Blood tests effective in detecting latent TB -study

LONDON, Apr 21 (Reuters) Blood tests could be more effective in detecting people with latent tuberculosis than the standard skin test, Italian researchers said today.

Many people with latent TB infection never develop the respiratory disease but detecting cases and providing treatment will be a key to eradicating the illness that kills 2 million people worldwide each year, according to public health experts.

Scientists at the University of Modena and Reggio Emilia in Italy who analysed the efficacy of three tests said the skin test alone was not adequate.

''To help control and possibly eliminate tuberculosis in low-prevalence areas, a specific and sensitive test for latent infection is needed,'' said Dr Luca Richeldi, who headed the study, in The Lancet medical journal.

''Two new blood tests ... might be more accurate than the tuberculin skin test.'' Tuberculosis is a contagious airborne disease that affects about 9 million people each year. The World Health Organisation (WHO) has warned that TB has reached alarming proportions in Africa where co-infection with HIV makes a lethal combination.

A person with tuberculosis can infect others with the TB germs, or bacilli, by coughing, sneezing, talking or spitting.

Every second another person is newly infected with TB bacilli. A person with active TB will infect 10-15 others every year if no treatment is given, according to the WHO.

Countries in sub-Saharan Africa have the highest incidence of the disease while half the world's cases are in Bangladesh, China, India, Indonesia and Pakistan.

Patients with TB are treated with the DOTS (Directly Observed Treatment, Short-course) programme -- an approach adopted by WHO that involves government commitment, patient surveillance and drug treatment.

Certain groups with latent TB including babies, young children, the elderly, people living with HIV and illegal drug users, are more likely to develop active TB and may need treatment.

Richeldi and other scientists who worked on the study said the blood tests could be used either in combination with the skin test or as a substitute to increase detection of latent TB.

''The choice of which diagnostic test to use should depend on the population being tested, the purpose of testing, and resources available,'' Richeldi added.

REUTERS PR HS0938