The empire strikes back

The empire strikes back A MAN in Connecticut died recently of a newly identified tick-borne disease called human granulocytic erlichiosis,, caused by a hitherto unknown bacte rium. A student in New York contracted a serious case of hanta infection, caused by a rare virus carried by r9dents. There was a fresh outbreak ofthe deadly Ebola virus in a city with a population of 6,00,000 in Zaire.

The plague resurfaced in India in, 1994 and shocked the world which had been sleeping easy, thinking the disease had been eradicated., Humankind is today besieged by lyme disease, toxic shock syndrome, legionnaire's disease and the chilling flesh-eating bacteria.

Scientists in the us now warn that humankind's best efforts to eradicate deadly diseases through vaccinations, antibiotics, sanitation and chemicals may be failing because viruses and bacteria - known and unknown - are mutating and developing resistance to antibiotics. Worse still, all these dangerous microbes have nature on their side.

"Our anti-microbial drugs have become less effective against many infectious agents andexperts in infectious diseases are concerned about the possibility of a 'post-antibiotic' era warns David Satcher, director, Center for Disease Control and Prevention (CDC), Atlanta, usA. "At the same time, our ability to detect, contain and prevent emerging infectious diseases is in jeopardy," he adds.

These microbes are enormously creative and evolutionary. Normally, benign microbes either find new hosts or swap genes to attain new virulence. Or *else; they simply mutate to avoid eradication by a drug designed to target their old incarnations.

"The life ambition of a bacterium is to become bacteria - plural," explains microbiologist Barry Bloom of the Albert Einstein College of Medicine in New York City. Bloom says that the enormous ability of microbes to stay in hiding and resurface after mutation makes it difficult for scientists to predict outbreaks clearly. Thanks to interna- tional surveillance, a new threat call occasionally be foreseen and defences readied. But not always. The Asian tiger mosquito, which traveled to the us from the Far East in 1985, spread rapidly in the hospitable, warm conditions of southern USA. Only years later did researchers identify it not only as the vector for deadly diseases such as dengue and yellow fever, but also observed that they fed on different kinds of animals including cows, horses, rats, birds and, of course, humans.

It may be difficult or impossible'to avoid lapses su~h as the importation of a ~ dangerous mosquito, but many other public health missteps are preventable. Whooping cough recently erupted in in the UK after many parents, concerned about rare complications from the per- tussis vaccine, left their children unpro- tected. There are many other such examples.

The current state of affairs can also be attributed to 50-odd years of wide- spread- but the often inappropri~te -use of antibiotics. When drug treat- ment is not aggressive enough or does not continue for the appropriate length of time, it kills only susceptible bacteria, leaving behind the stouter ones to mutate and resurface later.

CDC chief Levin also looks at disease from a broader perspective. "We believe that among the 'enabling factors' are changes in human demography and behaviour," he says. Levin attributes the resl,lrgence OfTB in New York City to crowded conditions' in prisons and in centres for the homeless.

"Malaria became a human disease only after the development of agricul- ture. Before that, there were not ~nough people to sustain it. You need a few hundred thousand people to sustain measles. We do not know that other diseases may require several million people. Giant cities are growing in developing nations now," Levin anguishes: He declares, "Our science is not adequate to combat the new dis- eases. Health and hygiene awareness is the best answer to the problem".

"We know we will never conquer infectious diseases," says Satcher . "The question is whether we can control these organisms, SQ that we can co-exist."

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