Engineer at a wastewater treatment plant
Credit: © kittirat roekburi/Shutterstock

In 2020, at the start of the global COVID-19 pandemic, officials began testing wastewater for the virus. This tool soon helped officials track where the virus was spreading and whether cases were dropping in certain communities. What is wastewater and why is it used to track viruses? Wastewater comes from residential purposes such as bathing, laundry, and dishwashing. Most of the water in our homes is used to carry away wastes. This water, and the wastes it carries, is called sewage. Recently, scientists have employed this water for another purpose –virus tracking! It might not wear a cape, but it is helping officials prepare for outbreaks and provide information for residents on COVID-19, monkeypox, and polio. All three of these viruses are spreading in the United States.

In most U.S. cities, a piping system under the streets carries away the sewage from homes, factories, hotels, and other buildings. A system of pipes that carries sewage from buildings is called a sanitary sewerage system. Sewage has a bad odor. But more important, it contains disease-producing bacteria. Most cities have treatment plants that clean sewage water and kill the bacteria in it. The treated water can then be returned to a river, stream, or lake.

Almost all of the sewage in the United States undergoes some type of sewage treatment. Only a little of the sewage is dumped untreated into rivers. The dumping of untreated sewage causes serious problems for the environment and for cities downstream that take their water from the same rivers. Untreated sewage looks and smells foul, and it kills fish and aquatic plants.

Water treatment can also help scientists and disease experts track harmful viruses. Lately, officials have been testing wastewater for COVID-19, monkeypox, and polio. Officials are trying to control the spread of viruses to prevent epidemics. An epidemic is an outbreak of disease that attacks many people at about the same time. An epidemic may last a few hours, a few weeks, or many years. A disease that spreads throughout the world is pandemic. Public health agencies are responsible for the control of epidemics. Immunizations can prevent epidemics of some infectious diseases. Vaccines are available for COVID-19, monkeypox, and polio. Other epidemics are prevented by maintaining clean food and water supplies, or by controlling insects and other animals that spread disease. Informing people about the causes of epidemics and methods of prevention is crucial in the control of epidemics.

The next time you walk by a smelly sewer, remember not all heroes wear capes or smell good. When you see the case numbers or affected areas, tell your family and friends we have our wastewater and many dedicated scientists to thank!

An electron microscope shows monkeypox virus particles.
Credit: Cynthia S. Goldsmith and Russell Regnery, CDC

On May 13, 2022, the World Health Organization was notified of two confirmed cases of monkeypox in the United Kingdom. Not the chickenpox, monkeypox! Since then, cases have been detected in Canada, Italy, Portugal, Spain, Sweden, and the United States. Many people are now asking: what is monkeypox and how bad is it?

Monkeypox is a viral disease that affects animals and, in rare cases, human beings. Scientists first isolated and identified the monkeypox virus from laboratory monkeys in 1958. They obtained it from monkeys that had an unusual rash of skin pustules (small bumps filled with fluid). Historically, such pustules were called pox, leading to the name monkeypox. Other animals, including rats, squirrels, and mice, can also carry monkeypox.

People that eat or get bitten by infected animals can catch monkeypox, but the virus does not spread easily from person to person. The disease is uncommon in human beings. The first human case of monkeypox was not recorded until 1970.

Monkeypox occurs naturally among wild animal populations of central and western Africa. Since the 1970’s, it has caused occasional outbreaks of illness among people in the region. In 2003, 71 people in Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconsin became ill with confirmed or suspected cases of monkeypox. They caught the disease after handling prairie dogs that were purchased at a pet shop in Illinois. Prairie dogs do not naturally carry the monkeypox virus. The animals became infected at the pet shop, where they were housed with a rodent called a Gambian giant rat that carried the virus. An animal dealer had imported the rat from Africa to sell it as a pet.

Several people were hospitalized in the 2003 outbreak, but there were no deaths. Physicians and veterinarians quickly quarantined (isolated) people and animals that might have been exposed to the virus. This action was designed to prevent the disease from spreading to other people, pets, or wild animals. Following the outbreak, the United States Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) banned the importation of rodents from Africa. They also banned the transport and sale of prairie dogs and African rodents within the United States.

