Zoonose IYER

7/30/2019 Zoonose IYER

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Epidemiologyand Control of

ZoonoticInfections

www.freelivedoctor.com


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EPIDEMIOLOGICAL TRIAD


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Epidemiology of Zoonoses


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Human environment interaction


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1 Zoonosis Intro & TSE

2 Rabies

3 Classic Zoonoses

4 Bioterrorism5 Vector-borne Diseases

6 Parasitic Zoonoses

7 Emerging Zoonoses

8 Foodborne Illnesses


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Introduction to Zoonoses

Definition

Importance

Etiologies

Animal Examples

Transmission Routes

Life Cycles


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Zoonoses

From the Greek:

Zoon: Animal

Noson: Disease

Diseases and infections which are naturally

transmitted between vertebrate animals andhumans

- WHO 1959


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Zoonoses

Does NOT include

Fish and reptile toxins

Allergies to vertebrates

Diseases in which animal-derived food serves as a

vehicle (e.g. hepatitis A contaminated deli meat)

Experimentally transmitted diseases


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Zoonoses

> 750 zoonotic diseases

60% of US Household have 1 pet

Multiple pets in the home

Human-animal bond

Exotic species as pets


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Zoonoses: Common Diseases

Frequency (CDC, 2003)

Salmonella 39,919

Lyme disease 18,991

West Nile (CNS) 2,862

Trichinosis 4


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Zoonoses

Spectrum of Disease Severity

Death = rabies

Severe illness = plague

Chronic illness = Q-fever

Mild illness = psittacosis


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Importance of zoonoses

Economics Zoonotic disease are expensive

Rabies post-exposure prophylaxis

GI illness due to Salmonella or Campylobacter lost

productivity, medical costs

Import/Export

BSE restriction on cattle

Avian Influenza restriction on chicken

Travel/Globalization

Decreased transit time - SARS

Remote area accessibility


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Zoonoses: Importance

Surveillance

Animals are sentinels

Prevention and Control

Animal = key component

Complications (e.g. Lyme disease)

Unknown reservoirs (e.g. Ebola)


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Zoonoses: Etiologic Classification

Viral

Bacterial

Parasitic

Mycotic


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Zoonoses: Viral Examples

Colorado tick fever Japanese encephalitis

Ebola Monkeypox*

Equine encephalitides(WEE, EEE, VEE)

Nipah*

Hantaviruses Rabies*

Hendra* Rift Valley fever

Herpesvirus B West Nile virus*

Influenza Yellow fever

* indicates covered in lectures


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Zoonoses: Bacterial Examples

Anthrax* Plague*

Brucellosis* Psittacosis*

Campylobacteriosis* Q fever*

Cat-scratch disease* Relapsing fevers

Leptospirosis* Salmonellosis*Listeriosis* Tularemia*

Lyme disease* Yersiniosis



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Zoonoses: Parasitic Examples

PROTOZOAL HELMINTHIC

Trypanosomiasis Baylisascariasis*

Babesiosis Cysticercosis

Cryptosporidiosis* Hydatidosis

Leishmaniasis Schistosome dermatitis

Giardiasis* Trichinosis*

Toxoplasmosis* Visceral larva migrans

and toxocariasis*



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Zoonoses: Mycotic Examples

Aspergillosis

Blastomycosis

Cryptococcosis*

Dermatophytosis*

HistoplasmosisSporotrichosis



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Zoonoses: Animal Species

Dogs & Cats

Rabies

Roundworm

Ringworm Lyme Disease (dogs only)

Cat Scratch Disease (cats only)

Food Animals Salmonella

E.coli

Brucellosis


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Zoonoses: Animal Species

Birds:

Psittacosis

West Nile

Cryptococcus

Reptiles, Fish, &Amphibians

Salmonella

Mycobacterium Wild Animals

Hantavirus

Plague

Tularemia


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Routes of Transmission

Direct

Droplet or Aerosol

Oral

Contact

Indirect

Foodborne

Water-borne Fomite

Vector-borne

Environmental


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Zoonoses - Life Cycle

ORTHOZOONOSES/DIRECT ZOONOSES

May be perpetuated in nature by a single

vertebrate species

E.g. rabies, brucellosis, anthrax


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Zoonosis: Rabies Life Cycle

Virusinoculation

(bite)

Salivary

gland

excretion


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Zoonoses - Maintenance Cycle

CYCLOZOONOSES

Requires more than one vertebrate

species but no invertebrate host

Most are cestodiases (tapeworm

diseases)

Taenia saginata and T. solium require man to

be one of vertebrate hosts

Others, such as hydatidosis, man is

accidentally involved


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Life Cycle:

www.freelivedoctor.com


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Zoonoses - Life Cycle

METAZOONOSES

Require both vertebrates and invertebrates to

complete transmission

All arboviral infections

West Nile virus, Saint Louis encephalitis

Some bacterial diseases

Plague, many rickettsia Some parasitic diseases

Leishmaniasis, schistosomiasis


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Zoonoses: Metazoonoses

Invertebrate Host: Mosquitoes Vertebrate Host: Birds

Incidental Hosts:

