Dr. Ashish JPost GraduateDept of MicrobiologyNavodaya Medical College,Raichur
SWINE SWINE FLU VirusFLU Virus
Koen-1919- Swine flu isolated. Smith Andrew and Laidlow-1933 Francis and Magill-1940 Taylor -1949
20th Century Outbreaks
1918 Spanish Flu 1957 Asian Flu 1968 Hong Kong flu 1976 Swine Flu scare 1977 Russian Flu scare 1997 Avian Flu scare
1918 - Spanish Flu (originated in birds).
First hit soldiers in Europe during World War I, as their immune systems were weakened by war.
The mortality rate was highest between 20 to 50 year olds. There was never any vaccine developed, after about 18 months, the virus seemed to just disappear.
The final death toll was written as 40 million people worldwide.
Soldiers whose
immunity was
weakened by war.
Many of the victims who have died in Mexico have been young and otherwise healthy. society's healthiest demographic
Structure of Virion
M1 protein
helical nucleocapsid (RNA plus NP protein)
HA - hemagglutinin
polymerase complex
lipid bilayer membrane
NA - neuraminidase
100 n m
Influenza virions are SMALL. The average eukaryotic cell diameter is 10,000 nm (10 microns), which is 100 times bigger than the influenza virion diameter.
http://www.med.sc.edu:85/pptvir2002/INFLUENZA-2002.ppt
Influenza Subtypes Types A & B
3 IMPs 8 Segments of RNA Responsible for
epidemics & pandemics
Type C 1 IMP
7 Segments of RNA Causes only mild infections
Subtype Viral Structure/Carriers
http://www-ermm.cbcu.cam.ac.uk/01002460a.pdf
Humans Swine Birds Horses Seals
Type A Humans
Type C
Type B
Humans Swine
Integral Membrane Proteins (IMP)
Matrix 2 (M2)
http://www.biotech.ubc.ca/db/TEACH/BANK/PPT/flu2.ppt
•Trimeric Protein•500 copies per virion
•Tetrameric Protein•100 copies per virion
•Tetrameric Protein•10 copies per virion
Hemagglutinin
Neuraminidase
http://ubik.microbiol.washington.edu/microm-pabio445/MM_445_lec3_2002_files/MM_445_lec3_2002.ppt
1) HA binds a cell GP at a Sialic Acid Binding Site
Fusion SchematicFusion Schematic
http://ubik.microbiol.washington.edu/microm-pabio445/MM_445_lec3_2002_files/MM_445_lec3_2002.ppt
1) HA binds a cell GP at a Sialic Acid Binding Site
2) Clathrin-Coated pit endocytoses virion
Low pH
Fusion SchematicFusion Schematic
http://ubik.microbiol.washington.edu/microm-pabio445/MM_445_lec3_2002_files/MM_445_lec3_2002.ppt
1) HA binds a cell GP at a Sialic Acid Binding Site
2) Clathrin-Coated pit endocytoses virion
3) Conformational Change: Hydrophobic binding of HA to vesicle membrane
Low pH
Fusion SchematicFusion Schematic
http://ubik.microbiol.washington.edu/microm-pabio445/MM_445_lec3_2002_files/MM_445_lec3_2002.ppt
1) HA binds a cell GP at a Sialic Acid Binding Site
2) Clathrin-Coated pit endocytoses virion
3) Conformational Change: Hydrophobic binding of HA to vesicle membrane
Low pH
Fusion SchematicFusion Schematic
4) RNPs are released into cytoplasm for replication and transcription (vRNA and mRNA)
Hemagglutinin (HA)
HA0 HA1
HA2
http://www.ccbb.pitt.edu/PDFFiles/150.pdf
HA Cleavage
Specific cleavage site is a basic sequence of AAs. Cleaving enzyme can determine pathogenicity of
virus. If the enzyme is ubiquitous in cells, then those cells can make virulent influenza.
