Most Common and Killer Disease Tuberculosis

 Most Common and Killer Disease Tuberculosis

Historically TB has been one of the world's worst killer disease. Traces of TB have been found in skeletons of the late Stone Age. It was one of the world's great killer diseases in the nineteenth century and was the largest single cause of death in England and Wales during that time, accounting for one-fifth of all deaths. By 1990, the numbers of children dying from the disease had been reduced to less than 1 in 1 million developed countries, but at least 30 million people worldwide still suffered symptoms, 95% of whom were living in the developing countries. Up to 3 million a year are currently are dying from TB, and up to one-third of the world's population carry the bacteria with no ill effects. In the early 1990s the WHO declared the disease a global emergency as cases in the developed world, including Britain, began to increase again and resistance to drugs began to grow. In 1992 there were 5802 new cases in England. Worldwide, 8 million new cases are reported every year. The disease is caused by a fungus-like bacterium  called Mycobacterium tuberculosis, first discovered by Robert Koch in 1882. It is sometimes referred to as the tubercle bacillus, bacilli being rod shaped bacteria. Two strains of the bacterium may cause the disease, the human and bovine forms. The latter can be present in cattle and can enter the milk of cows. It is very resistant and can remain alive for long periods in milk products. It is a very serious disease of cattle and has also been responsible for a great deal of illness and death in humans in the past, particularly in children. Today however, all milk in the UK is produced from cows that have been 'tuberculin tested', that is certified free of Mycobacterium. The milk also undergoes treatment at bottling plants where it is subjected to pasteurization, sterilization or ultra-high temperature. These processes destroy at least 99% of all bacteria, including all pathogens. Thus bovine tuberculosis is no longer of significance in humans. 

Mycobacterium Tuberculosis

                                               

Mycobacterium bovis BCG

 TB is caused by the bacterium Mycobacterium tuberculosis (also called tubercle bacillus) that is transmitted person-to-person by coughing and sneezing. Tuberculosis, commonly known as TB, is a bacterial infection that can spread through the lymph nodes and bloodstream to any organ in your body. It is most often found in the lungs. Most people who are exposed to TB never develop symptoms because the bacteria can live in an inactive form in the body. But if the immune system weakens, such as in people with HIV or elderly adults, TB bacteria can become active. In their active state, TB bacteria cause death of tissue in the organs they infect. Active TB disease can be fatal if left untreated. Because the bacteria that cause tuberculosis are transmitted through the air, the disease can be contagious. Infection is most likely to occur if you are exposed to someone with TB on a day-to-day basis, such as by living or working in close quarters with someone who has the active disease. Even then, because the bacteria generally stay latent (inactive) after they invade the body, only a small number of people infected with TB will ever have the active disease. The remaining will have what's called latent TB infection -- they show no signs of infection and won't be able to spread the disease to others, unless their disease becomes active.

Because these latent infections can eventually become active, even people without symptoms should receive medical treatment. Medication can help get rid of the inactive bacteria before they become active. Tuberculosis (TB) is a potentially serious infectious disease that mainly affects your lungs. The bacteria that cause tuberculosis are spread from one person to another through tiny droplets released into the air via coughs and sneezes.

Outbreak of tuberculosis caused by Mycobacterium bovis in golden Guernsey goats in Great Britain

Once rare in developed countries, tuberculosis infections began increasing in 1985, partly because of the emergence of HIV, the virus that causes AIDS. HIV weakens a person's immune system so it can't fight the TB germs. In the United States, because of stronger control programs, tuberculosis began to decrease again in 1993, but remains a concern.

Many strains of tuberculosis resist the drugs most used to treat the disease. People with active tuberculosis must take several types of medications for many months to eradicate the infection and prevent development of antibiotic resistance.

What is Tuberculosis?- Video