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Acquired immune deficiency syndrome (AIDS) - a disease caused by the human immunodeficiency virus (HIV), which kills or impairs cells of the immune system and progressively destroys the body's ability to fight infections and certain cancers. HIV is most commonly spread by sexual contact with an infected partner. The term AIDS applies to the most advanced stages of an HIV infection.
African trypanosomiasis (also called African sleeping sickness) - a systemic disease caused by parasite of the Trypanosoma brucei family and transmitted by the bite of the tsetse fly. There is West African trypanosomiasis and East African trypanosomiasis, referring to the areas in Africa where they are found.
Antibody - a special protein produced by the body's immune system that recognizes and helps fight infectious agents and other foreign substances that invade the body.
Asymptomatic - to be without noticeable symptoms of disease.
Cholera - an acute, infectious disease caused by the consumption of water or food contaminated with the bacterium Vibrio cholerae.
Colonoscopy - test to look into the rectum and colon through a long, flexible, narrow tube (called a colonoscope) with a light and tiny lens on the end.
Cryptosporidiosis - a diarrheal infection caused by the parasite Cryptosporidium. The parasite is transmitted after drinking or swallowing contaminated food or water, including water swallowed while swimming.
Dengue fever - a viral disease transmitted by Aedes mosquitoes mainly in tropical and subtropical areas of the world.
Diarrhea - frequent, loose, and watery bowel movements.
Diphtheria - a serious, infectious disease that produces a toxin (poison) and an inflammation in the membrane linings of the throat, nose, trachea, and other tissues.
Direct fluorescent antibody test (dFA) - a test most frequently used to diagnose rabies in animals; the brain of the animal is checked for the virus.
E. coli O157:H7 (also called E. coli. or Escherichia coli) - species of bacteria found in the intestines of man and healthy cattle; often the cause of urinary tract infections, diarrhea in infants, and wound infections.
Emerging infectious diseases - commonly defined as diseases that have newly appeared in a population, and/or diseases that have existed in the past, but are rapidly increasing in incidence or geographic range. Emerging diseases include: AIDS, Lyme disease, Escherichia coli O157:H7 (E. coli), hantavirus, and others. Re-emerging diseases include: malaria, tuberculosis, cholera, pertussis, influenza, and others.
Encephalitis - an inflammation caused by a viral infection. While specific viruses may vary and exposure occurs through insect bites, food or drink, or skin contact, travelers are most at risk from insect bites.
Endemic - a disease caused by the health conditions constantly present within a community. It usually describes an infection that is transmitted directly or indirectly between humans and is occurring at the usual expected rate.
Epidemic - a disease that spreads rapidly through a demographic segment of the human population, such as everyone in a given geographic area, or a similar population segment. Also refers to a disease whose incidence is beyond what is expected.
Fish poisoning - poisoning that occurs by eating various species of fish and shellfish at certain times of the year when they contain poisonous biotoxins. This can occur even if the fish is well cooked.
Giardiasis - an infectious, diarrheal disease caused by the parasite Giardia lamblia, also known as Giardia intestinalis, which can be transmitted through oral-fecal contact and by water contaminated by feces. Travelers are cautioned against drinking any untreated water.
Hemolytic uremic syndrome - a rare kidney disease that usually occurs in children and can be caused by eating food contaminated with E. coli O157:H7.
Hepatitis - inflammation of the liver that sometimes causes permanent damage; caused by viruses, drugs, alcohol, or parasites. Hepatitis has the following forms:
Hepatitis A - a form of infectious hepatitis caused by the hepatitis A virus. The virus may be spread by fecal-oral contact, fecal-infected food or water, and may also be spread by a blood-borne infection (which is rare).
Hepatitis B - a form of infectious hepatitis caused by the hepatitis B virus. Transmission of the hepatitis B virus occurs through blood and body fluid exposure such as blood, semen, vaginal secretions, or saliva.
Hepatitis C - a form of infectious hepatitis caused by the hepatitis C virus. Transmission of the hepatitis C virus occurs primarily from contact with infected blood, but can also occur from sexual contact or from an infected mother to her baby.
Hepatitis D - a form of infectious hepatitis caused by the hepatitis (Delta) virus. This form of hepatitis can only occur in the presence of hepatitis B. Transmission of hepatitis D occurs the same way as hepatitis B.
Hepatitis E - a form of infectious hepatitis caused by the hepatitis E virus. This form of hepatitis is similar to hepatitis A. Transmission occurs through fecal-oral contamination. Hepatitis E is most common in poorly developed countries and is rarely seen in the US.
