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TB STAT-PAK® II
Product Information
Globally, tuberculosis (TB) causes more human deaths than any other single infectious disease, with approximately 95% of cases and 98% of deaths occurring in the developing world. It is estimated that over 2 billion people are infected with the M. tuberculosis bacterium, which is equal to one-third of the world’s population. TB is a chronic bacterial infection that is spread in humans through the air and usually infects the lungs, although other organs are sometimes involved. Most persons who are infected with TB are asymptomatic (i.e., latent TB), with a relatively small percentage subsequently developing symptoms of the disease – i.e., active TB. The World Health Organization (WHO) estimates that each year another 8 million people worldwide will develop active TB. Mortality is estimated at 3 million annually.
M. tuberculosis is the primary etiologic agent of TB in humans. In addition to humans, a broad range of animal species are susceptible to TB, usually resultant from infection with M. bovis. Though more rarely isolated in humans, the bacterium M. bovis is responsible for tuberculosis in domestic ungulates (e.g., cattle, goats, sheep, etc.) as well as wild animals (e.g., deer, elk, badgers, possums) and captive exotic animals (e.g., elephants, giraffes, and camels, among others). Humans infected with M. bovis who subsequently go on to develop TB exhibit clinical symptoms indistinguishable from M. tuberculosis-infected TB, the pathogeneses of which are identical. While animal-to-human M. bovis infection is well documented, evidence of human-to-human transmission of M. bovis is limited and largely anecdotal. In infected populations, M. bovis shows a high degree of virulence for both humans and animals.
The WHO estimates that human TB morbidity and mortality for the 1990’s was 88 million and 30 million, respectively, with similar predictions for the current decade unless policies and practices in detection and treatment are dramatically altered. Most cases of TB occur in developing countries, 22 of which (mostly in Southeast Asia and Africa) have been designated “high prevalence endemic countries”.
The economic effects of TB are devastating, both for individuals and communities. The disease tends to strike individuals in their most productive years of 15-50. The adverse financial impact due to the potential loss of family income coupled with the expense of transportation to get to often distant health facilities for treatment and the cost of administering and monitoring TB for 6-9 months of daily therapy (i.e., DOTS) all conspire against both the macro-economy (i.e., society as a whole) as well as the micro-economy (i.e., family or individual) of those developing countries least able to afford it. Yet with the right treatment TB can be cured for less than US$20 per patient. The worldwide annual cost of TB control is estimated to be $4 Billion.
As a highly contagious, air-borne disease, transmission of TB usually results from close or casual contact with infected persons. When an infected person sneezes, coughs, spits, or talks they disseminate TB microorganisms that can be inhaled. Once introduced into the lungs, TB is able to avoid being destroyed by the body’s macrophages or granulomas – specialized cells of the immune system that destroy many bacteria, viruses, and other foreign bodies. As a result, the bacteria are able to spread throughout the newly infected person’s body, multiply, survive, and remain dormant for years. This stage of TB is called Latent TB. Active TB occurs when the bacteria infiltrate organ systems, the most common being the lungs (pulmonary TB). Clinical symptoms of TB include severe coughing, chest pain, blood in the sputum, acute weight loss, fever, and chronic fatigue.
TB and HIV interact perniciously, especially in sub-Saharan Africa where in some countries it is estimated that more than 50% of the population is infected with HIV. Because HIV weakens the body’s immune system, persons with latent TB who are also HIV reactive are at significantly greater risk of converting to active TB than their HIV nonreactive counterparts. In these areas of the world, TB has become the leading cause of death among people with HIV/AIDS.
Despite the importance of TB as a global public health problem, diagnosis and treatment of the disease, while effective, still relies on highly inaccurate diagnostic procedures that are more than 100 years old. Currently, a diagnosis of TB most often relies on Acid Fast Bacillus (AFB) smear technology from multiple sputum samples, developed by Robert Koch in 1882. However, this test may not detect as many as 50% of TB cases. Use of culture technology is slow (taking 3-4 weeks or longer) and not readily available in large areas of the developing world. Additionally, its cost is generally prohibitive in most cases. Reliance on X-Ray technology is highly insensitive as the technology can’t differentiate TB from Cancer or other pneumonias. Newer technologies are on the horizon, but they are both technologically demanding and expensive.
Alternative technologies that may supplement smear screening and increase the overall detection rate of TB include serological tests. CHEMBIO Diagnostic Systems, Inc. is developing such an assay that is rapid, easy to use, doesn’t require sophisticated equipment (can be used by most technicians in remote rural clinic settings), and augments the accuracy of more traditional test strategies.
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