Transcript View power point lecture on food borne infections that do not have to

Food Borne Infections
Organisms do not have to grow in
the food before it is eaten:
Food Borne Infections
• Organisms do not have to grow in the food
before it is eaten:
Bacteria
Typhoid
Cholera
TB
Brucellosis
Q-fever
Anthrax
Viruses
Hepatitis A
Polio
Anual incidence
Rotavirus
Enteroviruses
Parasites
Amoeboid disentry
Toxoplasmosis
Giardia lamblia
Cryptosporidium
Nematode
Helminths
Typhoid fever
– Diagnosis of typhoid fever
 Blood cultures are positive during the first
week and after the second week
 Stool cultures and sometimes urine cultures
are positive after the second week
 The Widal test is a serological test for
antibodies against Salmonella typhi.
 10% of those infected become short term
carriers and a smaller % become long-term
carriers due to persistence of the bacteria in
the gallbladder or urinary bladder.
S. typhi /typhoid cases in NZ from 1980 to 2004
Typhoid
Number of cases
35
30
25
20
15
10
5
2004
2002
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
1980
0
fever
Year
Salmonellosis cases in NZ from 1980 to 2004
3000
2000
Salmonellosis
1500
1000
500
Year
2004
2002
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
0
1980
Number of cases
2500
Other Bacteria
TB
Brucellosis
Q-fever
Anthrax
Incidence of TB
• Tuberculosis (TB) remains the leading cause of death
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worldwide from a single infectious disease agent.
Indeed up to 1/2 of the world's population is
infected with TB.
The registered number of new cases of TB worldwide
roughly correlates with economic conditions:
the highest incidences are seen in those countries
with the lowest gross national products.
WHO estimates that eight million people get TB every
year, of whom 95% live in developing countries.
An estimated 2 million people die from TB every
year.
Mortality
• It is estimated that between 2000 and 2020, nearly one
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billion people will be newly infected, 200 million people
will get sick, and 35 million will die from TB
After a century of decline TB is increasing and there are
strains emerging which are resistant to antibiotics.
This excess of cases is attributable to the changes in the
social structure in cities, the human immunodeficiency
virus epidemic, and failure of most cities to improve
public health programs, and the economic cost of
treating.
HISTORY
• TB is an ancient infectious disease caused by
Mycobacterium tuberculosis.
• It has been known since 1000 B.C.,
• Since TB is a disease of respiratory
transmission, optimal conditions for transmission
include:
– overcrowding
– poor personal hygiene
– poor public hygiene
1/2 of the world's population is
infected
• With the increased incidence of AIDS, TB has
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become more a problem in the U.S., and the
world.
It is currently estimated that 1/2 of the world's
population (3.1 billion) is infected with
Mycobacterium tuberculosis.
• Mycobacterium avium complex is associated with
AIDS related TB.
Brucella spp.
• Gram negative, coccobacilli bacteria
• Facultative, intracellular organism
• Environmental persistence
– Temp, pH, humidity
– Frozen and aborted materials
• Multiple species
Center for Food Security and
Public Health Iowa State
University - 2004
Species
Biovar/
Serovar
Natural Host
Human
Pathogen
B. abortus
1-6, 9
cattle
yes
B.melitensis
1-3
goats, sheep
yes
B. suis
1, 3
swine
yes
2
hares
yes
4
reindeer,
caribou
yes
5
rodents
yes
B. canis
none
dogs, other
canids
yes
B. ovis
none
sheep
no
B. neotomae
none
Desert wood
rat
no
B. maris
marine
mammals
Center for Food Security and
? Health Iowa State
Public
University - 2004
The Many Names of Brucellosis
Human Disease
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Malta Fever
Undulant Fever
Mediterranean Fever
Rock Fever of Gibraltar
Gastric Fever
Animal Disease
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Bang’s Disease
Enzootic Abortion
Epizootic Abortion
Slinking of Calves
Ram Epididymitis
Contagious Abortion
Center for Food Security and
Public Health Iowa State
University - 2004
Professor FEG Cox. The Wellcome Trust, Illustrated History of Tropical Diseases
Sir David Bruce
(1855-1931)
•British Army
physician and
microbiologist who
discovered
Micrococcus
melitensis
Center for Food Security and
Public Health Iowa State
University - 2004
Transmission to Humans
• Conjunctiva or broken skin contacting
infected tissues
– Blood, urine, vaginal discharges, aborted
fetuses, placentas
• Ingestion
