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Institute of Medicine (US) Forum on Microbial Threats. The Causes and Impacts of Neglected Tropical and Zoonotic Diseases: Opportunities for Integrated Intervention Strategies. Washington (DC): National Academies Press (US); 2011.

Cover of The Causes and Impacts of Neglected Tropical and Zoonotic Diseases

The Causes and Impacts of Neglected Tropical and Zoonotic Diseases: Opportunities for Integrated Intervention Strategies.

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Acute febrile illness

A type of illness characterized by a sudden onset of fever, which is an increase in internal body temperature to levels above normal.


An infectious disease caused by bacteria called Bacillus anthracis. Infection in humans most often involves the skin, the gastrointestinal tract, or the lungs.


A class of substances that can kill or inhibit the growth of some groups of bacteria. Originally antibiotics were derived from natural sources (e.g., penicillin from molds), but many currently used antibiotics are semisynthetic and modified with additions of man-made chemical components.

Antibody (also known as immunoglobulins, abbreviated Ig)

Antibodies are gamma globulin proteins that are found in blood or other bodily fluids of vertebrates and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses.


A molecule capable of eliciting a specific antibody or T-cell response.


An infection caused by the parasitic roundworm Ascaris lumbricoides. It is perhaps the world's most common worm infection, affecting approximately 1 billion people worldwide. The infection occurs in people of all ages, though children are affected more severely than adults. It is found in association with poor personal hygiene, poor sanitation, and in places where human feces are used as fertilizer.

Asymptomatic infection

An infection where the patient does not have any apparent symptoms (also known as a subclinical infection).


Microscopic, single-celled organisms that have some biochemical and structural features different from those of animal and plant cells.

Bovine tuberculosis

Tuberculosis in cattle caused by infection with the bacterium Mycobacterium bovis that can be transmitted to other animals and to humans.


An infectious disease caused by the bacteria of the genus Brucella. These bacteria are primarily passed among animals, and they cause disease in many different vertebrates. Humans become infected by coming in contact with animals or animal products that are contaminated with these bacteria, and the disease can cause a range of symptoms that are similar to the flu and may include fever, sweats, headaches, back pains, and physical weakness.

Buruli ulcer

A chronic, indolent, necrotizing disease of the skin and soft tissue caused by toxin-producing mycobacteria, Mycobacterium ulcerans. It is the third most common mycobacterial disease of immunocompetent hosts after tuberculosis and leprosy.

Chagas disease

A potentially life-threatening illness caused by the protozoan parasite Trypanosoma cruzi. Predominantly found in Latin America, T. cruzi is commonly transmitted to humans and other mammals by an insect vector.

Convenience sampling

A nonprobability sampling technique where subjects are selected because of their convenient accessibility and proximity to the researcher; see (accessed December 2, 2010).


A parasitic tissue infection caused by larval cysts of the pork tapeworm. These larval cysts infect brain, muscle, or other tissue and are a major cause of adult-onset seizures in most low-income countries. An individual acquires cysticercosis from ingesting eggs excreted by a person who has an intestinal tapeworm.

Cytomegalovirus (CMV)

A common virus that infects people of all ages. Most CMV infections are “silent”; most people who are infected with CMV have no signs or symptoms. CMV can cause symptomatic disease in people with a weakened immune system and in babies infected before birth.

Dengue/dengue hemorrhagic fever (DHF)

A vector-borne viral disease, dengue is transmitted between people by the mosquitoes Aedes aegypti and Aedes albopictus, which are found throughout the world. Dengue fever (DF) is caused by any of four closely related viruses, or serotypes, dengue 1–4. Infection with one serotype does not protect against the others, and sequential infections put people at greater risk for DHF and dengue shock syndrome (DSS).

Disability-adjusted life-years (DALYs)

A metric used to measure the morbidity impact associated with a disease. One DALY can be thought of as one lost year of “healthy” life. The sum of these DALYs across the population, or the burden of disease, can be thought of as a measurement of the gap between current health status and an ideal health situation where the entire population lives to an advanced age, free of disease and disability; see (accessed December 2, 2010).

Disease burden

The impact of a health problem in a population measured by financial cost, mortality, morbidity, or other indicators.


Also known as Guinea worm disease, dracunculiasis is caused by infection by the protozoan parasite Dracunculus medinensis. The disease affects poor communities in remote parts of Africa that do not have access to safe drinking water. There is no pharmaceutical or vaccine treatment for Guinea worm disease.


