Lecture 2

Microbial element is what makes our water clean. When it comes to safe, other factors come in play, such as accessibility and issues around scarcity of water. Millions of people reliant on surface water – surface water risky as it hasn’t been treated and when rains, run off from lands comes into water such as microbial content and faeces of animals. 144 million people dependent on surface water 785 million people don’t have access to safe drinking water 2 billion people drinking from faecal contaminated water 850,000 people die a year due to unclean, unsafe water

71% of people use a safely managed drinking water service WHO has set up a range of regulations for drinking water.

Sanitation and hygiene is important for water to prevent transmission of water bourn diseases

Water filtration Water is filtered through various rocks and course sand to remove particular matter Charcoal removes chemical impurities in water Individual water filtration can be done with filtration straws, however on a global scle it is more difficuilt Sewage treatment Raw sewage from toilet comes in and goes through some screens and gets mushed up. It then hits the grit chamber for disposal and the rest of the water mixed with effluent goes through clarifiers which allows organic matter to settle out and clean water goes through aeration tank and will settle out in secondary clarifier. If you bottle water for treatment, you take source and expose to ozone which destroys bacteria. Then go through various filtering steps which removes particulates and carbon filter, removes chemicals and pesticides. Then go through polisher and reverse osmosis (extracting salts from water and purify it). Then mineral control happens and is exposed to ozone before being bottled. Acceptable limits for clean safe drinking water: Mains water E.coli = 0/100ml Coliforms = 0/100ml – doesn’t mean 0 as if you sample litres upon litres youll find a lot of coliforms and E.coli. Waterborne diseases Bacterial: Cholera, gastroentetris

• Refugee camps are a place where loads of bacteria can enter water   Viral:   Norovirus, rotovirus   Protozoan:   Cryptosporidium parvum

Norovirus Family: Caliciviridae Genus: Norovirus Structure: Non-enveloped, icosahedral Size: 38nm diameter Nucleic acid: 7.5 kb positive sense, single stranded RNA (Baltimore Classification IV) Host and Virulence Factor: “Shape-shifter”; sheds billions of viral particles; small dose; highly contagious Dangerousness Score: 6 Norovirus genome organisation

• Has 3 different open reading frames
• Depending on the reading frame, give you 3 different genes that are being expressed   In the capsid protein region there is a functional impact in norovirus. Any changes in capsid has effects.   The capsid has high variability meaning it can escape the immune systems responses by changing rapidly.

Norovirus is endemic in the UK

Cryptosporidium Family: Cryptosporidiiae Genus: Cryptosporidium Human pathogens: C. parvum; C. hominis Risk factors: (un)intentional defecation in swimming pools; petting zoos/farms; young age Host Factors & Virulence: include symptomatic episodes of uncontrolled diarrhoea; immune suppression; reduced/lack of immunity (age associated) Dangerousness Score: 5

Oocysts is injected by people. Once it has been injected, it excystation occurs in the gut and invaded and multiplies before being released as future oocysts and contaminating water sources. Cattle are a major source of cryptosporidium Norovirus is mainly winter, cryptosporidium is sporing/autumn.