Sickness and death from ‘H5N1’ pale into insignificance when compared to many other infectious diseases that plague the world. But the dangers from new flu strains go well beyond those posed by this virus.

The bird flu known as ‘H5N1,’ which the world had largely forgotten about, suddenly sprang back into the news when recently the Food and Agriculture Organisation of the United Nations (FAO) issued a release warning of a ‘mutant strain’ of the virus that was spreading in Asia and beyond “with unpredictable risks to human health.”

Immediately afterwards, the World Health Organisation (WHO) issued a release of its own: “Based on available information, this evolution of the H5N1 virus poses no increased risk to public health. it is not considered unusual because influenza viruses are constantly evolving, especially in areas where they circulate regularly in poultry.”

The principal risk from the new mutant strain, designated H5N1-2.3.21, appears to be to poultry. The new virus is able to evade existing poultry vaccines against H5N1, and could therefore spread to other countries from China and Vietnam where it has been found.

As was the case with human flu vaccines whose composition needed to be reviewed annually, avian flu vaccines also needed to be regularly checked for their efficacy against viruses circulating in the field, the World Organisation for Animal Health (OIE) pointed out.

The OIE Reference Laboratory in Harbin, China, had developed a vaccine seed strain that experimentally protected poultry from the new virus. Registration and manufacture of a poultry vaccine with the new seed strain was in progress, it added in a press release.

Influenza virus are grouped into three types (A, B and C). Human pandemics have been caused by the type a viruses, which infect a wide range of birds and animals. The type a flu viruses are further categorised into subtypes based on two proteins they carry. The ‘H’ in the virus designation indicates the sort of haemagglutinin it possesses and the ‘N’ its neuraminidase subtype. While many subtypes are found in wild aquatic birds, only a few are able to infect humans.

When the highly pathogenic form of the H5N1 virus was first detected in dead geese in China’s Guangdong province in 1996, it didn’t attract much notice. But that changed the following year when it swept through Hong Kong’s live poultry markets and infected 18 people, a third of whom died. The administration in Hong Kong responded by culling all the poultry, which ended the outbreak.

The virus, however, continued to circulate in southern China. in the following years, it spread to other countries in the neighbourhood. But even in 2005, the virus was largely confined to South-East Asia. in May that year, the virus infected and killed a large number of migrating water birds that had gathered at the Qinghai Lake in western China.

“The deaths of swans and geese marked H5N1′s spread into Europe, India, and Africa,” remarked Robert G. Webster and Elena a. Govorkova of the Department of Infectious Diseases at the St. Jude Children’s Research Hospital in Memphis, U.S., in a paper published in the New England Journal of Medicine.

According to the FAO, “ since 2003, H5N1 has killed or forced the culling of more than 400 million domestic poultry and caused an estimated $20 billion of economic damage across the globe before it was eliminated from most of the 63 countries infected at its peak in 2006.” The virus was still firmly entrenched in six countries — Bangladesh, China, Egypt, India, Indonesia and Vietnam.

With outbreaks in poultry, the virus has from time to time jumped to humans too. since 2003, it has infected 565 people, according to data maintained by the WHO. more worrying is the fact that the resulting disease killed half of them.

However, an analysis published in Eurosurveillance recently by scientists at Germany’s Robert Koch Institute found that the human case-fatality rate from H5N1 infection varied from 28 per cent in Egypt to 87 per cent in Indonesia. even when adjusted for age, sex and time to hospitalisation, Egypt still had the lowest odds of people dying from the virus. Differences in the viral strains found in Egypt and Asia could not be ruled out as a factor, they said.

The scientists also noted that longer delay, from the onset of symptoms to hospitalisation and belonging to older age groups were associated with higher mortality.

Human sickness and death from H5N1 pale into insignificance when compared to many other infectious diseases that plague the world (malaria, for instance, is responsible for nearly a million deaths a year). But the worry has long been that this bird flu virus might take on a pandemic form and then sweep swiftly across the globe.

At present, the virus is not able to easily infect humans or pass from one individual to another. could the virus become better adapted to humans through mutation and exchanging genes with other flu viruses (a process known as reassortment)? If that does happen, would the H5N1′s lethality be reduced in the process?

The rationale for particular concern about a H5N1 pandemic was not its inevitability but its possible severe impact on human health, wrote J.S. Malik Peiris, a well-known virologist at the University of Hong Kong, and others in a paper published in 2007.

Such a pandemic, especially if it arose by the bird flu virus directly adapting to humans, rather than through genetic reassortment with a pre-existing human virus, could well be unusually virulent in humans. “thus, an H5N1 pandemic is an event of low probability but one of high human health impact,” they concluded.

When the flu pandemic of 2009 broke out, it was produced not by H5N1 but by a strain that made the leap from pigs to humans bearing a mix of human, swine and bird flu virus genes.

