Canada Geese Avian Influenza Memo to Town September 8th

7/28/2019 Canada Geese Avian Influenza Memo to Town September 8th

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To: The Harding Township Committee September 8, 2005

From: Roberta Shields

Re: Avian Influenza, Canada Geese and Human Health

This memo acknowledges the current world-wide concern over avianinfluenza, and tries to put that concern and Harding Townships resident Canadageese in some kind of context.

Sections I, II and III below are my laymans interpretation of theinformation on the websites of the US Centers for Disease Control and Prevention(CDC), the US Animal and Plant Health Inspection Service (APHIS), the WorldOrganization for Animal Health (OIE) and the World Health Organization (WHO).Excerpts from these websites, on which my interpretations are based, are shown inSection IV. The websites addresses and titles of documents from which theexcerpts were drawn are listed in Exhibit A.

I. THE CONCERN

Avian influenza has been around for thousands of years. It is common andusually a non-event in wild birds, but can be devastating to poultry flocks, whichare subject to a particularly lethal form of the disease.

The economic consequences to poultry farms can be significant, as flocks aredestroyed to prevent spread of the disease. Such outbreaks in poultry have beenrelatively rare. Past significant North American outbreaks mentioned includePennsylvania in 1983-84, Mexico from 1992 to 1995, and British Columbia and Texas

in 2004.

Until relatively recently, avian influenza was not believed to be infectious tohumans. That changed in 1997, when concurrent with a deadly epidemic in poultry,humans in Hong Kong were infected with high rates of mortality.

Since then, a highly pathogenic form of the virus has been circulating in partsof Asia and has become established in poultry populations there, despite efforts toeradicate it. This summer, both Russia and Kazakhstan reported outbreaks inpoultry. Deaths in migratory birds infected with the virus have also been reported.

Human cases of infection have been rare. So far, the virus does not transmiteasily from poultry to humans. Most, but not all, human cases have been linked to

direct exposure to dead or diseased poultry, notably during slaughtering,defeathering and food preparation.

If bird to human transmission were to occur more often, there would then bea greater likelihood that the virus in humans would change to a form that would beeasily transmitted from person to person, which could produce a world-wide humanepidemic.


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II. NATIONAL AND INTERNATIONAL AGENCY PLANS

AND RECOMMENDATIONS

New facts emerge daily on the suspect virus, where it has been found, how itis changing and how those changes are likely to affect human health. World healthauthorities are monitoring the situation closely, recommending current action and

planning for adverse outcomes. Clearly, international, Federal and State healthauthorities will be advising communities on appropriate actions to protect humanhealth, as the need arises.

Their websites already contain information about responses to threats ofavian flu, known or anticipated. Nothing in any of those websites contains anythingto indicate that there is, or ever has been, any recommendation that mass cullingaction be taken against wild birds.

Culling ofpoultry flocks has been done not only to stop the spread of thevirus and resulting economic disaster for poultry farmers, but also to reduce the poolof virus to which humans are exposed, and thereby reduce the risk of a humanepidemic.

The following excerpt from an August 30, 2005 press release by the OIE(World Organization for Animal Health) is of particular interest:

Following the recent concerns caused by outbreaks of avian influenzain Russia and Kazakhstan and by the risk of spread of the virus to otherregions of the world by migratory birds, the OIE recalls the necessity ofintensifying the fight against the disease at its sourcethat is in the avianproduction plants in contaminated countries. This represents the best way oflimiting the spread of the disease, of eradicating it and of reducing the risk ofthe virus concerned acquiring the attributes necessary for a human pandemicto occur. (OIE page 1)

The World Health Organization (WHO) issued the following endorsement in August2005:

WHO fully agrees with FAO (Food & Agriculture Organization of theUN) and OIE that control of avian influenza infection in wild bird populations isnot feasible and should not be attempted. Wild waterfowl have been know forsome time to be the natural reservoir of all influenza A viruses. Migratorybirds can carry these viruses, in their low pathogenic form, over longdistances, but do not usually develop signs of illness and only rarely die of thedisease. The instances in which highly pathogenic avian influenza viruseshave been detected in migratory birds are likewise rare, and the role of thesebirds in the spread of highly pathogenic avian influenza remains poorly

understood. (WHO UPDATE page 1)

Once the virus jumps easily from person to person, (not yet the case),chances are that the virus that would then be the problem for humans would lookdifferent from the virus now being tracked. People, not birds, would be the likelyprimary carrier of the virus to humans. All available resources likely would be busyvaccinating the human population and treating the sick, not culling wild birdpopulations, which might not even carry the form of the virus then dangerous tohumans.


