The World Health Organization has raised its swine flu pandemic alert up one level to Phase 4 - two levels below the highest phase.  The move comes after new cases of the virus that was first reported in Mexico were reported in several more countries. 

Following the second meeting of its Emergency Committee in as many days, the World Health Organization said it has decided to raise the international alert level for swine flu to Phase 4.

What prompted move?

Speaking from WHO headquarters in Geneva, Dr. Keiji Fukuda, Assistant Director-General for Health Security and Environment told reporters that this means there is sustained human-to-human transmission of the virus causing outbreaks in a contained geographic area.  

"If we look at the move and the change from Phase 3 to Phase 4, what this can really be interpreted as is a significant step towards pandemic influenza, but also it is a phase which says we are not there yet," said Dr. Fukuda. "In other words, at this time we think we have taken a step in that direction.  But a pandemic is not considered inevitable at this time."

Dr. Fukuda said that given the rapidly evolving situation, the World Health Organization raised the alert level in part to send a strong signal to countries that now is the time to strengthen their preparations for a possible influenza pandemic.

How many cases?

Forty cases of swine flu have been confirmed in the United States; six have been confirmed in Canada.  Spain confirmed its first case on Monday.  And suspected cases are being investigated in New Zealand, France, Israel and Scotland.  Some of the sick have recently returned from visits to Mexico, where officials suspect 149 people have died from the virus.

Governments around the world are urging caution with regard to travel to Mexico.  But the World Health Organization's Dr. Keiji Fukuda said the WHO is not recommending travel restrictions.

"At this point with the virus being widespread, from the international perspective, either closing borders or restricting travel would really have very little effect, if any effect at all, at stopping the movement of this virus," he said. "However, it would certainly cause a great deal of disruption for countries."

Symptoms to look for

Dr. Fukuda said the focus on the safety of populations means that steps can be taken to try to reduce the chances of spreading the virus, including avoiding travel if a person feels ill or seeking medical attention if they are sick.

The World Health Organization says swine flu is a highly contagious acute respiratory disease found in pigs and is caused by one of several swine influenza A viruses.  Symptoms are similar to seasonal flu, but cases have ranged from mild infections to severe pneumonia, resulting in death.