Avianflu Sars 05

8/11/2019 Avianflu Sars 05

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Emergingand Reemerging

DiseasesSevere Acute Respiratory Syndrome

(SARS)

Teresita S. de GuzmanDepartment of Medical Microbiology

College of Public Health

University of the Philippines, Manila


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Factors for Emergence

Microbial adaptation

Human susceptibility Climate and weather Changing ecosystems Land use and economic development Human behavior and demographics Technology and industry International travel and industry Breakdown of public health Poverty and social inequality War and famine Lack of political will

Intent to harm


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SomeEmerging iseases

SARS Avian influenza Nipah virus

Hendra virus Hanta virus E. coli 0157:117

variant vCJD (prion

disease)

West Nile fever

Rift Valley fever N. meningitidis

W135 Ebola

Crimean-CongoHF (hemorrhagic

fever)

WhitewaterArroyo virus

Lyme disease

Lassa Fever virus


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Brief History

SARSwas 1stdescribed during the

2002-2003 global outbreakof severe

pneumonia associated with human deaths

and person to person disease transmission

A large outbreak occurred in late 2002in

Guangdong Province, China

Starting late February 2003, similar illness

was reported concurrently in Vietnam,

Hongkong, Canada, Singapore, Thailand, etc.


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By the time the outbreak was contained

sometime July of 2003, 8,098probable

cases, with 774deaths were identified

in 29 countries ( CDC MMWR, 2003 & URL:

http://www.who.int/csr/sars/country/table2003_09_23/en/)

Initial clinical & laboratory results focused

on several known agents likeChlamydia,influenza virus, metapneumovirus, etc.

A virus isolated from the oropharynx of a SARS

patient subsequently identified as belonging to

Coronavir idaefamily by morphology thru EMstudies, additional culture isolates, immunohisto-

chemistry,immunofluorescence, serologic

assays, RT-PCR, miroarray analysis &

sequencing
http://www.who.int/csr/sars/country/table2003_09_23/en/http://www.who.int/csr/sars/country/table2003_09_23/en/


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1stidentified in Vietnam on

Feb. 28, 2003 on a patient with

severe pneumonia with no known

cause by Dr. Urbani, a WHO staff

who consequently died of the

disease in Thailand

super spreading event involving a

cluster of cases in Blk E of the AmoyGardens Housing State in Hongkong


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Rodents & cockroaches as

possible mechanical vectors of

transmission

defective U-traps in bathroom

aerosolization effect of exhaust

fan within small bathrooms cracked sewer pipe

person to person spread

Outbreak was due to unlucky

convergence of environmental

conditions, i.e.:


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The etiologic agent of the syndrome is

now recognized as the

SARSassociated coronavirus

(SARSCoV)


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Virology of SARS-CoV

Family: Coronaviridae

Genus: Corona virus

virions are spherical; 78 nm mean diameter

(+) RNA virus ; 29,727 nucleotide bases

helical nucleocapsid

enveloped with corona (crown)-like spikes

Antigenic groups:

Grp. 1 & 2- mammalian CoVHuman CoV

Grp. 3avian CoV

SARS (4th

lineage)


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Distinct Ultrastructural Features

Of SARS-Associated Coronavirus

Infected Cells

double-membrane vesicles

nucleocapsid inclusions

large granular areas of

cytoplasm


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SARS coronavirusis NOT

a mutant nor a recombination of

existing CoV ; it is NEWand

never seen in humans before

Pathogenesis: infects a variety of mammals & birds

not known number of isolates in humans

neurological symptoms rarely seen incubation period is 6 - 7 days

95% of patients develop symptoms

within 14 da.


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Transmission:

direct mucous membrane (eyes,

nose, & mouth

exposure to virus laden fomites

intense exposureaerosolizing procedures in

hospitals

role of oral-fecal transmissionis unknown

no reported cases yet of vertical

transmission


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Epidemiology:

Risks Factors

health care workers

increase in age (death common

among elderly male sex

presence of co-morbidics

care and slaughter of wildlife for human

consumption environmental contamination and

presence of mechanical vectors


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Virus is stable in feces and urine

At room temp. , 1-2 days

Stable for up to 4 days in diarrheic

stools

isolated in stools on paper, formicaplastered wall after 36 hrs.; glass slides

after 96 hrs.; plastic surfaces & stainless

steel after 72 hrs.loses infectivity after exposure to

disinfectant, etc.; rapidly killed by

560

C heat


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Other Clinical Manifestations

leucopenia; lymphopenia

raised LDHSpecimens to be Collected:

Blood

Respiratory secretions:nasopharyngeal aspirate (NPA)

nasopharyngeal swab (NPS)

oropharyngeal swab (ORS)sputum

Stool (in diarrheic cases)Place in virus transport media (VTM) keep at 40C

BSL-3 facilities & work practices


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Collect specimen during onset

of illness3 days

Maximum shedding of virus at early part

of infection

max. virus excretion from respiratory tract at

about 10 days

virus isolation in stools peaks at 12-14 da.

viral RNA detected in serum; peaks at

6-8 days; undetected by day 12

virus in urine detectable at day 10


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Diagnosis:

Negative staining EM (electronmicroscopy

RT-PCR (very specific but lackssensitivity and standardization)

ELISA

IFAT (immuno-fluorescent Ab test)


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Emergingand Reemerging

DiseasesAVIAN INFLUENZA

(BIRD FLU)

Teresita S. de GuzmanDepartment of Medical Microbiology

College of Public Health

University of the Philippines, Manila


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Information onAVIAN INFLUENZA

Avian influenza A (H5N1) is asubtype of the Type A influenza

virusFrom the family of RNA virusesOrthomyxoviridae

Wild birds are the natural hosts1stisolated from birds (terns) inSouth Africain1961


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The virus circulates amongbirds worldwide

Very contagious among and deadlyin birds, particularlydomesticated birds like chickens

The virus does not typicallyinfect

humansIn 1997, the 1stinstance of directbird-to-human transmission ofH5N1 was documented in an out-

break among poultry in Hong Kong


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Infected birds shed thevirus

in saliva, nasal secretions, andfecesAvian influenza viruses spread

among susceptible birds upon

contact with contaminatedsecretions

Most cases of H5N1infection inhumans are believed to be fromcontact with infected poultryor

contaminated excretions


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Current H5N1 Strain(implicated) In Outbreak

All genes are of bird origin; virus

has not acquired genes fromhuman influenza virus yet

There are likely differentvariations of H5N1 viruscirculating at this time


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Genetic sequencing done onsamples from South Korea&Vietnamshowed that theviruses are slightly different

Genetic sequencing of A(H5N1)virus samples from human cases inVietnam& Thailandshowed drug

resistance to antiviral amantadine& rimantadine (M2 inhibitors)commonly used vs influenza


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Remaining antivirals,oseltamavir& zanamavir

(neuraminidase inhibitors)should be effective still vs.H5N1 strain

Key to containing the outbreakis

the culling(killing) of sick andexposed birdsAll influenza virus can change.


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NO effective vaccine yet vs.

H5N1 avian flu virusAn available vaccine prototype

developed using the 2003 strain ofH5N1 (from Hongkong cases) cannotbe used to expedite vaccine

development; the virus has mutatedsignificantly


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Clinical course (based on the

1997 Hongkong outbreak): fever

sore throat cough severe respiratory distress

secondary to viral pneumonia(seen in several of the fatal cases)Previuosly healthy adults & children, & some

w/ chronic medical conditions were affected


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THANKYOU!!!

Avianflu Sars 05

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