Often referred to as hydatid disease or echinococcal disease, echinococcosis is a parasitic disease that affects both humans and other mammals, such as sheep, dogs, rodents, and horses. There are three different forms of echinococcosis found in humans, each of which is caused by the larval stages of different species of the tapeworm of the genus Echinococcus.


Cessation of transmission in a country, continent, or other limited geographic area; complete prevention of a clinical presentation of disease.


The constant presence of a disease or infectious agent within a given geographic area; it may also refer to the usual prevalence of a given disease within such an area.


Reducing the incidence of a disease to zero worldwide, such that further control measures are unnecessary; total interruption of transmission.

Feco-oral (or fecal-oral) infection

Infections that are spread by the ingestion of contaminated fecal material. Sometimes these types of infections are also spread by drinking water that is contaminated with infected fecal material.


The study of genes and their associated functions.

Global Health Initiative

A U.S. government development initiative launched in 2009 that will invest $63 billion over six years to help partner countries improve health outcomes through strengthened health systems, with a particular focus on improving the health of women, newborns, and children through programs including infectious disease, nutrition, maternal and child health, and safe water.

Hookworm infection

The hookworm is a parasitic nematode that lives in the small intestine of its mammalian host. Two species of hookworms commonly infect humans, Ancylostoma duodenale and Necator americanus. Hookworm is a leading cause of maternal and child morbidity in the developing countries of the tropics and subtropics.

Human African trypanosomiasis (HAT)

HAT is a protozoan parasitic disease of people and animals, caused by Trypanosoma brucei and transmitted by the tsetse fly. The disease is endemic in some regions of sub-Saharan Africa, covering about 36 countries and 60 million people.

Horizontal transmission

The spread of an infectious agent from one person or group to another, usually through direct contact with contaminated material, such as sputum or feces.


An accumulation of fluid in a sac, cyst, or bursa.


The condition in which a disease is present in a community at all times and with a high incidence.


A population or region in which the incidence of a disease is sufficiently low that the population has limited or no native immunity to it.

Incidence rate

The number of new cases of a specified disease during a defined period of time divided by the number of persons in a stated population in which the cases occurred.

Intelligence quotient (IQ)

A measure of a person's intelligence as indicated by an intelligence test; the ratio of a person's mental age to their chronological age (multiplied by 100).


A group of flagellated protozoa characterized by the presence of one or two flagella in the cell body and a “kinetoplast” within the mitochondrion. As human parasites, kinetoplastids are associated with Chagas disease, HAT, and leishmaniasis.


A protozoan parasitic disease belonging to the genus Leishmania. These parasites are transmitted by the bite of a sand fly and can infect animals and humans. Cutaneous leishmaniasis is the most common form; visceral leishmaniasis is a more severe form, affecting vital organs of the body.


A bacterial zoonotic disease caused by spirochaetes of the genus Leptospira that affects humans and a wide range of animals, including mammals, birds, amphibians, and reptiles. Though recognized among the world's most common zoonoses, leptospirosis is a relatively rare bacterial infection in humans.

Longitudinal studies

A correlational research study that involves repeated observations of the same items over long periods of time—often many decades. It is a type of observational study. Longitudinal studies are often used in psychology to study developmental trends across the life span, and in sociology to study life events throughout lifetimes or generations.

Lymphatic filariasis (LF or elephantiasis)

A parasitic disease caused by microscopic, threadlike worms. The adult worms only live in the human lymph system. The lymph system maintains the body's fluid balance and fights infections. Lymphatic filariasis is spread from person to person by mosquitoes. Lymphatic filariasis is a leading cause of permanent disability worldwide.


The prelarval form of any filarial worm. Certain blood-sucking insects ingest these forms from an infected host, and the microfilariae then develop in the body of the insect and become infective larvae.


Disease, illness; any departure, subjective or objective, from a state of physiological or psychologic well-being.

Neglected tropical diseases (NTDs)

A group of more than a dozen major chronic, mostly parasitic infectious diseases with high endemicity in the developing countries of Africa, Asia, and the Americas. NTDs are the most common infections of the world's poor, especially the bottom billion. Most are chronic and disabling parasitic infections, as well as selected bacterial and viral infections.

Neglected zoonotic diseases (NZDs)

Diseases transmitted between animal and human hosts—sometimes by means of a vector, or carrying species—that are endemic in many developing countries of Africa, Asia, and South and Central America (e.g., anthrax, bovine tuberculosis, brucellosis, cysticercosis, and echinococcosis rabies). These diseases sicken and kill livestock and have direct and indirect effects on human health.


A parasitic disease (also known as river blindness) caused by the filarial worm Onchocerca volvulus. It is transmitted through the bites of infected Simulium black flies, which breed in fast-flowing streams and rivers. Onchocerciasis is a major cause of blindness in many African countries.


