Waterbourne Pathogens

Microbiology: An introduction to the microbial world – WATERBORNE DISEASES

Freshwater and sea water = source of pathogens

* 2 main drains which take away waste water:

-toilets

-surface water drains (e.g. gutters for rainfall)

* Agents of waterborne disease may enter body via three main routes:

-Gastrointestinal

-Respiratory

-Skin

1) Examples of gastric waterborne pathogen

* CHOLERA = caused by Vibrio cholerae

-linked to malnutrition

-occurs in areas of extreme poverty

-symptoms: diarrhoea, severe dehydration

-can lead to death if untreated

-cholera toxin acts on the mucosal epithelium of digestive tract

-it prevents host cells from regulating sodium/chloride flux

-results in loss of water from host cells

* TYPHOID FEVER = caused by Salmonella typhi

-geographical distribution is similar to cholera

- disease of the gut

-transmission:

-- person to person

--sewage in water

--peritrichous flagella

-symptoms: fever, abdominal pains, headache, loss of appetite and weakness, rash of flat rose-coloured spots

-pathogenesis: bacteria induce apoptosis in order to invade human tissue

--10% of untreated people die

* NORWALK VIRUSES – this is an intestinal illness that had worldwide distrubition – often occurs in outbreaks (person to person transmission)

-common in UK

-Source of infection:

Human are the only known hosts – the infection is acquired by:

--swallowing contaminated food or water

--eating raw shellfish

--contaminated water used for prep of ice cubes and ready to eat food

-Symptoms: nausea, vomiting, diarrhoea, stomach cramps

--Severe illness/hospitalisation is uncommon – infected persons usually recover in 2 or 3 days without serious/long term health effects

* CRRYPTOSPORDIUM PARVUM – parasitic protozoan that causes cryptosporidiosis

-Oocysts = cyst containing a zygote formed by a parasitic protozoan such as the malaria parasite

--highly infectious –...