Glossary
General Terms
Adverse event: An injury or other undesirable outcome related to medical or public health intervention.
Antenatal: Occurring before birth; prenatal.
Blinded (study or trial): Participants are unaware of assignment to the intervention or control group. Being aware of intervention status can lead to conscious or unconscious bias in measurement of study outcomes. In a "Single-blind " study, the study subjects are unaware; in "double-blind " neither subjects nor researchers are aware. See also "Unblinded."
Clinically significant: A result (e.g. a treatment effect) that is large enough to be of practical importance to patients and healthcare providers. This is different than statistically significant (see).
Cochrane review: Cochrane Reviews are systematic reviews (usually meta-analyses) of evidence of the effects of health care interventions, following stanardized protocols for analysis and reporting. The reviews are maintained in a collection of databases, published on CD-ROM and the Internet and updated quarterly. See also "Meta-analyses".
Comorbidity: Presence of one or more diseases or conditions other than those of primary interest. In a study looking at treatment for one disease or condition, some of the individuals may have other diseases or conditions that could affect their outcomes
Confidence interval (CI): Measure of uncertainty around the main finding of a statistical analysis. Usually presented as a point estimate and a 95% confidence interval, which means that the true value of the finding is within this interval with 95% certainty. See also "Statistically significant".
Control group: The arm that acts as a comparator for one or more experimental interventions. (Also called comparison group.)
Cost-effectiveness: The economic value of resources required for an intervention to achieve a given unit of health benefit, such as an HIV case averted. Expressed as a ratio, "cost per HIV infection averted " or "cost per Disability Adjusted Life Year (DALY) averted." A lower ratio is more desirable.
Effectiveness: The reduction in risk of disease or death associated with an intervention implemented in a "real world " setting. Effectiveness may reflect the use of fewer intervention resources than would be ideal. For this reason, effectiveness is often less favorable than efficacy. See also "Efficacy".
Efficacy: The reduction in risk of disease or death associated with an intervention implemented in an ideal situation, such as a research study conducted in a referral hospital or community prevention using specially trained health workers. These studies usually have resources that are unavailable in a typical health care setting, so that efficacy may be higher than effectiveness in routine practice." See also "Effectiveness".
Global health: Health of populations in a global context that transcends the perspectives and concerns of individual nations.
Immune system: System of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function properly.
Incidence: The number of new cases of a disease or condition occurring in a specified population within a specified period. Often translated into a rate, e.g., number of new cases per 100 at-risk individuals per year. See also "Prevalence"
Intervention: In health, the process of intervening with people to try to prevent or treat disease, in a study or normal practice. In controlled trials, the word is sometimes used to describe the regimens in all comparison groups, including placebo and no-treatment arms.
Millennium Development Goals (MDGs): In 2000, eight Millennium Development Goals (MDGs) were agreed upon by all United Nations member countries. The MDGs provide a framework for improving health, education, gender equity, economic, and environmental conditions in developing countries. Measurable targets were set for developing countries with a goal to achieve them by 2015.
Meta-analysis: The use of statistical techniques in a systematic review to quantitatively integrate the results of included studies. Sometimes misused as a synonym for systematic reviews, which may not include a meta-analysis.
Morbidity: Illness or harm
Observational study: Study in which events are allowed to take their natural course. Changes or differences in one phenomenon are studied in relation to changes or differences in other(s), without intervention by the investigator. There is a greater risk of bias than in experimental studies. See also "Randomized control trial".
Parasite: Organisms that lives in or on another organism without benefiting the host organism. Examples include tapeworms and Plasmodium, the mosquito-borne parasite which causes malaria.
Placebo: A substance resembling a medication that has no known effect on the outcome of interest. Often used in clinical trials as a comparison to measure the effect of a medication under evaluation.
Prevalence: The number of cases of a disease or condition present in a given population at a specific time. Often expressed as a percent of the population at risk. See also "Incidence".