HUMANS, horses, amphibians, other mammals


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Risk Factors

Companion Animal

Dogs & roundworm

Rats & Rat Bite Fever

Occupational

Animal control workers & rabies

Wildlife biologists & hantavirus

Foodborne

Raw meat & E.coli

Unpasteurized dairy & Listeria


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Risk Factors

Recreational Activities

Camping & Lyme disease

Farm Settings Sheep & Q-fever

Cattle & Cryptosporidium

Travel

Malaysia & Nipha

Australia & Hendra


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FOOD-BORNE DISEASES


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Introduction

Causes of food-borne

diseases/illnesses:1. Chemical toxins (residues)2. Biotoxins endotoxins & exotoxins

3. Infectious agents exogenous &endogenous (zoonoses)


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Introduction contd

endotoxins & exotoxins

lipopolysaccharide (LPS) : proteinpart of bacterium : extracellular

no toxoid : toxoidlow potency : high potency

low specificity : high specificity


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Mode of action of some

bacterial toxins

S. aureusA(alpha-toxin)

E. coliB(shiga toxin)

C. botulinumC(exo-enzyme)

33


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Introduction contd

Food hygiene vs food safety

food hygiene microbiological safety offoodfood safety abscence of

chemicals/residues Not necessary to have sterile

food


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Prevention of food-borne diseases Organisms -

characteristics1. where from2. types & strains

3. behaviour in food4. survive or are killed by

measures to inactivate


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Prevention of food-bornediseases, contd

Food characteristics

Water activity (aw), pH andtemperature


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What influences occurrence of

food-borne diseases/illnesses? Food source

Food storage

Food preparation

Food handlers


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What influences occurrence of

food-borne diseases/illnesses?

Time-temperature abuse

Infected food handlers orinadequate hygiene during handlingof food

Consumption/use of unsafe foodsources


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Types of illnesses/diseases

Upper GIT nausea & vomiting

Lower GIT cramps & diarrhoea

Neurological signs

General symptoms


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Upper GIT signs

Nausea, retching, vomiting, abdominal pain,diarrhoea & prostration

S. aureusand its toxins

B. cereusand its toxin


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Lower GIT signsLower abdominal cramps & diarrhoea

Clostridium perfringens, Bacilluscereus

Salmonella, Shigella, ETE. coli,Yersinia enterocolitica,Campylobacter jejuni, Vibrio cholera


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Lower GIT signs, continued

Lower abdominal cramps & diarrhoea

Giardia intestinalis

Cryptosporidium parvum


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Neurological signsVisual disturbances, vertigo, tingling

sensation & paralysis

Clostridium botulinum


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General symptomsFever, chills, malaise, prostration, aches,swollen lymph nodes

S. typhi, L. monocytogenes, C. jejuni Hepatitis A


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Risks of contracting food-borne disease depend on:

Host susceptibilityAge

General health


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Infective dose

Frequently exptrapolated

Feeding studies (healthy, young adultvolunteers)

Estimates (data from outbreaks)

Worst case estimates


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Risk assessment

variable infective doses

Interaction food substrate &environment

pH susceptibility

Type and strain


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Control of food contamination

Micro-organisms in food & water

shellfishfruits & nuts

beanswatermelons

spices & herbsvegetables


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Infection of animals milk,eggs or meat

Contaminated skins and guts

- slaughter & dressing


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Pathogenic Bacteria

1

C. botulinum, C. perfringens - Soil, hide, faecal material

Staphylococcus aureustoxin - Human (nostrils and hands)

Listeria monocytogenes - Soil, hide, faecal material

Campylobacter spp. - GIT(esp. poultry)

E. coliO157:H7 - GIT

Salmonella spp. - GIT / Hide

Yersinia enterocolitica - GIT


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Ideal = growing & harvesting stages

But world is not sterile

Prevent, reduce or limit by:

Not allowing products from clinically illanimals to enter food chain

Classical meat inspection - gross

HACCP - microscopic

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The chain of production from farm to fork of foodfrom animals

Production

Processing

Final preparationand cooking

Farm, Feedlot, Fishing site

Slaughter Plant, Cannery,Packer, Food Factory

Final Kitchen:commercial,institutional or domestic


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The chain of production from farm to fork -

prevention can occur at each step

Production

Processing

Final preparationand cooking

Feed, water, manure treatment,biosecurity, probiotics, vaccines

HACCP, slaughter hygiene,pathogen reduction andelimination (pasteurization,irradiation)

Cooking, preventingcross-contamination,worker education and handwashing


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Prevention of Food Poisoning

WHO ten golden rules Food processed for safety

Thoroughly cook Eat immediately

Store carefully

Reheat thoroughly


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Prevention of Food PoisoningWHO ten golden rules contd

No contact between raw & cooked

Wash hands

Keep food preparation surfaces clean

Protect from pests

Use potable water


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Food-borne disease outbreaks

& food spoilage

Contamination with undesirable

micro-organisms Unacceptable levels of micro-

organisms

Treatment did not result ininactivation


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Food-borne disease outbreaks

& food spoilage

Preventing/limiting contamination Preventing/limiting spread

Preventing growth

Preventing survival of organisms& persistence of metabolites


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Microbiological/chemical hazards

Micro-organisms part of nature

Chemicals many are man-made Micro-organisms change numbers

Uneven distribution in food

Clinical symptoms acute Variable consumer susceptibility

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