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III. CONCLUSIONS RE HARDINGS RESIDENT CANADA GEESE

I could find no reports that the suspect highly pathogenic avian influenzavirus is present in New Jerseys resident Canada geese or any wild birds in NorthAmerica. Even if it were, it would be unlikely that these birds would be the source of

human infection. So far, the virus is hard for humans to catch and it is believed thatdirect contact with uncooked infected poultry is the likely source. Based on thecurrent facts, slaughtering Hardings resident (non-migratory) Canada Geese woulddo nothing to protect Hardings citizens from the highly pathogenic form of bird flunow of concern in Asia, Russia and Kazakhstan.

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The excerpts from which my interpretations were drawn begin on the next page.

Roberta Shields

CC: Wildlife Management Committee and Staff


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IV. DETAILED EXCERPTS

The excerpts that follow have been taken verbatim from the sourcesindicated. A list of those sources appears in Appendix A. The headings have beenadded to assist the reader.

What is Avian Flu?

Avian influenza, or bird flu is a contagious disease of animals caused by type Astrains of influenza virus that normally infects only birds and, less commonly,pigs.(WHO/FAQpage 1)

The disease, first recognized as a serious disease of chickens in Italy in 1878, occursworldwide. (WHOpage 1)

Which Birds Get Avian Flu?

All birds are thought to be susceptible to infection with avian influenza, though somespecies are more resistant to infection than others.(WHO page 1) Influenza A

viruses of all subtypes have been detected in more than 90 species of apparentlyhealthy wild birds. (WHO AI page 36)

Wild waterfowl, most notably ducks, are by far the most frequent carriers of thelargest variety of viruses. It is now recognized that wild waterfowl, gulls andshorebirds are the natural reservoir of all influenza A viruses. These birds havecarried the viruses without developing symptoms-presumably for thousands ofyears- in a relationship thought to represent optimal adaptation of a virus to its host.This huge, stable, benign and perpetual reservoir of viruses is also highly mobile.Wild waterfowl can carry viruses over great distances and excrete large quantities intheir feces, yet remain perfectly healthy. (WHO AI page 36 ) or develop mild andshort lived illnesses. (WHO/FAQ 2)

Other bird species, including domestic poultry, are less fortunate. In poultry, avianinfluenza causes two distinctly different forms of disease-one common and mild, theother rare and highly lethal. (WHO AI page 36)

Domestic poultry, including chickens and turkeys, are particularly susceptible toepidemics of rapidly fatal influenza.(WHO page 1)

Outbreaks of avian influenza, especially the highly pathogenic form, can bedevastating for the poultry industry and for farmers. For example, an outbreak ofhighly pathogenic avian influenza in the USA in 1983-84, largely confined to thestate of Pennsylvania, resulting in the destruction of more than 17 million birds at acost of nearly $65 million US dollars (WHO/FAQ page 2)

In the absence of prompt control measures backed by good surveillance, epidemicscan last for years. For example an epidemic of H5N2 avian influenza which began inMexico in 1992, started with low pathogenicity, evolved to the highly fatal form andwas not controlled until 1995. (WHO page 1)

Recent research has shown that viruses of low pathogenicity can, after circulation forsometimes short periods in a poultry population, mutate into highly pathogenicviruses. (WHO page 1)


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Emergence of H5N1 and human infection

Fifteen subtypes of influenza virus are known to infect birds, thus providing anextensive reservoir of influenza viruses potentially circulating in bird populations. Todate, all outbreaks of the highly pathogenic form have been caused by Influenza A

viruses of subtypes H5 and H7 (WHO page 1)

