Zoonoses in Life

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A brief overview of zoonotic diseases

• Zoonotic disease- An infection or infectious disease transmissible under natural conditions (not in a laboratory) from vertebrate animals to human beings

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Emerging zoonoses

• Approximately 75% of “emerging” human infectious diseases are zoonotic.

Emerging disease- disease that has appeared in a human population for the first time or has occurred previously, but is increasing in incidence (new cases) or expanding into areas where it had not been reported in the past 20 years

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Examples of Emerging Zoonotic Diseases

•West Nile Virus

•Hantavirus

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West Nile Virus

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West Nile Virus

What is West Nile virus?– West Nile virus is a virus that can make birds,

humans, and horses sick.

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West Nile Virus

• First occurrence in the United States was in 1999– Bronx Zoo, New York…veterinarians see birds (for example,

flamingoes and pheasants) dying – At the same time, humans were getting sick.– Misdiagnosed as Saint Louis Encephalitis (another virus).

• Now– Alaska and Hawaii are the only states where West Nile Virus

has not been detected.– In most states, West Nile Virus detected in all/nearly all

counties.

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West Nile Virus (2009)

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West Nile Virus

• Reservoir:– Wild birds

• Vector:– Mosquito

• Dead end host:– Horses and humans

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West Nile Virus

• Symptoms in humans– Headaches– Fever– Vomiting– Rash– Stiff neck

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West Nile Virus

• Symptoms in horses:– Weakness in the back legs– Inability to stand– Incoordination– Fever

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West Nile Virus

• How do you prevent West Nile virus?

– Reduce exposure to mosquitoes

– Mosquito control

– Vaccination of horses

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West Nile Virus

• How do you prevent West Nile virus?

– Stable horses at night

– Limit outdoor activity during peak mosquito

feeding times

• Dusk and dawn

– Use insect repellants

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West Nile Virus

Question:

How do most people become infected with West Nile virus?

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West Nile Virus

Answer:

By being bitten by an infected mosquito

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Hantavirus

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Hantavirus

• In May 1993, an outbreak of an unexplained pulmonary (lung) illness occurred in the southwestern United States, in an area shared by Arizona, New Mexico, Colorado and Utah known as "The Four Corners"

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Hantavirus

• Virologists at the Centers for Disease Control and Prevention (CDC) were able to link the symptoms with a virus, in particular a previously unknown type of hantavirus

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Hantavirus

Rodents shed the virus in their urine, droppings, and saliva. People get infected if:

• They breathe in air contaminated with the virus

• If a rodent with the virus bites them

• If they touch something that has been contaminated with rodent urine, droppings, or saliva, and then touch their nose or mouth (rare)

• Eat food contaminated by urine, droppings, or saliva from an infected rodent (rare)

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Hantavirus

• Symptoms in people:– Tiredness– Muscle aches– Coughing– Difficulty breathing

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Hantavirus

• Prevention:– Eliminate or minimize contact with rodents in your home,

workplace, or campsite.

– Seal up holes and gaps in your home or garage.

– Place traps in and around your home to decrease rodent infestation.

– Clean up any easy-to-get food.

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Hantavirus (Cases as of January 26, 2010)

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Hantavirus

Question:

What animals can potentially spread hantavirus to people?

a. Dogsb. Catsc. Rodentsd. Cattle

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Hantavirus

Answer:

c. Rodents!

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Zoonoses and bioterrorism

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What is bioterrorism?

• Bioterrorism- the use of living agents, such as man-made or natural disease pathogens, to attack people, animals, and plants

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Anthrax

• Agent: Bacillus anthracis

• Very large gram(+) rods BACTERIA

• Extremely resistant spores develop in the environment. – Spores recovered from 200+ year-old remains in

archeological digs!!

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Anthrax

• Anthrax in animals:– Anthrax in animals most commonly occurs following

ingestion of (eating) the organism, but can also occur by breathing in the organisms or through a wound.

– Herbivores (animals that only eat plants) are the most susceptible to disease, while carnivores (animals that eat primarily meat) are relatively resistant.

– Animals often die if they get anthrax.

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AnthraxHow can people get infected with anthrax?

– Direct contact with infected animals (for example, farmers, abattoir workers, veterinarians)

– Direct Contact with soils that were contaminated by an infected animal

– Occupational exposure with contaminated animal products (for example, those working with sheep and goat hides = "wool sorter's disease")…inhalation

– Ingestion of meat from infected animals

– Bioterrorism

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Anthrax

• Symptoms in people:– Skin lesions (if you become infected by touching

a contaminated item)

– Difficulty breathing (if you become infected by breathing in the organism)

– Vomiting and diarrhea (if you become infected by eating the organism)

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Anthrax

• Prevention:– Vaccinate high risk individuals (for example, laboratory

workers)– Control dust and allow for proper ventilation in industries

dealing with raw animal materials (for example, animal hides)

– Thoroughly wash, disinfect, or sterilize hair, wool and bone meal or other feed of animal origin prior to processing

– Do not sell the hides of animals exposed to anthrax or use their carcasses as food or feed supplements

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Anthrax and bioterrorism

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• In 2001, someone sent the bacteria that causes anthrax to people in the mail.– This is considered bioterrorism

• In contrast, every year both animals and humans become infected with anthrax through natural exposure with the environment.– This is not considered bioterrorism

Anthrax

Question:

Is anthrax caused by a bacteria, virus, or a parasite?