Humans: Argenine is present at cleavage site Cleaving enzyme is a tryptase called Clara Only produced in Clara cells, which are only found in
upper respiratory tractInfluenza infection is confined to this region of
the body
Neuraminidase
IMP: HA binds sialic receptors, NA releases virus or
progeny virus from receptor
Roles in viral entry/exit: Help virion navigate mucusal lining of respitory tract Release progeny virion from surface of host cell
Newest Class of drugs: Neuraminidase Inhibitors
Matrix 2
IMP: Homotetrameric Single pass transmembrane protein Roles in last 2 steps of entry
process Facilitates membrane fusion in
endosome Low pH in endosome activates M2 to open
ion channel. Hydrogens enter virus and activate HA to
undergo conformational change that results in membrane fusion with endosome
As a consequence, RNPs are released into cytoplasm
http://www.northwestern.edu/neurobiology/faculty/pinto2/pinto_flu.pdf
Nomenclature 3 Subtypes, coupled with variance of the antigenicity of
surface proteins (HA & NA) and the long history of influenza epidemics necessitate a nomenclature system to catalogue each strain.
A/Moscow/21/99/H3N2
Subtype NP & MI
Geographic Origin
StrainNumber
Year of Isolation
HA & NASub-strain
Antigenic Variation
Minor changes in the antigenic character Mutation rate highest for type A, lowest for type C Most meaningful mutations occur in HA1 protein When 2 virions infect a cell, there are 256 possible
combinations of RNA for offspring.
Antigenic Drift
http://www.biotech.ubc.ca/db/TEACH/BANK/PPT/flu2.ppt
Antigenic Shift Phylogenic evolution that accounts for emergence of new strains
of virus Immunologically distinct, novel H/N combinations Genetic reassortment between circulating human and animal
strains is responsible for shifts Segmented genome facilitates reassortment Only been observed in type A, since it infects many species
Seasonal Influenza
A public health problem each year
Usually some immunity built up from previous exposures to the same subtype
Infants and elderly most at risk
Influenza Pandemics
Appear in the human population rarely and unpredictably
Human population lacks any immunity
All age groups, including healthy young adults
Seasonal Epidemics vs. Pandemics
A H1N1 :new virus
Illness was first recognised in 1930.
The 2009 H1N1 virus is a hybrid of swine, avian and human strains
Influenza A (H1N1)
He says ice-cream made
him feel better, and Thank God
has now recovered full health.But the rest of the planet has a quick –
paced pandemic marching
on….'Patient Zero' in Swine Flu Outbreak Identified as 5-Year-Old Mexican Boy:
Edgar Hernandez
April 23 : S-OIV (swine origin influenza virus) confirmed,
same strain detected in two California children as in Mexico.
PAHO informed of Mexico cluster of S-OIV
MidMarch: La Gloria,Veracruz, 60% of the town's population is sickened by a respiratory illness of unknown provenance.
Mexico
April 16 : Mexico Authorities notify the PAHO (Pan American Health Organization) of the atypical pneumonia.
Canadian labs
WHO April 24: 2009 H1N1 first disease outbreak notice.
April 25: WHO Director General declares a formal “Public health emergency of international concern”
April 27: “containment of the outbreak is not feasible” pandemic alert raised from phase 3 to phase 4.
April 29: phase 4 to phase 5.
June 11: phase 5 to phase 6.
During this time interim, the WHO was vastly criticized for not announcing
phase 6
Phase 1 – animal to animal transmission.
Phase 2 – an animal influenza virus is capable of human infection.
Phase 3 - small outbreaks among close populations but
not through human to human contact.
Phase 4 - Human to human transmission
Phase 5 - spread across two countries or more in one of the WHO regions (continents).
Phase 6 – spread across two countries or more in one of the WHO regions plus spread to another WHO region.