Symptoms of the disease develop about two weeks after a person is exposed to the monkeypox virus. Symptoms include fever, headache, muscle pain, backache, and swelling of lymph nodes. Following the fever, a rash appears on the face and other parts of the body. The rash develops into fluid-filled pustules, which dry up and fall off. The illness lasts from two to four weeks. In Africa, from 1 percent to 10 percent of people infected with monkeypox die from the disease.

Physicians suspect monkeypox if a person shows the symptoms and has had contact with an infected person or animal. Laboratory tests are used to detect the monkeypox virus in samples from blood, pustules, or scabs of patients.

People can prevent infection by not handling wild animals that may carry the virus. The monkeypox virus is related to the virus that causes smallpox. Smallpox vaccine can protect against monkeypox when it is given before a person is exposed to the virus. Smallpox vaccination given after exposure to monkeypox may help prevent the disease or make it less severe. However, because the disease is uncommon, health officials do not recommend widespread smallpox vaccination to protect people from monkeypox.

July 28, 2014

The worst recorded epidemic of the deadly and highly contagious Ebola virus led the West African nation of Liberia today to close most of its border crossings. Liberia is one of three nations, along with Sierra Leone and Guinea, that are being hard hit by the virus. Liberia’s President Ellen Johnson-Sirleaf also issued restrictions on public gatherings and said areas hit by the virus could be quarantined. The current outbreak of Ebola hemorrhagic fever, which began in  March in southern Guinea, has killed at least 670 people, including the Liberian doctor who was heading his country’s efforts to contain the epidemic. Yesterday, Nigeria’s Arik Air suspended all flights into Sierra Leone and Guinea after Nigerian officials confirmed the first Ebola death in Lagos, Nigeria’s capital and the most populous city in Africa. Meanwhile, medical workers in Guinea were meeting hostility and resistance from residents who blamed them for spreading the disease.

Ebola hemorrhagic fever is characterized by massive internal bleeding as well as diarrhea and vomiting. It is spread by direct contact with such bodily fluids as saliva and blood and by contact with towels and other objects cotaminated by the virus. While animals, including chimpanzees and gorillas, can transmit the virus, the natural source is unknown. There is no cure or vaccine for the disease. Symptoms appear within 5 to 10 days of infection. About 80 to 90 percent of all people who become infected die, though patients who receive treatment while in the early stages of the disease have a slightly better chance of recovery. Treatment consists mainly of rehydration to replace lost body fluids.

The current Ebola outbreak began in southern Guinea in March and has spread to Liberia and Sierra Leone. (World Book map; map data © MapQuest.com, Inc.)

As of July 20, Ebola had killed 454 people in Sierra Leone; 314 in Guinea; and 224 in Liberia, according to the World Health Organization (WHO). Forty-five cases, including 28 deaths, were reported in those three countries between July 18 and 20 alone.

Most hemorrhagic viruses have a host, often a rodent or insect, which carries the virus but does not become ill. Scientists have not yet identified the host for the Ebola virus. However, the bushmeat trade is highly suspected of spreading the virus among people. The WHO has warned people against eating raw bushmeat and avoiding contact with infected apes, bats, and monkeys.

Additional World Book article:

• Disease Detectives (a special report)
• The Origin of New Diseases (a special report)

June 16, 2014

In a series of controversial experiments, scientists at the University of Wisconsin in Madison have re-created in a laboratory a strain of influenza virus that closely resembles the virus responsible for the Spanish flu pandemic (global occurrence) of 1918 that killed over 50 million people worldwide. The scientists contend that they re-created the deadly virus as a necessary step to help combat future flu pandemics. However, critics of the research argued that the experiments should be halted immediately as they pose a great threat to public safety.

Influenza tends to occur in widespread epidemics that occur most every year. Each outbreak is caused by a virus slightly different from earlier ones. Some strains (types) cause mild or moderate illness, and others cause many deaths. The Spanish flu of 1918 was the deadliest outbreak of influenza in history. Medical historians believe the Spanish flu virus, like many strains of influenza, probably originated in Asia. The disease quickly spread to the United States, Europe, Africa, and South America. During the height of the pandemic, the huge number of deaths severely disrupted many societies. Less severe pandemics occurred in 1957 and in 1968 but still resulted in many deaths.