– Raw milk & unpasteurized dairy products
– Rarely through undercooked meat
Center for Food Security and
Public Health Iowa State
University - 2004
Transmission to Humans
• Inhalation of infectious aerosols
– Pens, stables, slaughter houses
• Inoculation with vaccines
– B. abortus strain 19, RB-51
– B. melitensis Rev-1
– Conjunctival splashes, injection
• Person-to-person transmission is very rare
• Incubation varies
– 7-21 days to several months
Center for Food Security and
Public Health Iowa State
University - 2004
Center for Food Security and
Public Health Iowa State
University - 2004
B. melitensis
• Latin America, Middle East,
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Mediterranean, eastern Europe, Asia,
and parts of Africa
Accounts for most human cases
– In the Mediterranean and Middle
East
• Up to 78 cases/100,000 people/year
• Arabic Peninsula 20% seroprevalence
• Recent emergence in cattle on
Middle Eastern intensive dairy farms
Center for Food Security and
Public Health Iowa State
University - 2004
B. abortus
• Worldwide
• Some countries have
eradicated
• Notifiable disease in many
countries
– Poor surveillance and reporting
due to lack of recognition
– Fever of Unknown Origin (FUO)
Center for Food Security and
Public Health Iowa State
University - 2004
B. suis
• Biovars 1 and 3
– Worldwide problems where swine are raised
• Free
– United Kingdom, Canada
• Eradicated
– Holland, Denmark
• Low Incidence
– Middle East, North Africa
Center for Food Security and
Public Health Iowa State
University - 2004
B. canis
• Poorly understood
• 1-19% prevalence in
United States
• Rarely causes disease in
humans
Center for Food Security and
Public Health Iowa State
University - 2004
Brucellosis in U.S.: 1972-2002
350
Reported Cases
300
250
200
150
100
50
0
1972
2002
1977
1982
1987
Year Security and
Center for Food
Public Health Iowa State
University - 2004
1992
1997
Brucellosis
• United States
– Approximately 100 cases per year
– Less than 0.5 cases/100,000 people
– Mostly California, Florida, Texas, Virginia
– Many cases associated
with consumption of
foreign cheeses
Center for Food Security and
Public Health Iowa State
University - 2004
Prognosis
• May last days, months or years
• Recovery is common
• Disability is often pronounced
• About 5% of treated cases relapse
• Failure to complete the treatment regimen
• Sequestered infection requiring surgical drainage
• Case-fatality rate: <2% ( untreated)
– Endocarditis caused by B. melitensis
Center for Food Security and
Public Health Iowa State
University - 2004
Human Disease
• Neurological
– Depression, mental fatigue
• Cardiovascular
– Endocarditis resulting in death
• Chronic brucellosis is hard to define
– Length, type and response to treatment
variable
– Localized infection
• Blood donations of infected should not be
accepted
Center for Food Security and
Public Health Iowa State
University - 2004
•Q Fever
The Organism
• Coxiella burnetii
– Rickettsial agent
– Obligate intracellular parasite
– Stable and resistant
– Killed by pasteurization
– Two antigenic phases
• Phase 1: virulent
• Phase 2: less pathogenic
Center for Food Security and
Public Health Iowa State
University - 2004
History
• 1935
– 1st described in Queensland, Australia
– Found in ticks in Montana
• Outbreaks
– Among military troops
• When present in areas
infected animals
– Cities and towns
• Downwind from farms
Center for
Food
Security and
• By roads traveled
by
animals
Public Health Iowa State
University - 2004
with
Transmission
• Aerosol
– Parturient fluids
• 109 bacteria
per gram of placenta
– Urine, feces, milk
– Wind-borne
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Direct contact
Fomites
Ingestion
Center for Food Security and
Arthropods (ticks)
Public Health Iowa State
University - 2004
Transmission
• Person-to-person (rare)
– Transplacental (congenital)
– Blood transfusions
– Bone marrow transplants
– Intradermal inoculation
– Possibly sexually transmitted
Center for Food Security and
Public Health Iowa State
University - 2004
Epidemiology
• Worldwide
– Except New Zealand
• Reservoirs
– Domestic animals
• Sheep, cattle, goats
• Dogs, cats
– Birds
– Reptiles
Center for Food Security and
– Wildlife
Public Health Iowa State
University - 2004
Epidemiology
• Occupational and
environmental hazards
– Farmers, producers
– Veterinarians and technicians
– Meat processors, abattoir
– Laboratory workers
Center for Food Security and
Public Health Iowa State
University - 2004
Human Disease
• Incubation: 2-5 weeks
• One organism may cause disease
• Humans are dead-end hosts
– Usually show clinical signs of illness
• Disease
