Perspectives on Zoonotic Diseases Dave Van Metre, DVM, DACVIM

Perspectives on Zoonotic DiseasesPerspectives on Zoonotic Diseases

Dave Van Metre, DVM, DACVIMDave Van Metre, DVM, DACVIM College of Veterinary Medicine & Biomedical SciencesCollege of Veterinary Medicine & Biomedical Sciences

Colorado State UniversityColorado State University

ObjectivesObjectivesWhy are zoonotic diseases of greatest Why are zoonotic diseases of greatest

consequence today?consequence today?Risk factorsRisk factorsBenefits of animalsBenefits of animalsPreventative measuresPreventative measuresWhat roles can we play in educating the What roles can we play in educating the

public?public?

What is a zoonotic disease?

A disease shared by humans

and vertebrate animals

There are 1,407 known human There are 1,407 known human disease pathogens of whichdisease pathogens of which816 are zoonotic diseases816 are zoonotic diseases

Woolhouse, J Emerging Infectious Diseases11:2005Woolhouse, J Emerging Infectious Diseases11:2005

75% of human emerging 75% of human emerging infectious diseases are caused infectious diseases are caused

by zoonotic pathogensby zoonotic pathogens

J Emerging & Infectious Diseases J Emerging & Infectious Diseases volvol 11, 200511, 2005

Transmission of Zoonotic DiseaseTransmission of Zoonotic Disease

Who is at risk?Who is at risk?Veterinarians & veterinary techniciansVeterinarians & veterinary techniciansAnimal Emergency RespondersAnimal Emergency RespondersGeneral Public When Visiting:General Public When Visiting:

Petting zoosPetting zoosDog parksDog parksAnimal SheltersAnimal Shelters

Pet owners Pet owners New petNew petOutdoor catOutdoor catReptiles and birdsReptiles and birds

Animal shelter personnelAnimal shelter personnelAnimal control officersAnimal control officersPet retail facility personnelPet retail facility personnelLivestock producersLivestock producers44--H program participantsH program participantsSalebarn personnelSalebarn personnel

Society has changed!Society has changed!•• More people have contact with animals today More people have contact with animals today

than they did a century ago!than they did a century ago!•• Early 19Early 19thth century: 40% of the population were century: 40% of the population were

involved with agricultureinvolved with agriculture•• Today <2% are involved with agriculture, butToday <2% are involved with agriculture, but……

60% households have at least 60% households have at least one kind of pet one kind of pet --

An ever growing diversity of petsAn ever growing diversity of pets

A disease shared by A disease shared by humans humans

and animalsand animals

Marshfield index case, 5/26/03disseminated lesions

Wisconsin 2003Wisconsin 20037 confirmed 7 confirmed 34 suspect human cases34 suspect human cases

Gambian RatGambian Rat

Monkeypox VirusMonkeypox Virus•• Orthopox familyOrthopox family•• Spread animalSpread animal--toto--

human via blood or human via blood or bitebite

•• HumanHuman--toto--human human spread possiblespread possible

•• Clinical presentation Clinical presentation similar to smallpox similar to smallpox but milder but milder

SmallpoxSmallpox

What are the risksWhat are the risks for acquiring a zoonotic disease for acquiring a zoonotic disease

in Colorado?in Colorado?

Some Behaviors Are Clearly RiskySome Behaviors Are Clearly Risky

Those at greatest riskThose at greatest risk

•• Children less than 5 years old. Children less than 5 years old. •• Elderly. Elderly. •• Pregnant women. Pregnant women. •• People undergoing treatments for People undergoing treatments for

cancer. cancer. •• People who have received organ People who have received organ

transplants. transplants. •• People with HIV/AIDS. People with HIV/AIDS.

