The San Franicso Chronicle - Tuesday, September 28, 1999
Carl T. Hall, Chronicle Science Writer

The so-called Nipah virus, named for a village in Malaysia where it struck in 1997, underscores the global problem of emerging infectious diseases.

That is one of the central topics at the annual scientific meeting of the American Society for Microbiology held this week at Moscone Center in San Francisco. About 16,000 doctors, researchers and drug company representatives are attending.

Yesterday's sessions included encouraging -- although highly preliminary -- evidence on a potential new class of antibiotics for battling drug-resistant bacteria. Another early-stage study showed promising results for a new type of AIDS drug for those not helped by conventional therapy.

Every year or so, a mysterious disease outbreak is traced to a previously unrecognized microbe somewhere around the world, said C.J. Peters of the federal Centers for Disease Control and Prevention in Atlanta.

The Nipah virus was "a lot scarier and more serious" than the others, Peters said, "a wild card" of a bug capable of jumping easily from one species to another.

Two years ago, it caused 284 cases of encephalitis in Malaysia, killing 105 people, nearly all of whom were ethnic Chinese directly involved in the hog-farming industry. In order to stem the epidemic, authorities ordered some 1.2 million hogs destroyed and razed several farms in the center of the afflicted zone.

The outbreak ran its course over about seven months. "We think it is contained and is no longer being transmitted," Peters said.

But scientists are nowhere close to solving all the medical mysteries presented by sometimes-deadly microbes.

The Nipah virus, for example, appears to hide without causing disease symptoms in a species of fruit-eating bat. Yet scientists can only speculate as to why it emerged so suddenly and with such a vengeance in pigs, and was then passed to humans.

Some evidence suggests the problem was brought on by recent changes in hog-farming techniques practiced in the Malaysian countryside. Domestic or wild dogs -- along with farmers trying to move stock out of harm's way -- then may have spread the virus from one farm to the next.

A repeat outbreak of illness seems inevitable, experts warned, either from the Nipah virus or a previously unknown relative. At the same time, existing pathogens pose new problems.

The AIDS virus, in particular, has been shown capable of mutating into a drug-resistant form that can infect someone else. Dr. Douglas Richman of the University of California at San Diego reported growing evidence of more hard-to-treat infections.

That helped set the stage for the latest results yesterday from drug developers trying to keep one step ahead.

Early-stage testing of a drug called T-20, one of a new class of anti-HIV drugs called fusion inhibitors, was tested in 55 people who were taking combination AIDS drug therapies and who still had high levels of HIV.

The viral loads fell below measurement capabilities in 20 of the test subjects after four months, while dropping substantially in 33 others.

But experts said the drug, which requires twice-daily injection, may grant only a brief reprieve for patients with resistant forms of infection. The drug is being developed by drug giant Hoffmann-La Roche Inc. in a collaboration with Trimeris Inc., a Durham, N.C., biotech company.

On the antibiotics front, drugmaker Pharmacia & Upjohn said it will seek approval later this year for Zyvox, which has shown to be capable of killing germs resistant to common antibiotics, even including vancomycin, which is now held in reserve as the last-ditch defense against mutated pathogens.

Zyvox is a synthetic compound that disables bacteria by hitting a different molecular target than current drugs on the market.
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