It is critical to keep raw sewage out of the environment and away from people. Sewage pathogens have been linked to many illnesses, ranging from mild flu-like symptoms to serious disease, organ failure, and sometimes even death. The types of organisms that may be present in sewage, and the potential health effects associated with each, are described in the table below.

Health Effects

Viruses, such as Norwalk Virus

  • Diarrhea
  • Gastroenteritis
  • Hepatitis
  • Meningitis
  • Pneumonia
  • Paralysis
  • Respiratory infections

Protozoa, such as Cryptosporidium

  • Abdominal cramps
  • Intestinal parasites
  • Severe diarrhea
  • Ulcers

Bacteria, such as Escherischia coli

  • Abdominal pain
  • Cholera
  • Food poisoning
  • Severe diarrhea
  • Typhoid fever

Helminths (worms)

  • Anemia
  • Chest pain
  • Digestive problems
  • Fever
  • Insomnia
  • Muscle aches
  • Vomiting


People get exposed to pathogens by ingesting them, sometimes by accidentally swallowing contaminated water while swimming or drinking it from the tap. Pathogens can also be ingested via contaminated food, such as fish and shellfish that are caught in contaminated water. Once some people contract a pathogen-borne disease, they become carriers of the disease and can infect others through the fecal to oral route. Many healthy adults can fight off the milder forms of sewage-born illness, experiencing flu-like symptoms for a few days and then recovering completely. Others, including elderly people, children, and people with suppressed immune systems, are at greater risk for more severe disease.

Viruses are believed to be the major cause of disease contracted through direct contact with sewage, and are responsible for gastroenteritis, hepatitis, respiratory illness, and other health problems. One of the most common, the Norwalk Virus, is representative of a heterogenous group of viruses, also called small round structured viruses (SRSVs) or the Norwalk-like family of agents. Common names of the illness caused by the Norwalk and Norwalk-like viruses are viral gastroenteritis, acute nonbacterial gastroenteritis, food poisoning, and food infection.

The protozoan Cryptosporidium parvum causes cryptosporidiosis, a gastrointestinal disease that affects people and animals.Upon infection, this protozoan resides principally in the gastrointestinal tract and goes through its life stages as an intracellular parasite. In the intestines, it forms oocysts (similar to parasite eggs) that are shed in feces and which are the source of infection for new susceptible people.

Bacteria in sewage, such as Escherischia coli and enterococci, can cause many diseases and illnesses. Enterococci are bacteria that normally live in the bowel, intestines and digestive tracts of humans.The bacteria help to break down wastes in the body, but can cause urinary tract infections, wound infections and blood infections if they get out of their normal environment. Today, new strains of the bacteria, called VRE (Vancomycin Resistant Enterococcus), have developed a resistance gene to most antibiotics. Since enterococci are found normally in the intestines, every time an antibiotic is taken, the bacteria are exposed. This resistance gene makes it very difficult for doctors to treat a VRE patient. Those most at risk from VRE are people who are already seriously ill