HANOI: Bird flu has resurfaced with a vengeance in Vietnam – with five people falling ill in as many weeks – after no human cases had been reported for a year-and-a-half.

Health experts say the spike is a sobering reminder that the H5N1 virus remains deep-rooted and can kill at any time.

The virus also has flared elsewhere, with people falling ill in China, Egypt and Indonesia this month alone. And poultry outbreaks have resurfaced in Myanmar and as far afield as the Czech Republic.

Vietnam, previously hailed as Asia’s bright spot for beating back the virus, has seen an unexpected surge since last month, when it reported its first human case since November 2005. Two patients have died, two have recovered and one is critically ill.

“It’s always been lingering and loitering, but now it’s striking and we don’t know why”, said Peter Cordingley, spokesman for the World Health Organization’s Western Pacific region.

Vietnam was blindsided when the virus began ravaging poultry stocks across Asia in late 2003. The country logged dozens of human deaths and suffered huge financial losses before undertaking an ambitious campaign to vaccinate all poultry.

The plan worked well, and no outbreaks were reported throughout 2006 until the virus re-emerged earlier this year among birds.

The latest flare-up began in May and has affected poultry in 18 provinces, killing or forcing the slaughter of some 200,000 birds.

Four of the human cases were from the north and one was from central Vietnam, raising the bird flu death toll in the country to 44.

“The virus has all the time had the capability to infect humans”, said Hans Troedsson, WHO’s representative in Vietnam

“Why it happened now in May an didn’t happen in January and February, we don’t know”.

Agriculture officials say unvaccinated ducks are largely to blame for the recent problems. In March, the government lifted a ban on hatching and restocking waterfowl, which has led to more ducklings being raised and transported without being immunized.

Vaccination helps to decrease the spread of the virus, but even that is not foolproof because ducks must receive multiple shots each year to ensure immunity.

The virus has killed at least 191 people worldwide, according to the WHO. --- AP.