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Zoonoses and Veterinary Public Health
DVM, PHD, OKAMOTO Karoku
Prof. Veterinary Public Health, Dep. Veterinary Medicine,
Fac. Agriculture, Kagoshima University
Approximately 75% of recently emerging infectious
diseases affecting humans are diseases of animal
origin; approximately 60% of all human pathogens
are zoonotic.
Quoted from CDC, USA
Examples of emerging infectious disease
(Pathogen, Year, Natural reservoir)
BSE
1986/1993
Cow
SARS
2003
palm civet et.al
HPAI H5N1
1997/2003
Water bird
HPS
1993
Rodentia
HPS: Hantavirus Pulmonary Syndrome
SARS: Severe Acute Respiratory Syndrome
West Nile
1999
Bird/Mosquito
Ebola
1976
Monkey
H1N1 Pandemic
2009
Swine/Bird
Lassa
1969
Rodentia
Nipah virus
1998
Megabat/Swine
E. Coli O157
1982
Cow/Food
Hendra virus
1994
Megabat/Horse
VzHF
1991
Rodentia
BzHF
1994
Rodentia
Venezuelan & Brazilian
Hemorrhagic Fever
International Health Regulations(2005): IHR 2005
Annex 2 Decision instrument for the assessment and notification of events
Event detected by national surveillance system
National IHR Focal Point
Small pox
● Poliomyelitis(wild type)
●
Influenza(new subtype)
● Severe acute respiratory syndrome (SARS)
●
Each State Party shall notify WHO
within 24 hours of assessment.
●
Cholera
Plague
● Yellow fever
●
Viral haemorrhagic fevers(Ebola, Lassa,
Marburg)
●
●
West Nile fever
●
Others(Dengue fever, Rift Valley fever)
DOES THE EVENT MEET AT LEAST TWO OF THE FOLLOWING
CRITERIA?
I. Is the public health impact of the event serious?
II. Is the event unusual or unexpected?
III. Is there a significant risk of international spread?
IV. Is there a significant risk of international travel or trade restrictions?
Diseases in the red are zoonoses.
Event shall be notified to WHO under the International Health Regulations
Many of zoonoses have the potential to spread through
various means over long distances and to become global
problems.
Calvin W. Schwabe(1927 – 2006)
Veterinary Epidemiology, UC Davis
Classification of Zoonoses
Dr. Schwabe provided the following classification system of
zoonoses based on the type of life cycle of the pathogen.
Direct zoonoses are transmitted from an infected vertebrate host
to another host by direct contact, fomite or mechanical vector. The
pathogen does not undergo developmental change or propagation
during the transmission.
Cyclozoonosis requires more than one vertebrate host but no
invertebrate host is needed. An example is echinococcosis.
Metazoonoses does require an invertebrate host where the
pathogen multiples or develops before it can infect a vertebrate host.
Saprozoonoses are diseases transferred through a non-animal
reservoir, such as a plant, or through the abiotic environment, such as
through water or soil.
Direct zoonoses
an vertebrate host
Avian influenza, Rabies, Hantavirus,
Psittacosis, Bovine tuberculosis,
Brucellosis, E. coli O157, Anthrax
Cyclozoonosis
more than one vertebrate host
Echinococcosis, Cｙｓｔｉｃｅｒｃｏｓｉｓ,
Toxoplasmosis, Tｒｉｃｈｉｎｉａｓｉｓ
Saprozoonoses
Metazoonoses
an invertebrate host
West Nile fever, Yｅｌｌｏｗ ｆｅｖｅｒ, Ｒｉｆｔ
Ｖａｌｌｅｙ ｆｅｖｅｒ, Plague, Aｎｉｓａｋｉａｓｉｓ
non-animal reservoir
Tetanus, Bｏｔｕｌｉｓｍ, Aｓｐｅｒｇｉｌｌｏｓｉｓ,
Hｉｓｔｏｐｌａｓｍｏｓｉｓ, Tｏｘｏｃａｒｉａｓｉｓ,
Fascioliasis, Anthrax
The World Health Organization Expert Committee on
Zoonoses came up with the classification system of
zoonoses provided by Dr. Schwabe.