Viral Re-assortment
Reassortment in pigs
Reassortment in humans
Pandemic Influenza Virus
Pigs a Mixing vessel
Pigs can catch human and avian or bird flu. When flu viruses from different species infect pigs, they can mix inside the pig and new, mixed viruses can emerge.
Doctortvrao’s ‘e’ learning series
Where virus act in the body?
The influenza virus is a upper respiratory tract infection
Although called a respiratory disease, it affects the whole body, making you feel sick all over.
http://www.nlm.nih.gov/medlineplus/ency/imagepages/17237.htm
Transmission from person-to-person
by: Tiny droplets that come
from a person’s mouth and nose when they cough and sneeze.
Touching objects contaminated with particles from an infected person’s nose and throat.
http://www.lungusa.org/diseases/c&f02/influenza.html#what
Symptoms
Symptoms begin 1-4 days after infection.
You can spread the flu before your symptoms start and 3-4 days after your symptoms appear.
The following symptoms of the flu can vary depending a person’s age and overall health: Sudden onset of chills and fever
(101 – 103 degrees F) Sore throat, dry cough Fatigue, malaise Terrible muscle aches, headaches Diarrhea Dizziness
Is it a cold or the flu? Symptoms Cold Flu Fever: Rare Characteristic,high (102 –104 °F),lasts 3 –4 days Headache: Rare Prominent General Aches: Pains Slight Usual Often severe Fatigue: Quite mild Can last up to 2 –3
weeks Extreme Exhaustion: Never Early and prominent Stuffy Nose: Common Sometimes Sneezing: Usual Sometimes Sore Throat: Common Sometimes Chest Discomfort: Mild to moderate Common:can become
hacking cough severe
Risk Factors
Older age group 65 yr pregnancy chronic lung disease (eg., COPD, cystic fibrosis,asthma) congestive heart failure renal failure immunosuppression (due to underlying disease or therapy) haematological abnormalities (anemia, haemaglobinopathies) Diabetes mellitus Chronic hepatic disease socially unable to cope (i.e., without personal support at
home ).
Suspected Case : Person with acute febrile illness(fever≥38KC) with onset
# within 7 days of close contact with a person who is a confirmed case of swine influenza A, or
# within 7 days of travel to areas where there are one or more swine influenza cases, or
# resides in a community where there are one or more confirmed swine influenza cases.
Probable case : A person with an acute febrile respiratory illness who :
# is positive for influenza A, but unsubtypable for H1 and H3 by influenza RT-PCR or reagents used to detect seasonal influenza virus infection or,
# is positive for influenza A by an influenza rapid test or an IF assay plus meets criteria for a suspected case, or
# individual with a clinically compatible illness who is considered to be epidemiologically linked to a probable case.
Confirmed case: person with an acute febrile illness with laboratory confirmed swine influenza A(H1N1) virus infection at WHO approved laboratories by one or more of the following:
Real Time PCR Viral Culture Four Fold rise in virus specific neutralising
antibodies.
Close Contact : is defined within 6 feet of an ill person who is a confirmed, probable or suspected case of influenza A (H1N1) virus infection during the infectious period.
Acute respiratory Illness : is defined as illness of recent onset with at least two of the following:
Rhinorrhea or nasal congestion Sore throat Cough(with/without fever).
Complications – “Superinfection”
A bacterial “superinfection” can develop when the influenza virus infects the lungs.
The result? The bacteria that live in the nose and throat can descend to the lungs
and cause bacterial pneumonia. Who is most at risk?
People over 50, infants, those with suppressed immune function or chronic diseases.
Other complications include bronchitis, sinusitis and ear infections.
http://www.ecureme.com/atlas/version2001/atlas.asp
Complications in children:
Reye’s syndrome CNS and liver and children exhibit symptoms
of drowsiness, persistent vomiting and change in personality.
Transmission
Limited data indicate that transmission is similarly as in other influenza viruses. Spread is 1° from person to person through large-particle respiratory droplets. This requires close contact between source & recipient, as droplets do not remain suspended in air & travel only short distances (<1m ).
