The Frontlines | Age of Biology

A New Strategy
Viruses can mutate very rapidly, and a successful new strain may affect its host differently, or it may change the way the virus is transmitted. Many viruses, such as the Hanta virus, can only be transmitted to humans by an animal vector. Other viruses, such as the rhinovirus responsible for the common cold, can be passed directly between people. Using this method, viruses can spread more rapidly and can potentially be more dangerous.

In 1996, three years after the Four Corners outbreak, Dr. Delia Enria suspected another outbreak of Hanta virus in Pergamino, a city in Argentina. Samples sent to the Centers for Disease Control and Prevention (CDC) in the United States confirmed that the killer was another strain of Hanta virus. But there was another mystery to this outbreak.

A physician working with infected patients was himself infected. When he traveled 1000 miles away to visit a specialist, the specialist and later his wife became infected. Dr. Enria suspected human-to-human transmission -- something the Hanta virus was not supposed to do.

Dr. C.J. Peters at the CDC was skeptical of Dr. Enria's hypothesis, but he and a team of researches visited Argentina to check into the outbreak. They came with a list of other possible modes of transmission. They captured and tested rodents in the region, but they found no sign of Hanta virus. One by one, the other possibilities were crossed off the list, leaving only one -- Enria's human-to-human transmission.

If this new strain could pass between humans without an intermediate host, the virus could spread more rapidly through a population. However, the number of infections in this particular outbreak eventually stopped. The virus disappeared as mysteriously as it had appeared. But could it happened again?

The Frontlines | Age of Biology

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