Lecture 2. Water and Microbiology Flashcards
How many people are dependent on surface water?
144 million
How many people globally do not have access to safe drinking water?
785 million
How many people drink from faecally contaminated water sources?
2 billion
How many deaths per year are attributed to unsafe water supply, inadequate sanitation and lack of hygiene?
842,000 (361,000 in children <5)
How many people use a safely managed drinking water service?
71% global population (5.3 billion people)
How many people use at least a basic water service?
90% global population (6.8 billion people)
By 2015, how many countries had achieved over 75% coverage with at least basic drinking water services?
181
Starting from top to bottom, what does water pass through to be filtered
Rocks
Coarse sand
Charcoal
Fine sand
Cloth
What occurs in primary sewage treatment?
Raw sewage is filtered though screens into a communicator and then into a grit chamber. The sewage goes from the grit chamber through a primary clarifier which splits the sewage into a primary effluent and raw primary sewage.
What occurs in secondary sewage treatment?
The primary effluent enters an aeration tank before passing through a secondary clarifier. Secondary effluent is treated with disinfectant before being discharged to surface water. Activated sludge either passes through the aeration tank again or is removed for sludge treatment and disposal.
What are the steps to turn groundwater into bottled water?
Ozonisation → Sand filter → Carbon filter → Polisher filter → Reverse osmosis → Mineral control → Polisher → Ozonisation
What are the acceptable limits for clean safe drinking water?
E. coli = 0/100 ml
Coliforms = 0/100 ml
Total viable counts
37°C = 10 cfu/ml (colony forming units)
22°C = 100 cfu/ml
What are examples of waterborne bacterial diseases?
Vibrio cholerae 01 El Tor (Disease: Cholera)
E. coli 0157:H7 (Disease: gastroenteritis)
What are examples of waterborne viral diseases?
Norovirus (Symptoms: Diarrhoea and vomiting)
Rotovirus (Symptoms: Diarrhoea and vomiting)
What are examples of waterborne protozoan diseases?
Cryptosporidium parvum (Disease: Cryptosporidiosis)
Schistosoma spp. (Disease: Schistosomiasis (Snails)
Plasmodium spp. (P. falciparum, P. vivax, P. ovale, P.
malariae) (Disease: Malaria) (Mosquitoes)
Organisation of norovirus genome
Three open reading frames
ORF1: 200kDa poly-protein that is auto-processed by a virally encoded 3C-like protease to yield non-structural replicase proteins
ORF2: encodes structural capsid protein, 57kDa
ORF3: encodes minor structural protein, 22kDa
What is the host and virulence factor of norovirus?
“Shape-shifter”; sheds billions of viral particles; small dose; highly contagious
What is the variation in genotype I norovirus?
Variation is limited to creating differential binders
What is the variation in genotype II norovirus?
Variation creates differential binders and antibody escape mutants
Who reports weekly updates regarding outbreaks in the UK?
PHE
Is norovirus endemic or epidemic?
Endemic, but occasionally epidemic
What season is norovirus most common?
Winter, norovirus is also known as the winter vomiting bug
What are the host factors & virulence of cryptosporidium?
Include symptomatic episodes of uncontrolled diarrhoea; immune suppression; reduced/lack of immunity (age associated)
What are the risk factors of cryptosporidium?
(Un)intentional defecation in swimming pools; petting zoos/farms; young age
What season is cryptosporidium most common?
More common in spring and autumn
What age group is at most risk of cryptosporidium?
0-4 year olds and 25-29 (parents)