Pandemics have been caused by flu viruses that came over from animals, remarked Dr. Peiris when this correspondent met him last year. it was flu viruses from domestic livestock that were most likely to make the jump to humans.

Surveillance to monitor the viruses circulating in poultry and pigs was therefore essential. it was necessary to keep watch on whether such viruses were actively undergoing reassortment and if they possessed certain molecular markers, such as those for easily infecting humans, he added.

Pigs are of particular concern because they can become infected with both bird and human flu viruses, creating opportunities for gene swapping between viruses. The last three pandemics — and quite possibly the severe pandemic of 1918 too — were produced by flu strains that arose through such genetic reassortment.

Genes from the 2009 pandemic strain have been found in various reassortant viruses. a paper in the journal Science last year spoke of a novel virus that had been isolated from pigs in an abattoir in Hong Kong, which combined genes from the 2009 pandemic strain with those of a H1N2 virus.

Just recently, the U.S. Centers for Disease Control and Prevention reported a new H3N2 swine virus that had been able to infect children. The virus possessed a gene that had come from the 2009 pandemic strain.

In a paper earlier this year in the Proceedings of the National Academy of Sciences, a team of Chinese scientists showed in the laboratory that a mix of genes from the 2009 pandemic strain with those of the H9N2 bird flu virus could result in viruses that were more virulent than the parental forms. The H9N2 bird flu is found in poultry in many countries across Asia and so such reassortment could potentially occur naturally too.

The threat to human health from new flu viruses therefore go well beyond those posed by the H5N1 bird flu virus.

Flu viruses can evolve rapidly and scientists would like to find universal vaccines that can protect humans against all strains or at least a wide range of them. Current flu vaccines are able to target only closely related forms of a virus. As a result, the seasonal flu vaccine has to be modified annually depending on what viruses are circulating. As for pandemic strains, which are able to spread rapidly because few people have immunity to them, a vaccine can be mass manufactured only after the outbreak begins.

Recent research publications show that scientists are exploring a number of approaches for developing a universal flu vaccine. Francis S. Collins, director of the U.S. National Institutes of Health, was recently quoted as saying that he was “guardedly optimistic” that such a vaccine could be created within five years.

Oct. 22: a man suffering from cholera symptoms lies on the floor of the hospital in Marchand Dessalines, Haiti.

GENEVA — the United Nations asked for $164 million Friday to fight the cholera outbreak in Haiti that has already claimed 724 lives and is expected to continue spreading for up to a year.

The funds will be used by U.N. and non-governmental organizations to bring in additional doctors, medicines and water-purification equipment to treat up to 200,000 people who could show cholera symptoms ranging from mild diarrhea to severe dehydration, the global body said.

“We absolutely need this money as soon as possible,” said Elisabeth Byrs, a spokeswoman for the U.N. humanitarian office.

She told reporters in Geneva that the funds need to be provided quickly “otherwise all our efforts can be outrun by the epidemic.”

At least 11,125 cases of cholera have been confirmed in five of Haiti’s 10 districts since the outbreak began last month. ten deaths and 278 cases have occurred in the capital Port-au-Prince.

The World Health Organization said Friday that the epidemic isn’t likely to end soon.

“The projections of 200,000 cases over the next six to twelve months shows the amplitude of what could be expected,” said WHO spokesman Gregory Hartl. he noted that the current fatality rate of 6.5 percent is far higher than it should be.

“No one alive in Haiti has experienced cholera before, so it’s a population which is very susceptible to the bacteria,” Hartl said. “Once it is in water systems it transmits very easily, and it transmits among people who are often asymptomatic.”

“Cholera, now that it is in Haiti, probably the bacteria will be there for a number of years to come,” he added. “It will not go away.”

The cause of the outbreak in Haiti is still unknown. the country hadn’t seen cholera cases for decades before last month.

“The specific origin of this specific outbreak is something which probably will be investigated at some point, but what is important right now is the response on the ground,” Hartl said.

UNITED NATIONS, Dec. 17 (UPI) — the United Nations announced Friday the creation of an independent panel of scientific experts to explore the source of the cholera epidemic in Haiti.

“We are calling for an international panel and we are in discussions with WHO (the U.N. World Health Organization) to find the best experts to be in a panel, completely independent… (and) have the best investigation on the source of the outbreak,” the Under-Secretary-General for Peacekeeping Operations, Alain Le Roy, said at a U.N. press conference.

There has been speculation that U.N. peacekeepers from Nepal serving in Haiti may have been the source of the epidemic.

“There is no consensus among scientists on this issue,” Le Roy said.

None of the Nepalese peacekeepers had either tested positive for, or shown any symptoms of, cholera and repeated testing of water from their camp has not turned up any detectable strain of the disease, the U.N. says.

“We want to make the best effort to get to the bottom of this and find answers that the people of Haiti deserve,” U.N. Secretary-General Ban Ki-moon said.

Haiti was in an ongoing recovery operation from a January earthquake that killed more than 200,000 people when cholera broke out in October.