Prophylaxis: Measure taken for the prevention of a disease or condition
Public health: Approach to medicine that is concerned with the health of the community as a whole.
P-value: Probability that the difference observed in a study could have occurred by chance if the intervention and results were in reality unrelated.
Randomized controlled trial (RCT): A study of intervention efficacy which randomly assigns subjects to intervention and control groups. This study design is the least susceptible to bias, and therefore usually considered the most authoritative. See also "Placebo" and "Observational study".
Relative risk: Risk of an event (or of developing a disease) relative to exposure. Relative risk is a ratio of the probability of the event occurring in the exposed group versus a non-exposed group.
Relative risk reduction (RRR): We have defined this term in detail under the "Key Findings" tables.
Review: Article in the medical literature which summarizes a number of different studies and may draw conclusions about a particular intervention. Review articles are often not systematic.
Risk factor: Any factor that increases the chance of disease or injury.
Sexually transmitted infection (STI): Any disease transmitted by sexual contact. Caused by microorganisms that survive on the skin or mucus membranes of the genital area; or transmitted via semen, vaginal secretions, or blood. Includes AIDS, chlamydia, genital herpes, genital warts, gonorrhea, syphilis, yeast infections, and some forms of hepatitis.
Statistically significant: Result that is unlikely to have happened by chance. The usual threshold for this judgment is that the observed results (or more extreme results) would randomly with a probability of less than 5% if the "null hypothesis" were true (i.e., no real association of predictor and outcome). See also "Confidence Interval".
Surrogate endpoints: Outcome measures that are not of direct clinical importance but reflect important outcomes. For example, blood pressure is not felt by patients but it is often used as an outcome because it is a risk factor for stroke and heart attacks. Surrogate endpoints are usually physiological or biochemical markers that can be measured relatively quickly and easily and predict important clinical outcomes.
Systematic review: A review of a clearly formulated question that uses systematic and explicit methods to identify, select, and critically appraise relevant research, and to collect and analyze data from the studies that are included in the review. See also "Review" and "Meta-analysis".
Unblinded (study or trial): Participants know their assignment to the intervention or control group. This may increase the potential for bias in the outcomes. Studies may be unblinded because the risk of bias is deemed low, or because it appears infeasible or unethical to implement blinding. See also "Blinded."
Vaccine: Substance containing a deactivated infectious organism such as a virus, designed to stimulate the immune system to protect against subsequent infection. Preventive vaccines preempt infection from that organism. Therapeutic vaccines improve the ability of the immune system of an already-infected person to defend itself.
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Dengue
Biological control: Biological agents are intended to slow the spread of dengue by attracting or killing mosquitoes and/or their larva. Various insects, fish, tadpoles, copepods (tiny crustaceans) and even cats have been used for this purpose. Biological strategies can also include genetic modification or hormonomimetic compounds.
Chemical control, apply mosquito repellant: Use of topical anti-mosquito applications containing DEET, icaridin, or oil of lemon eucalyptus
Chemical control, treatment of adult mosquitoes: During outbreaks, emergency vector control can include the broad application of insecticides using hand-carried, vehicle-mounted or aircraft sprayers.
Chemical control, treatment of larval environments with insecticide: Use of insecticides to control larval habitats, particularly in households (e.g. water storage vessels).
Corticosteroids: Steroid hormones that are important for immune response.
Dengue Fever (“break-bone” fever): Virus-based disease, spread by the mosquito Aedes aegypti. Manifests with sudden onset of high fever, headache and other flu-like symptoms, as well as severe muscle and joint pains. Often accompanied by facial flush and/or a flat red rash.
Dengue Hemorrhagic Fever (DHF) Grades I & II: Serious complication of dengue fever. The patient becomes irritable, restless and sweaty. A shock-like state follows. Bleeding may appear as tiny spots of blood on the skin and larger patches of blood under the skin. In moderate DHF cases, all signs and symptoms abate after the fever subsides.