Avian influenza virus do not normally infect species other than birds and pigs. Thefirst documented infection of humans with an avian influenza virus occurred in HongKong in 1997, when the H5N1 strain caused severe respiratory disease in 18humans, of whom 6 died.(WHO page 2)

At some unknown time prior to 1997, the H5N1 strain of avian influenza virus begancirculating in the poultry populations of parts of Asia, quietly establishing itself. Likeother avian viruses of the H5 and H7 subtypes, H5N1 initially caused only milddisease with symptoms, such as ruffled feathers and reduced egg production, thatescaped detection. After months of circulation in chickens, the virus mutated to ahighly pathogenic form that could kill chickens within 48 hours, with a mortality

approaching 100%. The virus first erupted in its highly pathogenic form in 1997, butdid not appear again. The 1997 outbreak in Hong Kong SAR ended after all of HongKong SARs 1.5 million poultry were slaughtered within 3 days (29-31 December)(WHO AI page 8) Then towards the end of 2003, H5N1 suddenly became highlyand widely visible. (WHO AI page 7)

Since mid-December 2003, a growing number of Asian countries have reportedoutbreaks of highly pathogenic avian influenza in chickens and ducks. Infections inseveral species of wild birds and in pigs have also been reported. (WHO/FAQ page2)

Of all viruses in the vast avian influenza pool, H5N1 is of particular concern for

human health for two reasons. First, H5N1, though strictly an avian pathogen, has adocumented ability to pass directly from birds to humans. Second, once in humans,H5N1 causes severe disease with very high mortality. These two features combine tomake H5N1 of concern for a third and greater reason: its potential to ignite anespecially severe pandemic. (WHO AI page 7)

The detection so far of only a few human cases suggests that the virus may not beeasily transmitted from birds to humans at present. However, the situation couldchange quickly, as the H5N1 strain has been show to mutate rapidly and has adocumented propensity to exchange genes with influenza viruses from other species.(WHO/FAQ page 4)

Attempts to Keep H5N1 from Spreading to Humans

Opportunities for both the occurrence of further human cases and the emergence ofa pandemic virus are intrinsically linked to the presence of the H5N1 virus in poultry.(WHO AI page 35)

The spread of infection in birds increases the opportunities for direct infection ofhumans. If more humans become infected over time, the likelihood also increasesthat humans, if concurrently infected with human and avian influenza strains, couldserve as the mixing vessel for the emergence of a novel subtype with sufficient


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human genes to be easily transmitted from person to person. Such an event wouldmark the start of an influenza pandemic (WHO page 3)

The first priority, and the major line of defense, is to reduce opportunities for humanexposure to the largest reservoir of the virus: infected poultry. This is achievedthrough the rapid detection of poultry outbreaks and the emergency introduction of

control measures, including the destruction of all infected or exposed poultry stock,and the proper disposal of carcasses. (WHO/FAQ page 4)

In addition to the rapid destruction of infected animals, another opportunity toprevent human cases is through the protection of workers involved in cullingoperations. Workers involved in the culling of poultry flocks must be protected byproper clothing and equipment , against infection. These workers should also receiveantiviral drugs as a prophylactic measure.(WHO page 3)

The large outbreak in captive tigers, which occurred in October (2004) in Thailand, isthought to be linked to the feeding of contaminated whole chicken carcasses. If thishypothesis is substantiated, it will provide further evidence that contact with rawpoultry carcasses can be a significant source of exposure to the virus (WHO AI

page 39).

Restrictions on the movement of live poultry, both within and between countries, areanother important control measure. (WHO/FAQ page 2)

Current Developments

Epidemiologists can point to at least three conditions, not anticipated at the start of2004, that have subsequently become apparent. First the virus is now firmlyentrenched in the poultry populations of parts of Asia. Although most affectedcountries launched massive campaigns to eliminate the disease in poultry, only a fewhave been entirely successful. Even in those few instances, the risk that the disease

may be reintroduced remains ever-present. (WHO AI pg 41)

Second, no high-risk group, defined by occupation, exists for the targeting ofprotective measures. Surprisingly, no cases of H5N1 infection have occurred inpoultry workers, cullers, veterinarians, or laboratory workers. Nor have cases beendetected in health care workers, despite several instances of close unprotectedcontact with severely ill patients. Instead, the most vulnerable population has turnedout to be rural subsistence farmers and their families, and these people constitutethe true risk group. (WHO AI pg 41)

