| 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.
 |