Dengue Shock Syndrome (DSS) DHF Grades III & IV: Potentially fatal, primarily affects children under 10, can occur two to six days after the onset of DHF. Symptoms may include circulatory collapse, blueness around the mouth, blood in the stool, bleeding gums and nosebleeds. Without appropriate treatment mortality is high, ranging to 20% or more.
Environmental management, source reduction: Appropriate solid waste disposal and improved water storage practices, such as covering containers to deny mosquitoes a place to breed. Among the methods used by community-based programs to minimize mosquito populations.
Environmental vector management: Multiple interventions against mosquitoes used alone or in combination. These may include source reduction, spraying, bed nets, education, and biological controls.
Integrated vector management: Multiple interventions used in various combinations, including outdoor and indoor spraying with insecticides, water treatment with larvicide, source reduction, community-based education campaigns and fines.
Source reduction: Removal or modification of locations where mosquito breed.
Vector density: The prevalence of the mosquito Aedes aegypti (or more rarely, Aedes albopictus), which transmits dengue fever.
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Diarrhea
Cholera: Infection caused by the bacterium Vibrio cholera, transmitted primarily through feces-contaminated drinking water or food. The main symptoms are watery diarrhea, vomiting and abdominal pain. Can lead to rapid dehydration and electrolyte imbalance. Without medical care and/or rehydration therapy, cholera can be fatal within hours.
Dysentery: A disease characterized by severe diarrhea with passage of blood and mucus in the stool. Usually caused by bacterial, viral or parasitic infection.
Flocculation: The agglomeration (i.e., clumping) of particles suspended in water into larger particles (“flocs”) that can be removed by sedimentation or flotation. Flocculation-disinfectants are used as water treatment in water supply interventions against diarrhea.
Giardiasis (giardia): Infection of the small intestine by the single-celled organism Giardia lamblia, caused by swallowing water contaminated by raw sewage or animal waste. While easily treated in most cases, giardiasis usually causes abdominal cramping and severe diarrhea.
Hygiene interventions: Educational activities to encourage behaviors that reduce the danger of bacterial contamination, such as hand washing with soap, keeping animals away from food preparation areas, and proper disposal of human feces.
Hyponatremia: Metabolic condition in which there is not enough sodium (salt) in the body fluids, often caused by diarrhea. Symptoms include nausea and vomiting, headache, muscle weakness, spasms, seizures, and in untreated cases decreased consciousness or coma
Micronutrients: A nutrient or dietary mineral required by humans in small quantities, but which our bodies cannot produce. These include zinc, a critical element which becomes depleted during diarrhea among children and must be replaced using supplements.
Oral rehydration solution or salts (ORS): An inexpensive and drinkable mixture of water, essential electrolytes (salts) and sugar (traditionally glucose) that has proved to be a highly effective strategy for the management of watery diarrhea. See also "ORS - Reduced Osmolarity" and "ORS - Polymer-based".
ORS - reduced osmolarity: Lower concentrations of glucose and salt than in the traditional ORS formula, shown to be more effective for the treatment of children with acute diarrhea.
ORS - Polymer-based: Includes “glucose polymers” found in grains such as rice, wheat, sorghum and maize. This ORS releases glucose more slowly than traditional ORS, lessening sugar’s ability to cause dehydration.
Osmolarity: A measure of the concentration of a solution. Decreased concentrations of sodium and glucose in ORS formulas have been shown to reduce stool output, especially in infants and young children.
Parasitological failure: The demonstrable presence of parasites in the blood within a specified time after treatment.
Point-of-use treatment interventions: Action taken at the place where pathogens are directly encountered by those at risk, e.g., in the household. These include chlorination, solar disinfection, boiling and use of safe storage vessels.
Protozoa (or protozoon): Microorganisms that enter the intestinal tract and can cause diarrhea and other water and food-borne illnesses. Common pathogenic protozoa include the Giardia and Entamoeba species.
