The letter followed an earlier warning from Sir Liam that millions of Britons could fall victim to swine flu in the coming months. Government officials admitted last night that illness rates from the virus could reach 50 per cent.

Primary care trusts are now being briefed to expect that the pandemic could affect as much as 40 per cent of the workforce before the end of the year, with many worried that there could be a surge of cases in the autumn, according to health industry sources.

The Department of Health sought to reassure the public last night. A spokesman said: "Previous pandemics have seen total illness levels of 25-35 per cent. So our plans are as robust as possible, we have based them on illness rates of 50 per cent, though we do not anticipate it being this high in the current pandemic. Based on this figure, the workforce could be reduced by 15-20 per cent at the pandemic's peak. In the unlikely event that every school closed, this could rise to 35 per cent." He said it was impossible to predict when the pandemic would peak, but added: "As part of ongoing planning, the NHS is being asked to ensure that antiviral collection points could, if needed, be put into action in a week."

Keen to avoid panic, the Government is careful to present official statistics showing "laboratory-confirmed" cases, which currently stand at 2,244. Yet the true scale of infections is far higher than headline figures suggest. The total number of cases either confirmed by laboratory tests or "clinically presumed" currently stands at 3,725.

The ILO said HIV/Aids killed almost 3.5 million people of working age in 2005.

South Africa, among the worst-affected nations, has announced a plan aiming to halve the infection rate by 2011 and to boost the use of antiretrovirals.

In a speech to mark World Aids Day, UN Secretary General Kofi Annan urged more frank and open discussion of HIV/Aids.

All politicians had to consider themselves personally accountable for stopping the spread of the disease, Mr Annan said, as did every individual.

"It requires every one of us to help bring Aids out of the shadows and spread the message that silence is death," he said.

Skipping work without good reason? You have lots of company.

Unscheduled absenteeism at U.S. companies and organizations has climbed to its highest level since 1999, according to results of a recent nationwide survey of human resource executives in U.S. companies and organizations.

The survey, conducted for CCH by the Harris Interactive consulting firm, put the U.S. absenteeism rate at 2.5 percent in 2006, up from 2.3 percent a year ago and the highest since seven years ago when it was 2.7 percent.

It found that personal illness accounts for only 35 percent of unscheduled absences, with the rest due to family issues (24 percent), personal needs (18 percent), stress (12 percent) and entitlement mentality (11 percent).

For 1-in-5, the gain was 10 pounds or more.

Among others, 57 percent of government workers reported bigger waistlines, 54 percent of IT workers, and 53 percent of accounting/finance workers, compared to 35 percent of retail workers and 39 percent of sales workers.

In other words, not surprisingly, people with sedentary jobs report weight gain in larger numbers.

Anita and Cara were considered model employees at Weyco, an insurance consulting firm outside of Lansing, Mich., both having worked at the company for years. The women sat side-by-side, sharing workloads – and after work – sharing the occasional cigarette.

But at a company benefits meeting two years ago, the company president announced, "As of January 1st, 2005, anyone that has nicotine in their body will be fired," Anita remembers. "And we sat there in awe. And I spoke out at that time. 'You can't do that to us.' And then he said, 'Yes, I can.' I said, 'That's not legal.' And he came back with, 'Yes, it is.'"

And it was legal: in Michigan, there's no law that prevents a boss from firing people virtually at will. At Weyco, that meant no smoking at work, no smoking at home, no smoking period.

Weyco gave employees 15 months to quit, before subjecting them to random nicotine testing. If you fail, you're out.

While stress is one cause of high blood pressure, there are a number of other things that can contribute, such as a poor diet, drinking too much alcohol, being overweight or obese, eating too much salt and not doing enough exercise.

Dr Chantal Guimont and colleagues who carried out the latest study acknowledge that other factors may have contributed to the high blood pressure found in the white-collar workers that they studied.

However, they believe job stress is important and may chronically activate the nervous and cardiovascular system.

Dr Guimont said: "Our study supports the hypothesis that job strain, particularly in workers with low social support at work, may contribute to increased blood pressure."

