Issues

Infectious Diseases

Along with “good” micro-organisms that break down sewage, wastewater contains disease-causing bacteria, viruses, fungi and parasites. Sick and infected individuals or animals routinely shed these organisms into the system; and many of these organisms can thrive or even continue to multiply in wastewater. Most are transmitted to humans by swallowing (due to contaminated food, hands or cigarettes), but some can enter through intact skin (leptospirosis) or damaged skin (tetanus).

Studies show that wastewater workers have more parasitic infections than the general population. They also appear to have an increased rate of hepatitis A. Some researchers believe that sewer maintenance and treatment employees may have increased numbers of bacterial, viral and parasitic infections with no signs or symptoms of disease. These are called “sub-clinical” infections.

There is no way to predict if there are dangerous organisms in the wastewater. Examples of common disease-causing organisms include:

Bacteria

Bacteria are primitive, microscopic, one-cell organisms that can enter a worker’s body through swallowing, breathing and skin absorption. Examples of bacteria include:

  • Staphylococci can cause stomach and intestinal problems, fever, nausea, vomiting, headache and diarrhea. It can also cause skin infections as well as lung and respiratory disease.

  • Salmonella and shigella both can produce intestinal symptoms and distress, including high temperatures, vomiting and bloody stools.

  • Leptospirosis (Weil’s Disease) can produce intestinal symptoms, liver and kidney disease, eye problems and jaundice. It is especially common where rats are present.

  • E. coli can produce diarrhea, vomiting and fever.

  • Tulareisis can cause chills, fever and swollen lymph nodes.

  • Less commonly found bacteria in wastewater cause tuberculosis and cholera.

Viruses

Viruses are tiny particles of genetic material covered with a protein coating. Workers can absorb viruses into their bodies by breathing in contaminated water droplets or aerosols, swallowing contaminated water, eating or smoking with contaminated hands or through skin contact. Common disease-causing viruses include:

  • Influenza (“flu” virus) causes intestinal symptoms.

  • Hepatitis A is a virus that attacks the liver. It is transmitted by the fecal-oral (hand-to-mouth) route. The infectious agent is found in feces that can be swallowed if hands are not washed before eating, smoking or drinking. Hepatitis A causes fever, abdominal discomfort, nausea and jaundice (yellowing of the skin). The disease can last from a few weeks to several months, but recovery is usually complete.

  • Rubella (“German measles”) can cause serious birth defects in children whose mothers were exposed during pregnancy.

  • Polio causes paralysis and other effects to any worker who has not been vaccinated.

Bloodborne Diseases

  • Hepatitis B is a bloodborne virus that is transmitted through contaminated body fluids. These fluids include blood, semen, saliva and vaginal secretions. Workers can be infected on the job when infected fluids enter the bloodstream, either by exposure on the mucous membranes (nose or mouth) or through a puncture wound. Hepatitis B infection can have a range of illnesses and cause liver damage. Although some people never feel sick, other people become very ill and may die. Workers may be exposed to hepatitis B in a variety of different ways. For example, a worker may cut him or herself while cleaning sharp objects (such as syringes and needles) out of grates or bar screens, or coming into contact with large amounts of fresh blood or body parts. Although these types of exposure are uncommon, OSHA recommends that wastewater workers be vaccinated against hepatitis B if they are likely to be exposed to blood or syringes at work.

  • HIV/AIDS (Human Immunodeficiency Virus) is the virus that causes Acquired Immune Deficiency Syndrome (AIDS). Transmission of HIV, like hepatitis B, occurs when contaminated body fluids — blood, semen, vaginal secretions or breast milk — enter the bloodstream. HIV destroys the body’s immune system, leaving those infected at risk of developing “opportunistic” infections. The opportunistic infections eventually cause the deaths of HIV-infected persons. There are no known cases of on-the-job HIV transmission among wastewater treatment workers. It is quite unlikely that a sewer or wastewater treatment plant worker would contract HIV/AIDS on the job because HIV particles are not very concentrated in the blood and become further diluted in wastewater. To prevent transmission of bloodborne diseases such as HIV/AIDS or hepatitis B, sewer and wastewater treatment plant workers should receive hepatitis B vaccinations and wear heavy gloves when working with items that may cause cuts.
    For more information, see AFSCME’s Hepatitis B and HIV/AIDS fact sheets.