Hepatitis G - the newest form of infectious hepatitis. Transmission is believed to occur through blood and is seen in IV drug users, individuals with clotting disorders (such as hemophilia), and individuals who require hemodialysis for renal failure.
Immunization - a process by which protection to an infectious disease is administered.
Influenza (also called the flu) - a viral respiratory tract infection. The influenza viruses are divided into three types: A, B, and C.
Lyme disease (LD) - a multistage, multisystem bacterial infection caused by the spirochete Borrelia burgdorferi, a spiral-shaped bacterium that is most commonly transmitted by a tick bite.
Mad cow disease - scientifically known as bovine spongiform encephalopathy (BSE), this disease in cattle is related to a disease in humans called variant Creutzfeldt-Jakob disease (vCJD).
Malaria - a disease caused by a parasite that is transmitted person-to-person by the bite of an infected Anopheles mosquito. These mosquitoes are present in the tropics and subtropics in almost all countries. Malaria is the most deadly of all tropical parasitic diseases.
Mantoux test - A skin test used to identify most people with M. tuberculosis within six to eight weeks after initial exposure.
Measles - a very contagious viral illness characterized by a distinct rash and a fever; spread through airborne droplets of nasal secretions.
Meningitis - inflammation of the meninges, the membranes that envelop the brain and the spinal cord.
Mumps - an acute and highly contagious viral disease that usually occurs in childhood. Spread by airborne droplets from the upper respiratory tract, the disease usually takes two to three weeks to appear.
Pertussis (also called whooping cough) - mainly affects infants and young children; caused by a bacterium, it is characterized by paroxysms of coughing that end with the characteristic whoop as air is inhaled. Pertussis caused thousands of deaths in the 1930s and 1940s, but with the advent of a vaccine, the rate of death has declined dramatically.
Photophobia - low tolerance to bright light.
Poliomyelitis - a highly contagious infectious disease caused by various types of poliovirus. Spread though feces and airborne particles, the poliovirus usually causes no more than a mild illness. However, some of the more serious manifestations of the disease include meningitis, which can lead to extensive paralysis.
Post-Lyme disease syndrome (PLDS) - a condition also known as chronic Lyme disease, characterized by persistent musculoskeletal and peripheral nerve pain, fatigue, and memory impairment.
Rabies - a widespread, viral infection of warm-blooded animals. Caused by a virus in the Rhabdoviridae family, it attacks the nervous system and, once symptoms develop, it is 100 percent fatal in animals.
Rubella (also called German measles) - an acute viral infection that causes a mild illness in children and slightly more severe illness in adults. The disease is spread person-to-person through airborne particles and takes two to three weeks to incubate.
Salmonella infections - diarrheal infections caused by the bacteria Salmonella. There are many kinds of Salmonella bacteria that cause diarrheal illnesses in humans.
Sigmoidoscopy - examination of the rectum and lower part of the colon (sigmoid colon) using a flexible viewing tube passed through the rectum.
Smallpox - a highly contagious disease caused by a type of poxvirus; symptoms usually include a fever and a blistery-like rash.
Tetanus - an acute, sometimes fatal, disease of the central nervous system; caused by the toxin of the tetanus bacterium, which usually enters the body through an open wound. The tetanus bacteria live in soil and manure, but also can be found in the human intestine and other places.
Travel medicine - a specialized area of health care that focuses on the needs of travelers, particularly those who travel to other countries.
Traveler's diarrhea - a term used to describe the diarrhea caused by infection with bacteria, protozoa, or viruses ingested by consuming food or water that has been contaminated. Two life-threatening types of traveler's diarrhea are caused by cholera and giardiasis.
Tuberculosis (TB) - an infectious disease that was once a major killer worldwide. The predominant TB organism is Mycobacterium tuberculosis (M. tuberculosis). Spread person-to-person in airborne droplets caused by sneezing or coughing, the bacterium usually infects the lungs. However, due to improved nutrition, housing, sanitation, medical care, and the introduction of antibiotics, reported TB cases in the US have declined dramatically.
Typhoid fever - a life-threatening bacterial infection caused by the bacterium Salmonella Typhi (S. Typhi); often transmitted by contaminated water, food, or milk.
Viral hemorrhagic fevers - a term that refers to a group of illnesses caused by several distinct families of viruses. While some of these cause illnesses that are relatively mild, many cause severe, life-threatening diseases with no known cure, such as the Ebola virus.
Yellow fever - a viral disease that is transmitted by the Aedes aegypti mosquito.