Zoonoses

Epidemiology of diseases transmitted from animals to

humans

What are zoonoses?

Diseases that are transmitted from animals to humans

Bacillus anthracis Brucellosis Crimean-Congo hemorrhagic fever Rabies Hanta Virus Toxoplasmosis Campylobacter

What kind of animals transmit zoonoses?

Farm Animals

Cattle Swine Goats Cats & dogs Poultry

Wild Animals

Ticks Squirrels Raccoons Mice/rodents others

Farmers more susceptible to contracting zoonoses

1. More likely to share air and space with animals

2. More contact with domestic and wild animals

How are disease transmitted?

Every day contact with animals Transporting By-products (feces/urine) Scratches or bites From milk and milking Contaminated soils Contaminated meats

Common Zoonoses

Campylobacter

Common CarriersCattle

Sheep

Pigs

Dogs

Rodents

Poultry

Campylobacter

Transmission

Contaminated food or animals

Clinical presentation

Stomach ache Nausea Headache Diarrhea

Cat-Scratch Disease

Common carriers

Cats

Dogs

Cat-Scratch DiseaseBartonella henselae

Transmission

Scratches and puncture wounds from infected animals

Clinical presentation

Fever Skin papule Swollen lymph nodes

Salmonella

Common carriers

Cattle

Cats

Dogs

Horses

Poultry

Salmonella

TransmissionDirect contact with

animal or feces

Contaminated food

Clinical Presentation Chills Fever Headache Diarrhea Vomiting

Encephalitis

Common carriers

Horses

Rodents

Encephalitis

Transmission

Mosquito bites Tick bites

Clinical presentation

Lethargy Fever Headache Disorientation

Rabies

Common Carriers

CatsDogs

RaccoonsSkunks

BatsFoxes

Rabies

Transmission

Animal Bite

Contact with infected tissue, fluids or feces

Clinical presentation Fever Headache Agitation Confusion Seizures Excessive salivation

Toxoplasmosis

Common carriers

Cats

Sheep

Toxoplasmosis

Transmission

Ingestion of infected meats

Fecal contaminated soil

Clinical Presentation

Fever Swollen nodes Abortion Still-birth Mental retardation

Scabies

Common Carriers

Dogs

Raccoons

Scabies

Transmission

Direct contact with infected animals

Clinical presentation

Itching skin lesions

Prevention and Control

Assure an uncontaminated water supply

Add chlorination to water Connect to water supply Appropriate disposal of wastes

Prevent food contamination

1. Avoid unpasturized milk2. Wash hands3. Disinfect kitchen surfaces4. Wash raw fruits and vegetables5. Don’t defrost meats on the counter6. Use separate utensils for raw/cooked meat

Always drink pasteurized milk!

Protect pets from getting & transmitting diseases

Vaccinate cats and dogs against rabies Do not keep wild animals as pets Do not allow pets to drink from toilet Clean pet’s living area 1x/week Clean litter box daily

Pregnant women should not clean litter

boxes

Prevent tick bites

Wear repellent Wear appropriate clothing

Long-sleeved shirt Tuck pant legs into socks

Check yourself and pets after being in a tick-infested area

Treat animal scratches and bites seriously

Wash area with soap and water Apply anti-bacterial medication Bandage wound Consider medical attention

Most Zoonoses are preventable if cautionary

measures are taken!!

Food-borne and Water-borne Diseases

Epidemiology of diseases spread by food and water

Definition

Food-borne illness – two or more cases of a similar illness resulting from the ingestion of a common food

Water-borne illness – an illness that occurs after consumption or use of water intended for drinking or as illness associated with recreational water such as swimming pools, whirlpools, hot tubs, spas, water parks, and naturally occurring fresh and marine surface waters

Epidemiology - Food-borne

In the U.S. per year

76 million illness

325,000 hospitalizations

5000 deaths - most unknown pathogens Three known pathogens cause 1500 deaths

Salmonella

Listeria

Toxoplasma

Epidemiology - Food-borne

Cholera only bacterial food-borne illness that must be reported internationally

Hepatitis A only viral food-borne illness that is reported

Globally only 1-10% of food-borne illness incidences are reported.