Risk RecognitionRisk Recognition

Sick outdoor / hunter cat Sick outdoor / hunter cat

High fever, depressionHigh fever, depressionLymph node enlargement Lymph node enlargement

or abscessor abscess(+/(+/--) respiratory signs) respiratory signs

PlaguePlague•• YersiniaYersinia pestispestis

gram(gram(--), non), non--motile, motile, nonnon--spore forming spore forming bacillusbacillus

•• Fleas living on infected Fleas living on infected rodents spread rodents spread infection to humans, infection to humans, cats, deer, rabbitscats, deer, rabbits

•• Recovery offers Recovery offers temporary immunitytemporary immunity

Endemic Plague in the USEndemic Plague in the US

Counties with Plague-Positive Samples

1970 - 1994

Common reservoirs of Common reservoirs of YersiniaYersinia pestispestis

AerosolAerosol

Bubonic or Bubonic or SepticemicSepticemicPlaguePlague

PneumoniaPneumonia Contact

OropharyngealOropharyngeal &&Secondary pneumoniaSecondary pneumonia

Photographs: Ken Gage, Ph.D., Centers for Disease Control and Prevention, Fort Collins, CO

Bubonic PlagueBubonic Plague

‘‘BuboBubo’’ formation formation regional lymph nodesregional lymph nodes

Plague in catsPlague in cats

•• LymphadenopathyLymphadenopathy –– ‘‘BubonicBubonic’’ 53%53% MandibularMandibular area abscessesarea abscesses

•• SepticemicSepticemic•• PneumonicPneumonic

Most dangerous to peopleMost dangerous to people

•• Dogs frequently infected Dogs frequently infected but are rarely clinicalbut are rarely clinical

TularemiaTularemia•• Gram Negative bacillus: Gram Negative bacillus:

FrancisellaFrancisella tularensistularensis•• One of the most infectious One of the most infectious

bacteria knownbacteria known–– 10 or fewer bacteria will 10 or fewer bacteria will

result in infectionresult in infection

TransmissionTransmission

•• VectorsVectors–– HARD TICKSHARD TICKS

•• Human transmissionHuman transmission•• DermacenterDermacenter variabilisvariabilis

–– BITING FLIESBITING FLIES•• ChrysopsChrysops•• TabanusTabanus•• Mechanical transmissionMechanical transmission•• Infective for 14 daysInfective for 14 days

•• Direct contactDirect contact–– Skinning infected Skinning infected

animalsanimals

•• IngestionIngestion–– Infected tissuesInfected tissues–– Water Water –– Voles (Voles (MicrotusMicrotus spp)spp)

•• InhalationInhalation

Tularemia Cases 1990Tularemia Cases 1990--20002000

Clinical presentationsClinical presentations

Ulceroglandular (75Ulceroglandular (75--85%)85%)Ulcer and regional lymph Ulcer and regional lymph

node enlargementnode enlargementGlandular (5Glandular (5--10%)10%)OculoglandularOculoglandular

Conjunctivitis, cervical Conjunctivitis, cervical lymphadenopathylymphadenopathy

TularemiaTularemiaFluFlu--like illness with fever, headache, like illness with fever, headache,

generalized body aches and productive generalized body aches and productive or nonor non--productive coughproductive cough

Pneumonia (85%) Pneumonia (85%) pleural effusion (15%)pleural effusion (15%)

•• Untreated caseUntreated case--fatality rate fatality rate -- 3535--60%60%•• Culture diagnosis quite difficultCulture diagnosis quite difficult•• PersonPerson--toto--person spread not seenperson spread not seen

Kosovo

•• Nov 2001 Nov 2001 –– Feb 2002Feb 2002–– 715715 human caseshuman cases–– Ages Ages 1616--4444

•• Oropharyngeal formOropharyngeal form–– Rodent Rodent

contamination of contamination of food and waterfood and water

MMWR 2:2005

Cryptosporidium Cryptosporidium parvumparvum

•• Most common causes of waterborne Most common causes of waterborne disease within humans in the United disease within humans in the United States. States.

•• Serological surveys indicate that 80% Serological surveys indicate that 80% of the population has had of the population has had cryptosporidiosis.cryptosporidiosis.

•• Incubation period 2Incubation period 2--10 days10 days

CryptosporidiosisCryptosporidiosisTransmissionTransmission

FecalFecal--oraloralHuman to humanHuman to humanAnimal to humanAnimal to humanFood borneFood borneWaterborneWaterborne

Most common Most common outbreak source:outbreak source:Failures in solid waste Failures in solid waste

managementmanagement

EtiologyEtiologyCryptosporidium Cryptosporidium

parvumparvumReservoirsReservoirs

HumanHumanLivestockLivestockBirdsBirds

CryptosporidialCryptosporidial genotypesgenotypes

GENOTYPE IGENOTYPE IHumanHuman--human transmission onlyhuman transmission onlyNotNot infective for cattleinfective for cattleIsolated from major human outbreaksIsolated from major human outbreaks