Calvin Schwabe One Health Project
A CENTER OF EXCELLENCE AT THE INTERSECTION OF HUMAN,
ANIMAL, AND ENVIRONMENTAL HEALTH
Our Mission
To strengthen the UC Davis School of Veterinary Medicine's
commitment to the One World-One Health movement by educating
veterinarians of the future to integrate human, animal, and ecosystem
protection into their professional lives.
The Calvin Schwabe One Health Project fosters a diverse and
sustainable planet, with the goal of encouraging a new generation of
veterinary expertise in the integration of better health for humans,
animals, and their environment. To that end, One Health expands career
pathways for veterinary students in disciplines such as public practice,
wildlife and ecosystem health, food safety, herd health, disaster
preparedness, rural health, and zoonotic disease threats.
Metazoonoses
West Nile fever
Life cycle of West Nile virus (WNV)
１．WNV is spread by the bite of an infected mosquito (vector).
２．Mosquitoes become infected when they feed on infected birds(Reservoir).
３．WNV can cause most clinical cases in humans and horses that does generally
not allow transmission to others(Dead-end host).
Dead-end host
Vector
Mosquito
Bird
Human
Equine
Reservoir host
Other animals
Many of zoonoses have the potential to spread
through various means over long distances and to
become global problems.
West Nile fever suddenly occurred in the New York in 1999 .
A mosquito traveled by air?
★
Endemic area of Japanese encephalitis and West Nile fever
WNV Positive ratio
of dead birds
WNV Positive mosquito
Human case
Newark Liberty
International Airport
Kennedy International Airport
A mosquito arrived at this terminal.
Spread of West Nile virus in New York City in 1999
No. of patients
10000
8000
WNV amplification
between birds and
mosquitoes took three
years.
6000
4000
2000
62
0
21
66
fatality rate(%)
Initial high fatality rate may
20
due to the following reasons.
1. Diagnostic and treatment 18
system were not prepared.
16
2. The number of patients in 14
mild was increased with the
12
progression of surveillance.
10
3. Acquisition of immunity.
8
6
4
2
0
Progression of West Nile fever in USA(1)
No. of death
300
Why the number of death in 2002 was more than in
2003 when the number of patients peaked.
No. of State
affected
60
250
50
200
40
150
30
100
20
50
WNF occurred in almost all
Sates in 2002, and many
people acquired immunity.
0
10
0
Progression of West Nile fever in USA(2)
Small pox
Smallpox is an infectious disease unique
to humans(not zoonosis), caused by
Variola virus. The fatality rate for flat-type is
90% or greater and nearly 100% is observed in
cases of hemorrhagic smallpox.
Smallpox is believed to have emerged in
human populations about 10,000 BC. In the
early 1950s an estimated 50 million cases of
smallpox occurred in the world each year.
To eradicate smallpox, each outbreak had to
be stopped from spreading, by isolation of
cases and vaccination of everyone who lived
close by. This process is known as "ring
vaccination".
The global program on smallpox eradication
initiated by WHO in 1958 and intensified since
1967. The global eradication of smallpox
Hemorrhagic-type
smallpox.
was certified by a commission of
eminent scientists on December 1979.
Virus families not assigned to an order(65 Families)
Family: Poxviridae
Orthopoxvirus is a genus
Subfamily: Chordopoxvirinae of poxviruses that includes
Genus: Orthopoxvirus
many species isolated from
Camelpox virus
mammals. Although Variola
Cowpox virus
virus infects only human,
Ectromelia virus
some Orthopoxviruses have
Monkeypox virus
the ability to infect non-host
Raccoonpox virus
species, such as monkeypox
Taterapox virus
virus.
Vaccinia virus
I now offer a few topics
Variola virus
related with small pox
Volepox virus
eradication.
Genus: Parapoxvirus
Bovine papular stomatitis virus
Orf virus
Parapoxvirus of red deer in New Zealand
Pseudocowpox virus
Monkeypox was first found in
1958 in laboratory monkeys.
