avian influenza massi paola sezione di forlì izsler santa sofia,26.10.2006

Avian Influenza

Massi Paola

Sezione di Forlì

IZSLER

Santa Sofia,26.10.2006

La letalità media del virus dell’influenza aviaria H5N1 (OMS)

• Dal 2003 a giugno 2006 registrati presso l’OMS 205 casi di infezione con 113 decessi


• L’OIE segnala focolai epizootici negli uccelli domestici e selvatici in una cinquantina di Paesi


• Per il 50% i casi di contaminazione sono stati registrati nei soggetti con meno di 20 anni, il 90%in quelli con meno di 40 anni


• Quanto ai bambini colpiti dall’infezione, 21 avevano meno di 5 anni e 32 tra 5 e 9 anni.


• Il fatto che la maggior parte dei casi interessa soggetti di età compresa tra i 10 e i 29 anni potrebbe spiegare la loro presenza nei Paesi dove la popolazione è giovane


• Per esempio, Egitto e Indonesia, nel 2005, dove rispettivamente il 34 e il 28% della popolazione ha meno di 15 anni.


• Inoltre, i comportamenti legati all’età o al sesso (es.lo spiumaggio,la macellazione e la preparazione degli alimenti vengono effettuati dalle giovani donne e i bambini giocano con volatili infetti) aumentano il rischio di esposizione prolungata e di stretto contatto con i volatili infetti.


• Tuttavia, nessuna differenza statisticamente significativa è stata evidenziata fra gli uomini e le donne quanto al rischio dell’infezione


• Il livello generale di mortalità si assesta al 56%.E’ elevato per tutte le età anche se raggiunge il 73% dai 10 ai 39 anni

• Il livello più basso (18%) si registra negli over 50.

• Il livello di letalità differisce da quello dell’influenza stagionale”tradizionale”per la quale la mortalità più elevata si registra nelle persone più anziane.


• Il livello generale più elevato di mortalità si è raggiunto nel 2004 con il 73%

• Durante gli ultimi tre anni, l’incidenza di mortalità ha raggiunto il picco nel corso del periodo inverno-primavera dell’emisfero nord

DIAGNOSIS

• Clinical, gross amd microscopic findings

• Laboratory diagnosis

Meat-type and breeder turkeys

Before 1999

• We known H6 and H9 in turkeys • Respiratory signs• Inactivated vaccines

H7N1 LPAI1999 Year

Low pathogenicity avian influenza (LPAI)

Clinical findings• Mortality rates ranging from 5 to 97%

• Depending of the age, on a series of environmental factors (temperature,ventilation,hygienic conditions) and the presence of infectious agents

Low pathogenicity avian influenza (LPAI)

• During the fase acute of the disease, depression,ruffled feathers and congiuntivitis

• Swelling of infraorbital sinuses with caseous clots

• Egg production dropped from 30 to 80%

Swelling of infraorbital sinuses

Low pathogenicity avian influenza (LPAI

• Swelling of infraorbital sinuses with caseous clots

Low pathogenicity avian influenza (LPAI

Haemorrhagic tracheitis

Lungs congested and haemorragic

H7N1 HPAI 2000 Year

Severe depression in preagonic phase and dead birds on their back due to nervous signs and spastic contractions prior to death

Highly pathogenic avian influenza (HPAI)

• In meat-type and breeder turkeys, 100% mortality 48-72 hours from the onset of the first clinical signs.

• Drop in food consumption and nervous signs

Highly pathogenic avian influenza (HPAI)

• Post mortem findings

Haemorrhagic tracheitis with caseus clots

Pancreatitis and duodenitis

Necrosis of pancreas

Haemorrhages on the caecal tonsils

Polmonite acuta

Chicken

LPAI

Broilers and broilers breeders

Clinical findings

• In the majority of flocks, LPAI did not cause any clinical signs

• In a limited number of outbreaks was characterised by anorexia and mild respiratory signs, with low mortality, in the order of 2-3%

LPAI


• Polmonary and tracheal congestion with cattarrhal tracheitis

• Ovarian follicles haemorrhagic and oedematous

LPAI

Caged layers

Clinical findings• Only 10-20%of the birds with loss of appetite and

depression, with very mild respiratory signs and congestion of combs

• Drop in egg from 2 to 10% until 30%• Mortality between 0.5 and 2%

LPAI


• The lungs and tracheas were congested

• The ovary and oviduct edematous and haemorrhagic

Lungs and trachea congested

HPAI

• Chickens reared on litter• Clinical findings• 100% mortality 48-96 h.from the onset of the

first clinical signs• Anorexia, depression and cessation of egg-

laying were followed by complete reluctance to move and tremors of the head and paralysis of the wing and legs