Third, the health threat for this group has been compounded by the increasingtendency of human cases to occur in the absence of reported outbreaks in poultry.(WHO AI page 42)

Though far fewer outbreaks, affecting far fewer birds, were detected in the secondhalf of the year (2004) the threat to humans has actually become more dangerous.The virus is no longer causing large and highly conspicuous outbreaks on commercialfarms. Nor have poultry workers or cullers turned out to be an important risk groupthat could be targeted for protection. Instead, the virus has become stealthier:human cases are now occurring with no discernible exposure to H5N1 throughcontact with diseased or dead birds. This change has created a community-wide risk


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for large numbers of rural households and-for unknown reasons- most especially forchildren and young adults. (WHO AI page 35)

True to the nature of influenza A viruses, H5N1 is certain to continue to mutate,though the direction these changes will take cannot be predicted. If the viruscontinues to expand its avian and mammalian host range, the prospects for

eliminating the disease in animals will be come even grimmer. (WHO AI page 35)

The present high lethality of H5N1 would probably not be retained in an H5N1-likepandemic virus, as an avian influenza virus is expected to lose pathogenicity when itacquires the improved transmissibility needed to ignite a pandemic. More certain-andmore relevant to preparedness planning-is the fact that no virus of the H5 subtypehas probably ever circulated among humans, and certainly not within the lifetime oftodays world population. Population vulnerability to an H5N1-like pandemic viruswould be universal (WHO AI page 19)

The recent detection of highly pathogenic H5N1 in dead migratory birds-longconsidered asymptomatic carriersmay suggest another ominous change, but moreresearch is needed before any conclusion can be reached.(W HO AI page 38)

The history of all know human infections with avian influenza viruses readily revealsthe significance of the 2004 outbreaks for human health. They have caused thelargest number of severe cases of avian influenza in humans on record. Comparedwith the Hong Kong SAR outbreak in 1997, the 2004 H5N1 outbreak in humans hasalso been far more deadly. (WHO AI page 38)

Experience in south-east Asia indicates that human cases of infection are rare, andthat the virus does not transmit easily from poultry to humans. To date, the majorityof human cases have occurred in rural areas. Most, but not all, human cases havebeen linked to direct exposure to dead or diseased poultry, notably duringslaughtering, defeathering, and food preparation. No cases have been confirmed in

poultry workers or cullers. No cases have been linked to the consumption of properlycooked poultry meat or eggs. (WHO UPDATE page 2)

The Work Ahead

With the virus now endemic in poultry and expanding its avian and mammalian hostrange, the objective of averting a pandemic by eliminating further opportunities forhuman exposure no longer appears feasible. A second opportunity to avert apandemic could arise if the virus gradually improves its transmissibility amonghumans through adaptive mutation. Clusters of cases would be indicative, andsensitive surveillance might detect them. It is not know, however, whether rapidintervention with a pandemic vaccine,-if available in time- and antiviral drugs- ifquantities are sufficient-could successfully interrupt transmission, as this has never

been attempted.(WHO AI page 19)

H5N1 causes a disease with many disturbing and unusual features that are poorlyunderstood. The virus has crossed the species barrier twice in the past, in 1997 and2003, but the cases in 2004 and early 2005 constitute the largest and most deadlyhuman outbreak on record. With the virus now endemic in parts of Asia, sporadiccases and occasional family clusters need to be anticipated. The continuing risk ofmore cases, combined with the extremely high fatality, make it imperative tounderstand the disease and find an effective treatment. In response to this need,


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WHO is creating a network of clinical experts to expedite the exchange of experiencewith cases, compare results with different treatments and coordinate urgent researchon pathogenicity The expected outcomes are better diagnostic tools, more specifictreatments and improved infection control. (WHO AI page56)