African squirrels might be the
common host for the disease.
Rats, mice, and rabbits can get
monkeypox, too.
Direct zoonoses
Monkeypox
Seven years old girl
in Republic of Zaire
Human
monkeypox
Six months later,
she healed but
many pockmark
remained.
Monkeypox is an exotic
infectious disease caused by
the monkeypox virus, and is
usually transmitted to
humans from rodents, pets,
and primates through contact
with the animal's blood or
through a bite.
Human monkey pox can be
difficult to distinguish
clinically from smallpox.
Case-fatality ratios in Africa
have ranged from 1% to 10%.
It is assumed that
vaccination against smallpox
would provide protection
against human monkeypox
infection. Since the
eradication of smallpox in
1979, human case increase
gradually.
Endemic Human Monkeypox, Democratic Republic of Congo,
2001–2004
Emerg Infect Dis. 2007
Among 136 patients, 51 (37.5%) had
laboratory-confirmed MPX infection, 61
(44.8%) had laboratory-confirmed
chickenpox virus infection, and 1
(0.7%) had coinfection.
Age and sex distribution of
patients with monkeypox
Age
male
female
<4
5–14
15–24
25–34
>35
8/12
12/22
5/17
2/9
1/6
7/21
9/19
8/13
0/8
1/7
Total
28/66
24/68
Monkeypox positive/No.
cases investigated
Distribution of 52 confirmed cases of
human monkeypox.
762 rodents
Movement of imported African rodents to pet shops and
distribution of prairie dogs from a pet shop associated with
human cases of monkeypox, in 2003 USA.
MMWR 2003
Rodents and
prairie dogs
contacted with
each other.
African rodents were resell
to Japan, but 15 already
dead before arrival and
lived two rodents was not
infected.
All 35 human cases of
monkeypox were
associated with prairie
dogs.
Cowpox and Pseudocowpox virus
Milker's nodules
In 1796, Dr Edward Jenner used “cowpox
virus” to inoculate a patient to prevent
them from contracting smallpox. Discovery
of virus is in 1892(tobacco mosaic disease),
so it is not as clear what virus he used for
vaccine 100 years ago. In fact, milker's
What is cowpox?
nodule is usally caused by a parapox
virus(Pseudocowpox), not by cowpox virus.
Nowadays, cowpox is a rare disease. It
mostly occurs in Great Britain and some
European countries. Cows are no longer the
main carrier of the virus; instead woodland
rodents are the natural hosts of the virus
who then pass it on to domestic cats. Feline cowpox virus infection
Cowpox Virus Transmission from Pet Rats to Humans
Germany: Outbreak including 5 patients caused by
infected pet rats from the same litter in 2009.
Human cowpox infections seem to be increasing.
One obvious reason for an increase might be the
fading cross-protective immunity to cowpox after
the cessation of small pox vaccination.
Human cowpox is a disease of young people,
with half of all cases occurring in individuals
younger than 18 years, because of their not having
been vaccinated for smallpox, which may confer
some protection against cowpox.
16 years old boy
VARV: Variola virus
CPXV: cowpox virus
VACV: vaccinia virus
Brazilian Vaccinia Viruses and Their Origins
VACV species imported to Brazil in
1804, when human vaccine arrived at a
port on the arms of slaves returning from
Portugal. The species was maintained in
this manner(arm to arm) and in 1887 the
first animal vaccine was produced in
calves. In 1963, Brazilian VACVs(Group 1,
2) was isolated from the blood of a rice
rat captured near the edge of Amazon
rain forest. Since then, those virus were
naturally isolated from a wild rodent. In
1999, exanthematous outbreaks
affecting dairy cattle and their handlers
were reported.
Brazilian VACVs existed before the
beginning of the WHO smallpox
eradication vaccination campaigns.
Original animal vaccine strein imported in 1887
The virus that Dr. Edward Jenner used for
vaccination derived from milker's nodule in
1796 may be Brazilian VACVs.
