Food Borne Infections

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Food Borne Infections

• Organisms do not have to grow in the food before
  it is eaten   

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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
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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.

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Typhoidfever Salmonellosis
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Other Bacteria

• TB
• Brucellosis
• Q-fever
• Anthrax

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Incidence of TB

• Tuberculosis (TB) remains the leading cause of
  death 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. 

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Mortality

• It is estimated that between 2000 and 2020,
  nearly one 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.

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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

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1/2 of the world's population is infected

• With the increased incidence of AIDS, TB has
  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.

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Brucella spp.

• Gram negative, coccobacilli bacteria
• Facultative, intracellular organism
• Environmental persistence
• Temp, pH, humidity
• Frozen and aborted materials
• Multiple species

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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 ?
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The Many Names of Brucellosis

• Human Disease
• Malta Fever
• Undulant Fever
• Mediterranean Fever
• Rock Fever of Gibraltar
• Gastric Fever

• Animal Disease
• Bangs Disease
• Enzootic Abortion
• Epizootic Abortion
• Slinking of Calves
• Ram Epididymitis
• Contagious Abortion

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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

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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

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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

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B. melitensis

• Latin America, Middle East, 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

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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)

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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

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B. canis

• Poorly understood
• 1-19 prevalence in United States
• Rarely causes disease in humans

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Brucellosis in U.S. 1972-2002
350 300 250 200 150 100 50 0
Reported Cases
1972 1977 1982 1987
1992 1997 2002
Year
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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

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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 lt2 ( untreated)
• Endocarditis caused by B. melitensis

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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

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• Q Fever

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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

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History

• 1935
• 1st described in Queensland, Australia
• Found in ticks in Montana
• Outbreaks
• Among military troops
• When present in areas
  with infected animals
• Cities and towns
• Downwind from farms
• By roads traveled by animals

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Transmission

• Aerosol
• Parturient fluids
• 109 bacteria
  per gram of placenta
• Urine, feces, milk
• Wind-borne
• Direct contact
• Fomites
• Ingestion
• Arthropods (ticks)

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Transmission

• Person-to-person (rare)
• Transplacental (congenital)
• Blood transfusions
• Bone marrow transplants
• Intradermal inoculation
• Possibly sexually transmitted

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Epidemiology

• Worldwide
• Except New Zealand
• Reservoirs
• Domestic animals
• Sheep, cattle, goats
• Dogs, cats
• Birds
• Reptiles
• Wildlife

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Epidemiology

• Occupational and
  environmental hazards
• Farmers, producers
• Veterinarians and technicians
• Meat processors, abattoir
• Laboratory workers

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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

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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 (lt 1)
• Myocarditis, pericarditis, meningoencephalitis
• Death 1-2

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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

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Risk to Pregnant Women

• Most asymptomatic
• Transplacental transmission
• Reported complications
• In-utero death
• Premature birth
• Low birth weight
• Placentitis
• Thrombocytopenia

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Prognosis

• Overall case-fatality rate lt1 - 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

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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

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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

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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
• 1152 to phase I antigen
• 11024 to phase II antigen

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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

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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, granulomas, or
  death

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Morbidity and Mortality

• Prevalence unknown
• Endemic areas
• 18-55 of sheep with antibodies
• 82 of dairy cattle
• Morbidity in sheep 5-50

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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

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Prevention and Control

• Education
• Sources of infection
• Good husbandry
• Disposal of birth products (incinerate)
• Lamb indoors in separate facilities
• Disinfection
• 0.05 chlorine
• 1100 Lysol
• Isolate new animals

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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

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Epidemiology of Anthrax in Animal and Human Hosts
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Clinical Presentation of Anthrax Gastrointestinal
(Ingestion) Anthrax

• Virtually 100 fatal
• Abdominal pain
• Hemorrhagic ascites
• Paracentesis fluid may reveal gram-positive rods

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Treatment Prophylaxis

• Treatment
• Penicillin is drug of choice
• Erythromycin, chloramphenicol acceptable
  alternatives
• Doxycycline now commonly recognized as
  prophylactic
• Vaccine (controversial)
• Laboratory workers
• Employees of mills handling goat hair
• Active duty military members
• Potentially entire populace of U.S. for herd
  immunity

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The End