Lecture 2. Water and Microbiology

Question 1

How many people are dependent on surface water?

Answer 1

144 million

Question 2

How many people globally do not have access to safe drinking water?

Answer 2

785 million

Question 3

How many people drink from faecally contaminated water sources?

Answer 3

2 billion

Question 4

How many deaths per year are attributed to unsafe water supply, inadequate sanitation and lack of hygiene?

Answer 4

842,000 (361,000 in children <5)

Question 5

How many people use a safely managed drinking water service?

Answer 5

71% global population (5.3 billion people)

Question 6

How many people use at least a basic water service?

Answer 6

90% global population (6.8 billion people)

Question 7

By 2015, how many countries had achieved over 75% coverage with at least basic drinking water services?

Answer 7

181

Question 8

Starting from top to bottom, what does water pass through to be filtered

Answer 8

Rocks
Coarse sand
Charcoal
Fine sand
Cloth

Question 9

What occurs in primary sewage treatment?

Answer 9

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.

Question 10

What occurs in secondary sewage treatment?

Answer 10

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.

Question 11

What are the steps to turn groundwater into bottled water?

Answer 11

Ozonisation → Sand filter → Carbon filter → Polisher filter → Reverse osmosis → Mineral control → Polisher → Ozonisation

Question 12

What are the acceptable limits for clean safe drinking water?

Answer 12

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

Question 13

What are examples of waterborne bacterial diseases?

Answer 13

Vibrio cholerae 01 El Tor (Disease: Cholera)
E. coli 0157:H7 (Disease: gastroenteritis)

Question 14

What are examples of waterborne viral diseases?

Answer 14

Norovirus (Symptoms: Diarrhoea and vomiting)
Rotovirus (Symptoms: Diarrhoea and vomiting)

Question 15

What are examples of waterborne protozoan diseases?

Answer 15

Cryptosporidium parvum (Disease: Cryptosporidiosis)
Schistosoma spp. (Disease: Schistosomiasis (Snails)
Plasmodium spp. (P. falciparum, P. vivax, P. ovale, P.
malariae) (Disease: Malaria) (Mosquitoes)

Question 16

Organisation of norovirus genome

Answer 16

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

Question 17

What is the host and virulence factor of norovirus?

Answer 17

“Shape-shifter”; sheds billions of viral particles; small dose; highly contagious

Question 18

What is the variation in genotype I norovirus?

Answer 18

Variation is limited to creating differential binders

Question 19

What is the variation in genotype II norovirus?

Answer 19

Variation creates differential binders and antibody escape mutants

Question 20

Who reports weekly updates regarding outbreaks in the UK?

Answer 20

PHE

Question 21

Is norovirus endemic or epidemic?

Answer 21

Endemic, but occasionally epidemic

Question 22

What season is norovirus most common?

Answer 22

Winter, norovirus is also known as the winter vomiting bug

Question 23

What are the host factors & virulence of cryptosporidium?

Answer 23

Include symptomatic episodes of uncontrolled diarrhoea; immune suppression; reduced/lack of immunity (age associated)

Question 24

What are the risk factors of cryptosporidium?

Answer 24

(Un)intentional defecation in swimming pools; petting zoos/farms; young age

Question 25

What season is cryptosporidium most common?

Answer 25

More common in spring and autumn

Question 26

What age group is at most risk of cryptosporidium?

Answer 26

0-4 year olds and 25-29 (parents)