Rotavirus: The most common cause of severe diarrhea among infants and young children, and one of several RNA viruses that cause infections called “stomach flu” (though they have no relation to influenza)
Sanitation interventions: Strategies to provide a means of hygienic human excreta disposal, usually through the installation or improvement of latrines (public or household) and/or sewer connections.
Typhoid fever: An acute illness caused by infection with the Salmonella typhi bacteria, contracted from contaminated water and food. Onset is marked by fever, headache, constipation, malaise, chills, and muscle pain. Diarrhea is uncommon, and vomiting is not usually severe.
Water supply interventions: Strategies to neutralize diarrhea-causing microorganisms at the water supply level. These include improved water supply (such as a new well), or improved distribution tools (hand pump or other connection) at the household or public level. Interventions also include disinfection (e.g., with chlorine), filtering or flocculation-disinfection.
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HIV
Antiretroviral therapy (ART): Treatment that suppresses or stops a retrovirus such as the human immunodeficiency virus (HIV) that causes AIDS.
Antiretroviral drugs (ARVs): Drugs that inhibit the replication of HIV. When antiretroviral drugs are given in combination, HIV replication and immune deterioration can be delayed, and survival and quality of life can be improved.
Behavioral interventions: Activities designed to reduce HIV risk by altering the behaviors that expose people to the virus. Examples are voluntary HIV testing and counseling, or condom promotion and education.
Caesarean section: See definition in Maternal sepsis section.
Condom: A rolled sleeve, of latex or other material, designed to fit over the penis to prevent spread of disease and pregnancy.
Female condom (FC): Pre-lubricated pouch, made from plastic polyurethane or a synthetic latex, worn inside of her vagina during sex, to act as a barrier to sperm and sexually transmitted disease.
HIV: Human immunodeficiency virus, the virus that causes AIDS. HIV can be transmitted through infected blood, semen, vaginal secretions, breast milk, and during pregnancy or delivery. HIV destroys certain white blood cells called CD4+ T cells. These cells are critical to the normal function of the human immune system, which defends the body against illness. When HIV weakens the immune system, a person is more susceptible to developing a variety of cancers and becoming infected with viruses, bacteria and parasites. The disease has four stages: primary or acute HIV infection, asymptomatic, symptomatic, and advanced HIV disease (AIDS).
HIV counseling and testing: Testing for infection with HIV. Includes the biological (antibody or antigen) test, and varied levels of counseling before and especially after the test. Confidentiality must be assured.
Microbicides: Antimicrobial products formulated for application to the surface of the vagina and/or rectum for the prevention of HIV transmission during sexual intercourse.
Micronutrients: See definition in Diarrhea section.
Oropharyngeal candidiasis: Infection in the mouth and pharynx with a fungus of the genus Candida, especially C. albicans. May invade the lungs and bloodstream, especially in immunocompromised persons such as those with HIV.
Peer education: Training and supporting members of a group to effect change by members of the same group (eg, sex workers or injection drug users). Often used to effect changes in knowledge, attitudes, beliefs, and behaviors at the individual level.
Sero-discordant: Couples (either long or short term) in which one member is HIV-positive and the other is HIV-negative.
Sexually Transmitted Infection (STI): Any disease or infection that is spread through sexual contact.
STI mass treatment: The administration of an antibiotic to a population or core target group not based on symptoms, signs or laboratory tests, but based on their group’s likelihood of having an STI. Also called "presumptive treatment". Only bacterial STIs can be treated presumptively.
Syndromic management: Treatment approach based on identifying likely disease relying on a specified set of clinical symptoms and signs. Syndromic case management algorithms/ flowcharts are then used to guide treatment.
Voluntary adult male circumcision (VAMC, AMC or MC): The surgical removal of the foreskin of the penis or prepuce. In VAMC programs men voluntarily choose to undergo this procedure in a medical setting in order to reduce their risk of becoming HIV-infected.
