HANOI, VIETNAM - Vietnam, which has the world's second-highest death toll from bird flu, has responded quickly to prevent the spread of swine flu, the World Health Organization (WHO) said Monday.

Vietnam's Ministry of Health has told medical officials throughout the country to enhance surveillance and early detection measures, and to prepare for cases of the illness, the WHO said.

Health screening has been stepped up at airports and borders, it said.

'WHO has requested all nations to intensify surveillance for unusual outbreaks of influenza-like illness and severe pneumonia,' a WHO statement said. 'The Vietnam Ministry of Health has responded quickly to this request.'

There are no cases of the new swine flu in Vietnam, the WHO added.

Le Truong Giang, deputy head of the Ho Chi Minh City department of health, confirmed that Vietnam has resumed checking the temperatures of passengers arriving from overseas.

'We have been closely monitoring people, both Vietnamese and foreigners entering the country, especially those from or having transited through epidemic-hit areas,' Giang said from Vietnam's southern commercial capital.

'We will react very quickly in any situation,' Giang said, noting the country's experience fighting bird flu and SARS.

'This system of monitoring and preventing epidemics has been familiar to us.'

A Vietnamese woman died last week from bird flu, bringing to 56 the nation's toll from that disease since 2003.

'Given previous experiences dealing with both avian influenza and SARS, Vietnam already has many surveillance and early detection mechanisms in place,' said Shelaye Boothey, WHO's communications officer in Hanoi.

In 2003, Severe Acute Respiratory Syndrome (SARS), an often fatal flu-like disease, killed five people in Vietnam and nearly 800 worldwide.

The WHO said it is working closely with Vietnam's health ministry to develop procedures in the event of a swine flu outbreak.

In Mexico 103 people are confirmed or suspected to have died from swine flu, which has also infected but not killed people in the United States and Canada.

The new flu strain was apparently born when human and avian flu viruses infected pigs and became mixed.