Parasites

Parasites feed off other living organisms and can cause serious diseases in humans. Infection can occur when workers swallow these parasites and their cysts or if they touch their mouths, smoke with dirty hands or swallow contaminated food. Tapeworms, hookworms and roundworms are examples of parasites. The two most common parasites found in urban sewage are:

  • Entamoeba histolytica (also known as “amebiasis”) is commonly found in rural areas. It was responsible for the tragic death of one New York City sewage treatment plant worker. When a worker swallows water containing entamoeba cysts, the parasite may cause dysentery (diarrhea, cramps, fever and malaise) or produce no symptoms at all. In serious infections, entamoeba can break through the bowel wall, circulate through the body and attack other organs, especially the liver. Symptoms include bloody diarrhea, cramps and fever.

  • Giardia lamblia was once common in rural areas where infected animals contaminate streams. It can cause diarrhea and intestinal distress. Some infected individuals, however, show no symptoms of the disease.

Fungus

Fungi are primitive organisms that grow in decaying material. Workers in dusty sludge composting areas are exposed to fungi that may cause respiratory problems. Most notable is aspergillus fumigatus which causes “farmer’s lung,” a chronic, debilitating allergic lung disease. Aspergillus can also get into the middle ear and cause a severe infection.

Protecting Workers from Infection

The best protection against infection is to avoid direct contact with sewage water, droplets and aerosols. Management should institute engineering controls to reduce foaming at aeration basins and splashing of water around tanks. Adequate ventilation should be provided in grit chambers, bar screens and sludge areas.

Workers have become ill when cross connections occurred between a plant’s water supply and sewage lines. Management should check drinking water supplies routinely to avoid these outbreaks.

Workers should be trained about the nature of infectious diseases. Such training should include the nature of the hazard, methods of entry into the body, symptoms and areas in the facility where there may be a high risk of exposure to biological hazards.

When workers cannot avoid contact with sewage, management should provide the following protective equipment and services:

  • elbow-length rubber gloves;

  • rubber pants and jackets;

  • goggles;

  • disposable mask to be worn in dusty sludge areas or areas with heavy aerosols; and/or

  • commercial high temperature (160o) washing machines for work clothing (only high temperatures will kill cysts).

Workers should also take the following precautions:

  • Wash gloves before removing them; sinks should have pedal controls.

  • Wash hands before smoking and eating; a germicidal (disinfectant) soap should be used.

  • Keep protective clothing and equipment out of eating areas.

  • Keep work clothes and street clothes in separate lockers.

  • Shower and change into street clothes before going home.

  • Launder all work clothing on site — never take them home.

  • Consider all cuts or abrasions to be infected. Flush them with large amounts of clean, running water and antiseptic soap, and bandage them with a sterile dressing.

  • Workers should have a tetanus booster every 10 years and workers who have never been vaccinated for polio should consult a physician about getting a vaccination. Management should keep track of public health developments in case vaccinations against typhoid, paratyphoid, leptospirosis or diphtheria are needed. These shots should be given at management’s expense.

  • Workers should receive the hepatitis A vaccination. Workers who are in sewers that may contain fresh blood or come into regular contact with used syringes or body parts, should receive the hepatitis B vaccination.

  • Trucks that carry materials contaminated with sewage should be washed frequently.

  • Records should be kept of workers’ major and minor illnesses and complaints of irritation and discomfort.

  • Seek medical attention when you have diarrhea or are ill. Since doctors are often unaware of the connections between occupation and disease, be sure to inform your personal physician of job exposure to sewage.

In the case of the New York worker who died of entamoeba histolytica, the cause of his ailment was not discovered until he was on the operating table shortly before he died. Only then did the doctor think to ask the wife of this veteran sewage treatment plant worker if he had ever had any contact with raw sewage. This worker’s life could probably have been saved if the doctors had asked earlier where he worked. Many doctors are not familiar with treating parasitic infections. If there is any doubt, the workers should contact their health department or the Centers for Disease Control and Prevention.

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