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Malaria
Artemisinin-Based Combination Therapies (ACTs): A relatively new class of medications that are active against multi-drug resistant Plasmodium falciparum malaria. Artemisinin compounds are usually used in combination with other antimalarials. ACTs are well tolerated and effective for treatment, and may reduce malaria transmission by decreasing the presence of the parasite in the bloodstream.
Indoor residual spraying: Application of long-acting chemical insecticides in houses and domestic animal shelters, in order to kill the malaria-transmitting mosquitoes. The primary goals of IRS are reduction of mosquitoes' life span and reduction of the vector density in the affected areas.
Intermittent Preventive Treatment (IPT): Antimalarial drugs provided to pregnant women most often at antenatal consultations during the second and third trimesters of pregnancy. IPT can prevent transmission of malaria from a mother to her child by eliminating the parasites that are in the mother’s blood. Pregnancy reduces a woman’s immunity to malaria, increasing her risk of infection, severe illness, and death. Adverse pregnancy outcomes include low birth weight and spontaneous abortions. IPT reduces these risks.
Long-lasting Insecticide Impregnated Nets (LLIN): A prevention tool used to reduce the transmission of malaria by controlling the malaria-bearing Anopheles mosquito, which can transmit the malaria parasite to humans. These bed nets retain lethal concentrations of insecticide for at least 3 years. Previously, nets had to be retreated at intervals of 6-12 months, more frequently if the nets were washed. The need for frequent retreatment is a barrier to full implementation of insecticide-treated bed nets in endemic countries.
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Maternal Hemorrhage
Anti-Shock Garment: Garment used to apply pressure to the peripheral circulation, thus reducing blood flow and fluid exudation into tissues to maintain central blood flow in the presence of shock. For maternal hemorrhage, non-pneumatic.
Breast stimulation: Self- or mechanical stimulation of the mammary glands used to induce labor.
Hematocrit: Percentage of red blood cell mass of original blood volume. In general, losing blood causes hematocrit levels to decrease.
Hemoglobin: Oxygen-carrying compound in red blood cells. The amount of hemoglobin per 100 mL of blood is an index of the oxygen-carrying capacity of the blood.
Maternal hemorrhage: Loss of >= 500 ml of blood during the perinatal period.
Maternal mortality: Death of a woman from any cause related to pregnancy that occurs during pregnancy or within 42 days of pregnancy termination (e.g., birth, stillbirth, miscarriage, or abortion). The “Maternal Mortality Ratio” is a measure to determine the frequency of pregnancy-related deaths.
Uterine atony: Loss of effective contraction of uterine muscles following delivery. Can lead to acute hemorrhage.
Uterotonic: An agent used to induce contraction or greater tonicity of the uteru, used to induce labor and reduce postpartum hemorrhage.
Uterine massage: Massage of the uterus, after delivery of the placenta, to promote uterine contraction. Involves repetitive massaging or squeezing of the lower abdomen.
Stages of labor: Expulsion of both fetus and placenta from the uterus. First stage: onset of uterine contractions through the period of dilation of the os uteri. Second stage: expulsive effort, from complete dilation of the cervix through expulsion of the infant. Third or placental stage: From expulsion of the infant through full expulsion of placenta and membranes.
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Maternal Sepsis
Caesarean section: Delivery via an incision through the abdominal wall and into the uterus. Performed in response to signs of fetal distress.
Chorioamnionitis: Inflammation of the amnion following bacterial infection. Can lead to pneumonia, meningitis, or neonatal sepsis, and maternal bacteremia or sepsis. Treated with antibiotics.
Endometritis: Inflammation of uterus lining following bacterial infection. Most common among females of childbearing age in immediate postpartum period. Treated with broad-spectrum antibiotics.
