Scientists in the United Kingdom have devised a new ultra-rapid test that is sensitive enough to identify all strains of tuberculosis (TB) in just an hour.
TB is a chronic bacterial infection affecting the lungs, caused by the bacteria mycobacterium tuberculosis. The infection causes fever, cough, weight loss and blood in the phlegm or spit. It spreads via air droplets in the air from an infected person, from a cough or sneeze.
There has been a resurgence of TB in developed countries in recent years, believed to be linked to the strain's resistance to the drugs used to treat the disease.
According to the Centers for Disease Control (CDC) there were 12,904 cases reported in the United States in 2008.
The World Health Organization (WHO) estimates that 1.3 million people die each year worldwide from TB. The WHO also calculates that a third of the population actually carry the TB bacteria, five to 10 percent of whom will become sick with the disease in their lifetime.
The new test was devised by the Health Protection Agency (HPA) in the UK. Their findings will be presented at the HPA annual conference at the University of Warwick.
The current method for testing for the presence of TB bacteria involves testing the mucus coughed up by the lungs and then growing cultures in the lab. This procedure takes up to eight weeks for results, in which time numerous other people may have become infected.
There are faster tests available but none of them can correctly identify all the strains of bacteria. The new test concentrates on the DNA which is present in all strains of bacteria. A sample is taken from a patient suspected of carrying TB. A process called “polymerane chain reaction” takes place in which the volume of DNA is significantly amplified to make it easier to identify its genetic signature. This enables doctors to diagnose a person with TB, whatever bacterial strain they are carrying.
“We're excited to have developed this new test because it means we can potentially diagnose someone at a TB clinic within an hour and start them immediately on the treatment they need.