P24
A bullet-shaped part of a protein that surrounds the viral RNA within the envelope of HIV. The p24 antigen test looks for the presence of this protein in a patient's blood. A positive result for the p24 antigen suggests active HIV multiplication. Package Insert
A document, approved by the FDA and furnished by the manufacturer of a drug (inserted into the package), for use when dispensing the drug. The document indicates approved uses, contraindications, and potential side effects. Palliative
A treatment that provides symptomatic relief but not a cure. Palliative Care
Palliative care is an approach to life-threatening chronic illnesses, especially at the end of life. Palliative care combines active and compassionate therapies to comfort and support patients who are living with life-ending illnesses and their families. Palliative care strives to meet physical needs through relieving pain and maintaining quality of life while emphasizing the patient's and family's rights to participate in informed discussions and to make choices. This patient- and family-centered approach uses the skills of interdisciplinary team members to provide a comprehensive continuum of care, including spiritual and emotional needs. Pancreas
A gland situated near the stomach that secretes a digestive fluid into the intestine through one or more ducts and also secretes the hormone insulin. Pancreatitis
Inflammation of the pancreas that can produce severe pain and debilitating illness. Its onset can be predicted by rises in blood levels of the pancreatic enzyme amylase. Pancytopenia
Deficiency of all cell elements of the blood. Pandemic
A disease prevalent throughout an entire country or continent, or the whole world. See
Epidemic. Papilloma
A benign tumor (as a wart, condyloma, or polyp) resulting from an overgrowth of epithelial tissue. An epithelial tumor caused by a virus. See
Condyloma; Epithelium; JC Virus. Pap Smear
A method for the early detection of cancer and other abnormalities of the female genital tract, especially of the cervix. Parasite
A plant or animal that lives and feeds on or within another living organism (host), causing some degree of harm to the host organism. Parenteral
A route other than in or through the digestive system. For example, parenteral can pertain to blood being drawn from a vein in the arm or introduced into that vein via a transfusion (intravenous), or to injection of medications or vaccines through the skin (subcutaneous) or into muscle (intramuscular). Paresthesia
Abnormal sensations such as burning, tingling, or a "pins-and-needles" feeling. Paresthesia may constitute the first group of symptoms of nerve involvement in HIV infection. Parotid
Of, pertaining to, or in the region of the parotid gland, which is one of the salivary glands situated just in front of or below the ear. It is the largest of the salivary glands in man, and its duct opens into the interior of the mouth opposite the second molar of the upper jaw. Parotitis
Inflammation of the parotid gland, which is located at the angle of the jaw. Mumps is the most frequent cause of parotid swelling. Parotid swelling associated with HIV infection is seen in patients with lymphadenopathy syndrome. Partogram
A series of charted measurements used to assess the progress of labor. Partograms usually record information on fetal heart rate, cervical dilatation, fetal head descent, uterine contractions, amniotic fluid, maternal urine, drugs given (including ARV prophylaxis), maternal blood pressure, pulse, and temperature. In HIV-infected women, the number of vaginal examinations may also be charted. Also known as a partograph. Passive Antibody Transfer
The transfer of antibodies from another person or from an animal, either naturally--as from mother to fetus or to the newborn via breast milk--or by intentional inoculation as in gammaglobulin treatment. Passive Immunity
Immunity that does not come form immunization. It comes from another individual and is given to a patient in the form of antibodies such gammaglobulin. Passive Immunotherapy
Process in which individuals with advanced disease (who have low levels of HIV antibody production) are infused with plasma rich in HIV antibodies or an immunoglobulin concentrate (HIVIG) from such plasma. The plasma is obtained from asymptomatic HIV-positive individuals with high levels of HIV antibodies. Pathogen
Any disease-producing microorganism or material. Pathogenesis
The origin and development of a disease. PCP
See
Pneumocystis jiroveciPneumonia (PCP). PCR
See
Polymerase Chain Reaction (PCR). Pelvic Inflammatory Disease (PID)
Gynecological condition caused by an infection (usually sexually transmitted) that spreads from the vagina to the upper parts of a woman's reproductive tract in the pelvic cavity. PID takes different courses in different women, but can cause abscesses and constant pain almost anywhere in the genital tract. If left untreated, it can cause infertility or more frequent periods. PEP
