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Reduviid bug

A small cone-nosed biting bug commonly called the “kissing bug” responsible for the South American sleeping sickness called Chagras’ disease.

Reiter’s syndrome

A rare complication of Chlamydia and other infections characterized by arthritis and conjunctivitis.

Replacement vector

A cloning vector, including a bacteriophage, in which some of the DNA of the vector can be replaced with foreign DNA.

Replication

The process of duplicating or reproducing, as in the making of an exact copy of a polynucleotide strand of DNA or RNA.

RES (reticuloendothelial system)

A network of cells and tissues found throughout the body, especially in the blood, general connective tissue, spleen, liver, lungs, bone marrow, and lymph nodes. These cells are concerned with blood cell formation and destruction, storage of fatty materials, and the metabolism of iron and pigment, as well as playing a role in inflammation and immunity. Some of the cells are motile and can ingest and destroy unwanted foreign material. The RES cells in the spleen possess the ability to dispose of disintegrated erythrocytes, but do not destroy hemoglobin, which is liberated in the process. The RES cells located in the blood cavities of the liver are called Kupffer cells and work with cells of the general connective tissue and bone marrow to transform into bile pigment the hemoglobin released by disintegrated erythrocytes.

Reservoir in epidemiology

An organism or environment that normally harbors a pathogen.

Reservoirs of infection

Sites where microorganisms can persist and maintain their ability to infect.

Retroviruses

Viruses that possess single-stranded RNA that can produce a complementary DNA through the action of the enzyme reverse transcriptase. Retroviruses received the name “Retro” from their backwards manner of reproducing and include such viruses as leukoviruses and lentiviruses.

Reverse transcriptase

An enzyme found in Class 6 RNA viruses that copies RNA into DNA.

Reverse transcription

The process of copying information found in RNA into DNA.

Rhabdovirus

One virus of a number of viruses in the family Rhabdoviridae, infecting various vertebrate and invertebrate hosts; but only this one causes rabies.

Rheumatic fever

An inflammatory autoimmune disease caused by abnormal activation of the immune system following a group A strep throat infection and characterized by fever, rash, arthritis, abnormal movements, and damage to the heart valves.

Rhinoviruses

Genera of viruses of the family Picornaviradae primarily responsible for the common cold. Coryza is a profuse discharge from the mucous membranes of the nose. Consequently, the rhinoviruses are sometimes referred to as coryzaviruses. There are approximately 115 different rhinovirus serotypes that have been identified.

Rickettsieae

Obligate intracellular parasites classified between a virus and a bacteria. It has a cell wall like a virus, but is susceptible to antibiotics like a bacteria. Rickettsial diseases require an arthropod vector (fleas, mites, ticks, and lice ) for transmission. Common ricketsial diseases are Rocky Mountain spotted fever and typhus.

Ringworm

A fungal infection of the skin, which is not caused by a “worm” or parasite.

Riverblindness

A disease caused by a parasite transmitted to humans via the blackfly found mainly in Africa. The organism prefers the eyes and outer layers of skin. Thousands of them congregate in the eyes, producing impaired vision or blindness. In a related disease, Loa loa, worms can actually be seen moving across the front of the eyeball. The skin lesions cause such disfiguring sores that the victim is ostracized. Itching can be so intense that it drives many to suicide. Even though an antifilarial drug was invented by the Merck company and donated in the 1980s to needy nations, it did not reach the people because of such poorly run health programs. In 1995, another attempt was made, which may prove more successful.

RNA (ribonucleic acid)

A nucleic acid that carries information from DNA to sites where proteins are manufactured in cells and that directs and participates in the assembly of proteins.

Rocky Mountain Pus Club

A group of infectious disease doctors based in Idaho.

Rocky Mountain Spotted Fever

A dangerous hemorrhagic fever transmitted by tick bites and caused by a rickettsial microorganism.

Rosacea

A form of chronic acne.

Roth’s spot

A white spot surrounded by a red ring sometimes seen in the retina of the eye. It is caused by a number of diseases and conditions.

Roundworm (Ascaris lumbricoides)

A large white worm that lives for six months to three years in the human intestine, with the female laying a quarter of a million eggs a day. Eggs find their way into the mouths of others, hatch to form larvae, and migrate through the body causing allergy-type reactions before settling down for good in the intestines. They occur worldwide, but they are most common in tropical and subtropical countries. Roundworms are primitive worms of variable size that may be free living or parasitic, and are of the class Nematoda. They can be both parasitic and free living with muscles running the length of their bodies.

Rubella (German measles or three-day measles)

A disease produced by the rubella virus of the family Togaviridae, often confused with the measles virus from the family Paramyxoviridae. It is a mild childhood disease, but, if acquired in the womb, may severely damage the heart and brain of the developing fetus.

Rubeola

A synonymous name for measles in English and for German measles in French and Spanish.

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