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Anthrax

Answer:

A bacteria

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Foodborne zoonoses

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Salmonella

• Salmonella are bacteria

• In 1885, American veterinarian, Daniel E. Salmon, discovered the first strain of Salmonella from the intestine of a pig.

• Salmonella live in the intestines of humans and animals.

• Salmonella can survive for long periods in the environment. (especially if it is wet and warm)

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Salmonella

• Some Salmonella tend to infect certain animals.– Salmonella Pullorum- poultry

– Salmonella Gallinarum- poultry

– Salmonella Choleraesuis- pigs

– Salmonella Dublin- cattle

– Salmonella Typhi- humans (no animal carriers)

• Others have a comparatively wide host range (infect many different animals)– Salmonella Typhimurium

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Salmonella

• Salmonella spp. have been found in all species of mammals, birds, reptiles and amphibians that have been investigated

– Salmonella spp. are shed in the feces of both symptomatic (appear sick) and asymptomatic (don’t appear sick) animals

– Reptiles should always be considered a potential source of Salmonella• It has been illegal to sell turtles less than 4 inches in diameter since

1975 due to the risk of salmonellosis!!

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How can people get Salmonella?

• Eating raw/undercooked meat and eggs

• Eating unpasteurized milk products

• Cross-contamination– For example, using the same cutting board to cut

vegetables after cutting raw meat.

• Putting unwashed hands in your mouth after touching a person or animal shedding Salmonella.

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What are the symptoms of Salmonella infection?

• Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 1 to 3 days after infection.

• The illness usually lasts 4 to 7 days, and most persons recover without treatment. – May require treatment with antibiotics.

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Preventing salmonellosis

• You should not eat raw or undercooked eggs, poultry, or meat

• You should not consume raw or unpasteurized milk or other dairy products

• Cross-contamination of foods should be avoided– For example, always wash your cutting board after using it to cut

raw meat

• Wash your hands before and after preparing food and eating and after coming into contact with animals (including reptiles)

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Salmonella

Question:

True or false. You can get infected with Salmonella by eating undercooked meat.

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Salmonella

Answer:

True. Eating undercooked meat can increase your risk of Salmonella and other foodborne bacterial infection.

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Zoonoses and pets

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Intestinal parasites of dogs and cats

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Hookworms- commonly found in the intestines of dogs and cats

Roundworms- commonly found in the intestines of dogs and cats

Intestinal parasites of dogs and cats

• How are these parasites transmitted to people?– People have direct contact with soil or sand contaminated

by the feces of dogs and cats infected with hookworms.

– People ingest infective eggs of roundworms in contaminated soil.

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How to prevent intestinal parasites of dogs and cats

• Take your dog or cat to the veterinarian regularly so that they can receive deworming medication.

– Puppies may she parasite eggs into the environment at less than one month of age.

– A single female roundworm can produce more than 100,000 eggs/day!!!!

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How to prevent intestinal parasites of dogs and cats

• Immediately collect and dispose of pet feces in order to prevent the eggs from becoming infective.

– Roundworm eggs infect a person within 2-4 weeks and can remain in the environment for years.

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How to prevent infection in people

• Wash hands after touching or playing with pets (or after exposure to potentially contaminated sites).

• Don’t eat sand or dirt!

• Regularly clean play areas and keep outdoor play areas (such as sandboxes) covered or fenced off.

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Intestinal parasites of dogs and cats

Question:

Which of the following is/are ways to prevent becoming infected by an intestinal parasite of dogs or cats?

a. Wash your hands after playing with your pet.b. Take you pet to the veterinarian for regular deworming.c. Clean up dog feces and scoop a cat’s litter box regularly.d. All of the above

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Intestinal parasites of dogs and cats

Answer:

d. All of the above.

Deworming will help keep your pet free of intestinal parasites while hand washing and cleaning up after you pet will prevent the spread of any parasites that an animal may still have.

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Rabies

• Rabies is a virus that can affect all mammals, including humans. – Racoons, skunks, foxes, coyotes, and bats are the

most common reservoirs for the virus.

• Infection results in damage to the nervous system and death.

• The virus is transmitted through the bite of an infected animal (direct transmission).

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Rabies

• Infectious materials include:

• Saliva• Central nervous system tissue• Cerebrospinal fluid

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Rabies

• Rabies: Non-infectious Materials

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Urine or feces Blood Skunk spray

Rabies

• Rabies is not transmitted through:

– general contact, or

– infectious material touching intact skin, or

– through inanimate objects, such as food and water bowls.

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How can you prevent yourself and your pets from being infected with rabies?

• Make sure your dog or cat is vaccinated against rabies.

• Stay away from wild animals (for example, raccoons and foxes).

• Don’t approach a dog or cat that you don’t know.

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Rabies

• Question:

Which of the following animals can be infected by the rabies virus?

DogsCatsBatsBirdsRaccoonsLizards

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Rabies

• Answer:

Which of the following animals can be infected by the rabies virus?

DogsCatsBatsBirdsRaccoonsLizards

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