Emerging Infectious Emerging Infectious Diseases in WildlifeDiseases in Wildlife

SDLA Group 4SDLA Group 4

4 Feb 20104 Feb 2010

The ProblemThe Problem

Newly emerging diseasesNewly emerging diseases Gain notoriety after human infectionGain notoriety after human infection Cross-species transmissionCross-species transmission Animal vectorsAnimal vectors

– Birds Birds – BatsBats– Marine MammalsMarine Mammals

Bird MigrationBird Migration

Bird migration as a mechanism for disease Bird migration as a mechanism for disease spreadspread

Birds on the moveBirds on the move– >300 species native to North America move to >300 species native to North America move to

Central, South America, and the West IndiesCentral, South America, and the West Indies– Along the seaboardAlong the seaboard– Ex of long distance extreme- Arctic TernEx of long distance extreme- Arctic Tern– Geese and swansGeese and swans– Europe and Asia- east to westEurope and Asia- east to west– Very variable and complexVery variable and complex

Elliptical, sharp bends, nomadic wanderingElliptical, sharp bends, nomadic wandering

BirdsBirds

Influenza AInfluenza A– Highly segmented RNA virusHighly segmented RNA virus– Infects most mammals and birdsInfects most mammals and birds– Zoonotic after mammalian infectionZoonotic after mammalian infection

Effects of virusEffects of virus– Severe respiratory infectionsSevere respiratory infections– Birds may be asymptomaticBirds may be asymptomatic

BirdsBirds

TransmissionTransmission– Airborne through sneezingAirborne through sneezing– Contact with bodily secretionsContact with bodily secretions– Birds to pigs to humansBirds to pigs to humans

Environmental FactorsEnvironmental Factors– Fecal to oral transmission on farmsFecal to oral transmission on farms

BirdsBirds

West Nile VirusWest Nile Virus– Single stranded RNA - FlavivirusSingle stranded RNA - Flavivirus– Infects mainly birds, mosquito vectorInfects mainly birds, mosquito vector– ZoonoticZoonotic

Effects of virusEffects of virus– AsymptomaticAsymptomatic– FeverFever– Encephalitis (rare)Encephalitis (rare)

BirdsBirds

TransmissionTransmission– From birds via mosquitoesFrom birds via mosquitoes– Airborne through sneezingAirborne through sneezing– Contact with bodily secretionsContact with bodily secretions

Environmental FactorsEnvironmental Factors– Warmer temperatures increase Warmer temperatures increase

mosquito presencemosquito presence– Asymptomatic birds spread virus over Asymptomatic birds spread virus over

distancesdistances

BirdsBirds

Lyme DiseaseLyme Disease– Gram-negative spirochetal bacteriaGram-negative spirochetal bacteria– Tick-borne diseaseTick-borne disease– Deer and bird hostsDeer and bird hosts– ZoonoticZoonotic

Effects of virusEffects of virus– FeverFever– RashRash– Joint and muscle painJoint and muscle pain

BirdsBirds

TransmissionTransmission– Spread through deer ticksSpread through deer ticks– Birds introduce ticks to new areasBirds introduce ticks to new areas

Environmental FactorsEnvironmental Factors

BatsBats

Severe Acute Respiratory Syndrome Severe Acute Respiratory Syndrome (SARS)(SARS)– CoronavirusCoronavirus– Infects bats, palm civets, raccoon dogs, Infects bats, palm civets, raccoon dogs,

hog badgershog badgers– ZoonoticZoonotic

Effects of virusEffects of virus– Upper respiratory infectionUpper respiratory infection– Fever, cough, sore throatFever, cough, sore throat

BatsBats

TransmissionTransmission– Airborne through sneezingAirborne through sneezing– Contact with bodily secretionsContact with bodily secretions– Ingestion of contaminated meatIngestion of contaminated meat

Environmental FactorsEnvironmental Factors– Large populations in a small area Large populations in a small area

increases spread of virusincreases spread of virus

BatsBats

Lyssavirus and RabiesLyssavirus and Rabies– Helical RNA virusesHelical RNA viruses– Infects warm-blooded animalsInfects warm-blooded animals– ZoonoticZoonotic

Effects of virusEffects of virus– Attacks neural tissueAttacks neural tissue

Severe encephalitisSevere encephalitis Aversion to waterAversion to water

– Death (~100% in untreated humans)Death (~100% in untreated humans)

BatsBats

TransmissionTransmission– Blood, saliva, urineBlood, saliva, urine– Most common when saliva enters a bite Most common when saliva enters a bite

woundwound

Ecological FactorsEcological Factors– Has cast a shadow on bats throughout the Has cast a shadow on bats throughout the

world.world.– Protocols put into place to prevent spread of Protocols put into place to prevent spread of

these viruses (DEFRA: Pet Travel Scheme)these viruses (DEFRA: Pet Travel Scheme)

