Any of several processes in which undesirable impurities in water are removed or neutralized; for example, chlorination, filtration, primary treatment, ion exchange, and distillation. It includes treatment of WASTE WATER to provide potable and hygienic water in a controlled or closed environment as well as provision of public drinking water supplies.
Practice of adding fluoride to water for the purpose of preventing tooth decay and cavities.
A rating of a body of water based on measurable physical, chemical, and biological characteristics.
Water Pollutants, Chemical
Fluids composed mainly of water found within the body.
A branch of engineering concerned with the design, construction, and maintenance of environmental facilities conducive to public health, such as water supply and waste disposal.
A chronic endemic form of hypoplasia of the dental enamel caused by drinking water with a high fluorine content during the time of tooth formation, and characterized by defective calcification that gives a white chalky appearance to the enamel, which gradually undergoes brown discoloration. (Jablonski's Dictionary of Dentistry, 1992, p286)
A greenish-yellow, diatomic gas that is a member of the halogen family of elements. It has the atomic symbol Cl, atomic number 17, and atomic weight 70.906. It is a powerful irritant that can cause fatal pulmonary edema. Chlorine is used in manufacturing, as a reagent in synthetic chemistry, for water purification, and in the production of chlorinated lime, which is used in fabric bleaching.
Inorganic compounds that contain chlorine as an integral part of the molecule.
Constructions built to access underground water.
Water Pollution, Chemical
A species of parasitic protozoa that infects humans and most domestic mammals. Its oocysts measure five microns in diameter. These organisms exhibit alternating cycles of sexual and asexual reproduction.
INFLAMMATION of any segment of the GASTROINTESTINAL TRACT from ESOPHAGUS to RECTUM. Causes of gastroenteritis are many including genetic, infection, HYPERSENSITIVITY, drug effects, and CANCER.
The withholding of water in a structured experimental situation.
A family of gram-negative, facultatively anaerobic, rod-shaped bacteria that do not form endospores. Its organisms are distributed worldwide with some being saprophytes and others being plant and animal parasites. Many species are of considerable economic importance due to their pathogenic effects on agriculture and livestock.
The routing of water to open or closed areas where it is used for agricultural purposes.
Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.
A plant genus of the family FABACEAE that is a source of prosopis gum.
Infection with nematodes of the genus Dracunculus. One or more worms may be seen at a time, with the legs and feet being the most commonly infected areas. Symptoms include pruritus, nausea, vomiting, diarrhea, or asthmatic attacks.
Substances used on inanimate objects that destroy harmful microorganisms or inhibit their activity. Disinfectants are classed as complete, destroying SPORES as well as vegetative forms of microorganisms, or incomplete, destroying only vegetative forms of the organisms. They are distinguished from ANTISEPTICS, which are local anti-infective agents used on humans and other animals. (From Hawley's Condensed Chemical Dictionary, 11th ed)
Islands lying between southeastern North America and northern South America, enclosing the Caribbean Sea. They comprise the Greater Antilles (CUBA; DOMINICAN REPUBLIC; HAITI; JAMAICA; and PUERTO RICO), the Lesser Antilles (ANTIGUA AND BARBUDA and the other Leeward Islands, BARBADOS; MARTINIQUE and the other Windward Islands, NETHERLANDS ANTILLES; VIRGIN ISLANDS OF THE UNITED STATES, BRITISH VIRGINI ISLANDS, and the islands north of Venezuela which include TRINIDAD AND TOBAGO), and the BAHAMAS. (From Webster's New Geographical Dictionary, 1988, p1330)
A shiny gray element with atomic symbol As, atomic number 33, and atomic weight 75. It occurs throughout the universe, mostly in the form of metallic arsenides. Most forms are toxic. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), arsenic and certain arsenic compounds have been listed as known carcinogens. (From Merck Index, 11th ed)
Liquid water present beneath the surface of the earth.
Infection with flukes (trematodes) of the genus SCHISTOSOMA. Three species produce the most frequent clinical diseases: SCHISTOSOMA HAEMATOBIUM (endemic in Africa and the Middle East), SCHISTOSOMA MANSONI (in Egypt, northern and southern Africa, some West Indies islands, northern 2/3 of South America), and SCHISTOSOMA JAPONICUM (in Japan, China, the Philippines, Celebes, Thailand, Laos). S. mansoni is often seen in Puerto Ricans living in the United States.
The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.
The science, art or practice of cultivating soil, producing crops, and raising livestock.
Prolonged dry periods in natural climate cycle. They are slow-onset phenomena caused by rainfall deficit combined with other predisposing factors.
