Zoonoses from Milk and Water Flashcards
(48 cards)
What are the (3) classic milkborne pathogens?
Mycobacterium bovis
Brucella
Coxiella burnetti
How do pathogens get into milk?
Bacteria infect the animal systemically and colonize the mammary glands
Bacteria can be secreted into milk in a chronic fashion, often with minimal symptoms in the animal
In addition to milk, there can be _____ transmission to people
Direct
Percutaneous or mucous membrane contact with infectious fluids
Aerosol exposure
Who are most at risk for zoonotic infections from organisms in milk?
People who work with infected animals or premises are at highest risk : farmers, veterinarians, and abattoir workers
T/F: Some imported soft cheeses are not pasteurized and therefore, have potential for zoonotic transfer
TRUE
Where do most cases of M. bovis occur?
Countries without pasteurization of milk or control programs in cattle
Pulmonary TB (M. bovis) cannot be discriminated from M. ________ via skin testing or x-rays, only by ________.
M. tuberculosis
culture
What percentage of “M. tuberculosis” cases in countries that do not pasteurize milk or test cattle are actually M. bovis?
10-30%
What are the 3 major zoonotic transmission routes of mycobacterium bovis?
Aerosol (from infected cattle to other cattle and to people who work with cattle)
Oral exposure: to milk, feces, LN contents
Percutaneous exposure: abattoir workers, necropsy, etc
How can M. bovis be controlled?
Eliminate the animal reservoir
Milk pasteurization
What clinical signs might you see in a person with Brucellosis?
aka “undulant fever” or “malta fever”
- recurring fever, can last for months
- abortions can occur if pregnant
- Pleiomorphic symptoms: neurological, endocarditis, possibly chronic fatigue
What is the causative agent of Q Fever? What signs might you see in a human infected?
Coxiella burnetii - causes a non specific febrile illness
Abortions if pregnant
Chronic pleiomorphic symptoms
May also present as atypical pneumonia or hepatitis
What is the most pathogenic species of brucella in people?
Brucella melitensis
It infects a variety of animals and is mostly found in the Mediterranean and other intensive goat-farming regions
What brucella species is highly pathogenic in people, and has a worldwide distribution (with the exception of places with successful eradication processes)?
Brucella abortus
Seen in cattle, bison, buffalo, horses, dogs etc
What two brucella spps are the least pathogenic in humans, but still a zoonotic concern?
B. suis and B. canis
How do people get infected with brucella?
Ingestion, mm exposure , or percutaneous inoculation with: aborted placenta, fetus or fetal fluids, unpasteurized milk, blood, urine, semen, feces, and vaginal secretions
*feed/water contaminated with these materials
What methods are taken to control brucella?
Elimination of the animal reservoir
Reduce public exposure by pasteurization of milk and milk used to make soft cheeses
Is there an eradication program for Coxiella burnetti in the USA?
NO
Greater than 90% of dairy herds in the US have C. burnetii (20-30% of cattle are shedding at any given time)
The basis of pasteurization standards is based upon what pathogen?
Coxiella burnetti
**this protects the public but not animal workers/farmers
How is C. burnetti transmitted?
***Aerosol exposure
Percutaneous and mm exposure
Is C. burnetti an environmental issue? Why or why not?
YES
It causes abortion - there are large amounts of pathogen in the aborted placenta and fetus: survives in water, soil, milk, and meat for WEEKS TO MONTHS
Chronically excreted in milk and feces (possibly urine)
What are some barriers to control?
Wildlife reservoirs
Social cost/veterinary infrastructure
Compliance of animal owners
What two protozoa pathogens pose a threat via water transmission?
Crypotosporidium
Giardia
How long can cryptosporidium and giardia survive in water if conditions are good?
MONTHS