Influenza viruses (shown here are greatly magnified and artificially colored) may cause flu when they are inhaled. (© Linda Stannard, UCT/SPL from Photo Researchers)

The Wisconsin scientists, led by Yoshihiro Kawaoka, isolated several genes from influenza viruses that normally infect wild ducks in Asia. These “avian influenza” (also known as “bird flu) viruses often mutate so they can infect mammals, including humans, and spread in global pandemics. Using a technique known as “reverse genetics,” the scientists used the individual genes to reconstruct an entire flu virus. They compared this rebuilt virus to virus samples from frozen corpses of victims of the 1918 Spanish flu pandemic recovered in Alaska. The rebuilt virus was 97 percent identical to the deadly Spanish flu virus.

The scientists infected ferrets with the re-created virus so they could study how it infected and spread among mammals. Kawaoka contends that such experiments are important so scientists can understand why the 1918 Spanish flu virus was so lethal, compared to other strains of flu that originate in wild birds. For example, the scientists identified a mutation in the rebuilt virus that enabled it to spread more easily from one animal to another. Scientists argue that continued research will help them better understand how the virus infects animals and makes them ill. This information will be useful for developing effective vaccines and treatments to combat future flu pandemics.

Other scientists argue that the research is too dangerous to continue and that another Spanish flu pandemic is unlikely to occur naturally. They claim that the most serious risk lies with the rebuilt virus being released from the high-security laboratory through some accident. Should an infected research animal escape, the deadly virus could spread rapidly in a new global pandemic with catastrophic results. The United States National Institutes of Health (NIH) which funds the controversial research, insisted that proper safety measures are being taken and that funding for the research would continue.

Additional World Book articles:

• SARS
• Swine flu
• Influenza: A New Threat from an Old Foe (a Special Report)
• Medicine in the 21st Century: The Promise of Genetics (a Special Report)

May 14, 2013

Officials at the World Health Organization (WHO) expressed concern that a severe respiratory disease caused by a newly identified virus, which has killed at least 18 people in the Middle East and Europe, can be spread from person to person. The virus is a previously unknown type of coronavirus. A coronavirus from this same family triggered the outbreak of Severe Acute Respiratory Syndrome (SARS), which swept through Asia in 2003 and 2004, infecting more than 8,000 people and killing almost 800. The new coronavirus is related to, but distinct from, the virus that caused SARS. In both SARS and this new disease, patients develop severe pneumonia and sometimes kidney failure, leading to death.

During a pandemic, people may cover their face with masks to protect themselves from a communicable disease. (© Jorge Dan, Reuters)

In humans, coronaviruses are among the many viruses that cause common colds. Corona is the Latin word for crown, and the name coronavirus comes from the crownlike spikes that can be seen on the surface of the virus when it is viewed under a powerful electron microscope. Other types of coronaviruses cause serious or fatal disease in such livestock as hogs, cattle, and chickens.

The new outbreak of disease began in the Middle East in late 2012. The first cases were reported from Saudi Arabia, Dubai, and Jordan. Public-health experts do not yet know where this news SARS-like coronavirus originated. Many suspect it may be a coronavirus that normally infects animals. Closely related coronaviruses have been isolated from camels and bats from the Middle East. Medical experts think that perhaps such a coronavirus underwent a mutation that now allows it to infect humans. Most of the 34 reported cases occurred among people who likely had some contact with infected animals.

By May 2013, other cases have been reported from Germany, the United Kingdom, and most recently France, among individuals who had recently returned home from travel to the Middle East.  However, one patient in France became ill after sharing a hospital room with a patient who fell ill with the virus after returning from Dubai, leading health officials to worry that the virus can spread from person to person when an infected person coughs or sneezes.

Health officials have not yet issued travel warnings or other taken other precautions to prevent the spread of the disease. Officials remain watchful since other coronaviruses have had the ability to spread rapidly across the world in global pandemics. However, there is no evidence that this new coronavirus has the ability to become so widespread.

