Global movement of pathogens linked to free-ranging and ...€¦ · pathogens linked to free-ranging and captive wildlife ... Exotic introduction into ... – dog-dingo crosses –

Global movement of pathogens

linked to free-ranging and captive wildlife

Howard PharoAnimals Risk Analysis

Global movement?• Wild animals move – with their pathogens• Locally, usually within environmental limits

• Might be across international borders • Migration over long distances = global• Human-mediated

– Translocations into the wild are rare– Mostly movement of pet or zoo animals

• Pathogens emerge & spread – often without clear cause

• How good is our current knowledge?– Surveillance gaps

• Role for risk analysis

Classical swine fever in European wild boar• Outbreaks are self limiting in most wild boar populations• But the virus may circulate for years in others• Recognised as a reservoir and possible source of

infection for domestic pigs– Considered source of ~ 100 outbreaks in Germany

1993-2002 • Considerable surveillance investment in the EU

– Database development• Mapping• Spatial modelling

Slide courtesy of Christoph StaubachFriedrich Loeffler Institut, Germany

Rabies in Europe

• Predominantly sylvatic– Wildlife account for 80% of cases

(WHO)– Red fox (Vulpes vulpes) 80% of

these– Raccoon dog in Eastern Europe

• Oral vaccine developed 25 yrs ago– Highly effective– Aerial distribution– Many European countries now

free

Rabies in Northern Italy• October 2008 – fox rabies reappears in NE Italy after 13 yrs

absence• 2009 – a number of oral vaccination campaigns• Further spread Westward

– To Veneto region• Recording of GPS data

– culled/dead foxes • Analysis of clustering

Slide courtesy of Paulo Mulatti

Istituto Zooprofilattico Sperimentale delle Venezie

• Upper altitude limit for baiting increased to 2300 m

White nose syndrome

Discovered in a single New York cave in February 2006

Spread South & West

More than a million hibernating bats of nine species have been killed by the disease in 14 states

Geomyces destructansProbably spread by spores on bats themselves

Present in Europe without disease; co-evolution?

Predicted risk & observed spread

Pteropid fruit bats - Flying foxes• Hendra (Queensland 1994) – bats – horses – humans

– 13 outbreaks in horses, 4 spread to humans• Bat lyssavirus (Australia 1996)

– 7th member of the lyssavirus genus – 2 human deaths

• Nipah (Malaysia 1999) – bats – pigs & humans – 105 human deaths, 1 million pigs culled

Is this global movement or the inevitable result of man encroaching further on previously undisturbed environments?

Pilchard mortalitiesAustralia & New Zealand 1995

Slide courtesy of Richard Whittington, University of Sydney

Huge losses – up to 60% in some populations

WESTERN

AUSTRALIA

NORTHERN

TERRITORY

SOUTH

AUSTRALIA

QUEENSLAND

NEW SOUTH

WALES

VICTORIA

TASMANIA

22 March20 April3 May

6 May

30 May

31 April2 May

5 May10 May12 May

15 May19 May

24 May30 May

2 June3 June5 June

Pilchard deaths 1995

16.06 Hauraki Gulf

20.06 Bay of Islands15.07

29.08

17.09 Wellington Harbour

19.06 Firth of Thames

05.09

03.07

3000 km

NNinety Mile

Beach

Southern bluefin tunaSea cage aquaculture

-fed imported frozen pilchards

Slide courtesy of Richard Whittington, University of Sydney

Herpes virus observed by EM

No culture systems

30 km /d, against current

Newly emerged latent virus?Exotic introduction into a naïve population?

West Nile virus• Flavivirus – same group as JE• 1937 Uganda• Africa, E Europe, W Asia, Mid East• Corvidae family (crows, jays, magpies) • 1999 outbreak New York City

– Infected mosquitos on aircraft or ships?– Viraemic human?– Infected birds most likely

• Spread in the US was probably by seasonal migrations of birds

• 1999-2000 spread along Atlantic seaboard• 2000-2002 rapid spread westward – 47 states

affected by 2008

Avian influenza and migratory waterbirds• Ducks – USA - 1970s

– Dabbling ducks positive (esp Mallards) )– LP virus in faeces of up to 60% ducks

• 1mg faeces contains infectious dose• Migrate south for winter• Stopover at ponds on poultry farms • Contamination of water supply• LP virus mutates to HP after introduction into

poultry• But duck migrations do not cross

the equator

Most outbreaks involve humans• US live bird markets• Asia - interface b/t domestic & wild ducks• Wild bird reservoir of HPAI unlikely• Intensive broiler production has become

the new focus in Asia – density of farming

• H5N1 probably endemic in much of Asia

• Biosecurity is the key– Implementation

challenges

Flubird - Database on Influenza viruses in migratory birds in Europe Slide courtesy of Christoph Staubach

Friedrich Loeffler Institut, Germany

Geographic distribution of samplesSlide courtesy of Christoph StaubachFriedrich Loeffler Institut, Germany

Slide courtesy of Christoph StaubachFriedrich Loeffler Institut, GermanyMaps of flyways