Voyages of Christopher Columbus(1492-1504)
Cyclozoonosis
Skunk, liver. The inner
surface of the cyst is lined by
hydatid sand, and the cyst is
surrounded by a thick
capsule of fibrous connective
tissue
Iowa Sate Univ.: CFSPH
Echinococcosis
(Hydatid Disease)
Human, liver. Multiple thinwalled hydatid cysts project
from the capsular surface of
the liver.
WHO: Echinococcosis
Echinococcus granulosus
Oral intake
Humans are
accidental
intermediate
hosts and are
not able to
transmit the
disease. There
are areas of
high endemicity
in southern
South America,
Mediterranean
coast, southern
part of Russia,
Middle East,
south-western
Asia, northern
Africa, Australia,
Kenya, New
Zealand and
Uganda.
Relate to wool
industry
Echinococcus multilocularis
Definitive Host
Fox
Dog
Cat
ingesting eggs
shed in the
feces
predatism
Intermediate Host
Rodent
E. multilocularis is found primarily
in the northern hemisphere. It is
widely distributed in continental
Europe, and also occurs in much
of northern and central Eurasia
eastward to Japan (where it is
found only on the island of
Hokkaido), and in North America,
where it primarily occurs in
Canada, Alaska and the north
central U.S. from Montana to
central Ohio.
CFSPH: Echinococcosis
Rebun island
For the production of fur, red foxes were
imported in Rebun island in 1924. First patient
with hydatid cyst was detected in 1937, after a
in 1965
lapse of 2 years reaching 129 patients.
Hokkaido authorities gave instructions to
destroy all foxes and stray dogs.
Although the outbreak resolved, a hydatid
patient was detected in east area of Hokkaido
in 1965, and infection of Ezo red foxes were
confirmed diffusely. Since then, about 10
patients each year continues to suffer the
disease. Several monkeys, gorillas and orangutans died by hydatid
desease in 2 zoological gardens in 1992 and 1994. By this circumstance,
the Zoo were forced to shut. Since 1999, anthelmintic pellet including
Praziquantel(Biltricide: effective against flatworms) were put in place
widely where foxes are ranging.
Before After
キツネの駆虫に関するガイドライン
参考資料
1989-98 2000-05
199
Nuber of points captured
Nuber of foxes captured 5,157
313
Nuber of positive foxes
Positive rate(%)
6.1
148
3,840
18
0.5
80
70
No. of foxes captured: 25,358
No. of hydatid foxes:
5,174
Positive rate: 20.4%
No. of stray dogs : 9,945
No. of hydatid dogs: 99
Positive rate: 1.0%
8
7
北海道におけるエキノコックス症対策の経緯
6
60
Fox
50
5
40
4
30
3
20
2
Dog
10
1
0
0
1966
1971
1976
1981
1986
1991
1996
2001
2006
Progression of prevalence of Echinococcosis in the foxes
and dogs at Hokkaido through 1966-2008.
0.3
0.25
0.2
Echinococcus specific
PCR using Cox1 primer
0.15
0.1
北海道におけるエキノ
コックス症対策の経緯
0.05
0
Number of pigs slaughtered: 27,321,373
Number of hydatid pigs:
31,253
Positive rate: 0.11%
Progression of prevalence of Echinococcosis in the pig
slaughtered at Hokkaido through 1983-2008.
Saprozoonoses
Anthrax
In May 1881 Louis Pasteur performed
a public experiment to demonstrate
his concept of vaccination.
The trial was held under the
supervision of two graziers
and three government officials
at Junee Junction in Australia
during September and
October 1888. The trial was
undertaken on 39 sheep and 6
cattle. It was a complete
success: all vaccinated
animals remained in very
good health, whereas all 19
Pasteur's Vaccine of Anthrax
unprotected sheep and one of in Australia: as a preventative
the two non-vaccinated cows against Cumberland Disease
died within a few days.
in sheep, cattle and horses.
When conditions are not conducive to growth and
multiplication of the vegetative bacilli, B. anthracis
tends to form spores. These spores are extremely
resistant to inactivation by heat or chemicals, and
can survive in the environment for decades.
Capsulated B. anthracis in the blood of
an animal that has died of anthrax.
