AVIAN INFLUENZA

AVIAN INFLUENZA

What is it?

How does it affect birds?

How does it affect me?

What is AI

Virus

What is AI

RNA

Neuraminidase (9)

Haemaglutinin (16)

What is AI

H-Highly

P-PathogenicA-Avian

I-Influenza

HPAI-H5N1

Waterbirds (ducks, gulls and shorebirds) are the natural reservoir

Role of wild birds

Type A - wild and domestic birds, humans, pigs, horses and marine mammals.

Types B & C - humans, less severe disease

From Fields Virology, 4th ed, Knipe & Howley, eds, Lippincott Williams & Wilkins, 2001, Fig. 47-3.

Waterbirds are the natural reservoir for AI viruses. All 16 HA and 9 NA combinations occur. The strains endemic to waterfowl are all low pathogenicity. Pigs are an interesting factor in the evolution of influenza viruses because they are the one animal that can act as a mixing bowl for combining human and avian viruses into new AI strains. In areas where pigs, birds and people coexist in close proximity it can potentially facilitate the creation of new AI viruses.

Avian Influenza in Waterfowl

Subclinical/mild disease of the respiratory/GI tract

Fecal-oral transmission routeAll AI endemic to waterfowl is low pathAIV is in evolutionary stasis in waterfowl

(H6 viruses isolated 81 years apart were 95.3% identical)

Lesser Scaup. Takashi Koike.

Blue-winged Teal. David Stimac.

To date, all known AI viruses endemic to waterfowl have had low pathogenicity. AI Usually doesnt cause clinical illness in wild birds. May cause subclinical or mild disease of the respiratory or gi tract. It is spread via ingestion of the virus shed in feces, saliva and nasal discharges. The virus in waterfowl havent changed much. AI viruses are found in waterfowl year round with the highest occurrence of infection occuring in juvenile waterfowl in late summer. In other species, the number of shorebirds (primarily ruddy turnstone) and gulls (herring) is highest during spring and then again in the early fall.

Domestic poultry is an atypical host for AI in which it undergoes rapid sequence evolution to become highly pathogenic

.

H3, H4, H6 most common

~10%

~60%

Prevalence of H5N1 in wild birds-2006

Africa.

0/3500 samples from Chad, Mali, Ethiopia and Morocco (Vincent Martin, Nairobi meeting April 2006).

Czech Republic

12/2038 (0.53%) dead wild birds positive (OIE Dis Info v19 #17).

France

66/14,000 (0.47%) wild birds positive (NDTV, 4/22/06).

UK

1/891 (0.11%) dead swans H5N1 positive (0.11%) (DEFRA, 4/21/06).

PANDEMIC

Human disease that spreads beyond large regions (e.g. between continents)

Lesser Scaup. Takashi Koike.

Blue-winged Teal. David Stimac.

To date, all known AI viruses endemic to waterfowl have had low pathogenicity. AI Usually doesnt cause clinical illness in wild birds. May cause subclinical or mild disease of the respiratory or gi tract. It is spread via ingestion of the virus shed in feces, saliva and nasal discharges. The virus in waterfowl havent changed much. AI viruses are found in waterfowl year round with the highest occurrence of infection occuring in juvenile waterfowl in late summer. In other species, the number of shorebirds (primarily ruddy turnstone) and gulls (herring) is highest during spring and then again in the early fall.

Domestic poultry is an atypical host for AI in which it undergoes rapid sequence evolution to become highly pathogenic

.

1997

2003

First H5N1 Detection

Wild bird detections

Qinghai Outbreak - May 2005

Wild birds affected at Qinghai Nature ReserveMainly bar-headed geese (Anser indicus)Gulls (2 species)

Source: Liu et al., 2005. Science.

Liu et al., 2005. Science.

One unusual aspect associated with this H5N1 outbreak has been the occurrence of sick and dead waterfowl.

Red is location of Qinghai Nature Reserve. In May and June 2005, an H5N1 outbreak occurred on the reserve killing over 1000 migratory birds, primarily bar-headed geese. ***Need paper for more details -- such as clinical signs and number as risk.

Green are the provinces with H5N1 outbreaks in 2004.

Yellow are the reported prevalent sites in those provinces.

Arrows indicate migratory paths of the bar-headed geese.

Poultry?

Wild birds?

H5N1-Whos spreading it?

1997

2003

Distribution of AI receptor in humans vs birds

CLINICAL SIGNS OF H5N1 IN HUMANS

Fever

Headache

Muscle pain

Diarrhea

3-4 days illness onset

12-29 days death

CASE FATALITY RATE

(Probability of dying if you get it)

Probability

BOTTOM LINE:

1) H5N1 is hard to get.2) If you get it, odds of dying are 50:50.

What is the risk of my getting H5N1?

Its all relative

Handling live sick birds with known H5N1

Handling live sick birds

Necropsying dead bird

Swabbing live bird w. gloves

Picking up dead bird w. gloves

Sitting in this workshop

H5N1 has not been found in North or South America

Questions?

From Fields Virology, 4th ed, Knipe & Howley, eds, Lippincott Williams & Wilkins, 2001, Fig. 47-3.

Waterbirds are the natural reservoir for AI viruses. All 16 HA and 9 NA combinations occur. The strains endemic to waterfowl are all low pathogenicity. Pigs are an interesting factor in the evolution of influenza viruses because they are the one animal that can act as a mixing bowl for combining human and avian viruses into new AI strains. In areas where pigs, birds and people coexist in close proximity it can potentially facilitate the creation of new AI viruses.

Lesser Scaup. Takashi Koike.

Blue-winged Teal. David Stimac.

To date, all known AI viruses endemic to waterfowl have had low pathogenicity. AI Usually doesnt cause clinical illness in wild birds. May cause subclinical or mild disease of the respiratory or gi tract. It is spread via ingestion of the virus shed in feces, saliva and nasal discharges. The virus in waterfowl havent changed much. AI viruses are found in waterfowl year round with the highest occurrence of infection occuring in juvenile waterfowl in late summer. In other species, the number of shorebirds (primarily ruddy turnstone) and gulls (herring) is highest during spring and then again in the early fall.

Domestic poultry is an atypical host for AI in which it undergoes rapid sequence evolution to become highly pathogenic

.

Lesser Scaup. Takashi Koike.

Blue-winged Teal. David Stimac.

To date, all known AI viruses endemic to waterfowl have had low pathogenicity. AI Usually doesnt cause clinical illness in wild birds. May cause subclinical or mild disease of the respiratory or gi tract. It is spread via ingestion of the virus shed in feces, saliva and nasal discharges. The virus in waterfowl havent changed much. AI viruses are found in waterfowl year round with the highest occurrence of infection occuring in juvenile waterfowl in late summer. In other species, the number of shorebirds (primarily ruddy turnstone) and gulls (herring) is highest during spring and then again in the early fall.

Domestic poultry is an atypical host for AI in which it undergoes rapid sequence evolution to become highly pathogenic

.

Liu et al., 2005. Science.

One unusual aspect associated with this H5N1 outbreak has been the occurrence of sick and dead waterfowl.

Red is location of Qinghai Nature Reserve. In May and June 2005, an H5N1 outbreak occurred on the reserve killing over 1000 migratory birds, primarily bar-headed geese. ***Need paper for more details -- such as clinical signs and number as risk.

Green are the provinces with H5N1 outbreaks in 2004.

Yellow are the reported prevalent sites in those provinces.

Arrows indicate migratory paths of the bar-headed geese.