AIDS or acquired(adquirida)
immunodeficiency syndrome, fatal disease caused by a rapidly mutating
retrovirus that attacks the immune system and leaves(deja)
the victim vulnerable to infections, malignancies(malignidades),
and neurological disorders(trastornos).
It was first recognized as a disease(enfermedad)
in 1981. The virus was isolated(aislado)
in 1983 and was ultimately named the human immunodeficiency virus (HIV).
There are two forms of the HIV virus, HIV-1 and HIV-2. The majority of cases
worldwide(en todo el
mundo)
are caused by HIV-1. In 1999 an international team of genetic scientists
reported that HIV-1 can be traced(localizado)
to a closely related strain(variedad
estrechamente relacionada)
of virus, called simian immunodeficiency virus (SIV), that infects a
subspecies of chimpanzee ( Pan troglodytes troglodytes ) in W central
Africa. Chimpanzees are hunted(cazados)
for meat in this region, and it is believed(se
cree)
the virus may have passed from the blood of chimpanzees into humans through
superficial wounds(heridas
superficiales), probably in the early 1930s.
Action of the Virus
In a process still imperfectly understood(comprendido),
HIV infects the CD4 cells(células)
(also called T4 or T-helper cells) of the body's immune system(sistema
inmunitario), cells that are necessary to activate B-lymphocytes(linfocitos)
and induce(inducen,
provocan)
the production of antibodies(anticuerpos).
Although the body fights back(trata
de devolver la agresión, contraataca), producing billions of
lymphocytes daily to fight the billions of copies of the virus, the immune
system is eventually(finalmente) overwhelmed(abrumado,
abatido), and the body is left(queda)
vulnerable to opportunistic infections and cancers.
Signs and Symptoms
Some people develop flulike symptoms(síntomas
parecidos a los de la gripe)
shortly after(poco
después)
infection, but many have no symptoms. It may be a few months or many years
before serious symptoms develop in adults; symptoms usually develop(se
desarrollan)
within(durante)
the first two years of life in infants infected in the womb(matriz)
or at birth(al
nacer). Before serious symptoms occur, an infected person may
experience fever, weight loss(pérdida
de peso), diarrhea, fatigue, skin rashes(erupciones
cutáneas), shingles(herpes),
thrush(afta (infección))
, or memory problems. Infants may fail to develop normally(puede
que no logren desarrollarse normalmente).
The definition of AIDS has been refined as more knowledge(conocimiento)
has become
available(se ha
vuelto disponible). In general it refers to that period in the infection when the CD4
count goes below(por
debajo de) 200 (from a normal count of 1,000) or when the
characteristic opportunistic infections and cancers appear. The conditions
associated with AIDS include malignancies such as Kaposi's sarcoma ,
non-Hodgkin's lymphoma, primary lymphoma of the brain, and invasive
carcinoma of the cervix(cuello
uterino). Opportunistic infections characteristic of or more
virulent in AIDS include Pneumocystis carinii pneumonia , herpes simplex ,
cytomegalovirus , and diarrheal diseases caused by cryptosporidium or
isospora. In addition, hepatitis C is prevalent(prevalece,
predomina) in intravenous drug users
and hemophiliacs(hemofílicos)
with AIDS, and an estimated 4 to 5 million people who have tuberculosis are
coinfected with HIV, each disease hastening(acelerando)
the progression of the other. Children may experience more serious forms of
common childhood ailments(dolencias
típicas de la infancia)
such as tonsillitis(amigdalitis,
anginas)
and conjunctivitis . These infections conspire to cause a wide range(amplio
rango)
of symptoms (coughing(tos),
diarrhea, fever and night sweats(sudores
nocturnos), and headaches) and may lead(llevar)
to extreme weight loss, blindness(ceguera),
hallucinations(alucinaciones),
and dementia before death occurs. |