Salmonella Septicemia
Salmonella is a bacterium that enters the body through ingestion of contaminated food or water. Symptoms of infection include nausea, vomiting, and diarrhea. Salmonella septicemia is a severe infection that circulates through the whole body. Recurrent Salmonella septicemia is considered an AIDS-defining condition in people with HIV.

Salvage Therapy
Also known as rescue therapy. An HIV treatment regimen designed for people who have used many different anti-HIV drugs in the past, have failed at least two anti-HIV regimens, and have extensive drug resistance.

SAMHSA
See: Substance Abuse and Mental Health Services Administration

SAT
See: Subcutaneous Adipose Tissue

SC
See: Subcutaneous

Seborrheic Dermatitis
A skin condition common in people with HIV. It is characterized by loose, greasy or dry, white to yellowish scales, with or without reddened skin. Seborrheic dermatitis may involve the skin of the scalp, eyebrows, eyelids, nasolabial creases, lips, behind the ears, in the external ear, and on the trunk, particularly over the sternum and along skin folds. The cause is unknown.

Secondary Prophylaxis
See:    Maintenance Therapy

Sepsis
A serious blood-borne infection that is usually caused by bacteria. Immunocompromised people, such as those with HIV disease, are at increased risk for sepsis.

Seroconversion
The process by which a newly infected person develops antibodies to HIV. These antibodies are then detectable by an HIV test. Seroconversion may occur anywhere from days to weeks or months following HIV infection.
See Also:   Window Period

Serologic Test
A laboratory test to determine if an individual has antibodies to a particular foreign invader, such as a virus. A positive serologic test indicates that an individual is infected or has had an infection in the past.

Seroprevalence
The number or proportion of people in a given population who have positive serologic tests for a particular infection.

Serum
The clear, thin, and sticky fluid that separates from blood when it clots.

Serum Glutamic Oxaloacetic Transaminase (SGOT)
See:    Liver Function Tests

Serum Glutamic Pyruvate Transaminase (SGPT)
See:    Liver Function Tests

Set Point
The viral load established within a few weeks to months after infection, after the initial burst of virus replication has subsided. The viral set point is thought to remain steady for an indefinite period of time if the infection is not treated with anti-HIV drugs. An individual's viral set point may determine how quickly HIV infection will progress without treatment. Higher set points suggest that disease will progress faster than lower set points.

Sexually Transmitted Disease (STD)
Any infection spread by the transmission of organisms from person to person during sexual contact.

SGOT
See: Serum Glutamic Oxaloacetic Transaminase

SGPT
See: Serum Glutamic Pyruvate Transaminase

Shingles
A disease caused by varicella zoster virus (VZV), which also causes chickenpox. VZV remains in the nerve roots of everyone who has had chickenpox and can become active years later to cause shingles. Shingles causes numbness, itching, or severe pain followed by clusters of blister-like lesions in a strip-like pattern on one side of the body. The pain can persist for weeks, months, or years after the rash heals.
See Also:   Varicella Zoster Virus

Side Effects
The actions or effects of a drug (or vaccine) other than desired therapeutic effects. The term usually refers to undesired or negative effects, such as headache, skin irritation, or liver damage.

Simian Immunodeficiency Virus (SIV)
A virus similar to HIV that can infect monkeys, chimpanzees, and macaques and can cause a disease similar to AIDS in some of these animals. Because the two viruses are closely related, researchers study SIV as a way to learn more about HIV. However, SIV cannot infect humans, and HIV cannot infect monkeys.

SIT
See: Structured Intermittent Therapy

SIV
See: Simian Immunodeficiency Virus

SJS
See: Stevens-Johnson Syndrome

Spinal Tap
Also known as lumbar puncture. A procedure in which cerebrospinal fluid from the lower spine is extracted with a needle for examination.

Splenomegaly
Enlargement of the spleen.

Sputum Analysis
Method of detecting certain infections (especially tuberculosis) by analyzing sputum, the mucus matter that collects in the respiratory and upper digestive passages and is expelled by coughing.

Standard of Care
A treatment plan that experts agree is appropriate, accepted, and widely used for a given disease or condition.

