| Transmission and Incidence
 
 HIV is not transmitted by casual contact; transmission requires a direct 
    exchange(intercambio) 
    of body fluids, such as blood or blood products, breast milk(leche 
    materna), semen, or vaginal secretions, most commonly as a 
    result of sexual activity or the sharing of needles(agujas) 
    among drug users. Such a transmission(tal 
    transmisión) may also occur from mother to baby 
    during pregnancy(embarazo) 
    or at birth. Saliva, tears, urine, feces(heces), 
    and sweat do not appear to transmit the virus.
 
 By the end of 2002 it was estimated that 42 million people were infected 
    with HIV worldwide, the great majority in Third World countries(países 
    del tercer mundo); some 25 
    million had died from AIDS. The disease in sub-Saharan Africa, which has 
    been especially hard hit(duro 
    golpe), in the main(en 
    general) 
    has been transmitted heterosexually and has been exacerbated(exacerbado, 
    incrementado) 
    by civil wars and refugee problems and less restrictive local mores(costumbres) 
    with regard to(con 
    relación a) 
    sex. Some(unos) 
    29 million people were infected with HIV in this region, where, in many 
    countries, the prevalence(predominancia) 
    of AIDS has lowered(disminuido) 
    the life expectancy(esperanza 
    de vida). The epidemic(epidemia) 
    also has manifested itself in Asia (especially in India, China, Myanmar, 
    Thailand, and Cambodia) and Latin America.
 
 In the United States, the demographics of AIDS have changed over time(con 
    el tiempo). In the 1980s it was seen mainly(principalmente) in homosexual and 
    bisexual men and was one of the spurs(acicates) 
    to the gay-rights(derechos 
    de los homosexuales) 
    movement , as activists lobbied for(presionaron) 
    research and treatment monies and began education and prevention programs. 
    Also in the early years(años 
    recientes), before careful screening of blood products was 
    deemed necessary(considerado 
    necesario), the virus was contracted by an estimated 9,000 
    hemophiliacs, and a small number of people were infected by surgical(quirúrgico) 
    or emergency blood transfusions. Before long(poco 
    después), however, the majority of new HIV infections were seen 
    in drug users who contracted the disease from shared needles or unprotected 
    sex. A large proportion of infected women are drug users or partners(compañeros) of drug 
    users. Nearly a third(casi 
    una tercera parte) 
    of the infants born to HIV-infected women are infected with the virus. (Some 
    of these infants test positive for AIDS only because of the mother's 
    antibodies and later test negative.)
 
 
 Tests and Treatment
 
 Various blood tests now are used to detect HIV. The most frequently used 
    test for detecting antibodies to HIV-1 is enzyme immunoassay. If it 
    indicates the presence of antibodies, the blood is more definitively tested 
    with the Western blot(mancha) 
    method. A test that measures directly the viral genes(genes 
    virales) 
    in the blood is helpful in assessing(evaluar) 
    the efficacy of treatments.
 
 There is no cure for AIDS. Drugs such as
    AZT , ddI, and 
    3TC have proved effective(han 
    demostrado ser efectivas) 
    in delaying(retrasar) 
    the onset(aparición) 
    of symptoms in certain subsets(subconjuntos) 
    of infected individuals. The addition of a protease inhibitor, such as saquinovir or amprenavir, to AZT and 3TC has proved very effective, but the 
    drug combination does not eliminate the virus from the body. A recently 
    approved drug not in the protease inhibitor group, efavirenz (Sustiva), must 
    be taken with protease inhibitors or older AIDS medicines. Opportunistic 
    infections are treated with various antibiotics and antivirals(antivíricos), 
    and patients with malignancies may undergo(sufrir) chemotherapy(quimioterapia). 
    These measures may prolong life or improve(mejorar) the quality of life, but drugs 
    for AIDS treatment may also produce painful or debilitating side effects.
 
 Some 30 experimental AIDS vaccines have been developed and tested, but none 
    has yet proved clearly effective, including one that underwent(experimentó, 
    siguió) 
    full-scale testing(test 
    a gran escala). The development of a successful vaccine against 
    AIDS has been slowed(enlentecido) 
    because HIV mutates(muta, 
    cambia) 
    rapidly, causing it to become unrecognizable(irreconocible) 
    to the immune system, and because, unlike(al 
    contrario que) 
    most viruses, HIV attacks and destroys essential components of the very 
    immune system a vaccine is designed to stimulate.
 
 Governments and the pharmaceutical industry continue to be under pressure(bajo 
    presión) 
    from AIDS activists and the public in general to find a cure for AIDS. 
    Attempts at prevention through teaching “safe sex” (i.e., the relatively 
    safer sex accomplished by the use of condoms), sexual abstinence in 
    high-risk situations, and the dangers to drug users of sharing needles have 
    been impeded(impedido) 
    by those who feel that such education gives license(tal 
    educación otorga licencia, derecho a) to promiscuity and 
    immoral behaviors.
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