An organism living in, with, or on another organism.


A microorganism that causes disease.

Prevalence rate

The total number of persons sick or portraying a certain condition in a stated population at a particular time or during a stated period of time, regardless of when that illness or condition began, divided by the population at risk of having the disease or condition at the point in time midway through the period in which they occurred.

Protozoa and protozoan parasites:

Protozoa are microscopic, unicellular organisms that can be free-living or parasitic in nature. They are able to multiply in humans, which contributes to their survival and also permits serious infections to develop from just a single organism. Transmission of protozoa that live in a human intestine to another human typically occurs through a fecal-oral route (for example, contaminated food or water or person-to-person contact). Protozoa that live in the blood or tissue of humans are transmitted to other humans by an arthropod vector (for example, through the bite of a mosquito or sand fly).


The large scale of proteins, especially their structures and functions.

Q fever

A disease caused by infection with Coxiella burnetii, a bacterium that affects humans and other animals. This organism is uncommon but may be found in cattle, sheep, goats, and other domestic animals. The infection results from the inhalation of endospores and from contact with the milk, urine, feces, vaginal mucus, or semen of infected animals.


An often fatal viral zoonotic disease that causes acute encephalitis in warm-blooded animals.


Any person, animal, arthropod, plant, soil, or substance (or combination of these) in which an infectious agent normally lives and multiplies, on which it depends primarily for survival, and in which it reproduces itself in such manner that it can be transmitted to a susceptible vector.

Rickettsial disease

Infection caused by a variety of obligate intracellular, Gram-negative bacteria that are usually transmitted by ectoparasites such as fleas, lice, mites, and ticks.


A parasitic disease (also known as bilharzias) caused by trematode flatworms of the genus Schistosoma. Although it has a low mortality rate, schistosomiasis often is a chronic illness that can damage internal organs and, in children, impair growth and cognitive development. Schistosomiasis is the second most socioeconomically devastating parasitic disease after malaria.

Subclinical infection

An infection where the patient does not have any apparent symptoms (also known as an asymptomatic infection).


The continuing scrutiny of all aspects of occurrence and spread of a disease that is pertinent to effective control.


Parasitic flatworms or cestodes. Live tapeworm larvae (coenuri) are sometimes ingested by consuming undercooked food. Once inside the digestive tract, a larva can grow into a very large adult tapeworm. Cysticercosis is a disease of humans involving larval tapeworms in the human body.


The parasitic disease caused by the larvae of two species of Toxocara roundworms: T. canis from dogs and, less commonly, T. cati from cats.


Disease associated with a single-celled parasite called Toxoplasma gondii. Of those who are infected, very few have symptoms because a healthy person's immune system usually keeps the parasite from causing symptomatic illness.


An infectious eye disease, resulting from infection of the eye with Chlamydia trachomatis, that is the leading cause of the world's infectious blindness. Globally, 41 million people suffer from active infection, and nearly 8 million people are visually impaired as a result of this disease.

Trematode infections

Infections caused by parasitic flatworms (also known as flukes) that infect humans and animals. Infected individuals transmit trematode larvae in their feces.


Bacteria that cause chronic infections (e.g., yaws [also known as framboesia, pian], endemic syphilis [bejel], and pinta), which often present as skin lesions.


Infection by a soil-transmitted helminth also known as whipworm. These parasitic worms live in the large intestine, and whipworm eggs are passed in the feces of infected persons.


A biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and it is often made from weakened or killed forms of the microbe. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and “remember” it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.


A carrier—especially an arthropod—that transfers an infective agent from one host (which can include itself) to another.


Transmitted from one host to another by a vector.


The presence of virus in the blood of the host.


A small infectious agent that can only replicate inside the cells of another organism. Viruses are too small to be seen directly with a light microscope. Viruses infect all types of organisms, from animals and plants to bacteria and archaea.

Water-based diseases

Diseases (e.g., schistosomiasis, Guinea worm disease) transmitted by a vector that spends part of its life cycle in the water and another part as parasites of humans and animals.

Water-washed diseases

Those diseases whose transmission is facilitated by insufficient quantities of water (regardless of its quality) for personal and domestic hygiene.


An infection caused by Treponema pertenue that is a significant public health problem in three countries of the Southeast Asia region.


Microbes that are naturally transmitted between animals and humans that cause disease in human populations but can be perpetuated solely in nonhuman host animals (e.g., influenza, rabies).

Copyright © 2011, National Academy of Sciences.
Bookshelf ID: NBK62501


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