Contact with respiratory-droplet contaminated surfaces is another possible source of transmission.
As data from influenza viruses H1A1 are limited, potential for ocular, conjunctival, or GI infection is unknown.
Being a novel influenza A virus, transmission from infected persons to close contacts maybe common. All respiratory secretions & bodily fluids (diarrheal stool) of H1N1 cases should be considered infectious.
Facilities Needed
Proper screening and triage facilities Proper holding areas Proper examination rooms Changing areas
Hospital Admission Hospital Admission policiespolicies
Depending on phase of pandemic, admission policies Depending on phase of pandemic, admission policies vary from admitting all probable / suspected cases to vary from admitting all probable / suspected cases to only admitting those who are ill or with complications. only admitting those who are ill or with complications.
In early phases; to prevent importation or to reduce viral In early phases; to prevent importation or to reduce viral transmission in the country, all suspect influenza H1N1 transmission in the country, all suspect influenza H1N1 cases will be admitted in designated hospitals and kept cases will be admitted in designated hospitals and kept in isolation. in isolation.
In full pandemic situation, where cases go beyond In full pandemic situation, where cases go beyond capacity of health facilities to cope, a policy of capacity of health facilities to cope, a policy of surveillance & Tx. at home or the use of non-traditional surveillance & Tx. at home or the use of non-traditional health facilities may be instituted. Hospital admissions health facilities may be instituted. Hospital admissions will only be for those with respiratory distress or with will only be for those with respiratory distress or with assoc complications of influenza or those in high riskassoc complications of influenza or those in high risk groups (ie.with co-morbidities). Such admission policies groups (ie.with co-morbidities). Such admission policies will be updated as pandemic evolves. will be updated as pandemic evolves.
INVESTIGATIONS
Confirmation of influenza A(H1N1) infection is through:
Real time RT PCR or
Isolation of the virus in culture or
Four-fold rise in virus specific neutralizing antibodies.
Diagnosis: Diagnosis:
Rapid influenza tests, and serum samples can be
used to confirm infection by the influenza virus since the symptoms of the flu are similar to the symptoms caused by other infections.
Serology test to be done include Complement fixation test. HAI
MANAGEMENT OF MANAGEMENT OF SUSPECTED AND SUSPECTED AND CONFIRMED CASESCONFIRMED CASES
Detailed history obtained: clinical, travel and contact history including occurrence of respiratory disease in contact patients during the last 10 days
Clinical workup should follow measures stated in Syndromic Approach Protocol for acute respiratory syndromes
Virology samples sent to Virology Unit, IMR Bacteriology samples are processed in respective hospitals All specimens should be transported in accordance to
Guidelines of Transport of Infectious Material. In event of death, post-mortem should be performed in
accordance with Guidelines For Post-Mortems Involving Unknown/Uncertain Infectious Agents
Dead bodies handled as per Guidelines on Handling of Bodies with HIV/AIDS
DISCHARGE OF DISCHARGE OF PATIENTSPATIENTS The patients can be discharged with the following
criteria: Suspected cases:
When PCR results are negative (IMR)
If patient is still unwell, he can be transferred out of isolation ward
Probable & Confirmed cases: At least 7 days from onset of illness
and Completed at least 5 days of antiviral therapy
and Well / asymptomatic
If the patient has fulfilled the first 2 criteria but is still recovering, he can be transferred out of isolation ward
Surveillance
The global surveillance network determines which strains of the influenza virus will make-up the vaccine.
Surveillance Cont’d: After both parties agree, the vaccine is
manufactured from inactivated viruses.
I already have the flu…Now what? Increase liquid intake like water, juice, and
soups. Get plenty of rest for the 7 to 10 days during
which the symptoms may persist. Take anti-fever drugs to relieve the fever. Anti-viral drugs have recently been designed
to treat the flu. If patients begin taking these drugs within 48 hours after their symptoms begin, the drugs may reduce the length of the illness by about 1 to 2 days.
