What a standard of care now is that anyone who's exposed in the hospital will get antibiotic therapy to prevent secondary spread of, of whooping cough.

One reason for W.H.O.'s cautious optimism is that 23 of the 26 countries affected so far by SARS have stopped transmission of the initial imported cases without significant secondary spread.

Doctors point out that most cases are isolated and secondary spread of the disease is rare.And they stress meningococcal meningitis is treatable if its picked up early.

This secondary spread of infection proceeds most rapidly under cool, humid conditions, the optimum conditions being a temperature between 15 C and 22 C and a relative humidity of at least 90%.

There has been no secondary spread from person to person.

If a case occurred in this country, the steps would confine the disease to the individual animal and prevent secondary spread.

But he added that countries like Vietnam must develop stronger monitoring systems to detect any possible imported cases and improve infection control systems to prevent secondary spread.

However, free moisture is not needed for secondary spread via conidia; high atmospheric humidity is sufficient.

After initial infection in streamside populations, secondary spread via zoospores quickly infects all downstream individuals.

With the ongoing replication of the virus a secondary spread occurs, with the seeding of the CNS.