Zoonoses pathogens

A zoonosis or zoonose is any infectious disease that can

be transmitted between species (in some instances, by a

vector) from animals to humans or from humans to animals

(the latter is sometimes called reverse zoonosis or

anthroponosis). In a study of 1415 pathogens known to affect

humans, 61% were zoonotic .

OverviewZoonosis

History

Interactions between animals and humans have occurred since the beginning of time.

As animals became domesticated and a close bonds developed between animals and humans, the occurrence of zoonotic diseases increased.

Significant Zoonitic Pandemics

1700s, Mongols invaded Europe Mongols carried plague with them This lead to “black death” or

plague pandemicKilled 1/3 of European population

Significant Zoonitic Pandemics

Early 1900’s “Spanish flu” transmitted from pigs to humans

Decimated 20 million people worldwide

Continues to pose a threat to humans

Today’s threat involving zoonotic diseases is considered to be partly due to human involvement in which the artificial multiplication of these pathogens can be used as biological terrorism.

Contemporary Threats

PrevalenceLargely UnknownBoth serological studies and anecdotal discuss

ion have been used to generate estimates1997 a study trying to assess the prevalence o

f antibodies against Bartonella henselae and B. quintana was done at a veterinary conference. The results indicated that 7.1% of the veterinary population had antibodies which was no different from the general population studies at an earlier time.

Types of Pathogens Viruses Bacteria Fungi Others

Rickettsia Protozoa Parasites

Always assume every animal is

shedding pathogens

How Diseases SpreadFecal-oral

Fecal contamination is not always obvious

Many pathogens may survive for long periods of time in the environment.

Parvovirus ringworm and some worm eggs can survive for years

How Diseases SpreadBy air (aerosol

)Upper respirat

ory infection (URI-cats)

Kennel （ Kennel ） cough (dogs)

How Diseases SpreadAnimal bites or sali

vaFeline leukemiaFIV （ Feline Immun

odeficiency Virus ）RabiesBacteria that can ca

use bite wound abscesses

How Diseases SpreadThrough direct contactRingwormScabies Ear

mitesHookworm

larvae

How Diseases Spread By insect “vectors”

Mosquitoes spread heartworms and encephalitis Fleas spread tapeworms, cat scratch fever,

plague, typhus, etc. Ticks spread Lyme disease, Rocky Mountain

Spotted Fever, and more Vectors must be controlled in the shelter

Eliminate standing water (mosquitos) Treat fleas on animals and in environment Keep grass cut to limit ticks

How Diseases SpreadBy infected objects (fomites)

Ringworm spread by spores on pet hair

Cage walls, toys, and bedding Peoples’ hands – including staff!

12 Tips to Help You Avoid Zoonotic Diseases Stay current on appropriate vaccinations

(tetanus, rabies) Wash hands frequently with antibacterial soap

before eating or smoking After handling each animal or cage

Wear long pants and sturdy shoes or boots Use gloves Wear safety glasses and mask when spray

cleaning Disinfect scratches and bite wounds thoroughly,

then cover them.

12 Tips to Help You Avoid Zoonotic Diseases Don’t allow animals to lick your face or any

open wounds Learn safe & humane animal-handling

techniques, and user proper equipment Seek assistance when handling questionable

animals Report any bites or injuries to supervisor Tell your physician where you work Consider other work if you are

immunosuppressed.

※ Bacillus anthracis ( 炭疽芽孢杆菌 )

※ Yersinia pestis ( 鼠疫耶尔森氏杆菌 )

※ Brucella ( 布鲁氏菌 )

※ Francisella ( 弗朗西斯氏菌属 )

※ Coxiella ( 考克斯氏体属 )

※ Bartonella ( 巴尔通氏体属 )

……※

Common zoonoses pathogens

Bacillus anthracisBacillus anthracis

Robert Koch’s original micrograhps of the anthrax bacillus

※ Large (1 - 3 µm in width × 5 – 10 µm

in length), G+ rod with a tendency to

form very long chains.