– Asymptomatic (50%)
– Acute
– Chronic
Center for Food Security and
Public Health Iowa State
University - 2004
Acute Infection
• Flu-like, self limiting
• Atypical pneumonia (30-50%)
– Non-productive cough, chest pain
– Acute respiratory distress possible
• Hepatitis
• Skin rash (10%)
• Other signs (< 1%)
– Myocarditis, pericarditis, meningoencephalitis
• Death: 1-2%
Center for Food Security and
Public Health Iowa State
University - 2004
Chronic Disease
• 1-5% of those infected
– Prior heart disease, pregnant women,
immunocompromised
• Endocarditis
• Other
– Osteomyelitis
– Granulomatous hepatitis
– Cirrhosis
• 50% relapse rate after antibiotic therapy
Center for Food Security and
Public Health Iowa State
University - 2004
Risk to Pregnant Women
• Most asymptomatic
• Transplacental transmission
• Reported complications
– In-utero death
– Premature birth
– Low birth weight
– Placentitis
– Thrombocytopenia
Center for Food Security and
Public Health Iowa State
University - 2004
Prognosis
• Overall case-fatality rate <1 - 2.4%
• 50% cases self-limiting
• Only 2% develop severe disease
• Active chronic disease
– Usually fatal if left untreated
– Fatality for endocarditis: 35-55%
– 50-60% need valve replacement
Center for Food Security and
Public Health Iowa State
University - 2004
Case
• Male dairy farmer
– Age 46
– Sudden onset
• Fever, chills, cough
• Weight loss
– Initially thought it was influenza
– Symptoms persisted for 2 weeks
– Presented to emergency room
• Again influenza was the diagnosis
Center for Food Security and
Public Health Iowa State
University - 2004
Large Animal Case
• Referral to infectious disease specialist
– Tested positive for Q fever
– Antibiotics for 5 days
– Resolved in 2 weeks
• Epidemiology
– No recent calvings on his farm
– Two beef cattle herds across the road
• 2 out of 14 tested positive for Q fever
Center for Food Security and
Public Health Iowa State
University - 2004
Small Animal Case
• 1985, Nova Scotia, Canada
– 33 cases of Q fever
• 25 were exposed to cat
• 17 developed cough
• 14 developed pneumonia
– Most common symptoms
• Fever, sweats, chills, fatigue, myalgia, headache
– Cat tested positive for C. burnetii
• 1:152 to phase I antigen
• 1:1024 to phase II antigen
Center for Food Security and
Public Health Iowa State
University - 2004
Animal Disease
• Sheep, cattle, goats
– Usually asymptomatic
– Reproductive failure
• Abortions, stillbirths
• Retained placenta
• Infertility
• Weak newborns
• Low birth weights
• Mastitis in dairy cattle
– Carrier state Center for Food Security and
Public Health Iowa State
University - 2004
Animal Disease
• Other animal species
– Dogs, cats, horses, pigs, camels, buffalo,
pigeons, other fowl
– Asymptomatic
– Reproductive failure
• Laboratory Animals
– Rats, rabbits, guinea pigs, hamsters
– Varies from asymptomatic to fever,
Center for Food Security and
granulomas, or
death
Public
Health Iowa State
University - 2004
Morbidity and Mortality
• Prevalence unknown
– Endemic areas
• 18-55% of sheep with antibodies
• 82% of dairy cattle
• Morbidity in sheep: 5-50%
Center for Food Security and
Public Health Iowa State
University - 2004
Prevention and Control
• Pasteurization
• Vaccination
– Human and animal
– Not available in U.S.
• Eradication not practical
– Too many reservoirs
– Constant exposure
– Stability of agent
in environment
Center for Food Security and
Public Health Iowa State
University - 2004
Prevention and Control
• Education
– Sources of infection
• Good husbandry
– Disposal of birth products (incinerate)
• Lamb indoors in separate facilities
– Disinfection
• 0.05% chlorine
• 1:100 Lysol
• Isolate new animals
Center for Food Security and
Public Health Iowa State
University - 2004
Anthrax
• How heat resistant is Bacillus anthracis (B.
Anthracis)?
Spores
• Moist heat resistance
• D value at 90ºC (194ºF) - 2.5-7.5
minutes
• D value at 95ºC (203ºF) - 1.7-4.2
minutes
• Not That much killed with thorough
cooking
Epidemiology
of Anthrax in
Animal and
Human Hosts
Clinical Presentation of Anthrax
Gastrointestinal (Ingestion) Anthrax
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Virtually 100% fatal
Abdominal pain
Hemorrhagic ascites
Paracentesis fluid may reveal gram-positive rods
Treatment & Prophylaxis
 Treatment
• Penicillin is drug of choice
• Erythromycin, chloramphenicol acceptable alternatives
• Doxycycline now commonly recognized as
prophylactic
 Vaccine (controversial)
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Laboratory workers
Employees of mills handling goat hair
Active duty military members
Potentially entire populace of U.S. for herd immunity