Emerging Zoonoses and Species Jumping

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Emerging Zoonoses and Species Jumping Educat
ional Objectives Understand the differences
between Zoonoses and Species Jumping Give
disease examples of each
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Definitions
Zoonoses- transmission of the infectious agent
to humans from an ongoing reservoir life cycle
in animals, without the permanent establishment
of a new life cycle in humans. Species Jumping-
the infectious agent derives from an ancient
reservoir life cycle in animals, but they have
established a new life cycle in humans that no
longer involves the animals.
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Emerging Infectious Diseases- nearly
all are zoonotic or species jumping agents
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Animals Involved in Species Jumping
Arthropods (e.g. ticks and mosquitoes) Wild
animals (e.g. chimps and rodents) Domestic
animals (e.g. dogs and cats) -draught (e.g.
horses) -food (e.g. poultry and cattle)
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Elements that Contribute to the Emergence of a
New Zoonoses
Microbial/viral (e.g. mutations and
evolution) Individual host (e.g. acquired
immunity (vaccination) and lack of immune
surveillance (AIDS) Population host (e.g.
transportation and urban crowding) Environmental
(e.g. ecological and climate influences)
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Increases in Zoonotic Pathogens
Global human and livestock populations continue
to grow -this brings people and animals in
closer contact Advanced transportation makes
long distance travel possible in less than the
incubation period of most infectious
agents Massive ecological and environmental
changes brought about by humans Zoonotic
agents may be the choice for many bioterrorist
activities
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History of West Nile Virus (WNV)
In 1937, WNV first isolated from a febrile woman
in the West Nile Distinct of Uganda Negative
strand RNA virus of the family Flaviviridae Same
serogroup as Japanese encephalitis virus In
1957, WNV outbreak in Israel Early 1960s, WNV
noted in horses in Egypt and France In 1999, WNV
first seen in North America
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West Nile Virus Human Cases in the US

• 1999 -62 cases with 7 deaths in New York only
• 2000 -21 cases with 2 deaths in 3 states
• 2001 -66 cases with 10 deaths in 10 states
• 2002 -4156 cases with 284 deaths in 40 states
• 2003-9862 cases with 264 deaths in 46 states
• 2004 -2539 cases with 100 deaths in 42 states
• 2005 -3000 cases with 119 deaths in 44 states
• 2006 -4269 cases with 177 deaths in 44 states
• 2007 -3630 cases with 124 deaths in 43 states
• 2008 -1356 cases with 44 deaths in 46 states
• 2009 -720 cases with 32 deaths in 38 states
• 2010 -1021 cases with 57 deaths in 41 states
• 2011 -as of 8/30-104 cases with 4 deaths

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U.S. cases of West Nile for 2002
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U.S. cases of West Nile for 2003
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U.S. cases of West Nile for 2004
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U.S. cases of West Nile for 2005
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U.S. cases of West Nile for 2007
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West Nile Virus
-Spread by mosquitoes, which transmit it from
infected birds. mosquito species does make some
difference. -Alligators have WNV titers as high
as birds, thus they can serve as a reservoir
too. -Certain titers need to be reached in
order to infect mosquitoes. Horses and humans
do not have high titers. -300 captive alligators
that died in 2002 in Florida, necropsies showed
the alligators had high viral loads of WNV.
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Finding WNV in NYC First 8 cases
were in a 2 x 2 mile radius in NYC Older
patients that most had been outside a lot Lots
of mosquito breeding places and dead crows
around the area Exotic birds died at the Bronx
zoo Birds had died of encephalitis and had WNV
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West Nile Fever Incubation
is 3-15 days Symptoms fever, headache,
backache, myalgia, Can include nausea,
vomiting diarrhea, rash, muscle weakness,
paralysis.weakness and confusion can go on for
months afterwards Encephalitis usually does not
have muscle weakness and paralysis
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Other WNV
In the US during 2002, 23 cases of WNV were
transmitted through blood donations. Blood in
now screened for WNV 8/8/03 American Red Cross
reported 31 positive blood donations in
Nebraska, the highest number of positive donors
in US 9/12/03 More than 150 Colorado blood
donors tested positive for West Nile virus, thus
more than 35,000 people statewide might be
infected. 116 positive from Nebraska. WNV shows
symptoms in only 20 of the people who contract
it. Fatality rates have dropped from 7 (2002)
to about 3. Equine vaccine- some questions for
pregnant horses, but definitely all
non-pregnant horses should be vaccinated, since
fatality rate is 35.
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Questions about WNV
How did West Nile virus get into this
country? -a mosquito on an airplane? -a bird on
an airplane? Why were there less cases? Are
birds or people getting immune? Why are so many
people subclinical?
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Monkeypox

• -Normally occurs in central and western Africa
• -It is called monkeypox because it was first
  found in 1958 in laboratory monkeys
• -African squirrel are likely the common host, but
  rats, mice, rabbits, (maybe any mammal) can get
  monkeypox
• First reported in humans in 1970
• -It belongs to the orthopoxvirus group of
  viruses. Other orthopoxviruses that cause
  infections in humans include variola (smallpox),
  vaccinia (used for smallpox vaccine), and cowpox
  viruses.