See
Postexposure Prophylaxis (PEP). Perianal
Around the anus. Perinatal
Pertaining to or occurring in the period shortly before and after birth, variously defined as beginning with completion of the 20th to 28th week of gestation and ending 7 to 28 days after birth. Perinatal Transmission
Transmission of a pathogen, such as HIV, from mother to baby before, during, or after the birth process. Peripartum
See
Perinatal. Peripheral Neuritis
Inflammation of far portion of the nerves or the nerve endings, usually associated with pain, muscle wasting, and loss of reflexes. Peripheral Neuropathy
Condition characterized by sensory loss, pain, muscle weakness, and wasting of muscle in the hands or legs and feet. It may start with burning or tingling sensations or numbness in the toes and fingers. In severe cases, paralysis may result. Peripheral neuropathy may arise from an HIV-related condition or be the side effect of certain drugs, some of the nucleoside analogues in particular. Peritonitis
Inflammation of the peritoneum (the lining of the abdominal cavity). Persistent Generalized Lymphadenopathy (PGL)
Chronic, diffuse, noncancerous lymph node enlargement. Typically it has been found in persons with persistent bacterial, viral, or fungal infections. PGL in HIV infection is a condition in which lymph nodes are chronically swollen in at least two areas of the body for 3 months or more with no obvious cause other than the HIV infection. PGL
See
Persistent Generalized Lymphadenopathy (PGL). Phagocyte
A cell that is able to ingest and destroy foreign matter, including bacteria. Phagocytosis
The process of ingesting and destroying a virus or other foreign matter by phagocytes. See
Macrophage; Monocyte. Pharmacokinetics
The processes (in a living organism) of absorption, distribution, metabolism, and excretion of a drug or vaccine. Phenotype
The genetic makeup of an organism such as HIV as it interacts with the environment. In the case of HIV, the virus may interact with cells and drugs. Phenotypic resistance testing determines whether an organism is susceptible to a specific drug in a test tube. Contrast with genotype. PI
See
Protease Inhibitors. Placebo
A substance that has no activity, often used in a clinical study so that participants do no know if they are receiving the active (study drug) or the inactive placebo. This approach assists in performing clinical studies and determining whether a drug is active against a disease. Placebo-Controlled Study
A method of investigation of drugs in which an inactive substance (placebo) is given to one group of patients, while the drug being tested is given to another group. The results obtained in the two groups are then compared to see if the investigational treatment is more effective in treating the condition. Placebo Effect
A physical or emotional change, occurring after a substance is taken or administered, that is not the result of any special property of the substance. The change may be beneficial, reflecting the expectations of the patient and, often, the expectations of the person giving the substance. Placental Barrier
A temporary organ separating the mother and fetus. The placenta transfers oxygen and nutrients from the mother to the fetus and permits the release of carbon dioxide and waste products from the fetus through the mother. Placenta Previa
Positioning of the placenta over the opening to the birth canal so that separation usually precedes the infant's birth. This is an important cause of painless third-trimester bleeding. Plasma
The liquid part of the blood and lymph that contains nutrients, electrolytes (dissolved salts), gases, albumin, clotting factors, wastes, and hormones. Platelets
Active agents of inflammation that are released when damage occurs to a blood vessel. The platelets stick to the blood vessel walls, forming clots to prevent the loss of blood. Some persons living with HIV develop thrombocytopenia, a condition characterized by a platelet count of <100,000 platelets per cubic millimeter of blood. PLHA
People living with HIV/AIDS PLWHA
People living with HIV/AIDS PML
See
Progressive Multifocal Leukoencephalopathy (PML). PMTCT
Prevention of mother-to-child transmission (of HIV) Pneumocystis jiroveci Pneumonia (PCP)
An infection of the lungs caused by Pneumocystis jiroveci, which is thought to be a protozoan but may be more closely related to a fungus. P carinii grows rapidly in the lungs of persons with AIDS and is a frequent AIDS-related cause of death. P carinii infection sometimes may occur elsewhere in the body (skin, eye, spleen, liver, or heart). Polymerase Chain Reaction (PCR)
A laboratory process that selects a DNA segment from a mixture of DNA chains and rapidly multiplies it to create a large sample of a piece of DNA. It is a sensitive laboratory technique that can detect and measure HIV in a person's blood or lymph nodes (also called RT-PCR). It is also a means of measuring the amount of virus in the blood (viral load). Polyneuritis