GENOTYPE IIGENOTYPE IIAnimalAnimal--animal and animalanimal and animal--human human

transmission (zoonotic)transmission (zoonotic)Associated with animal waste contactAssociated with animal waste contact

Human CryptosporidiosisHuman Cryptosporidiosis

Incubation: 1Incubation: 1--12 days12 daysSelfSelf--limiting in limiting in immunocompetentimmunocompetentNausea and abdominal painNausea and abdominal painWatery diarrhea: 3Watery diarrhea: 3--4 days duration4 days durationImmunosuppressedImmunosuppressed patientspatients

Persistent diarrheaPersistent diarrheaPersistent sheddingPersistent shedding1010--20% of AIDS patients affected20% of AIDS patients affected

Human outbreaksHuman outbreaks

Solid Waste FailuresSolid Waste FailuresGeorgia, 1987Georgia, 1987

13,000 people affected13,000 people affectedMilwaukee, WI, 1993Milwaukee, WI, 1993

403,000 people affected403,000 people affectedDairy farms along 2 rivers upstream ??Dairy farms along 2 rivers upstream ??

Austin, TX, 1998Austin, TX, 1998150 people affected150 people affected170,000 gallons of raw sewage into local creek170,000 gallons of raw sewage into local creek

Human outbreaksHuman outbreaksPublic Water Parks & Swimming PoolsPublic Water Parks & Swimming Pools

Georgia, 1995Georgia, 1995Louisiana 1988Louisiana 1988Wisconsin 1993 Wisconsin 1993

Food Service RelatedFood Service RelatedGeorgia Day Care, 1995Georgia Day Care, 1995

Food worker shedding Food worker shedding oocystsoocystsSpokane WA Banquet, December 1997Spokane WA Banquet, December 1997

Infected food service workers: Green onionsInfected food service workers: Green onions

Control and preventionControl and prevention

Personal hygienePersonal hygienePublic educationPublic educationIsolation of affected people from food Isolation of affected people from food

handling or child care jobshandling or child care jobsProper fecal waste managementProper fecal waste management

Q FeverQ FeverCoxiellaCoxiella burnettiiburnettiiOne organism may cause infectionOne organism may cause infectionOften symptomatic in animalsOften symptomatic in animalsRare cause of abortion in sheep & Rare cause of abortion in sheep &

goatsgoatsInhalationInhalation most common way to most common way to

get infectedget infectedObstetrical assistance to sheep or Obstetrical assistance to sheep or

goatsgoatsUnpasteurized milk, soft cheesesUnpasteurized milk, soft cheeses

Q Fever in HumansQ Fever in HumansIn untreated patients, case fatality rate is 1%; In untreated patients, case fatality rate is 1%;

-- death is rare in treated patientsdeath is rare in treated patientsFever accompanied by chills, headache, weaknessFever accompanied by chills, headache, weakness

About half of patients present with pneumoniaAbout half of patients present with pneumoniaNo personNo person--toto--person transmissionperson transmission

Chronic form (65% mortality)Chronic form (65% mortality)((ValvularValvular endocarditisendocarditis))

Heart disease Heart disease

3 Key messages 3 Key messages Living happier, healthier lives with animalsLiving happier, healthier lives with animals

Three stepThree step--processprocess1.1. PreventionPrevention

•• Vaccination, parasite controlVaccination, parasite control•• Basic biosecurityBasic biosecurity

Three steps (continued)Three steps (continued)

2.2. Appropriate sanitation / hygiene practicesAppropriate sanitation / hygiene practices• Cleaning and disinfecting animal

areas as needed• Hand washing!• Don’t eat or drink in animal facilities

3.3. Early diagnosis and treatmentEarly diagnosis and treatment• Both people and animals!

Tell your doctor that you work with animals!

Animals are important part of Animals are important part of our cultureour culture

•• Agriculture Agriculture •• CompanionsCompanions•• Service and working Service and working

animalsanimals•• WildlifeWildlife

Benefits of contact with animals outweigh the risks!

Rocky Mountain Regional Center of ExcellenceRocky Mountain Regional Center of ExcellenceFor Biodefense & Emerging Infectious DiseasesFor Biodefense & Emerging Infectious Diseases