Today is World Tuberculosis Day, and as we take time to mark our calendars, there is nothing but dread in recognising the resurgence of a disease thought long dead.

Coupled with global poverty, wide-spread drug use, and powerful modern diseases such as Acquired Immune Deficiency Syndrome (AIDS) and Human Immuno-deficiency Virus (HIV), this old-world killer has returned with a vengeance. This year alone, medical science estimates up to 266,000 HIV-positive people will succumb to TB.

The HIV/AIDS pandemic has provided TB with a new lease on life. The United Nation's World Health Organisation (WHO) estimates one in three HIV-positive persons will die by TB, with world-wide infections increasing by about three million people in 1998.

At least one-third of Earth's population -- 1.9 billion people -- are already infected with TB and an additional 300 million are estimated to fall victim within the decade.

The lethal association between HIV and TB is frighteningly simple -- HIV destroys the immune system, leaving the person highly susceptible to an `opportunistic' disease such as TB.

One of the oldest diseases known to mankind, TB is caused by the airborne bacterium mycobaterium tuberculosis .

The bacteria is spread through casual contact when an infected person expels the germs by coughing, spitting, even talking. TB bacteria can remain in the air for several hours and thrive in a closed environment for years.

Only a person with active pulmonary TB -- the most common form of the disease -- is contagious. Pulmonary TB attacks the lungs, eating ragged holes in the tissue and rupturing blood vessels.

As the immune system struggles to overcome the infection, the pitted lungs gather pus causing various symptoms such as coughing, loss of weight and appetite, severe sweating at night, weakness, shortness of breath and chest pains.

The bacteria can live in a person's body without obvious symptoms, a stealth technique known as TB infection. Then, without warning, it breaks away, leading to full-blown TB.

If left without proper treatment, the infected person will typically spread the infection to between ten and 15 other people each year.

Bermuda has a low prevalence of the disease, with only six cases reported to the Health Department over the past year.

The Health Department screens HIV patients yearly and all suspected cases are referred by a physician to the Epidemiology Department.

Those who are HIV-positive -- their immune systems already compromised -- are more likely than others to become infected with TB, and a large percentage of them will fall seriously ill.

TB is the only major opportunistic infection that can spread through the air to otherwise healthy people as well.

So, while HIV/TB dual infections continue to rise, so too will the bacterium spread more rapidly to the larger population.

Until now, the world hot spot has been sub-Saharan Africa, which continues to struggle under increased caseloads of TB.

But the dual epidemic may cause an even more vicious attack in Asia -- home to two-thirds of the world's active TB cases and where HIV is spreading faster than anywhere else on Earth.

As a result, researchers predict that the number of TB cases accredited to HIV infection in Asia will rise from two percent in 1990 to 14 percent by the year 2000.

And as the epidemic spreads, medical professionals face an uphill battle in not only diagnosing the disease, but in treating it as well.

Health workers must battle constantly to ensure patients follow the lengthy treatment programme (six to nine months of treatment) and take their medication as prescribed.

Meanwhile the science itself is not perfect; some of the treatment regimes can have serious side-effects on HIV-positive patients. One potentially dangerous drug is thiacetazone, which can cause a patient's skin to peel painfully from the body.

Yet, even in HIV-positive people, TB can be cured if diagnosed in time and treated properly.

With correct treatment, an otherwise healthy individual can survive the disease while HIV-positive individuals can add an average of two extra years to their life.

Left untreated however, even the healthiest patient could die within five years, suffering in slow agony as their wasted body succumbs to constant coughing and nightly fevers.

The prognosis for an HIV-positive patient is even more bleak -- death will come swiftly -- often within months.

A skin test is the only way to find out if a person is infected with TB. This test is usually done on the arm with a small needle used to inject the testing material, tuberculin, under the skin.

Within two or three days, a health worker can check to see if there is a reaction to the test. If the test is positive, a bump about the size of a pencil eraser or bigger will appear on the arm.

But a person who is HIV-positive may not react at all to the test and further tests will need to be administered.

Also a chest x-ray can reveal damage to the lungs which may indicate an active TB case while the lab tests phlegm for the presence of the bacterium. Once diagnosed, a patient needs constant vigilance to guard against reacquiring TB disease.

Those who have either TB symptoms or have had close, repeated exposure to a TB patient should also be tested. Both HIV-positive and HIV-negative persons should be screened yearly, medical experts recommend.

Alcoholics, injection-drug users, people with certain medical conditions such as cancer and diabetes as well as underweight people are more likely to fall prey to TB.

This is because their bodies are usually weaker and are unable to fight off the infection.

BCG is the only known TB vaccine, and while this immunisation prevents severe TB in children, it does little for adolescents or adults.

At best, the vaccination gives protection for 15 years and only shields those who are uninfected.

With WHO predicting millions of new TB cases within the next four years, the alliance with HIV will only add fuel to TB's fire. And if the world fails to respond to the twin threat, then the outlook becomes even more grim.