※ Obligate aerobe

※ Glutamyl-polypeptide capsule

※ Nonmotile

※ Forms oval, centrally located

endospores and the spore remain viable

in soil for decades

Biological character

2. Cultural character

On blood agar, nonhemolytic colonies characterized

by a rough, uneven surface with multiple curled extensions

at the edge resembling a “Medusahead”

Colonies of Bacillus anthracis on blood agar.

Mucoid colonies of Bacillus anthracis. This

culture was probably incubated at an

increased CO2 tension (5% CO2) which

greatly enhances production of the poly-D-

glutamyl capsule and accounts for the

mucoid colony type.

2. cultural character

PathogenesisPathogenesis

Virulence depends on Virulence depends on 2 factors2 factors

※ ※ CapsuleCapsule

※ ※ 3 toxins3 toxins

CapsuleCapsule

C=Capsule; S=S-layer; P=Peptidoglycan

※ ※ Coded by pX02 plasmidCoded by pX02 plasmid

※ ※ Made up of Made up of D-glutamic acidD-glutamic acid

※ ※ Non-toxic on its ownNon-toxic on its own

※ ※ Only encapsulated Only encapsulated B. anthracisB. anthracis

virulentvirulent

※ ※ Most important role during Most important role during

establishment of diseaseestablishment of disease

△ △ Protects against phagocytosis & lysis Protects against phagocytosis & lysis

during vegetative stateduring vegetative state

ToxinsToxins

※ Coded by pX01 plasmid

※ AB model

△ Binding

△ Activating

※ Protective antigen (PA), edema factor (EF) & lethal

factor (LF)

△ Make up 50% of proteins in the organism

※ Heterogeneous protein complex made up of 3

components

ToxinsToxins

△ Individually non-toxic

△ PA+LF lethal activity

△ EF+PA edema activity

△ EF+LF inactive

△ PA+LF+EF edema & necrosis; lethal

※ ※ Protective antigen (PA, 83kDa)Protective antigen (PA, 83kDa)

△△ PagPag gene gene

△ △ Binds to receptor & helps internalize other 2 proteinsBinds to receptor & helps internalize other 2 proteins

※ ※ Edema factor (EF, 89 kDa)Edema factor (EF, 89 kDa)

△△ CyaCya gene gene

△ △ Adenylate cyclase Adenylate cyclase

△ △ Affects all cellsAffects all cells

※ ※ Lethal factor (LF, 87 kDa)Lethal factor (LF, 87 kDa)

△ △ LefLef gene gene

△ △ More important virulence factorMore important virulence factor

△ △ Metalloprotease Metalloprotease

△ △ Cleaves mitogen activated protein kinase kinase(MAPKK)Cleaves mitogen activated protein kinase kinase(MAPKK)

△ △ Affects only macrophagesAffects only macrophages

ToxinsToxins

OutcomeOutcome ※ ※ Do not understand exactly how symptoms occurDo not understand exactly how symptoms occur

※ ※ EF converts EF converts ATP to cAMPATP to cAMP

△ △ Increases cAMP levels over 1,000 foldIncreases cAMP levels over 1,000 fold

△ △ Impairs neutrophil functionImpairs neutrophil function

△ △ Alters water homeostasisAlters water homeostasis

■ ■ EdemaEdema

OutcomeOutcome ※ ※ LF cleaves MAPKK LF cleaves MAPKK at its N terminusat its N terminus

△ △ Disrupts pathways involved in cell growth & maturationDisrupts pathways involved in cell growth & maturation

△ △ Increased synthesis of tumor necrosis factor-Increased synthesis of tumor necrosis factor-αα & &

interleukin-1interleukin-1ββ

△ △ Macrophage lysisMacrophage lysis

■ ■ Septic shock & deathSeptic shock & death

※ ※ Death probably results from high levels of bacteria secreting Death probably results from high levels of bacteria secreting

LF toxins in bloodLF toxins in blood

△ △ At death, blood contains as many as At death, blood contains as many as 101099 bacilli/ml bacilli/ml

(depending on the species)(depending on the species)

Anthrax: transmissionAnthrax: transmission

※ ※ Anthrax is a major disease threat to herbivorous animals.Anthrax is a major disease threat to herbivorous animals.

