmented genome with eight single stranded RNA segments

•These genes get reassorted and produce a very different strain altogether- “Antigenic shift”

•2009 viral strain had undergone triple reassortment and contain genes from the avian, swine, and human viruses

PATHOGENESIS•Virus particle may settle on

nasopharyngeal, tracheobronchial, conjuctival, or other respiratory mucosal epithelial cells.

•H1N1 2009 strain can also additionaly bind to the 2,3-linked sialic acid receptors that are present in the lower respiratory tract and cause diffuse alveolar damage and thereby causing pneumonia in healthy individuals

COMMON CLINICAL FEATURES•Fever•Sore throat•Rhinorrhea•Myalgia & Arthralgia•Headache•Vomiting•Diarrhoea

EXTRA PULMONARY MANIFESTATION•CVS- Chest pain, hypotension

•CNS- Seizures, lethargy, altered mental status, weakness or paralysis

•OTHERS- Decreased urine output, cyanosis, dehydration

COMPLICATIONS•PULMONARY - Progressive viral

pneumonia, Secondary bacterial pneumonia, ARDS

•CNS - Encephalitis, Encephalopathy, GBS, ADEM

•CVS - Myocarditis, Pericarditis•OTHERS – Renal failure,

Rhabdomyolysis, Ryes syndrome, Hemophagocytosis, Multi organ failure syndrome

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