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...used of the lice-killing chemicals called synthetic pyrethroids. In recent years, however, the frequency of infestations has increased, and ever greater numbers of children are becoming reinfested within days of treatment. All this has led health officials and researchers to begin worrying about the emergence of a resistant strain of the insect, impervious to permethrin...
Researchers speculate that overexposure to permethrin may have sparked a process of natural selection in lice. A similar use of preventive insecticides encouraged the rise of resistant strains of the mosquitoes and black flies responsible for transmitting malaria and African river blindness. Although no definitive studies on resistant strains of head lice have been completed in the U.S. (results of a Harvard investigation won't be ready for several months), two recent papers from Israel and the Czech Republic seem to support the resistant-strain theory. Says Thomas Bell, health officer for three counties in Washington State...
...people outside the medical community paid much attention last May when a three-year-old Hong Kong boy died of a mysterious flu that usually infects only birds. Even this fall, when seven more people came down with the same viral strain--and one of them died--doctors found comfort in the fact that the virus did not seem to be spread from person to person. But then last week two young cousins of one of the victims fell ill with what appeared to be the same disease, prompting medical authorities in the U.S. and China to warn that this...
From two deaths to millions may seem like a big leap. But this strain of influenza, called H5N1, though highly virulent in birds, has never before been known to attack humans. Since no human can count on having a natural immunity to what is essentially a bird virus, we could prove especially vulnerable to infection. First discovered in South African terns in 1961, H5N1 has already raced through poultry farms in southern China, killing caged fowl by the thousands...
FOWL FLU Several people in Hong Kong have contracted a deadly strain of influenza previously found only in birds. The big concern: it could be passed from person to person--and eventually spread worldwide...