Anti-viral drugs: General background All anti-viral drugs inhibit viral replication but they
act in different ways to achieve this. Drugs that are effective against influenza A viruses:
amantadine and rimantadine. Drugs that are effective against influenza A viruses
and influenza B viruses: zanamivir and oseltamivir.
Amantadine Rimantadine Zanamivir Oseltamivir
Type of Influenza virus infection indicated for use
Influenza A Influenza AInfluenza A Influenza B
Influenza A Influenza B
Administration oral oral oral inhalation oral
Ages approved for treatment of flu
1 year 14 year 7 years 18 years
Ages approved for prevention of flu
1 year 1 year not approved not approved
http://wdhfs.state.wy.us/epiid/fluvac.htm
Zanamivir and Oseltamivir
These drugs are neuraminidase inhibitors. They prevent the NA proteins on the surface of
the IV from removing sialic acid from sialic acid-containing receptors.
Viral budding and downstream replication of IV are inhibited when sialic acid remains on the virion membrane and host cell.
The emerging IV’s stick to the cell plasma membrane or other viruses since the sialic acid is still on the surface of the cell and the virion.
Neuraminidase inhibition
http://www.tamiflu.com/hcp/neuramin/neura_index.asp
Standard Operating Procedures
Reinforce standard infection control precautions i.e. all those entering the room must use high efficiency masks, gowns, goggles, gloves, cap and shoe cover.
Restrict number of visitors and provide them with PPE.
Provide antiviral prophylaxis to health care personnel managing the case and ask them to monitor their own health twice a day.
Dispose waste properly by placing it in sealed impermeable bags labeled as Bio- Hazard.
Personal Protective Equipment(PPE)
N95
PERSONAL PROTECTIVE EQUIPMENT
Remove PPE in the following order:
• Remove gown (place in rubbish bin).
• Remove gloves (peel from hand and discard into rubbish bin).
• Use alcohol-based hand-rub or wash hands with soap and water.
• Remove cap and face shield • Remove mask - by grasping elastic behind ears – do not touch front of mask
• Use alcohol-based hand-rub or wash hands with soap and water.
• Leave the room.
• Once outside room use alcohol hand-rub again or wash hands with soap and water.
HAND HYGIENE
Hands should be washed frequently with soap and water / alcohol based hand rubs/ antiseptic hand wash and thoroughly dried preferably using disposable tissue/ paper/ towel.
After contact with respiratory secretions or such
contaminated surfaces.
Any activity that involves hand to face contact
such as eating/ normal grooming / smoking etc.
CHEMO PROPHYLAXIS
It is indicated for :
All close contacts of suspected, probable and confirmed cases. Close contacts include household /social contacts, family members, workplace or school contacts, fellow travelers etc.
All health care personnel coming in contact with suspected, probable or confirmed cases
CHEMO PROPHYLAXIS
Oseltamivir is the drug of choice. Prophylaxis should be provided till 10 days after last exposure
(maximum period of 6 weeks)
For weight <15kg 30 mg OD 15-23kg 45 mg OD 24-<40kg 60 mg OD >40kg 75 mg OD
For infants: < 3 months not recommended unless situation judged critical
due to limited data on use in this age group 3-5 months 20 mg OD 6-11 months 25 mg OD
ADVERSE REACTION
Oseltamivir is generally well tolerated, gastrointestinal side effects (transient nausea, vomiting) may increase with increasing doses, particularly above 300 mg/day.
Occasionally it may cause bronchitis, insomnia and vertigo. Less commonly angina, pseudo membranous colitis and peritonsillar abscess have also been reported.
There have been rare reports of anaphylaxis and skin rashes.
There is no recommendation for dose reduction in patients with hepatic disease.
