الفهرس 
TuberculosisOnly 14 pages are availabe for public view
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Abstract
Tuberculosis is a growing international health concern, since it is the biggest killer among the infectious diseases in the world today, despite the use of a live attenuated vaccine and anti tuberculous therapy. After years of decline, TB has re-emerged as a serious public health problem worldwide, especially with increased drug resistance among MTB strains which hinders the success of TB control programs. The most common clinical manifestation of TB is pulmonary disease. Extra-pulmonary TB accounts for about 50% of HIV-positive patients. While radiography is a commonly performed investigation, it must be remembered that patients with HIV co-infection may not have typical radiographic features of pulmonary tuberculosis. Latent TB is a clinical syndrome caused by exposure to M. tuberculosis, followed by establishment of infection and host’s immune response to control bacillary growth, forcing it into a quiescent state in the infected tissue. It is characterized by a reduction of bacterial metabolism, by the action of cellular immune response which can not eradicate the infection. As the immune system begins to fail, latent infection can be reactivated, leading to the development of active TB, even after several decades of initial infection. Reactivation can be induced by various factors, all of which compromise the immune system’s efficacy, such as HIV co-infection, malnutrition, aging, drug use, cancer, diabetes, chronic renal insufficiency and immunosuppressive drug therapy. Sputum smear microscopy is one of laboratory diagnosis of TB. Culture of M. tuberculosis in clinical specimens is substantially more sensitive than smear microscopy. Culture can be performed using solid media, such as Lowenstein-Jensen. The drawback of culture is the long time to results (10–14 days for liquid culture and 3–4 weeks for solid culture), which is a consequence of the long doubling time of M. tuberculosis. At least 50 (and up to 90) percent of patients with acute HIV infection develop symptoms consistent with acute infection, although timing and duration are variable. For most symptomatic patients, acute illness develops within one to four weeks after transmission, and symptoms usually persist for two to four weeks. Simultaneous infection of HIV and (MTB) is a deadly combination affecting large populations in Africa, Asia, Latin America and Eastern Europe. Progressive immune dysfunction caused by HIV infection increases susceptibility to MTB infection as well as progression from latent infection to active tuberculosis (TB) disease. Furthermore, when HIV and MTB-co-infected individuals are treated with antiretroviral drugs against HIV, they may develop an immune reconstitution inflammatory syndrome, where the recovering immune system starts to react to the bacterial infection, resulting in increased morbidity. Coinfection with HIV may worsen the course and complicate the diagnosis and management of TB. The effects of HIV infection on TB include altered clinical presentation, such as paucibacillary and disseminated TB, which increases the challenge of making an accurate diagnosis in a proper time . Throughout the course of HIV disease, there is an increased risk of acquiring or reactivation of TB and reinfection with it despite treatment with antiretroviral drugs. The effects of TB on HIV infection include an increase in HIV viral load (reported in some but not all studies) with suppression of CD4+ cell count, TB is a most important opportunistic disease in HIV infected patient and high early mortality in TB and HIV coinfection, particularly at low CD4+ cell counts, has been observed despite antiretroviral therapy in resource-limited settings. Further, overlapping toxicities of drugs used to treat TB and HIV infections complicate delivery of effective therapy. Pulmonary TB remains the most frequent form of active TB in HIV-1 infected persons, even those with low CD4 counts. Although the clinical presentation of pulmonary TB is different to the presentation of pulmonary TB in HIV-1 uninfected patients, the most common symptoms remain cough, fever, night sweats and significant weight loss. Relative to HIV-1 uninfected patients, weight loss and fever are more common, whereas haemoptysis is less common and some studies have reported a decreased proportion of patients with cough. Extrapulmonary TB and disseminated TB (active TB at more than one non-contiguous anatomical location) are more common in HIV-1 infected persons, especially as the CD4 count declines. Wide dissemination of TB in advanced HIV-1 may occur. There may or may not be coexistent pulmonary TB. It was recognized before the HIV-1 era that the immune response to TB contributes to pathology and protection. During the early period of rapid immune recovery on ART, immunopathology in the form of the immune reconstitution inflammatory syndrome (IRIS) has emerged as an important clinical entity altering the clinical presentation and course of TB infection. IRIS is believed to result from dys-regulated recovering immune responses driving exaggerated inflammation directed at the antigens of opportunistic pathogens. The principles of tuberculosis treatment in HIV-infected individuals are the same as those in HIV-negative individuals. However, specific issues include regimen length and schedule of administration of anti tuberculosis drugs, timing and drug combinations of antiretroviral drugs, overlapping toxic effects, drug interactions, and occurrence of immune reconstitution.