Inflammation of many nerves at once. Polyvalent Vaccine
A vaccine that is active against multiple viral strains. Positive Test
Any result that indicates that a person has a disease or infection. For HIV, a positive test indicates that the person has been infected with HIV. Postexposure Prophylaxis (PEP)
As it relates to HIV disease, a potentially preventative treatment using antiretroviral drugs to treat individuals within 72 hours of a high-risk exposure (e.g. needlestick injury, unprotected sex, needle sharing) to prevent HIV infection. Postnatal
Occurring after birth, especially during the period immediately after birth. Postpartum
See
Postnatal. PPD Test
See
Purified Protein Derivative (PPD). Preconception Counseling
Recommended for all women of childbearing age as a component of their primary medical care. The purpose of preconception care is to identify risk factors for adverse maternal or fetal outcome, provide education and counseling targeted to the patient's individual needs, and treat or stabilize medical conditions prior to conception in order to optimize maternal and fetal outcomes. Prenatal
The period preceding birth, during which the fetus develops in the uterus. Prepartum
See
Prenatal. Prevalence
A measure of the proportion of people in a population affected with a particular disease at a given time. Primary HIV Infection
See
Acute HIV Infection. Primary Isolate
HIV taken from an infected individual (as opposed to being grown in laboratory cultures). Probability
The chance, or likelihood, that a certain event will occur. Proctitis
Inflammation of the rectum. Prodrome
A symptom that indicates the onset of a disease. Products of Conception
Tissues resulting from a pregnancy, such as the placenta. Progressive Multifocal Leukoencephalopathy (PML)
A rapidly debilitating opportunistic infection caused by the JC virus that infects brain tissue and causes damage to the brain and the spinal cord. Symptoms vary from patient to patient but include loss of muscle control, paralysis, blindness, problems with speech, and an altered mental state. PML can lead to coma and death. Prophylactic Drug
A drug that helps to prevent a disease or initial infection. See
Prophylaxis. Prophylaxis
Treatment to prevent the onset of a particular disease (primary prophylaxis), or the recurrence of symptoms in an existing infection that has been brought under control (secondary prophylaxis, maintenance therapy). Protease
An enzyme that breaks down proteins into their component peptides. HIV's protease enzyme breaks apart long strands of viral protein into the separate proteins making up the viral core. The enzyme acts as new virus particles are budding off a cell membrane. Protease is the first HIV protein whose three-dimensional structure has been characterized. See
Proteins. Protease Inhibitors
Antiviral drugs that act by inhibiting the virus' protease enzyme, thereby preventing viral replication. Specifically, these drugs block the protease enzyme from breaking apart long strands of viral proteins to make the smaller, active HIV proteins that comprise the virion. If the larger HIV proteins are not broken apart, they cannot assemble themselves into new functional HIV particles. HIV protease inhibitors include indinavir, ritonavir, saquinavir, nelfinavir, amprenavir, atazanavir, and fosamprenavir. Protease-Sparing Regimen
An antiretroviral drug regimen that does not include a protease inhibitor. Proteins
Highly complex organic compounds found naturally in all living cells. Proteins are a source of heat and energy to the body. They are essential for growth, the building of new tissue, and the repair of injured tissue. Protocol
The detailed plan for conducting clinical studies. It states the trial's rationale, purpose, drug or vaccine dosages, length of study, routes of administration, who may participate (Inclusion/Exclusion Criteria), and other aspects of trial design. See
Inclusion/Exclusion Criteria. Protozoa
Large group of one-celled (unicellular) animals, including amoebas. Some protozoa cause parasitic diseases in persons with AIDS, notably toxoplasmosis and cryptosporidiosis. See
PPneumocystis jiroveci Pneumonia (PCP). Pruritis
Itching. Pulmonary
Pertaining to the lungs. Purified Protein Derivative (PPD)
Material used in the tuberculin skin test (TST); the most common test for exposure to Mycobacterium tuberculosis, the bacterium that causes tuberculosis (TB). PPD is sometimes used synonymously with TST. In the PPD test, a small amount of protein from TB is injected under the skin. If patients have been previously infected, they will mount a delayed-type hypersensitivity reaction, characterized by a hard red bump called an induration. Purpura (ITP)
See
Immune Thrombocytopenic Purpura (ITP). PWA
Person with AIDS. Also known as PLWA, person living with AIDS. | 