Statins
A shortened name for a class of cholesterol-lowering drugs called HMG-CoA reductase inhibitors. Drugs in this class lower cholesterol by slowing down the body's production of cholesterol and by increasing the liver's ability to remove cholesterol from the blood.
See Also:   Cholesterol

STD
See: Sexually Transmitted Disease

Stem Cell
A "generic" cell that can make exact copies of itself indefinitely, but can also produce specialized cells for various tissues in the body, such as heart muscle, brain tissue, and liver tissue.

Steroid
A general class of substances that are structurally related to one another and share the same chemical skeleton. Some hormones and drugs are steroids. For example, natural testosterone and its man-made derivatives help build muscle mass. Corticosteroid drugs are used to reduce swelling and pain.

Stevens-Johnson Syndrome (SJS)
A severe and sometimes fatal form of skin rash characterized by red, blistered spots on the skin; blisters in the mouth, eyes, genitals, or other moist areas of the body; peeling skin that results in painful sores; and fever, headache, and other flu-like symptoms. Internal organs may also be affected. SJS may occur as a severe reaction to certain medications, including NNRTIs used to treat HIV infection.

STI
See: Structured Treatment Interruption

Stomatitis
Inflammation or irritation of the mucous membranes in the mouth.

Structured Intermittent Therapy (SIT)
A type of structured treatment interruption that is characterized by time-based treatment cycles (weeks or months on and off anti-HIV drugs).
See Also:   Structured Treatment Interruption

Structured Treatment Interruption (STI)
Also known as a "drug holiday." A planned, doctor-supervised discontinuation of anti-HIV drugs. Goals of STI include reduced toxicity, reduced treatment costs, and improved quality of life.

Subclinical Infection
An infection or phase of an infection without obvious symptoms or signs of disease.

Subcutaneous (SC)
Beneath the skin, or administration of a substance beneath the skin.

Subcutaneous Adipose Tissue (SAT)
A type of adipose (fat) tissue found directly under the skin. Both loss (lipoatrophy) and gain (lipohypertrophy) of this fat tissue can occur as a side effect of HIV infection and some of the drugs used to treat HIV infection, especially PIs and NRTIs.
See Also:   Visceral Adipose Tissue

Substance Abuse and Mental Health Services Administration (SAMHSA)
The lead agency within the U.S. Department of Health and Human Services (DHHS) for improving the quality and availability of substance abuse prevention, addiction treatment, and mental health services in the United States.

Subtype
HIV is classified into two types, HIV-1 and HIV-2. Within HIV-1 are groups of similar viral strains. These are the major (M) subtype and non-M (new [N] and outlier [O]) subtypes. The majority of HIV-1 infections are by M-subtype viral strains. Subtype M HIV-1 is further broken down into nine genetically distinct strains known as clades.
See Also:   Clade

Subunit HIV Vaccine
Also known as component vaccine. Subunit vaccines contain only part of the HIV virus (such as individual proteins or peptides) produced in the laboratory by genetic engineering techniques.
See Also:   Vaccine
                   Genetic Engineering

Superinfection
A new infection acquired on top of an existing infection. For example, a person infected with one strain of HIV-1 can, if exposed to a different strain, become infected with the new strain in addition to the existing strain. Superinfection can complicate HIV treatment by requiring additional drugs to target the newly introduced HIV strain.

Surrogate Endpoint
See:    Clinical Endpoint

Susceptible
Having little resistance to a specific infectious disease. Also used to describe an HIV strain that is not resistant to a particular anti-HIV drug.

Syncytium
A giant cell formed by the fusing together of two or more smaller cells. HIV-infected cells can fuse with uninfected cells to form syncytia. The presence of so-called syncytia-inducing variants of HIV has been correlated with rapid disease progression in HIV-infected individuals.

Syndrome
A set of symptoms or conditions that occur together and suggest a certain disease or an increased chance of developing a disease.

Syndrome X
See:    Metabolic Syndrome

Synergy
An interaction between two or more drugs that produces an effect greater than the sum of their individual effects.

Syphilis
A sexually transmitted disease (STD) caused by the bacterium Treponema pallidum. In the early stage of syphilis, a genital or mouth sore called a chancre develops, but eventually disappears on its own. However, if the disease is not treated, the infection can progress over years to affect the heart and central nervous system. Syphilis can also be transmitted from an infected mother to her fetus during pregnancy, with serious health consequences for the infant.

Systemic
A term used to describe a disease or treatment that affects the body as a whole.