The Response to a Pandemic

Based on historical patterns, influenza pandemics can be expected to occur, onaverage, three to four times each century when new virus subtypes emerge and arereadily transmitted from person to person. However, the occurrence of influenzapandemics is unpredictable. In the 20th century, the great influenza pandemic of1918-1919, which caused an estimated 40 to 50 million deaths world wide, wasfollowed by pandemics in 1957-1958 and 1968-69. All measures that could mitigatethe impact of a pandemic and can be set up in advance are best undertaken nowrather than during the chaos of a pandemic. Such measures fall into three maincategories: advance warning that the virus is improving its transmissibility, earlyintervention to halt further adaptation or forestall international spread, and urgentdevelopment of a pandemic vaccine. (WHO AI page 44)

At the earliest stage of a pandemic, when large numbers of cases are not yetoccurring, measures such as simple hand-washing, the use of masks, and voluntaryquarantine of patients might help reduce transmission. If only a few countries areaffected, travel-related measures, such as exit screening for persons departing fromaffected areas, might delay international spread somewhat, but cannot stop it. Onceefficient and sustained human to human transmission has been established, thecontainment of pandemic influenza is not considered feasible. (WHO AI page 53)

When large numbers of cases begin to occur, priorities need to change, moving awayfrom efforts to reduce transmission and international spread and towards thereduction of morbidity and mortality. Several measures, such as contact tracing andfollow up will no longer be either effective or feasible because of the sheer number of

cases. Other measures, such as entry screening at airports and borders, will have noimpact (WHO AI pg 53)

The banning of public gatherings and the closing of schools were considered the onlymeasures that could dampen the spread of pandemic influenza. Even the mostextreme option-severe restrictions on international travel and trade-was thought tobring nothing more than a few weeks of freedom from a disease whose internationalspread might be forestalled, but never stopped. (WHO AI page 29)

For health authorities, the biggest challenge presented by the 1957 pandemic wasthe provision of adequate medical and hospital services. Measures to delay the speedof spread and thus flatten the peak occurrence of cases were considered justified ifthey allowed the maintenance of medical and other essential services. (WHO AI

page 29)

In Lessons from the 3 pandemics of the last century:(No mention of the need to kill wild birds.) It does say:Over the centuries, most pandemics have originated in parts of Asia where densepopulations of humans live in close proximity to ducks and pigs. In this part of theworld, surveillance for both animal influenza and clusters of unusual respiratorydisease in humans performs an important early warning function. (WHO AI page32)


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Some public health interventions may have delayed the international spread of pastpandemics, but could not stop them. Quarantine and travel restrictions have shownlittle effect. As spread within countries has been associated with close contact andcrowding, the temporary banning of public gatherings and closure of schools arepotentially effective measures. The speed with which pandemic influenza peaks and

then disappears means that such measures would probably not need to be imposedfor long. (WHO AI page 32)

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A list of documents from which these

excerpts were taken is on the next page.


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Exhibit A

Primary Sources:

Centers for Disease control: www.cdc.gov

Animal and Plant Health Inspection Service: www.aphis.usda.gov

World Health Organization: www.who.int

World Organization for Animal Health: www.oie.int(OIE was created in 1924 by 28 countries, it predates the UN)

Excerpts taken from these documents:

WHO: Avian influenza, Avian influenza (bird flu) and the significance of itstransmission to humans, January 15, 2004. (This 4 page document is found at:www.who.int/mediacentre/factsheets/avian_influenza/en/print.html )

WHO/FAQ: Avian influenza frequently asked questions, January 29, 2004. (This 6page document is found at:www.who.int/csr/disease/avian_influenza/avian_faqs/en/print.html )

WHO AI: Avian influenza: assessing the pandemic threat, January, 2005, WHO/CDS2005.29 (This 62 page document is found at:www.who.int/csr/disease/influenza/WHO_CDS_2005_29/en , then click on English-[pdf.2.61 Mb])

WHO UPDATE: Geographical spread of H5N1 avian influenza in birds-update 28situation assessment and implications for human health, August 18, 2005. (This 3page document is found at www.who.int/csr/don/2005_08_18/en/print.html)

OIE: Evolution of the animal health situation with regard to avian influenza August2005 (this 1 page document is found at www.oie.int/eng/press/en_050829.htm

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Printed documents are available on request

Canada Geese Avian Influenza Memo to Town September 8th

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