HPAI

• Caged layers• Clinical findings• The disease moved more slowly within the

flock• Sonnolence, cessation of egg-laying and

feed consumption.• Cianotic coombs with tremors of the head

HPAI

• Post-mortem findings

• Pancreatitis, caecal tonsils haemorrhagic• Internal organs appeared congested• Urate deposits in the kidney

Duck and goose

HPAI

Clinical findings• Incoordination and tremors and mortality 50-

60%

Post mortem findings• Pancreatic lesions• Heart congested• Duodenum congested

Japanese quail(coturnix coturnix japonica)

HPAI

• Severe respiratory condition, prostration and diarrhoa

• Nervous signs with torticollis and opistothonus

• High mortality

Ostrich (struthio camelus)

Ostrich (struthio camelus)

• Clinical signs were observed only in juvenile (7-9 months of age)

• anorexia, depression• Feed consuption dropped• Nervous signs• haemorrhagic faeces• Mortality 1-20%

H7N3 LHAI 2002 year

Laboratory diagnosis

A presumptive diagnosis can be made by

• Detecting antibodies

A definitive diagnosis of AI is established by:

1. Direct detection of AI viral proteins or genes in specimens such as tissues, swab, cellculture or embryonating eggs

2. Isolation and identification of AI virus

Sample selection and storage

• Tracheal and cloacal swabs or tissues collected

• If the samples can be tested within 48h. After collection they may be kept at 4°C; if over 48-72 h., storage at -70°C

Direct detection of AI viral protein or Nucleic acid

• Antigen capture ELISA to detect viral antigens in samples

Elisa sandwich virologicaCon Mab anti NPA (HB65)


• a human influenza test (Directigen Becton-Dickinsos) used to detect influenza viral antigen

• This antigen capture enzyme immunoassay was found to be specific and sensitive in tracheal swabs

KIT IMMUNOENZIMATICO

Kit immunoenzimatico

Tamponi ed estratti d’organo per kit rapido

Commercial Rapid Ag Tests

• Advantages • 1. Rapid• 2. User-friendly• 3. On farm test

• Disadvantages• 1. Very high cost• 2. Poor sensitivity


• Polymerase chain reaction methods used are more sensitive than virus isolation procedures

RT-PCRRT-PCR

H7H5 M

M ctrl+ 1 2 3 4 Ctrl-

H5+ H7+

Metodo identificativo del genoma virale

PCR-Real Time

Quantitative real time PCRQuantitative real time PCR

Allows detection of the amplicon as it Allows detection of the amplicon as it accumulates by measuring light emission accumulates by measuring light emission via a specific probe. This light emission is via a specific probe. This light emission is linked to amplicon productionlinked to amplicon production

PCR

• Advantages

Sensitivity/ specifity Rapid test

• Disadvantages

• High cost

Virus isolation

• Chicken embryos,10-11 days old,inoculated via the allantoic cavity

Virus isolation

• The presence of virus is demostrated by chicken erythrocyte haemagglutinating activity (HA) in the allantoic fluid

Virus isolation

• Plaque assay on cell monolayers (MDCK)

MDCKMadin Darby Canine

Kidney Cells

Virus identification

• 1) H.I. assay against NDV and other paramixo


• 2) Double immunodiffusion test AGP to dectect the type-specific NP and matrix proteins


• 3) ELISA with monoclonal antibodies reacts with the nucleoprotein or matrix proteins


• 4) The next spet is to determine the antigenic subtype of the surface antigens: HA and NA

• The HA is identified in the HI test using a panel of antisera prepared against the distinct HAs

VIRUS ISOLATION

• Disadvantages

No rapid Cost

• Advantages

• Virus isolation is important for patogenicity studies

Serology

Specific antibodies detect as earlyas seven days after infection

Serology

• In serological surveillance programs:

• A) AGP test is used for the detection of anti-NP antibodies

• Group specific

Serology

• B) ELISA assays have been developed to detect antibodies AI virus

Serology

• C ) Once influenza is detected by AGP or ELISA, HI test and ELISA with Mabs can be used to determine the HA subtype

• Subtype specific

Paolo Cordioli

avian influenza massi paola sezione di forlì izsler santa sofia,26.10.2006

Documents