A selective triazine herbicide. Inhalation hazard is low and there are no apparent skin manifestations or other toxicity in humans. Acutely poisoned sheep and cattle may show muscular spasms, fasciculations, stiff gait, increased respiratory rates, adrenal degeneration, and congestion of the lungs, liver, and kidneys. (From The Merck Index, 11th ed)
Large vessels propelled by power or sail used for transportation on rivers, seas, oceans, or other navigable waters. Boats are smaller vessels propelled by oars, paddles, sail, or power; they may or may not have a deck.
Collection, analysis, and interpretation of data about the frequency, distribution, and consequences of disease or health conditions, for use in the planning, implementing, and evaluating public health programs.
Conservation of Natural Resources
Sodium or potassium salts of long chain fatty acids. These detergent substances are obtained by boiling natural oils or fats with caustic alkali. Sodium soaps are harder and are used as topical anti-infectives and vehicles in pills and liniments; potassium soaps are soft, used as vehicles for ointments and also as topical antimicrobials.
Colony Count, Microbial
Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing.
Intestinal Diseases, Parasitic
One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.
An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.
An acute diarrheal disease endemic in India and Southeast Asia whose causative agent is VIBRIO CHOLERAE. This condition can lead to severe dehydration in a matter of hours unless quickly treated.
United States Environmental Protection Agency
A class of porins that allow the passage of WATER and other small molecules across CELL MEMBRANES.
Contamination of the air, bodies of water, or land with substances that are harmful to human health and the environment.
A parliamentary democracy with a constitutional monarch in southeast Asia, consisting of 11 states (West Malaysia) on the Malay Peninsula and two states (East Malaysia) on the island of BORNEO. It is also called the Federation of Malaysia. Its capital is Kuala Lumpur. Before 1963 it was the Union of Malaya. It reorganized in 1948 as the Federation of Malaya, becoming independent from British Malaya in 1957 and becoming Malaysia in 1963 as a federation of Malaya, Sabah, Sarawak, and Singapore (which seceded in 1965). The form Malay- probably derives from the Tamil malay, mountain, with reference to its geography. (From Webster's New Geographical Dictionary, 1988, p715 & Room, Brewer's Dictionary of Names, 1992, p329)
Nephelometry and Turbidimetry
Chemical analysis based on the phenomenon whereby light, passing through a medium with dispersed particles of a different refractive index from that of the medium, is attenuated in intensity by scattering. In turbidimetry, the intensity of light transmitted through the medium, the unscattered light, is measured. In nephelometry, the intensity of the scattered light is measured, usually, but not necessarily, at right angles to the incident light beam.
The act of cleansing the hands with water or other liquid, with or without the inclusion of soap or other detergent, for the purpose of destroying infectious microorganisms.
A climate which is typical of equatorial and tropical regions, i.e., one with continually high temperatures with considerable precipitation, at least during part of the year. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Geographic Information Systems
An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.
Deoxyribonucleic acid that makes up the genetic material of bacteria.
The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.
Animate or inanimate sources which normally harbor disease-causing organisms and thus serve as potential sources of disease outbreaks. Reservoirs are distinguished from vectors (DISEASE VECTORS) and carriers, which are agents of disease transmission rather than continuing sources of potential disease outbreaks.
The constant presence of diseases or infectious agents within a given geographic area or population group. It may also refer to the usual prevalence of a given disease with such area or group. It includes holoendemic and hyperendemic diseases. A holoendemic disease is one for which a high prevalent level of infection begins early in life and affects most of the child population, leading to a state of equilibrium such that the adult population shows evidence of the disease much less commonly than do children (malaria in many communities is a holoendemic disease). A hyperendemic disease is one that is constantly present at a high incidence and/or prevalence rate and affects all groups equally. (Last, A Dictionary of Epidemiology, 3d ed, p53, 78, 80)
Techniques used in studying bacteria.
Infections with bacteria of the genus CAMPYLOBACTER.
Parasite Egg Count
Determination of parasite eggs in feces.
RNA, Ribosomal, 18S
A province of Canada lying between the provinces of Manitoba and Quebec. Its capital is Toronto. It takes its name from Lake Ontario which is said to represent the Iroquois oniatariio, beautiful lake. (From Webster's New Geographical Dictionary, 1988, p892 & Room, Brewer's Dictionary of Names, 1992, p391)
A species of trematode blood flukes of the family Schistosomatidae. It is common in the Nile delta. The intermediate host is the planorbid snail. This parasite causes schistosomiasis mansoni and intestinal bilharziasis.
Molecular Sequence Data
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
Sequence Analysis, DNA
Any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). It may result from natural factors such as changes in the sun's intensity, natural processes within the climate system such as changes in ocean circulation, or human activities.