Zoonoses from Milk and Water Flashcards
classically milk-borne bacteria
Brucella spp.
Coxiella burnettii
Mycobacterium bovis
“classic” milkborne pathogens
- Bacteria infect the animal systemically colonize the mammary glands
- Bacteria can be secreted into milk in a chronic fashion, often with minimal symptoms in the animal
Modern pasteurization is based on…
Coxiella burnetii
Do we pasteurize all milk?
Not quite…
– Farmers on the farm
– Foreign travel
– “Raw milk” movement
– Imported soft cheeses
True/False: there can be direct transmission to humans in addition to transmission via milk
True:
- Percutaneous or mucous membrane contact with infectious fluids
- Aerosol exposure
Most M. bovis cases occur in…
…countries without pasteurization of milk or control programs in cattle
Transmission routes: M. bovis
- Aerosol
- oral exposure (intestinal or cervical lymphadenitis)
- percutaneous exposure (lymphadenopathy of draining LN)
M. Bovis: Aerosol transmission to people =
pulmonary TB (culture to differentiate from M. tuberculosis)
Control of M. bovis
- Eliminate animal reservoir (test-and-slaughter)
- milk pasteurization
True/False: Human infections of Brucella and Coxiella are easy to diagnose
False: difficult to diagnose without good index of suspicion
“undulant fever” or “Malta fever”
Brucellosis in humans
- recurring fever, abortions, Pleiomorphic symptoms: neurologic, endocarditis, possibly chronic fatigue
“Q fever”
Coxiella burnetii in humans
- abortions, pleiomorphic symptoms
- may present as atypical pneumonia or hepatitis
most pathogenic Brucella spp in humans
Brucella melitensis
Brucella abortus
pathogenic in humans
worldwide distribution
Brucella suis and canis
less pathogenic in humans
Brucella transmission
Ingestion
mucous membrane exposure
percutaneous inoculation
(Aborted placenta, fetus, fetal fluids, Unpasteurized milk, blood, urine, semen, feces, and uterine/vaginal secretions, Feed/water contamination)
controlling Brucella spp
Eliminate reservoir
monitor swine
reduce public exposure: pasteurization of milk and milk used to make soft cheeses
Coxiella burnetii: Q Fever
Used for the basis of pasteurization standards
Infects all dairy species
No eradication program in USA
Pasteurization of milk
Transmission of Coxiella burnetii
Extremely infectious via aerosol exposure (percutaneous and mucous membrane)
An issue of environmental contamination (aborted placenta/fetus, milk, feces, water, soil, meat)
Veterinary exposure is most likely from environmental sources on farms
Barrier to control (milkborne)
wildlife reservoirs
social costs/veterinary infrastructure
compliance of animal owners
Cryptosporidium and Giardia
Protozoan parasites (Cryptosporidium is coccidia‐like; Giardia is flagellated)
transmission via water > food!
Infected animals can contaminate water supplies
True/False: both Cryptosporidium and Giardia are diverse
True
C. parvum
zoonotic
cattle are reservoir
C. hominis
human to human
urban municipal water systems
estimated number of people with Giardia
200 million people in Africa, Asia, and Latin America have Giardia but only 50,000 cases reported
exact zoonotic capacity of Giardia has been long debated
zoonotic types of Giardia
humans infection groups: type A and B
- 10-20% cattle is type A
- 50% dogs and cats have type A or B
True/ False: Cryptospiridiosis in humans is usually severe
False: mild=diarrhea; severe in immunocompromised patients
Giardia causes
chronic intestinal infections
prevention of Cryptosporidium & Giardia
proper treatment (filtration) of drinking water; wash produce; reduce exposure to recreational water; no diapers in swimming pools!
True/False: Leptospirosis is a waterborne disease
True
Leptospirosis infects…
kidneys/ excreted in urine
how long can animals excrete Leptospirosis in their urine
> 1 year
Leptospirosis survives best in…
warm freshwater or mud
Leptospirosis infection via…
Ingestion of water containing Leptospira
Mucous membrane or broken skin contact with water containing Leptospira
Contact with animal urine containing Leptospira
Clinical Leptospirosis (acute)
Fever, depression, lethargy, +/‐ icterus
Headache/malaise/ocular pain in people
Acute renal damage or failure
Clinical Leptospirosis (chronic)
Large animal abortions, stillbirths, weak offspring
Chronic renal insufficiency
control of Leptospirosis
reduce reservoir (rodent control) reduce human exposure (clean water, wear gloves when handling urine)
Trematode life cycle
Definitive host = a vertebrate Intermediate host(s) = aquatic Accidental hosts can be infected percutaneously
Trematodes as zoonosis
Anthroponotic as well as zoonotic species
Disease occurs anywhere with appropriate water conditions and presence of intermediate hosts
2nd most important human parasite after malaria
Schistosoma spp.
Schistosoma japonicum
zoonotic: have domestic animal reservoirs
Control of Schistosomiasis
Avoid swimming in fresh water
Treat reservoir hosts; kill intermediate molluscs
Swimmer’s Itch
Caused by skin invasion by the aquatic stage of bird trematodes (Humans cannot be the definitive host)
Humans are accidental hosts – can result in skin lesions
Fasciola spp. (Cattle Liver Flukes)
Important animal disease
Humans can be infected (vegetables contaminated with metacercariae)
- Humans are NOT infected via eating liver
In some parts of the world it is quite common in humans
cause bovine abortion and are zoonotic
Brucella abortus
Leptospira spp.
Coxiella burnetii
Listeria monocytogenes