Epidemiology - Food-borne

List of most common bacterial food-borne illness, listed in order of occurrence

1) Campylobacter

2) Salmonella

3) Shigella

4) E. Coli

Epidemiology - Food-borne List of most common viral food-borne illness

1) Norwalk virus

2) Astroviruses

3) Rotaviruses

4) Enteric adenoviruses 23,000,000 incidences per year in the U.S Spread person to person via fecal-oral route Infectious at low doses; foods act as transfer

media only

Diagnosis

Important to the history is the exact time of exposure which can help narrow down the causative agent

History

History of two or more people within a household becoming ill at the same time more likely food-borne vs. two people becoming ill within 24-36h.

History

Identify food handling practices

a) length of preparation before

consumption

b) cooking time and reheating

c) possible cross contamination

d) people with poor hygiene

History

Identify activities that increase risk of exposure

restaurants

day care centers

street-vended food or raw seafood

overseas travel

camping-ingestion of lake/stream water Check to see if patient is on antibiotics or

medications that reduce gastric acidity

Physical Examination

Determine hydration statusPresence of blood in the stoolExclude other diarrheal illness

Diagnostic Tests

Blood cultures – suspect bateremia Gram stain - identifies campylobacter with

66-99% sensitivity Fecal leukocytes - if positive = higher culture

yield Ova and parasites - done in the ER

Diagnostic Tests

Stool cultures only if pt

1) febrile

2) bloody diarrhea

3) severe abdominal pain

4) clinically severe or persistent

5) significant historical risk factors for

food-borne illness

Bacillus anthracis

Incubation period – 2d-weeks Signs and symptoms – nausea, vomiting,

bloody diarrhea, abdominal pain Duration – weeks Food Source – contaminated meat Lab testing – blood

Bacillus cereus

Enterotoxin Incubation period – 1-6h Signs and symptoms – sudden fever, nausea,

vomiting, may have diarrhea Duration – 24h Food Source – rice, meat Lab testing – none Treatment – supportive only

Brucella spp.

Incubation period – 7-21d Signs and symptoms – fever, chills, headache,

myalgias, arthralgias, bloody diarrhea Duration – weeks Food Source – raw milk, goat cheese, meats Lab testing – blood, serology

Clostridium botulinum

Adults, children Incubation period – 12-72h Signs and symptoms – vomiting, diarrhea, diplopia,

dysphagia, descending muscle weakness Duration – variable, can end in death Food Source – improperly canned foods, fermented fish,

garlic, herb-infused oils, baked potato in foil, foods kept in a warm oven for hours

Lab testing – stool, serum, and food assayed for toxin at CDC or state labs

Treatment – botulinum antitoxin

Clostridium botulinum

Infants Incubation period – 3-30d Signs and symptoms – lethargy, poor feeding,

hypotonia Duration – variable Food Source – honey, home-canned foods Lab testing – stool, serum, and food assayed for

toxin at CDC or state lab Treatment – botulinum immune globulin

Campylobacter

Incubation period – 2-5d Signs and symptoms – bloody or watery diarrhea,

cramps, fever Duration – 2-10d Food Source – Poultry, milk, water Lab testing – special stool culture

Clostridium perfringens

Incubation period – 8-16h Signs and symptoms – watery diarrhea, nausea,

cramps Duration – 24-48h Food Source – meat, poultry, gravy, dried or

precooked foods Lab testing – quantitative culture of stool Treatment – supportive only

Enterohemorrhagic E. coli

Incubation period – 1-8d Signs and symptoms – bloody diarrhea, abdominal

pain, vomiting Duration – 5-10d Food Source – undercooked meat, unpasteurized

dairy products, milk, raw fruit and vegetables, salami, contaminated water, salad dressing, yogurt, acidic foods

Lab testing – specific stool culture Treatment – supportive only

Enterotoxigenic E. coli (traveler’s diarrhea)

Incubation period – 1-3d Signs and symptoms – watery diarrhea, vomiting,

cramps Duration – 3-10d Food Source – fecal contamination of food Lab testing – specific stool culture

Salmonella spp.

Incubation period – 1-3d Signs and symptoms – diarrhea, fever, cramps, vomiting, s.

typhi and paratyphi cause chills, myalgia, headache, with rare diarrhea

Duration – 4-7d Food Source – eggs, poultry, unpasteurized milk or juice, raw

fruits and vegetables, street venders, fecal water contamination Lab testing – stool cultures Necessitates typhoid immunization for travelers

Shigella spp.

