Water and Wastewater Microbiology
Bacterial Pathogens - "The Big 5"
Salmonella - salmonellosis
S. typhimurium - typhoid fever
Shigella - shigellosis
Enterotoxigenic E. coli (ETEC) - diarrhea
Vibrio cholerae - cholera
Camplyobacter jejuni - gastroenteritis
Viral Pathogens - Over 120 enteric viruses, all pathogenic to humans, low minimum infectious dose
Hepatitis A - hepatitis
Norwalk-like agents - gastroenteritis
Virus-like 27 nanometer particles - gastroenteritis
Rotavirus - gastroenteritis
Protozoal Pathogens - "The Big 3" in Temperate Zone Countries
Cryptosporidium parvum - cryptosporidiosis
Giardia lamblia - giardisis
Entamoeba histolytica - amoebic dysentery
Different pathogens can be transmitted by a variety of sources. For example, Giardia and Cryptosporidium outbreaks are often associated with cattle, and E. coli 0157:H7 outbreaks are usually tied to beef products. Giardia is also spread by deer (backpacker's disease), and Canada geese feces have been found to contain Cryptosporidium, Giardia, and Campylobacter. Salmonellosis is commonly associated with hogs (as well as Vibrio), poultry, and waterfowl, and Campylobacter is widespread in poultry and waterfowl. Most viral gastroenteritis is caused by contact with human feces. All of these organisms pose a risk to human public health.
Disease Outbreaks Today (http://www.cdc.gov/mmwr//mmwr_ss.html)
Waterborne Diseases and the fecal-oral route
Worldwide - 250 million cases, 10 million deaths
U.S. - 30-40 outbreaks/yr, 10,000 cases total (these are averages, range is much wider)
Onsite: Average of 10-12 outbreaks/yr, 2,500 cases (no reporting required)
Community: 10-15 outbreaks/yr, 5,000 cases (reporting is mandatory, CDC)
Recreational: 10-12 outbreaks/yr, 2,000 cases (no reporting required)
Why so low in the U.S.?
Community wastewater treatment
Standards for onsite systems
Treatment of drinking water
Mandatory nationwide vaccination programs
With filtering and chlorinating of public water supplies, drinking water in the U.S. is among the cleanest in the world. These practices, combined with proper sewage treatment and immunization have virtually eliminated diseases such as typhoid fever, cholera, and polio in the U.S. (but these diseases are still common in many other parts of the world). There are some 30-40 outbreaks of waterborne disease and roughly 10,000 cases of illness from these outbreaks in the U.S. each year. This is less than 10% of the number of out breaks that occurred some 40 years ago, before the development of public water and sewer systems. There are some 10 to 20 outbreaks yearly with roughly 2,000 cases of illness associated with recreational water use.
Who is at Risk?
Roughly one-half of the current outbreaks and one-third of the illnesses mentioned above are from contamination in well water. Seepage or overflow from improperly functioning septic systems has been cited as the most common cause of well water contamination. Reporting outbreaks and illnesses of waterborne disease in non-community water sources and recreational waters is voluntary, so nobody knows how many disease outbreaks caused by contaminated well water or by recreational exposure to contaminated water there really are.
Escherichia, Enterobacter, Klebsiella, Citrobacter
Escherichia, Klebsiella, Citrobacter (60% to 90% of total coliforms are fecal coliforms) 90%+ of fecal coliforms are Escherichia (usually E. coli) (http://www.bsi.vt.edu/biol_4684/Microbes/Ecoli.html)
Presence-Absence Test (http://www.bsi.vt.edu/biol_4684/BST/NOWRA.pdf)
Most-Probable Number (http://www.bsi.vt.edu/biol_4684/mpncoli.html)
Membrane Filtration (http://www.bsi.vt.edu/biol_4684/mfcoli.html)
The "Fecal Streptococci"
Enterococcus - 18 species, all enteric (http://www.bsi.vt.edu/biol_4684/Microbes/entero.html)
Streptococcus - 40+ species, 8-10 enteric
Membrane Filtration (http://www.bsi.vt.edu/biol_4684/mfstrep.html)
Virus Detection (coliphages? http://filebox.vt.edu/cals/cses/reneau/projects/agar.html)
Protozoal Detection? (a DNA probe? http://www.bsi.vt.edu/biol_4684/Microbes/crypto.htm)
Bacterial Source Tracking
The total maximum daily load (TMDL) initiative currently being implemented in the U.S. will result in the identification of waters that contain fecal bacteria of different origins, such as human, wildlife, and livestock. Correct source identification will allow development of BMPs that target actual sources, rather than estimated ones.
Source Tracking Webpage: http://www.bsi.vt.edu/biol_4684/BST/BST.html