Dr. Ajit Lalvani and colleagues from University of Oxford, UK has found a new theory from the results of their experiment in which BCG vaccination which is administered world wide for children's to prevent from Tuberculosis infection is also found to be an effective treatment in patients with TB infection. The researchers studied the risk factors involved for TB infection in 979 children, of which 770 children's had BCG scar, as the absence of BCG scar implies that the children is very vulnerable to infection, while the presence of a BCG scar was associated with a 24% reduction in risk of being infected.
The researchers have developed a new Blood test, ELISpot test which is used to detect accurately T cells. This test is more accurate and specific compared to the old Tuberculin Skin Prick Test, which cannot differentiate between BCG vaccination and TB infection.
There are about 10 million cases of TB globally each year and 1 in 3 people are infected with the TB bacterium. BCG is the most widely used vaccine worldwide, but its mechanism of protection is poorly understood. It is thought to prevent progression of infection to active TB but whether it protects against the acquisition of infection itself has not been investigated in humans. The most frequent source of infection being the human excretes from the respiratory tract, which has large number of tubercle bacilli. Studies are being underway to find if there is any relationship between genetic components, which may be a risk factor.
As the tubercle bacillus can involve every organ system, its clinical manifestations are variable, ranging from fatigue, weakness, weight loss and fever may be signs of tuberculosis disease. Pulmonary involvement giving rise to chronic cough and spitting of blood usually is associated with far advanced lesions. Meningitis or urinary tract involvement can occur in the absence of other signs of tuberculosis. Blood stream dissemination leads to military tuberculosis with lesions in many organs and a high mortality.
Dr Lalvani states: "Contrary to prevailing theory that BCG vaccination protects only against tuberculosis disease, our results suggest that the vaccine also protects against tuberculosis infection . . . Our findings show that children can be protected against TB infection by vaccination and this opens a new door for the development of new, improved vaccines."
Source: The Lancet.