Maternal sepsis: Infection of genital tract occurring between onset of membrane rupture or labor and 42nd day postpartum, in which fever and any of the following are present: Pelvic pain, abnormal vaginal discharge, abnormal odor of discharge and delay in rate of reduction of uterus size.
Pelvic inflammatory disease (PID): Acute infection of the upper genital tract structures in women, involving any or all of the uterus, fallopian tubes, and ovaries. PID primarily effects sexually active women, and is often associated with sexually transmitted infections such as gonorrhea and chlamydia.
Secondary infertility: Difficulty conceiving after having already conceived, with initial pregnancy either carried to term or ending in miscarriage.
Sepsis: Presence of pathogenic organisms, or their toxins, in the blood or tissues resulting in systemic inflammatory response.
Skilled birth attendant: An accredited health professional—such as a midwife, doctor or nurse—who has been formally educated and trained in the skills needed to manage uncomplicated pregnancies, childbirth and the immediate postnatal period, and in the identification, management and referral of complications in women and newborns. Traditional birth attendants are excluded from the category of skilled attendant.
Traditional birth attendant: A person, especially in a developing country, who assists a woman during labor and delivery with skills learned by apprenticeship or personal experience rather than by formal training.
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Tuberculosis
Active tuberculosis: TB bacteria become active if the immune system cannot stop them from multiplying. People with active TB disease can spread the disease and often exhibit symptoms such as heavy coughing, fatigue, chills and fever. See also "Tuberculosis" and "Latent tuberculosis".
Directly observed treatment, short-course (DOTS): A strategy to enhance treatment of tuberculosis (TB). Combines diagnosis and registration of TB patients followed by standardized multi-drug treatment, given under direct and supportive observation.
Latent Tuberculosis: The bacterium that causes TB lies dormant in the body. People with latent TB usually have a positive skin test reaction, but have no symptoms and are not contagious. Untreated latent TB, especially in people with weak immune systems, can develop into active and contagious TB. In others, latent TB bacteria may remain inactive for a lifetime. See also "Tuberculosis" and "Active tuberculosis".
Multidrug-Resistant Tuberculosis (MDR-TB): Any strain of TB resistant to standard first-line drugs. MDR-TB usually arises when people take enough medication to feel better, but not the full amount prescribed. Though weaker bacteria are killed; stronger bacteria reproduce and require larger doses or a new drug. MDR-TB is a serious problem in developing countries with limited access to health services. See also "XDR-TB"
Tuberculosis (TB): A bacterial infection caused by Mycobacterium tuberculosis. The disease usually affects the lungs but can spread to other parts of the body in serious cases. An individual can become infected with TB when another person who has active TB coughs, sneezes, or spits. Not all people who become infected with TB will develop symptoms. Those who do not become ill are referred to as having latent TB and cannot spread the disease to others. See also active TB disease and latent TB disease.
XDR-TB: Acronym for “extensively drug-resistant tuberculosis,” a strain of bacteria that is stronger than MDR-TB and resistant to both first-line and second-line drugs.
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Unintended Pregnancy
Diaphragm: Flexible ring covered with a domed sheet of elastic material used in the vagina to prevent pregnancy.
Family planning: The ability of families or persons to anticipate and attain their desired number of children and the spacing and timing of births. It is achieved through use of contraceptive methods and the treatment of involuntary infertility. A woman’s ability to space and limit her pregnancies has a direct impact on her health and well-being as well as on the outcome of each pregnancy.
Hormonal contraception: Birth control methods that act on the endocrine system using steroid hormones, including estrogen and progesterone.
Intrauterine device (IUD): Small plastic T-shaped device placed into the uterus to prevent pregnancy. Promotes contraception by altering the lining of the uterus through the release of copper particles or hormones. Can be used continuously for 5 to 10 years.
Spermicide: Chemical agent destructive to spermatozoa.
Vaginal ring contraception: Flexible polymer ring inserted into the vagina that releases contraceptive hormones.