Exam 2 Zoonoses from Milk & Water Flashcards
Classic Milk born pathogens
- Mycobacterium bovis
- Brucella spp.
- Coxiella burnetii
Mycobacterium bovis: What disease in people
Tuberculosis, intestinal TB
Mycobacterium bovis: What USA Control Program
Eradication in cattle
Pasteurization
Brucella spp: What disease in people
Undulant fever
Malta fever
Brucella spp: Waht USA Control Program
Eradication in cattle
Eradication in swine
Pasteurization
Coxiella burnetii: What disease in people
Q fever
Coxiella burnetii: What USA Control Measure
Pasturization
What organism is modern pasteurization based on?
Coxiella burnetii
In addition to milk, how can these organisms be transmitted?
- percutaneous or mucous membrane contact with infectious fluids
- aerosol exposure
What people or premises are at risk?
Veterinarians
Farms
Abattoir workers
When isn’t the milk pasteurized?
- Farmers on the farm
- Foreign travel
- “Raw Milk”
- Imported soft cheeses
M. bovis and M. tuberculosis cannot be distinguished vis skin test (T/F)
True
10-30% of “M. tuberculosis” cases in countries that don’t pasteurize milk or test cattle are actually M. bovis. (T/F)
True
M. bovis transmission routes
- aerosol
- oral: intestinal form seen in cats and people
- percutaneous: causes lymphadenopathy, can become systemic
Controlling M. bovis
- eliminate animal reservoir (test-and-slaughter); difficult controlling wild reservoir & mexican cattle
- milk pasteurization: doesn’t protect workers
Brucella & Coxiella diagnosis difficulties
Need good suspicion to help with diagnosis.
Bruc: “undulant or Malta fever,” recurrent , can last for months. Abortion possible. pleiomorphic symptoms
Cox: “Q fever” nonspecific fever. Abortions possible.pleiomorphic symptoms
Brucella melitensis
- most pathogenic for people
- goats (& sheep, caribou, pigs, dogs…)
- Mediterranean & goat-farming areas
Brucella abortus
- pathogenic in people
- Cattle (bison, buffalo, elk…)
- worldwide, except where eradicated
Brucella suis & canis
less pathogenic for people
Brucella transmission
-ingestion
-mucous membane exposure
-percutaneous inoculation
(B. canis rare in humans, but several vet cases from blood contact)
Brucella control
- eliminate reservoir (vaccination, milk monitored, testing on sale, slaughter of infected animals)
- swine monitored
- pasteurization of milk
Coxiella burnetti: Q fever
- basis of pasteurization standards
- infects all dairy species (subclinical mastitis??)
- NO Eradication program in US. >90% of herds are positive
- Pasteurization
Coxiella burnetti transmission
- Aerosol Exposure very infectious!
- Environmental contamination from: aborted placenta & fetus, milk & feces. Survives in water, soil, milk, meat
Problems with control of milk born organizms
- wildlife reservoirs reinfect herds
- social cost
- compliance of owners
Which is worse: water or food born?
Water
- difficult to kill with chlorine, must filter water
- environmentally stable life stage, can survive for months in water
- can also contaminate surface of food
Cryptosporidum parvum
- zoonotic
- cattle are reservoir
- typically rural settings
- flooding of waste ponds into surface water
Cryptosporidium hominis
- human-to-human
- urban municipal water systems
- seware treatment doesn’t always kill oocysts
Giardia
- affects many species (which then become infectious)
- 200 million people have it, but only 50,000 cases are reported
- 10-20% of cattle have type A
- up to 50% of cats & dogs have Type A or B
- humans have type A or B
Cryptosporidiosis in people
- usually mild
- diarrhea
- severe disease in immunocompromised pt.
Giardia in people
- chronic intestinal infection
- intermittent shedding of cysts
- young children “amplify”
Prevention of crypto & giardia
- proper filtration of drinking water
- wash produce
- reduce exposure to recreational water
- no diapers in swimming pools
Estimate of US surface water contaminated with giardia
97%
Leptospira reservoirs
- waterborne
- domestic & wild animals
- clinical disease in people, dogs, livestock, horses, ect
Leptospira infects which system?
Urinary
- bacteria in urine for >1 year
- causes renal insufficiency and sometimes hepatic damage
Leptospira infection via
- warm freshwater or mud
- ingestion of contaminated water
- mucous membrane or broken skin contact
- contact with contaminated urine
Leptospira acute diesase
-fever, depression, lethargy \+/- icterus -Headache/malaise/ocular pain -Acute renal damage or failure -May have biliary stasis, hepatic necrosis
Leptospira chronic disease
- LA abortions, stillbirths, weak offspring
- Chronic renal insufficiency
Control of Leptospirosis
- reduce reservoir (rodent control, treatment w/ Ab, vaccines)
- reduce human exposure (clean/treated water supply, PPE when suspected case)
Trematode life cycle
- Definitive host= vertebrate
- Intermediate host(s)- aquatic
- Accidental hosts can be infected percutaneously
Schistosomiasis
- 2nd most important human parasite after Malaria
- Africa, South America, South/southeast Asia
Schistosomiasis control
- avaid swimming in freshwater
- treat reservoir hosts; kill intermediate molluscs
Schistosomiasis in humans
- Swimmer’s itch
- skin invasion by aquatic stage of bird trematodes
- humans are accidental hosts- can result in skin lesions
Fasciola (cattle liver flukes)
- cattle/sheep infected via vegetation near streams with snails
- humans infected by contaminated vegetable (ie watercress), NOT via eating liver
4 organisms that cause bovine abortion and are zoonotic
- Brucella abortus
- Leptospira spp.
- Coxiella burnetii
- Listeria monocytogenes
