Acquired Immune Deficiency Syndrome (AIDS) - NOT original
Acquired
Immune Deficiency Syndrome (AIDS)
(See also
Kaposi's Sarcoma and Pneumocystis carinii Pneumonia). A terminal, secondary immunodeficiency
syndrome characterized by dysfunction of cell-mediated immunity and manifested
by opportunistic infections and malignancies.
Causes and
Incidence
The cause is
thought to be one of several related retroviruses (human immunodeficiency virus,
or HIV) that convert viral RNA into a proviral DNA copy, which is incorporated
into the DNA of the host cell. The proviral copy then is duplicated with normal
cellular genes during each cellular division. HIV is a blood-borne virus and
commonly is transmitted through exchange of body fluids during sexual contact,
through parenteral exposure or fetal exposure to blood, and through select body
fluids from an individual infected with HIV. Infants are at risk of acquiring
the HIV during fetal development, delivery, or breast-feeding from an
HIV-positive mother. High-risk behavior for HIV exposure includes unprotected
sexual activity and IV drug use with shared needles.
Occupational
transmission to health care workers is possible through needle sticks or other
exposure to HIV-infected blood. Individuals infected with HIV who are
asymptomatic are in a carrier state and may transmit the disease without
displaying any of the characteristic signs of AIDS.
AIDS is a global
pandemic, and it is predicted that more than 110 million people worldwide will
be infected with HIV by the end of the century. As of 1991 more than 1.1
million people worldwide had died.
In the United
States the incidence of AIDS has steadily increased from 3.46 per 100,000
population in 1985 to 40.20 per 100,000 population in 1993. Although it is far
too early to interpret the reasons, in 1994 the incidence of reported AIDS
cases dropped slightly, to 30.07 per 100,000 population. All races and ethnic
groups are affected. Currently men far outnumber women as victims of the
disease. However, the fastest rise in cases is occurring among minority women.
The median age range for all individuals with AIDS is 30 to 39 years.
Disease
Process
The current
theory holds that as HIV is reproduced, it affects the immune system by
infecting the T-helper cell lymphocytes, which usually coexist in a 2:1 ratio
with T-suppressor cells. As the viruses replicate, masquerading as helper
cells, the number of real helper cells declines, and the T-suppressor cells eventually
dominate, leading to immunosuppression and a lowering of the body's prime
defense mechanism against intracellular pathogens and the formation of
malignant tumors.
Symptoms
AIDS is a
chronic, progressive, terminal illness that can be divided into four stages, as
defined by the federal Centers for Disease Control and Prevention (CDC):
Stage I
An acute, flulike
syndrome that develops at the time of initial infection and lasts from days to
weeks
Stage II
An asymptomatic, HIV-positive
carrier state that may persist for years
Stage III
Generalized,
persistent lymphadenopathy
Stage IV
The development
of other disease processes, including (1) constitutional disease (weight loss
greater than 10% of body weight, persistent diarrhea, fever, malaise, oral
thrush); (2) neurologic disease (peripheral neuropathies, paresthesia,
myelopathy, dementia); (3) opportunistic infections (bacterial, viral, fungal,
or protozoal) and their accompanying clinical features; (4) secondary
neoplasms; and (5) other conditions (e.g., endocarditis, interstitial
pneumonitis, immune thrombocytopenic purpura)
Potential
Complications
The complications
are numerous and are associated with the various opportunistic infections or
neoplasms, as well as the repetitive nature of the infections. These infections
eventually overwhelm the body's compromised immune system, leading to massive
infectious invasions in every body system and, eventually, death.
Diagnostic
Tests
Clinical evaluation
Any of the above
manifestations; history of high-risk behavior
Enzyme-linked
immunosorbent assay (ELISA)
Screening test
for HIV antibody (may be positive
from 0 to 12 months after exposure)
Western blot/
immunofluorescent assay
To confirm
reactive seropositive results
obtained by ELISA test
WBCs/lymphocytes
Depressed
T-cell
studies
Reduced
reactivity and function of T
cells; reduced number of T-helper cells, increased number of T-suppressor cells
B-cell studies
Numbers and function
normal or increased
Natural killer
(NK) cells
Reduced activity
Complement
Normal or
increased
Treatments
Surgery
Tumor excision of
some related neoplasms
Drugs
Experimental treatment
with various retroviral drugs such as zidovudine (Retrovir; formerly
azidothymidine [AZT]); didanosine (Videx; formerly dideoxyinosine [ddI]; and
zalcitabine (Hivid; formerly dideoxycytidine [ddC]), using CD4 lymphocyte
counts as a treatment guide; prophylaxis with trimethoprim-sulfamethoxazole
tablets to prevent Pneumocystis carinii pneumonia (PCP); rifabutin prophylaxis
for Mycobacterium avium infection; drugs specific for various opportunistic
infections; chemotherapy for carcinomas; prophylactic use of zidovudine
following exposure through penetrating injuries is controversial
General
Measures to
improve overall health (e.g., no smoking, balanced nutrition, drug
rehabilitation, flu vaccine, pneumococcal vaccine, hepatitis B vaccine);
supportive measures for coping with and adapting to the effects of the disease
(e.g., counseling, support groups); instruction in how the disease is spread in
order to promote prevention, particularly among high-risk groups; use of
universal precautions by health care workers and family members to prevent
transmission.