Shorter AZT Treatment Still Reduces Mother-Fetus HIV Transmission

      BOSTON, Oct. 5 (UPI) -- Infectious disease experts report that a shorter-than-standard antiviral treatment can lower the rate at which HIV-positive mothers infect their fetuses to about 5 percent and at only one-fifth the cost.

      Lead investigator Dr. Marc Lallemant of Muang, Thailand, and his colleagues found that shortening the treatment only works to a point, however. In fact, the shortest-treatment arm of the study was cancelled prematurely because transmission rates proved double the longest-treatment arm, or 10.5 percent of the time.

      The findings are especially important to developing countries, where the $1,000 price per standard course of treatment is prohibitive.

      Standard treatment in the United States starts the mother on zidovudine, also known as AZT and Retrovir, at 28 weeks into her pregnancy. After birth, the newborn is put on the same drug for another six weeks.

      The study, which is reported in the Boston-based New England Journal of Medicine, followed 1,437 women in Thailand who enrolled in the Perinatal HIV Prevention Trial.

      The randomized, double-blind trial assembled four groups, abbreviated long-long, long-short, short-long and short-short. Mothers were given AZT from either 28 weeks (long) or 35 weeks (short) to giving birth; babies for either six weeks (long) or three days (short).

      Without any treatment, rates of transmission from mother to fetus are between 20 and 30 percent. Premature births can transmit the virus up to 40 percent of the time.

      In Lallemant''s study, however, the average maternal-fetal transmission rate among women who received the long-long treatment dropped to 6.5 percent -- consistent with most First-World findings.

      But the team also found the long-short and short-long combinations worked well in protecting children. Treating the mother for six weeks and the baby for three days, for example, yielded 4.7 percent -- not statistically different from the long-long''s 6.5 percent, the researchers reported.

      They added that when treatment is delayed until 35 weeks into the pregnancy, the baby will need the full week''s treatment with ziduvodine.

      Maternal-fetal transmission rates are very high in developing nations, explained Lallemant. Many researchers are seeking ways are to lower the rate in a manner affordable for these nations. A shorter course of treatment was one option that had appeal.

      Lallemant said it may still be possible to achieve the shorter treatment by adding another drug, nevirapine, to the mix. He added that he and his colleagues are poised to start a new trial that will test this approach: long term zidovudine in the mother, a single dose of the powerful antiviral when labor starts, and 3 days of zidovudine for the baby.

      "If it works in the long-short, the results will certainly apply to the short-short treatment," he told United Press International.

      Dr. Yvonne Bryson, director of the Maternal Child Immunology Clinic at the University of California, Los Angeles, said the findings of this study are encouraging because they do indicate "there is a reduction in transmission even with the short-short treatment. This is very encouraging."

      Bryson, an early researcher in maternal-fetal transmission of HIV, also heads the LA Pediatric AIDS Consortium.

      Among poorer populations, "the problem comes in identifying the women who are HIV positive. Many times we don''t have this information until later in the pregnancy," she said. So knowing that shorter-term treatment is effective, "offers an important option."

      She said most experts believe that "most of the in-utero transmission of HIV occurs during the third trimester." Babies who are not infected while in the womb may become infected during birth by exposure in the vagina. That''s why women who are HIV-positive are good candidates for Cesarean section, a procedure that also reduces the rate of transmission, explained Bryson.

      "But in poor nations like African countries or Thailand, C-section is not an option," she said.

      Bryson believes the best option may be the type of combination approach -- adding in nevirapine at the onset of labor. In an editorial that accompanies the study, Drs. Catherine Peckman and Marie-Louis Newell of the Institute of Child Health, London, wrote, "the results of the current trial suggest that when a woman receives the longer regimen of zidovudine prophylaxis during pregnancy, prolonged treatment of the infant may not have additional efficacy."

      They noted the findings will likely have minimal impact in industrialized nations, where the practices of antiviral treatment and Cesarean delivery have already cut transmission rates.

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