Incubation period – 24-48h Signs and symptoms – bloody diarrhea, fever,

cramps Duration – 4-7d Food Source – fecal food or water contamination,

person-person spread by fecal-oral contamination

Lab testing – stool cultures

S. Aureus

Incubation period – 1-6h Signs and symptoms – sudden severe nausea,

vomiting, diarrhea Duration – 24-48h Food Source – unrefrigerated meats, potato

and egg salad, cream pastries Lab testing – none Treatment – supportive only

Vibrio cholerae

Incubation period – 24-72h Signs and symptoms – severe watery diarrhea

and vomiting Duration – 3-7d death from dehydration Food Source – contaminated water, fish, shellfish,

street vendors Lab testing – specific stool cultures

Yersinia spp.

Incubation period – 24-48h Signs and symptoms – mimics appendicitis, can

have a rash Duration – 1-3 weeks Food Source – undercooked pork, unpasteurized

milk, contaminated water Lab testing – specific stool or blood cultures

Epidemiology of diseases spread by arthropod vectors

Vector-borne Disease Mortality Distribution

WHO, 2005

Majority of Vector-borne Disease (VBD) burden borne by developing countries

High amount in Africa

Vector-borne Disease What is VBD? Types of VBD transmission:

Human-vector-human

(Anthroponotic Infections)

Vector

Humans

Humans

Vector

MalariaDengueYellow fever

Animal-vector-human

(Zoonotic Infections)

Vector Vector

Animals

AnimalsHumans Lyme disease

Hantaviral diseaseMost arboviral diseases (e.g., WNV)

Vector-borne Diseases of Concern

Disease Pathogen Vector Transmission

Protozoan

Malaria Plasmodium falciparum, vivax, ovale, malariae

Anopheles spp. Mosquitoes Anthroponotic

Leishmaniasis * Leishmania spp. Lutzomyia & Phlebotomus spp. Sandflies

Zoonotic

Trypanosomiasis * Trypanosoma brucei gambiense, rhodesiense

Glossina spp. (tsetse fly)

Zoonotic

Chagas disease * Trypanosoma cruzi Triatomine spp. Zoonotic

* WHO neglected tropical disease Hill et al., 2005

Vector-borne Diseases of Concern (cont.)

Disease Pathogen Vector Transmission

Viral

Dengue * DEN-1,2,3,4 flaviviruses Aedes aegypti mosquito Anthroponotic

Yellow fever Yellow fever flavivirus Aedes aegypti mosquito Anthroponotic

Encephalitis(West Nile, Lyme, etc.)

Flavi-,alpha- and bunyaviruses

Mosquitoes and ticks Zoonotic

Firlarial nematodes

Lymphatic filariasis * Brugia malayi, timori, Wuchereria bancrofti

Anopheles, Culex, Aedes mosquitoes

Anthroponotic

Onchocerciasis * Onchocerca volvulus Simulium spp. blackflies Anthroponotic

* WHO neglected tropical disease Hill et al., 2005

Vector-borne Disease Dynamics

Susceptible population

• Migration (forced)

•Vector environment

Vector•Survival, lifespan

•Reproduction/breeding patterns

•Biting behavior

Pathogen

•Survival

•Transmission

•Replication in host

Pathophysiologic pathways

Individual/population

Health

Genetic/constitutional

factors

Individual riskfactors

Social relationships

Living conditionsLivelihoods

Institutions (including medical

care)

Social and economic

policies

Environmental Determinants of Human Disease

Pathophysiologic pathways

Individual/populationHealth

Genetic/constitutional

factors

Individual riskfactors

Social relationships

Living conditionsLivelihoods

Institutions (including medical

care)

Social and economic

policies

Climate?

Environmental Determinants of Human Disease (cont.)

Case Study I: Malaria

40% world population at risk 500 million severely ill Climate sensitive disease1

No transmission where mosquitoes cannot survive

Anopheles: optimal adult development 28-32ºC

P falciparum transmission: 16-33ºC

Highland malaria2

Areas on the edges of endemic regions

Global warming El Niño3

Outbreaks

Estimated incidence of clinical malaria episodes (WHO)

1 Khasnis and Nettleman 2005; 2 Patz and Olson 2006; 3 Haines and Patz, 2004

McDonald et al., 1957

Case Study I: Malaria (cont.)