NZ migratory shorebirds

• Bar tailed godwit (Limosa lapponica)– 100,000

• Red knot (Calidris canutus)– 70,000

• Ruddy ternstone (Arenaria interpres)– 5000

• Pacific golden plover (Pluvialis fulva)– 1200

• Red-knecked stint (Calidris ruficolis)– About 500

• A number of other sandpipers, curlews, whimbrel etc in low hundreds

Migration flyways for subpopulations of red knot (Calidris canutus)

Surveillance in NZ waterbirds• No evidence of any AI viruses in migratory waders• Duck surveys show a low prevalence of LPAI viruses• Where did these duck viruses come from?• Perhaps with the originally imported ducks

– British stock from Australia– Many introductions, from 1860s to about 1920

• Very little movement of ducks over the Tasman– Generally populations in both Australia and New

Zealand are sedentary• Conclusion: Risk from HPAI in migratory birds negligible

Not all animal movement is natural dispersal or migration

• Human-mediated animal movements pose risks• New Zealand example

– Endemic mammals only bats• First humans arrived ~ 1000 yrs ago

– Polynesian rat, dog• European colonisation 200 yrs ago

– Many species of animal introduced

200 years of introductions to New Zealand• Livestock

– sheep, cattle, pigs, horses, poultry)

• Wild animals (for hunting)– Deer (7 spp)– Thar– Chamois– Wallaby (5 spp)– Rabbit– Hare– Waterfowl (ducks, swans)

• Biocontrol agents– Hedgehog– Stoat, Ferret, Weasel

• Birds – 30 spp– mainly passerines– Parrots

• Mistakes– Rats, mice– Possums

• Pets– Cat, dog, cagebirds etc

Introduction of pathogens?• Most normal livestock pathogens were introduced• Numbers of wildlife introduced were generally low

compared to livestock• No wild canines introduced • Many introduced livestock became environmental pests

– Possum, goat, thar– Rabbit, hare

• Ferret, stoat, weasel

Avian malaria in New Zealand• Plasmodium relictum - 3 strains present

– 1 endemic (Polynesian strain)– 2 introduced (sparrows, blackbirds)

• Introduced to Hawaii from Europe 200 yrs ago– Key role in bird extinctions

• Few effects in New Zealand – colder climate limiting mosquito

density?• May be involved in some deaths of

saddlebacks and yellow-eyed penguins

PRRS emergence in Europe & USA• Disease emerged Nth America & Europe ~ 1990

– Arterivirus identified 1991• Seropositives back to 1979 in Canada, 1988 in E Germany • European & American genomes distinct

• 40% divergence• Most recent common ancestor of PRRS? - LDV of mice? • Hypothesis (Forsberg, 2005)

– Mutant LDV jumps species to wild boar (in Sachsen-Anhalt, ~1880)

– Infected wild boar imported Carolina 1912– Independent evolution for 70 years– From wild boar to pigs synchronously?

Pathogen spill-back in NZ – possums and bovine tuberculosis• 60-70 million possums by 1990s• Major vector for bovine TB by

1970s

Photos courtesy of Paul Livingstone, AHB

Other wildlife vectors of bovine TB• Ferrets in New Zealand

Photos courtesy of Paul Livingstone, AHB

Other wildlife vectors of bovine TB• Ferrets in New Zealand• Badgers in UK

Other wildlife vectors of bovine TB• Ferrets in New Zealand• Badgers in UK• Feral buffalo in Australia

Photos courtesy of Graham Wilson

Hydatids – Echinococcus spp• New Zealand and Tasmania

– No wild or feral canids– Dog-sheep cycle – Eradication achieved by dog registration

and anthelminthic treatment

Echinococcus granulosis - Australia• Highly susceptible wildlife hosts• Definitive hosts

– Dingos– dog-dingo crosses– foxes

• Intermediate– Marsupials – Wild boar

• Eradication not feasible

Photos courtesy of David Jenkins

Echinococcus multilocularis in Germany • Endemic in wildlife ; fox – mouse cycle• Brandenberg, Germany

– GPS records for 6000 foxes shot 1995-2001• Spatial modelling

– Identification of potential risk factors for infection in foxes

– Vegetation type– Wetness

Prediction map of the distribution of E. multilocularis(using a GEE model)

Notifications 2005-2009

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#Slide courtesy of Christoph StaubachFriedrich Loeffler Institut, Germany

Risk Analysis for captive wild animals

• Exotic wild animals prohibited – environmental risk assessment needed

• New Zealand’s history of pest animals– Possums, rabbits etc– Approval very rare

• Zoo animals for containment– Normal IRA process

Diversity of Zoo animal IRAs• Tasmanian devils• White rhinos• Primates• Marsupials & monotremes• Rodents• Sharks• Tapirs• Elephants• Pandas

Characteristics of zoo animal IRAs• Volume of trade likely to be very low• Source known (rarely considered from wild)• Benefits difficult to argue against

– Public interest– Conservation of international biodiversity– Cooperative breeding programmes

• Risks are potentially quite different– Analytical investment may be high

• Risks can be managed

Conclusions• Local movements of wild animals may be important for

some diseases• Long-distant migration important for LPAI but HPAI

develops after global movement• Role of movement for fish diseases not well

understood• Surveillance of wildlife expensive, data often scarce• Captive wildlife risks can be managed• Risk analysis can be applied in many situations to

guide decision-making

New Zealand wildlife

Thank you for your attention