Other World Book articles:

• The Origin of New Diseases (a Special report)
• Public Health and Safety 2003 (a Back in time article)
• Zoonosis

August 23, 2012

The current outbreak of West Nile virus is one of the largest on record in the United States, with four times the usual number of cases for this time of year, announced the Centers for Disease Control and Prevention (CDC) on August 22. According to the CDC, never before have so many illnesses been reported this early. “We’re in the midst of one of the largest West Nile outbreaks ever seen in the United States,” CDC official Lyle Petersen told The Washington Post. So far this year, 1,118 illnesses have been confirmed, with 41 deaths. In an average year, fewer than 300 cases are reported by mid-August. Approximately half of the 1,118 cases have been in Texas.

Epidemiologists suggest that the combination of a mild winter, early spring, and unusually hot summer has resulted in a-larger-than-normal number of mosquitoes. Mosquitoes acquire the virus from birds they bite and carry it to human beings. The first known case of West Nile in the United States was reported in New York City in 1999.

A worker in Louisiana sprays chemicals on timber to control the mosquito population and halt the spread of the West Nile virus. The virus is transmitted through the bites of mosquitoes. Public health officials use pesticides to eliminate mosquitoes. (Dan Currier, The News Star)

To avoid West Nile, the CDC recommends:

• Using an insect repellent containing an EPA-registered ingredient.
• Maintaining screens on windows and doors.
• Emptying standing water from flower pots, buckets and barrels, and children’s wading pools and changing the water in pet dishes and bird baths.

Additional World Book articles:

• Disease Detectives (a special report)
• New York City 1999 (a Back in Time article)
• New York City 2000 (a Back in Time article)
• Public health 2002 (a Back in Time article)
• Public health 2003 (a Back in Time article)
• Public health 2004 (a Back in Time article)

May 24, 2012

A group dedicated to eradicating polio worldwide launched an emergency plan after recent outbreaks of the disease threatened countries that previously had been free of polio. The group, known as the Global Polio Eradication Initiative (GPEI), headquartered in Geneva, Switzerland, was launched by the World Health Organization (WHO), national governments, the U.S. Centers for Disease Control and Prevention, the United Nations Children’s Fund (UNICEF), and Rotary International in 1988.

Polio, officially known as poliomyelitis, is an infection caused by a virus. Some people may have only such mild, short-term symptoms as headache, sore throat, and vomiting. Others may develop back and leg pain that leads to permanent paralysis.

In the past, polio epidemics were common throughout the world and greatly feared. However, during the 1950′s, American researcher Jonas E. Salk developed the first vaccine against polio. In 1961, an oral vaccine developed by another American researcher, Albert B. Sabin, was approved. The vaccines quickly became part of the standard vaccination regimen recommended for children. Since then, polio has been nearly eliminated in developed countries. From 1955 to 1957 in the United States, inoculation reduced the incidence of polio by 85 to 90 percent. When GPEI was founded in 1988, more than 350,000 children in more than 125 countries were paralyzed from polio each year. By the first decade of the 2000′s, the incidence of polio had been reduced by 99 percent.

Dr. Salk administers the polio vaccine to a child in 1954 as part of a mass testing program. (Courtesy of March of Dimes Foundation)

In early 2012, health officials at WHO were thrilled to announce that India (the second most populous country in the world) had been free of polio for one year. Nevertheless, polio remains endemic (constantly present somewhere in the population) in Afghanistan, Pakistan, and Nigeria. In addition, China, Tajikistan, and West Africa reported large outbreaks of polio in 2012, their first cases in many years. Epidemiologists (doctors who study epidemics) determined that the disease had spread into China from Pakistan and into West Africa from Nigeria.

An infant in Afghanistan is immunized against polio through a program administered by UNICEF. (Courtesy of AP/Wide World)

GPEI officials urged donor countries to step up funding so that the group could intensify its efforts to increase vaccination coverage in Afghanistan, Pakistan, and Nigeria. The group hoped that more technical assistance and greater social mobilization would increase accountability, coordination, and oversight of each country’s vaccination campaign and ease cultural misconceptions that often interfere with immunization.

Additional World Book articles

• Iron lung
• March of Dimes Foundation
• Roosevelt, Franklin Delano
• Fighting a Persistent Foe (a special report)
• Medicine 1955 (Back in Time article)
• Medicine 1959 (Back in Time article)
• Medicine 1960 (Back in Time article)
• Medicine 1961 (Back in Time article)
• Medicine 1963 (Back in Time article)
• Nobel Prizes 1954 (Back in Time article)