WHO, 2008b

Malaria Transmission Map

Case Study 2: Lyme Disease

Stafford, 2007

Transmission Cycle of Lyme Disease

Case Study 3: Dengue

Whitehead et al., 2007

Transmission Cycle of Dengue

T. b. gambienseT. b. gambiense

T. b. rhodesiense

T. b. rhodesiense

Case Study 4: African Trypanosomiasis

Trypanosomiasis Trypanosomosis, spread

by tsetse flies, imposes a huge burden on African people and livestock

Many aspects of the vectors’ life cycles are sensitive to climate, and spatial distributions can be predicted using satellite-derived proxies for climate variables

Source: David Rogers, Oxford

Case Study 4: African Trypanosomiasis (cont.)

IMMUNIZATION

active passive

Active immunization

Inactivated virus Live attenuated virus Bacterial protein or polysaccharides

These immunogens are carried out BEFORE exposure to a disease

Passive immunization

Pooled immune globulins that contain specified amounts of antibody used for individuals who have recently been or may soon be exposed to a disease

Differences

Passive immunization can never have a life-long protective effect.

Active immunization towards most of the diseases have a life-long protective effect.

(5-20 years)

Differences

Passive immunization: protective effect starts immediately

Active immunization: protective effect starts a few weeks later

Differences

In passive immunization there is a greater possibility for the hypersensitity reactions to occur than there is in active immunization

Therefore epinephrine, corticosteroids, antihistaminics must be at hand.

Post-infection immunity

Immunity towards certain diseases can also be achieved by acquiring the disease

Measles, Hep.A have life-long post-infection immunity

Herd immunity

Used for the immunity of the whole population.

At least 70% of the population must be immune.

Variables of herd immunity

characteristics of organism ıts mode of transmission period of infectivity ıncubation time size of the population duration of artificial or post-infection

immunity

Active immunizing agents

Tetanus bacterial toxoid i.m. Diphteria bacterial toxoid i.m. Rubella live attenuated virus s.c. Measles live attenuated virus s.c. Mumps live attenuated virus s.c.

Active immunizing agents

Poliomyelitis inactivated virus oral or i.m. Rabies HDCV i.m. Hepatitis B recombinant DNA i.m.

Passive immunizing agents(Human immunoglobulin)

Tetanus management of wounds Rabies post exposure prophylaxis of animal

bites Measles prevention or modification of

disease before likely exposure or after contact (not used in the control of epidemics)

Passive immunizing agents(Human immunoglobulin

Hepatitis A modification of disease of househod contacts (not used in the control of epidemics)

Antivenin for snake, spider, or scorpion bite.

Tetanus prophylaxis in wound management

For clean wounds tetanus toxoid (active immunization) is indicated unless the patient has received two or more doses of toxoid within five years

For unclean or deep wounds in addition to toxoid 250 units of TIG (passive immunization)should be administered at separate sites

Rabies

Postexposure prophylaxis always includes both passive and active immunization except for persons who have previously been actively been immunized

RIG (20iu/kg) i.m. And around the bite HDCV (Human Diploid Cell Vaccine) on

days 1,3,7,14 and 28

COLD CHAIN IN VACCINATION

Vaccines should be at certain temperatures at the Ministry of Health, Health Directorate of the Province, Health Institutions and the Mobile Health team

Vaccines should be transported at certain temperatures

Vaccines should never be kept above 80 C even at the mobile team

CONDITIONS FOR KEEPING VACCINES AT A REFRIGERATOR AT PRIMARY HEALTH ARE LEVEL :

one health personnel should be the responsible person for this refrigerator

nothing but only vaccines and related water should be kept in this refrigerator

there should be a thermometer inside the refrigerator the responsible person must check the temperature 2

times a day and mark it on a chart sticked to the door of the refrigerator

no vaccine shouldbe kept inside the door of the refrigerator

space should be kept in between the vaccines for cold air circulation

a virus vaccine should not touch a piece of ice refrigerator should be kept at a distance of at

least 20 cm from the wall refrigerator should be placed away from the

sunlight