Zanamivir causes severe bronchoconstriction
MONITORING
The suspected cases should be constantly monitored for clinical / radiological evidence of lower respiratory tract infection hypoxia and shock. Look for
Pulse ,Blood Pressure, Temperature and Resp. rate
Oxygen saturation
level of consciousness
Rhonchi and basal rales.
Input/output charting
SUPPORTIVE THERAPY
Patients with signs of tachypnea, dyspnea, respiratory distress and oxygen saturation less than 90 per cent should be supplemented with oxygen therapy.
Patients with severe pneumonia and acute respiratory failure (SpO2 < 90% and PaO2 <60 mmHg with oxygen therapy) must be supported with mechanical ventilation.
If the laboratory reports are negative, the patient would be discharged after giving full course of oseltamivir. Even if the test results are negative, all cases with strong epidemiological criteria need to be followed up.
Low dose corticosteroids (Hydrocortisone 200-400 mg/ day) may be useful in persisting septic shock (SBP < 90).
Vaccine
Vaccines are available to be given to pigs to prevent swine influenza.
Vaccination most effective measure for reducing impact of influenza.
Vaccine recommended for people most at risk.
Two types of vaccines TIV LAIV.
INFECTION CONTROL MEASURES AT HOME
Get plenty of sleep, be physically active,manage your stress, drink plenty of fluids , and eat nutritious food.
Persons & their household members should be told frequent hand washing with soap and water ; use alcohol based hand gel.
When the patient is within 6 feet of other family member, he should wear a face mask/ handkerchief / tissues.
Sweeping and dusting to be done with wet cloth. Small amount of disinfectant may be mixed in water . ( absolute alcohol )
If any family member develop any symptom, report to health authorities.
Precautions to continue during the period of infectivity
ALGORITHM FOR MANAGEMENT OF PATIENT WITH H1N1 A INFLUENZADOES THE PATIENT HAVE TWO OF THE FOLLOWING SYMPTOMS? |RHINORRHEA/NASAL CONGESTION, SORE THROAT, COUGH(WITH/WITHOUT FEVER(≥38C)
| ________ |_________________________ | | YES NO | |HAS THE ILLNESS STARTED LOOK FOR OTHER ILLNESSWITHIN 7 DAYS OF CLOSE CONTACT |WITH A CONFIRMED SWINE INFLUENZA |CASE/TRAVEL TO AFFECTED AREAS/ OR RESIDENCE |IN AN AFFECTED AREA | |____________________________________NO | YES | ADMIT THE PATIENTCOHORT IN A WELL VENTILATED WARD WITH BEDS KEPT 1MTR APARTSEND NASOPHARYNGEAL/THROAT SWAB FOR RTPCR/VIRAL CULTURESEND PAIRED SERA SAMPLESTART TAMIFLU(75 mg BD for 5 days)MONITOR VITALS/SaO2 FOR COMPLICATIONS | | SEE RESULTS OF VIRUS SPECIFIC INVESTIGATIONS | |POSITIVE NEGATIVE | | | |COMPLETE THE COURSE COMPLETE THE COURSEAND D/S AFTER 7 DAYS AND D/S.THE SYMPTOMS HAVESUBSIDED/MONITOR FORCOMPLICATIONS
Conclusion
Outbreak caused by novel influenza 2009 A(H1N1).
Rapidly spreading across the globe. Antigenically distinct to other seasonal flu. Higher transmissibility as compared to
circulating seasonal flu Diagnosis PCR. Treatment is Oseltamivir and Zanamivir.
References
CDC manual for treatment of swine flu WHO manual of Swine flu FDA approved treatment for swine flu NIV manual of swine flu Emergence of novel influenza virus H1N1, V Ravi, IJMM. 2009 vol3 Emergence of Swine flu- Dr. T. R Rao Medical daily internet reference Harrison manual of internal medicine Jawertz text book of medical microbiology Ananthnarayan text book of medical microbiology Topley and wilson textbook of medical microbiology
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