Avian Influenza 15 subtypes of influenza in birds most pathogenic H5, H7 waterfowl (wild duck) are...
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Transcript of Avian Influenza 15 subtypes of influenza in birds most pathogenic H5, H7 waterfowl (wild duck) are...
Avian Influenza
15 subtypes of influenza in birds mostpathogenic H5, H7
waterfowl (wild duck) are the naturalreservoir of avian influenza virus
domestic poultry (chicken, turkey)are susceptible to epidemic fatal
pigs can infected with avian and mammalianinfluenza virus
Influenza VirusFamily Orthomyxoviridae
Genus Influenzavirus A, B
Avian influenzaH1 15N1 9
All highly pathogenic avian influenzais Influenza A; Subtype H5, H7
Human influenzaH 1, 2, 3N 1, 2
History of “Human Avian-Flu
1997 Hong Kong H5N1 1861999 Hong Kong H9N2 2/02003 Netherland H7N7 831/2003 Hong Kong H5N1 21/2004 Vietnam H5N1 186/2004 Thailand H5N1 32/
Year country strain outcome(case/death)
28 Jan 2004
Resistance to Physical and Chemical Action
Temperature : Inactivate 56๐c in 3 hours 60๐c in 30 min
pH : Inactivated by acid pH
Chemicals : Inactivated by oxidizing agent Sod. Dodecyl sulfate Lipid solvents propiolactone
Disinfectant : Inactivated by formalin, lodine compound
Survival : long period in tissus, feces, water
Transmission of Avian-Flu
1. Direct contact with secretion esp. feces of poultry
2. Indirect contact from feed, water, equipment clothing
3. Human-to-human :- possible but low risk
(CID 2002; 34:558-564)
Clinical Forms of Human Avian-Flu
1. Asymptomatic
2. Mild URI
3. Severe pneumonia
4. Multiple organ failure
(CID 2002; 34:558-564)
Clinical Features of Human Avian-Flu
Fever ConjunetivitisHeadache DiarrheaMalaiseMyalgia Severe PneumoniaSorethroat ARDSCough Organ failureRunny rose
Clinical Manifestations of Severe H5N1 Infection
No predictor of progression of disease
Bacterial superimposed pneumonia wereunlikely to be the causes
Manifestation of severe disease- primary viral pneumonia- lymphopenia- impaired liver function- impaired renal function- prolonged clotting time
H5N1 Infection in Hong Kong 1997 (18 cases)
Mean age (yr) 3 26
M : F 5 : 2 3 : 8
Pneumonia 0 11
GI symptom 2 8
mean WBC 11,200 3,900
Lymphocytopenia 0 11
Pancytopenia 0 2
Renal failure 0 4
Characteristic Mild Severe (N=7) (N=11)
18 Human Avian-Flu in HK 1997
18 cases
Mild URI Pneumonia7 cases 11 cases
Survived died5 cases 6 cases
(ARDS, organ failure)
Postmortem finding in 2 patients
Both reactive hemophagocytic syndrome
lung-hemorrhage, fibrinous exudate no viralinclusion
renal tubular necrosis
liver fatty change
RT-PCR for H5N1 found in renal tissue, bone marrow, spleen, liver
Cytokine-driven conditions reactivehemophagocytic syndrome
Lab. Diagnosis of “Human Avian-Flu”
1. Culture (Madin-Darby canine kidney cells) - Cytopathic effect prelim. using H5 specific RT-PCR or immunostaining with monoclonal antibody
2. H5 specific RT-PCR
3. Rapid test :- IFA from NP, endotracheal :- antigen detection
4. Serodiagnosis :- NT in paired serum
Treatment of Avian-Flu
1. Supportive care :- Ventilator support when needed
2. Antiviral agents eg. Amantadine, Rimantadine, Zanamivir, Oseltamivir etc (Antiviral agents is the most effective when given within 2 days of onset, but don’t know in Avian Flu)
Influenza Antiviral Medications
Chemoprophylaxis :- Amantadine, Rimantadine, Oseltamivir
70-90% efficacy in healthy adult
high risk group eg. nursing home,hospital
Treatment :- (same as above),Zanamivir x 5 days
treat within 2 days after onset
reduce symptoms, shorten time by 1-2 days, less contagious to other
Antiviral Drug for Influenza
Virus A A A and B A and B
Administration Oral Oral Inhalation Oral
Treatment >1 y of age >13 y of age >7 y of age >1 y of age
indications1
Prophylaxis >1 y of age >1 y of age Not licensed >13 y of age
indications1
Adverse effects Central nervous Central nervous Bronchospasm Nausea,
system, anxiety system, anxiety vomiting
Amantadine Rimantadine Zanamivir Oseltamivir
1 Licensed ages.
Daily Dosage Oseltamivir (Tamiflu®) in Children
For Prophylaxis and Treatment
Weight < 15 kg ; Oseltamivir 30 mg, bid x 5d.
16-23 kg ; Oseltamivir 45 mg, bid x 5d.
24-40 kg ; Oseltamivir 60 mg, bid x 5d.
> 40 kg ; Oseltamivir 75 mg, bid x 5d.
Vaccine for Avian-Flu
Influenza vaccine do not protection against H5N1
No H5N1 vaccine available
Vaccine composition change every year(antigenic drift)
Prevention of Avian-Flu for Health Care Worker
Same as SARS measure
1. Isolation room
2. PPE (as SARS is more than enough)
3. disinfectants of material
Risk of H5N1 Infection among HCWs Exposed to H5N1 patients, HK.
Median age 30 29 0.1
No (%) of nurses, 171 (79) 234 (76) 0.2doctor
No (%) with 121 (56) 190 (61) 0.2poultry exposure
No (%) H5N1 8* (4) 2 (0.7) 0.01antibody-positive
Characteristics Exposed Non-Exposed P(N=217) (N=309)
(JID 2000; 181:344-8)* all were contact without protection because late diagnosis and severe illness* 2 cases of seroconversion
Prevalence of H5 antibody-positive individuals in cohorts, stratified
by poultry exposure
Household contacts 45a 5/24 (21) 1/21 (5) .13
Tour group members 26 1/16 (6) 0/10 (0) .62
Coworkers
exposed 23 0/9 (0) 0/14 (0) NA
Not exposed 24 0/3 (0) 0/21 (0) NA
No. of antibody-positive individuals/total (%) Exposed Not exposed
Cohort n to poultry to poultry P
(JID 1999; 180:1763-70)
Factors Influenzing HCW AcquiredH5N1 from Patient
1. Severity of patient - quantity of virus
2. No. of days from admission to diagnosis
3. Infection - control practice - droplet precaution (human to human unlikely to occur, if occur it is asymptomatic)
History of Human Influenza
1918 1957 1968 1977
Spanish Flu
Asian Flu
Hong Kong Flu
Russian Flu
H1N1
H2N2
H3N2
H1N1
year
Influenza Pandemics :-could it occur ?
Pandemic influenza 3-4 times/century(1st 1918-1919 : 2nd 1957-1958 : 3rd 1968-1969)
more human infected with human (H1, H2, H3) and avian influenza
“mixing vessel” pandemic
expert suspect pandemic occur soon
Thank you