Rain and other agents can
disperse the spores to other
locations. Heavy rains, alternating
with dry periods, may concentrate
the spores and result in
outbreaks among grazing animals.
Spores and vegetative
cells of B. anthracis
Virtually all mammals and some
birds can contract anthrax, but
susceptibility varies widely and most
clinical cases occur in wild and
domesticated herbivores. Cattle,
sheep, and goats are considered to be
highly susceptible; horses somewhat
less so. Pigs, other omnivores, and
carnivores are more resistant to
disease, but they may become ill if the
dose is high. Birds are highly
resistant.
Enlarged spleen has a ‘blackberry jam’ consistency.
Bloody discharges from the
nose, mouth, and anus
Louisiana State Univ.:
World Anthrax Site
20,000-100,000 cases estimated globally/year
Human case rates for anthrax are highest in Africa and
central and southern Asia. Where the disease is infrequent
or rare in livestock, it is rarely seen in humans.
300
Number of cases
250
200
150
100
50
It was revealed that the application of
Cow bone meal was very effective to crop
growth in Kagoshima Prefecture
consisting of volcanic ash soils in the
middle of Edo period.
The bone meals imported from
China and Korea in Meiji period
Equine
were contaminated with Anthrax
spores.
Human
0
Occurrence of Anthrax in Kagoshima prefecture
through 1908-1932
30
In Japan, only one animal-Anthrax case in
several years was reported recently. The
spores still may be distributed in the soil, the
number of them do not reach the onset dose.
By the oral route, minimum infectious dose
for sheep was 3.5 x 10 4 spores and that the
dose needed to ensure lethal infection in
sheep, horses and cattle was 5 x 108 spores.
20
WHO: Anthrax in humans
and animals
60
Number of cases
50
40
10
0
Numer of cattles with Anthrax in Japan, 1960-2000
400
Number of deaths
350
300
During the first documented outbreak of anthrax, in the
summer of 1962, 281 bison died in the eastern Slave River
Lowlands.
Outbreaks soon became widespread,
extending during the course of the next
few years to as far south as bison herds in
the Sweet Grass area.
Number of Bisons in National Park
250
200
150
100
50
No cases of
human anthrax
have been
diagnosed in the
last two decades
in Canada.
Wood Buffalo National Park
Slave River Lowlands
Mackenzie Bison
Liard River Valley (Nahanni)
Wood Bison in the NWT
0
4500
1800
1555
400
Wood bison is designated as the Status
of Endangered Wildlife in Canada
Number of bisons died of anthrax in Canada
Anthrax in U.S.
Cutaneous anthrax
Early 1900s: 200 cases annually
Late 1900s: 6 cases annually
Inhalational anthrax
20th century: 18 cases/16 fatal
Outbreaks of anthrax in wild
animals including bison were
a public health threat in
United States, formerly.
CDC: Epizootiology and
Ecology of Anthrax
Distribution by decade of 75 cases of
anthrax in humans in Texas, 1935 to 2001.
2001 Anthrax Letters
2001
anthrax
attacks
The second
letter dated at
9 November
Who did it for
• 22 cases
what purpose?
– 11 cutaneous
The truth has
– 11 inhalational
not been
• 5 deaths (all inhalational)
revealed until
now.
– Index case in Florida
– 2 postal workers in Maryland
– Hospital supply worker in New York City
– Elderly farm woman in Connecticut
Aum Shinrikyo
• Japanese religious cult
• 1993
– Unsuccessful attempts at biological terrorism
– Released anthrax from office building
• Vaccine strain used – not toxic
– No human injuries
• Successful attempt in 1995
– Sarin gas release in Tokyo subway
– 1,000 injured – 12 deaths
A group behaving fanatically would
exist in any country. It is an
unavoidable phenomenon resulting
from the mentally suffering society.
Guru in the cult
The International Health Regulations
(2005) provide not only the ability of the
world community to cope with public
health emergencies affecting more than
one country, but they have important
implications for biosecurity, including
the response to transborder incidents
involving the accidental or deliberate
release of biological or chemical agents
or radiological materials.