Transcript West Nile Virus

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.
b.
c.
d.
Dogs
Cats
Rodents
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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Anthrax
How 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
• 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
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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
Hookworms- commonly found in
the intestines of dogs and cats
Roundworms- commonly found
in the intestines of dogs and cats
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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.
b.
c.
d.
Wash your hands after playing with your pet.
Take you pet to the veterinarian for regular deworming.
Clean up dog feces and scoop a cat’s litter box regularly.
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
Urine or feces
Blood
Skunk spray
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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?
Dogs
Cats
Bats
Birds
Raccoons
Lizards
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Rabies
• Answer:
Which of the following animals can be infected by
the rabies virus?
Dogs
Cats
Bats
Birds
Raccoons
Lizards
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