BatsBats

Nipah/Hendra virusesNipah/Hendra viruses– SS non-segmented RNA SS non-segmented RNA

(Paramyxoviridae)(Paramyxoviridae)– Infects flying foxesInfects flying foxes– ZoonoticZoonotic

Effects of virusEffects of virus– Acute respiratory illness (Hendra)Acute respiratory illness (Hendra)– Severe encephalitis (Nipah)Severe encephalitis (Nipah)– DeathDeath

BatsBats

TransmissionTransmission– Body FluidsBody Fluids– UrineUrine– Ingestion of contaminated meatIngestion of contaminated meat– Bat migration spreads disease to new Bat migration spreads disease to new

areasareas

Notable CasesNotable Cases– 1994, Australian horses1994, Australian horses– 1998, Malaysian pigs1998, Malaysian pigs

Cetacean MorbillivirusCetacean Morbillivirus

OverviewOverview– Single strand RNA virus of family Single strand RNA virus of family

ParamyxoviridaeParamyxoviridae– Infects dolphins, porpoises, pilot whalesInfects dolphins, porpoises, pilot whales– Not zoonoticNot zoonotic

Effects of virusEffects of virus– PneumoniaPneumonia– Non-suppurative meningo-encephalitisNon-suppurative meningo-encephalitis– Lymphoid cell depletionLymphoid cell depletion– DeathDeath

Cetacean MorbillivirusCetacean Morbillivirus TransmissionTransmission

– Pilot whales and other species thought to be Pilot whales and other species thought to be reservoirs of infection, spreading the virus to reservoirs of infection, spreading the virus to other speciesother species

Ecological FactorsEcological Factors– Increased susceptibility if immunosuppressed and/or in Increased susceptibility if immunosuppressed and/or in

poor nutritional statepoor nutritional state– PCBs and DDTs act as immunosuppresive agentsPCBs and DDTs act as immunosuppresive agents– Exposure to natural neurotoxins (e.g. brevetoxin)Exposure to natural neurotoxins (e.g. brevetoxin)– Increase in sea surface temperatures (global warming) Increase in sea surface temperatures (global warming)

decreases abundance of fishdecreases abundance of fish

BrucellosisBrucellosis

OverviewOverview– Gram-negative bacteria of the genus Gram-negative bacteria of the genus BrucellaBrucella– Infects marine mammals including whales, Infects marine mammals including whales,

dolphins, porpoises and sealsdolphins, porpoises and seals

Effects of virusEffects of virus– Marine MammalsMarine Mammals

Fetal abortionFetal abortion MastititsMastitits EncephalitisEncephalitis PneumoniaPneumonia

– HumansHumans SeizuresSeizures Recurrent feverRecurrent fever Dramatic weight lossDramatic weight loss Intracerebral Intracerebral

granulomasgranulomas

BrucellosisBrucellosis

TransmissionTransmission– In marine mammals it is spread from mother to In marine mammals it is spread from mother to

fetusfetus– Interspecies and cross-species transmissionInterspecies and cross-species transmission– In humans, ingestion of infected foods and In humans, ingestion of infected foods and

contact with possibly infected marine mammalscontact with possibly infected marine mammals

Ecological FactorsEcological Factors– Environmental factors in emergence of Environmental factors in emergence of

brucellosis is unknownbrucellosis is unknown

ToxoplasmosisToxoplasmosis

OverviewOverview– Intracellular protozoan parasite of the family Intracellular protozoan parasite of the family

Toxoplasma gondiiToxoplasma gondii– Infects all mammals as well as arthropods ie Infects all mammals as well as arthropods ie

musselsmussels

Effects of virusEffects of virus– PneumoniaPneumonia– EncephalitisEncephalitis– MyocarditisMyocarditis

ToxoplasmosisToxoplasmosis

TransmissionTransmission– Wild and domestic felines are only known hostsWild and domestic felines are only known hosts– Feline fecal contamination flowing from land to Feline fecal contamination flowing from land to

seasea– Ingestion of Contaminated food/drinkIngestion of Contaminated food/drink– TransplacentallyTransplacentally

Ecological FactorsEcological Factors– Degradation of marine environment leading to Degradation of marine environment leading to

food scarcityfood scarcity– Immunosuppressed species more at riskImmunosuppressed species more at risk

Why Should We Care?Why Should We Care?

PredictionPrediction

PreventionPrevention

ConservationConservation

““In humans, an estimated 75% of In humans, an estimated 75% of emerging diseases are zoonotic, with emerging diseases are zoonotic, with wildlife representing a large and wildlife representing a large and mostly unknown resevoir.”mostly unknown resevoir.”

Questions?Questions?