A tick doesn't look like trouble--until you come down with Lyme disease. The tick-borne infection sickens more than 10,000 people each year, and without early antibiotic treatment it can progress from a mild malaise to arthritis, heart problems, and even facial paralysis. In the past, the best defenses against Lyme disease were bug repellent, tucked-in clothing, and vigilant checking for the ticks that transmit the disease-causing spirochete, Borrelia burgdorferi. But this past year two companies, SmithKline Beecham and Pasteur Merieux Connaught, reported successful human trials of Lyme disease vaccines. Both are made from a bacterial surface protein that stimulates antibody production. When a tick bites a vaccinated person, it sucks in antibodies that inactivate bacteria in the tick's gut. The hope is that any B. burgdorferi the tick is carrying will be disabled before they can make their way into the person's bloodstream.
To achieve immunity, people need booster shots after six months and, most likely, annual vaccinations. Tick checks, however, are still necessary because the antibodies work only in the tick gut--they won't protect you if tick-borne pathogens slip into your blood. As of mid-November, the vaccines were awaiting FDA approval. Says Phillip Baker, the program officer for Lyme disease at the National Institute of Allergy and Infectious Diseases, "I suspect that after they've been used for two or three years, we're going to see a big drop-off in the number of cases."
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Birth Order The traditional method of baby making offers a 50-50 chance of having a girl. Boys and girls both inherit an X chromosome from Mom, but Dad can contribute an X chromosome, in which case the baby will be a girl, or a Y chromosome, resulting in a boy. If, however, you could separate Dad's X-bearing sperm from his Y-bearing sperm, you could increase the odds of conceiving a girl. And that is what researchers at the Genetics and IVF Institute in Fairfax, Virginia, did. In September they announced a sperm-sorting technique that almost guarantees that a girl will be conceived.
X chromosomes tend to carry a bit more DNA--2.8 percent more--than Y chromosomes, and the new technique cleverly highlights that difference by labeling sperm DNA with a dye that glows in the light of a laser. The labeled sperm are then sorted by glow: the bigger the glow, the better the chance that the sperm harbors a longer chromosome (presumably X). If the selected sperm make the grade, they are flushed into the woman's uterus or used to fertilize eggs in vitro. In a small trial, sperm selected to produce girls created pregnancies of the desired sex more than 90 percent of the time. But the technique for selecting sperm bearing the Y chromosome is far less discriminating. Only 65 percent of the sperm selected for the Y chromosome are likely to harbor it. (The institute has not yet released data on pregnancy results for couples using Y-sorted sperm.)