※ ※ People become infected by thePeople become infected by the cutaneouscutaneous route (direct route (direct

contact with diseased animals, industrial work with hides, contact with diseased animals, industrial work with hides,

wool, brushes, or bone meal), bywool, brushes, or bone meal), by inhalationinhalation (Woolsorter's (Woolsorter's

disease), or bydisease), or by ingestioningestion (meat from diseased (meat from diseased

animals).animals).

Clinical InformationClinical Information

Three forms of AnthraxThree forms of Anthrax

※※ Cutaneous Cutaneous anthraxanthrax

△ △ Skin Skin

△ △ Most commonMost common

△ △ Spores enter to skin through small lesionsSpores enter to skin through small lesions

※※ Inhalation Inhalation anthraxanthrax

△ △ Spores are inhaledSpores are inhaled

※ ※ Gastrointestinal Gastrointestinal (GI)(GI) anthraxanthrax

△ △ Spores are ingestedSpores are ingested

△ △ Oral-pharyngeal and abdominalOral-pharyngeal and abdominal

肺内炭疽

肠内炭疽

脾内炭疽

Laboratory diagnosis of anthraxLaboratory diagnosis of anthrax

※ ※ Gram stainGram stain

※ ※ Culture of Culture of B. anthracisB. anthracis from the blood, skin lesions, from the blood, skin lesions,

vesicular fluid, or respiratory secretionsvesicular fluid, or respiratory secretions

※ ※ Rapid detection methodsRapid detection methods

△ △ PCR for detection of nucleic acidPCR for detection of nucleic acid

△ △ ELISA assay for antigen detectionELISA assay for antigen detection

△ △ Other immunohistochemical and immunoflourescence Other immunohistochemical and immunoflourescence

examinationsexaminations

Bacillus anthracisBacillus anthracis in Gram stain in Gram stain

Gram Stain AnalysisGram Stain Analysis

△ △ Useful for cutaneous and inhalation Useful for cutaneous and inhalation

anthrax.anthrax.

△ △ A blood sample or skin lesion is A blood sample or skin lesion is

taken from the patient and cultured taken from the patient and cultured

for for 6 to 24 hours6 to 24 hours. .

△ △ Identify whether the bacteria come Identify whether the bacteria come

from the anthrax category.from the anthrax category.

Treatment of anthraxTreatment of anthrax

※ ※ antibiotics antibiotics

※ ※ Antibody to the toxin complex is neutralizing and Antibody to the toxin complex is neutralizing and

protectiveprotective

Binding of a Neutralizing Antibody to the Protective Antigen Subunit of the B. anthracis toxin

Neutralizing Antibodies to B. anthrax toxin

Defense: Protection Against AnthraxDefense: Protection Against Anthrax

※ ※ VaccinationVaccination

Very Effective: 2 dose efficacy against monkeys Very Effective: 2 dose efficacy against monkeys

(human response believed to be very similar)(human response believed to be very similar)

※ ※ Early DetectionEarly Detection

Extremely important: eliminate much of danger.Extremely important: eliminate much of danger.

Time lag between exposure and symptoms is primary Time lag between exposure and symptoms is primary

reason for the high mortality rate experienced with reason for the high mortality rate experienced with

anthrax infectionsanthrax infections

※ ※ Contaminated animal, carcass or hide should be burned.Contaminated animal, carcass or hide should be burned.

※ ※ Pre/Post Exposure Antibiotic TreatmentPre/Post Exposure Antibiotic Treatment

※ ※ Decontamination of Exposed AreasDecontamination of Exposed Areas

※ ※ Use of Protective Clothing & EquipmentUse of Protective Clothing & Equipment

Defense: Protection Against AnthraxDefense: Protection Against Anthrax

Exercises:1.Briefly describle the three forms of Anthrax?1.Briefly describle the three forms of Anthrax?

2.Briefly describle the mechanism of anthrax toxi2.Briefly describle the mechanism of anthrax toxinn