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How was monkeypox introduced into the US?
-A shipment of animals from Ghana that was
imported to Texas on April 9 is the probable
source. -The shipment contained approximately
800 small mammals (9 different species). These
included rope squirrels, tree squirrels, Gambian
giant rats, brush-tailed porcupines, dormice,
and striped mice. -Evidence of infection was
found in some animals. They were separated from
the rest of the shipment on the day of their
arrival, but there was already likely widespread
infection among the remaining animals in the
shipment. -CDC laboratory testing of some
animals by using PCR and virus isolation
demonstrated that at least 1 Gambian giant rat, 3
dormice, and 2 rope squirrels from the April 9
importation were infected with monkeypox
virus. -Gambian rats from this shipment were kept
in close proximity to prairie dogs at an
Illinois animal vendor implicated in the sale of
infected prairie dogs.
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How did people catch monkeypox?
People bought infected prairie dogs at pet stores
and swap meets If they were bitten or if they
touched the animals blood, body fluids, or
rash, they were infected Epidemiology showed
that there was not person to person spreading.
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What are the symptoms of monkeypox?
About 12 days after people are infected, they get
fever, headache, muscle aches, backache, swollen
lymph nodes, and they feel tired. One to 3 days
(or longer) after the fever starts, they get a
rash that develops into raised bumps filled with
fluid. The bumps go through several stages before
they get crusty, scab over, and fall off. The
illness usually lasts for 2 to 4 weeks. There
is no specific treatment for monkeypox. Epidemiol
ogic criteria is exposure to -a new exotic or
wild mammalian pet obtained on or after April
15 2003
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Number of cases reported to the CDC

STATE of cases Illinois 16
Indiana 20 Kansas 1 Missouri 2 Ohio
1 Wisconsin 39 Total 79
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African Trypanosomiasis
Called Sleeping Sickness, vector is the tsetse
fly Classical example of an emerging infection,
1890-1930 Leading public health problem in
Africa during that time, colonialism brought it
to new areas Nearly eliminated by 1960 using
population screening, case treatment,
chemoprophylaxis Re-emerging infection in
central Africa
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Trypanosome Lifecycle
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African Trypanosomiasis, cont.
West African East African Agent T.
brucei gambiense T. brucei rhodesiense Vector r
iverine tsetse fly savanna tsetse
fly Distribution west/central Africa
east/south Africa Reservoir human
antelope/cattle Disease chronic (years) rapid
progression 1-4 weeks Mortality 100
100 At risk rural persons rural, visitors to
game reserves
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Problems Estimating Disease Burden
60 million people at risk, but lt2 million
screened No health facilities in many areas at
risk Conflict or insecurity in epidemic
foci Outbreaks in 2004 reported in DRC, Angola
Clinical diagnosis is difficult until late in
disease -intermittent fever -lymph node
swelling -headaches and sleep disturbance -weigh
t lose (they look like AIDS) -lab diagnosis is
hard (antigenic variation)
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Prevalence of trypanosomiasis
-In 1986, WHO est. that 70 million people lived
in transmission areas. -In 1998, 40,000 cases
were reported, but it was estimated that 300,000
to 500, 000 cases were undiagnosed. -Villages
in the Congo, Angola, and Sudan, prevalence has
reached 50. -By 2005, surveillance had been
reinforced and new cases dropped. 1998-2004
cases fell from 40,000 to 18,000. -The
estimated cases is currently between 50,000 and
70,000.
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Management of Trypanosomias
Disease management in three steps 1) Screening
for potential infection. Serological tests and/or
checking for swollen cervical glands. 2)
Diagnosis shows whether the parasite is
present. 3) Staging to determine the disease
progression. -examination of cerebro-spinal
fluid by lumbar puncture
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Treatments for Trypanosomias
First stage treatments Pentamidine discovered
in 1941, used against T.b. gambiense. Despite a
few undesirable effects, it is well tolerated by
patients. Only drug easily available in the
US. Suramin discovered in 1921, used against
T.b. rhodesiense. Effects in the urinary tract
and allergic reactions. Second stage
treatments Melarsoprol discovered in 1949,
used against both forms. Arsenic derivative with
many side effects. Fatal encephalopathy (3 to
10). 1997 resistance up to 30. Eflornithine
was registered in 1990. Only effective against
T.b. gambiense. Less toxic alternative to
melarsoprol, but the regimen is strict and
difficult to apply.
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Dealing with Zoonoses
Why are they jumping? Can we predict or stop it?
Who will be the worlds doctor? Who will be
the worlds expert on zoonotic diseases? New
strategies need to be developed to deal
specifically with emerging zoonoses These
strategies need to involve more field and lab
research than traditional surveillance