Each ill person is expected to infect two others. Symptoms should appear within two days. Flu spreads most among school-age children — expect a 40 percent attack rate among them compared to 20 percent among working adults. But, with caring for sick relatives and stay-at-home precautions to avoid infection, 40 percent of the workforce could be absent for weeks at a time.

To minimize workplace infection, the report gives the most in-depth advice yet for businesses to take such steps as cleaning offices -- flu can live on hard surfaces for 48 hours -- and minimize employee contact by not shaking hands and staying 3 feet from co-workers.

But the 3-feet advice assumes flu only spreads in the large droplets of coughs and sneezes; tiny droplets that stay suspended in the air for long periods can spread it, too.

"Those are the kinds of uncertainties that make it hard to be very dogmatic" about health tips, cautioned Dr. John Treanor, a University of Rochester flu specialist.

In their analysis, Park and his colleagues found that the bank tellers, clergy, aircraft mechanics and hairdressers had highest odds of dying from Alzheimer’s disease. For Parkinson's disease, the highest risks were among biological scientists, teachers, clergy members and other religious workers.

The risk of death from presenile dementia -- a form of dementia that arises before the age of 65 -- was greatest among dentists, graders and sorters in industries other than agriculture and, again, clergy.

Veterinarians, hairdressers and graders and sorters had the highest risks of dying from motor neuron disease, the most common form of which is amyotrophic lateral sclerosis, also known as Lou Gehrig's disease — an invariably fatal degeneration of the central nervous system that causes muscle wasting and paralysis.

In another era, the task of caring for elderly parents often fell to the unmarried daughter who never left home and never worked for a living. But now, in a 21st-century twist on the 19th-century spinster, career women like Ms. Geist who have made their mark in the world are returning home to care for parents in old age.

They are embracing a filial role that few could have imagined in their futures and are doing so by choice. In fact, sociologists are beginning to give the phenomenon a name: the Daughter Track, a late-in-life version of the Mommy Track, a career downsizing popular with younger women.

Women, now as always, bear a disproportionate burden for elder care and often leave jobs, either temporarily or permanently, when the double duty becomes overwhelming , according to recent studies of family care-giving, women in the workplace and retirement patterns. Although there is no precise count of how many women have walked away from careers to care for their parents, more of them than ever are financially independent, unmarried or childless, which makes it more feasible than it might be for women with families at home. And never have more parents needed adult children to care for them, what with long life expectancy and disabling conditions like Alzheimer's disease.

"Smart corporations are paying attention" to the challenges that caring for elderly parents presents, said Meryle Mahrer-Kaplan, vice president of advisory services at Catalyst, which has more than 300 corporate members interested in the issues of women in the workplace. "It's so pressing because you can't plan for it, you can't put it off, and it's not a good-news activity. It weighs people down."

When employees come down with the flu or other illness and still go to work, it's called "presenteeism," as opposed to "absenteeism," explains The Early Show medical correspondent Dr. Emily Senay.

Although it's done out of job dedication in many cases, it really doesn't help to have an employee in the office who is spreading an infection to others, in addition to not being able to work as well due to their own illness.

Loggers recorded 85 fatalities in 2004, a rate of 92.4 deaths for every 100,000 workers, more than 22 times the rate among all workers. Loggers deal with tremendous weights when they fell trees and it's not always possible to know exactly where a tree will fall or when. Too, they often work on steep hillsides, in poor weather, and in a hurry.

Aircraft pilots matched that death rate of 92.4 and 109 of them died on the job. Many of these were in the general aviation category, small aircraft manned by bush pilots, air-taxi pilots, and crop-dusters. Their equipment can be old and the maintenance less stringent than among the big airlines, adding to the danger.

The fishing industry is a perennial leader as measured by death rate and 2004 was no different; 38 fishermen died, a rate of 86.4 per 100,000. Drowning is the most common cause of death in this industry, but fishermen also suffer from fatal accidents in handling some of the heavy equipment that the modern fisheries employ.

There were 5,139 work-related injuries and illnesses in the 110,236 U.S. job records Dembe analyzed. More than half of these were in jobs with extended working hours or overtime.

Working longer hours, such as at least 12 hours a day, was associated with a 37 percent increase in illness or injury, while working at least 60 hours a week was associated with a 23 percent increase. Long commuting had no impact on the rate, the researcher found.