Waterborne diseases Flashcards
What are 4 important water-borne pathogenes?
- e. coli
- campylobacter
- vibrio cholera
- cryptosporidium
What are water-borne diseases?
diseases caused by ingestion of contaminated water
What are water washed diseases?
diseases caused by poor personal hygiene and skin and eye contact
What are water-based diseases?
diseases caused by parasites found in intermediate oragnisms living in contaminated water
What are water-vector related diseases
caused by insect vectors esp mosquitos that breed or feed near contaminated water
What are 12 factors causing re-emergence of zoonotic pathogens
- changing patterns of water use
- population factors
- travel, recreation
- water scarcity, climate change, weather events
- conflict, disaster
- increased urbanization, colonizatino
- increased demand for animal protein, fresh vegetables
- increased antimicrobial used
- concentrated animal husbandry, feedlots
- domestic pet density
- economic disturbance
- international trade patterns
Explain walkerton ontario 2000 scenario
widespread illness, bloody diarrhea/hemorrhagic uremic syndrome
7 died
PFGE used to compare strains
pulsenet canada used
traecd back to nearby cattle farm–not doing anything wrong
biofilm formation on the copper line
What were reported causes of the walkerton outbreak?
- ecological important boundaries don’t match political ones
- contaminated well located in area engineers advised against
- change of responsibility with improper training
- unclear roles and responsibilities
- heavy rainfall
How is risk of O157:H7 from animal waste minimized?
- on farm biosecurity
- vaccination
- waste treatment before release
How is risk of O157:H7 from animal waste minimized?
- on farm biosecurity
- vaccination
- waste treatment before release
How is cryptosporidium spread?
- water contaminated with feces
- contact with infected persion
- water contaminated with animal feces
What is the primary means to remove cryptosporidium oocysts from water?
filters becuase resistant to chemical disinfection
What is the minimal dose to get infected with cryptosporidium
10 oocysts
What are some features of cryptosporidium oocysts?
immediately infective
appear at onset of symtoms
can be in stool for weeks without symptoms
can remain infective outside body for 2-6 months
What are three sources of infection with cryptosporidium?
- recreational water
- contact with livestock
- drinking water
- person to person
How are cryptosporidium parvum and homminis distinguished in the lab?
real time PCR
What are factors that contribute to cryptosporidium outbreaks? REMEMBER
- small oocysts
- wide host range
- close associations between human and animal health
- large number of oocysts excreted
- low infective dose
- robust oocyts resistant to chlorine
- infectious sporulated oocysts excreted
why was there a cryptosporidium outbreak in Milwaukee?
storm washed fecal contamination, system failure allowed crypto to pass into water filters and proliferate in water supply
Why did the outbreak in North Battleford occur?
- the drinking water intake is below the sewage outfall
- operations supervisor retired early
- repair to the water treatment area
- there was not coagulant sludge retained when it was restarted. There was not the proper material to seed and settle out material–solids contact unit
What is a characteristic of waterborne outbreaks?
high proportion of the population is affected, illness is experienced in all age groups, affected persons have epidemiological link to on community or water source
What constitutes a waterborne outbreak? remember?
- 2 or more people with similar illness
2. epidemiological evidence that implicates water as porbable cause
Large municiple outbreaks are due to one or more of?
- inadequate disinfection
- cross connections
- inadequate control over treatment process
- interruption in treatment
- disruption in service
- infiltration of polluted water
What is information used in water outbreak investigation?
- water plant process monitoring data
2. pu
What is information used in water outbreak investigation?
- water plant process monitoring data
- public health results for clin lab, emergency room, physician visits for gastroenteritis
- school, daycare absences
- nursing home diarrheal rates
- sale of anti-diarrheal drugs
what is an indicator organism?
e. coli
Why is e. coli an indicator organism?
- universally present in large numbers in feces of humans and warm-blooded animals
- readily detectable by simple methods
- does not grow in natural waters
- persistence in water and removal by treatment similar to waterborne pathogens
- when resources are scarce it is recommended to test more drinking water more frequently with a simple test rather than less often by several tests
- criterion: e. coli not detectable in 100mL sample
Why is cryptosporidia and giardia not routinely tested in SK
analysis rates have low recovery
2. present methods do not ID viable oocysts
how many times is water checked if there are 500 people?
2x/month
How often is water tested for chemicals in a town of 5000?
once every 2 years
Why is tap water better than bottled water?
it is not tested as frequently
what can get rid of crypto and giardia in water?
UV light, ozone
