Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0037116 (silicosis)
 1,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

For many years tuberculosis has been known to occur with greater frequency among persons with disorders that impair host defenses. In most instances these processes interfere with the immune response to Mycobacterium tuberculosis, whereas, in a few, such as silicosis, the probable abnormality is a nonimmune defect in macrophage function. Infection with the human immunodeficiency virus (HIV) causes progressive and ultimately profound depression of both humoral and cell-mediated immunity and, thus, is an extremely potent risk-factor for tuberculosis. Presumably the major effect of HIV infection that predisposes persons to developing tuberculosis is the reduction in circulating T-helper (CD4+) lymphocytes which causes a reduction in cytokine production and a consequent decrease in the functional capabilities of macrophages. However, a number of questions concerning pathogenesis of tuberculosis related to HIV remain. Available data suggest that the magnitude of the risk for developing tuberculosis among persons infected with both HIV and M. tuberculosis is very high, 8% in one prospective study. Because of the epidemic of HIV infection, the progressive downward trend in the incidence of tuberculosis in the United States has reversed and in 1989 there was a 5% increase in the number of cases. Preliminary data for 1990 suggest that there will be an 8 to 10% increase over 1989. Also in the United States approximately 3% of tuberculosis patients have been found to be HIV seropositive. The clinical features of tuberculosis in patients with HIV infection vary depending on the degree of immunosuppression. With mild immunosuppression early in the course of HIV infection tuberculosis presents in a "typical" way with positive tuberculin skin tests, upper lobe cavitary infiltrates on chest film and positive sputum smears and cultures. As the HIV infection progresses, the mode of presentation of tuberculosis becomes more "atypical" with negative skin tests, multiple sites of involvement, chest films showing diffuse noncavitary infiltrates often accompanied by intrathoracic lymphadenopathy. The key to diagnosis is maintaining a high index of suspicion for tuberculosis, especially in patients with advanced HIV disease and including appropriate laboratory examinations in the evaluations of such persons. Regardless of the stage of HIV infection the response to treatment for tuberculosis is generally favorable if it is begun promptly. Standard therapy utilizing isoniazid, rifampin, and pyrazinamide with or without ethambutol have been associated with high rates of cure. Relapse has been uncommon. There has been, however, at least one outbreak of tuberculosis caused by isoniazid and rifampin resistant organisms in which the response to therapy was very poor.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Clinical features, diagnoses, and management of tuberculosis in immunocompromised hosts. 194 27

After a first infection with M. tuberculosis, reactivation of the disease may be prevented by chemoprophylaxis with isoniazid or rifampicin. Such chemoprophylaxis should be administered to all subjects with an immune defect due to HIV infection, immunosuppressors, severe diabetes, renal insufficiency or silicosis. Extensive sequelae of tuberculosis on chest X-ray are also a major risk of reactivation without treatment. Tuberculosis is most likely to become active during the first three years following first infection for an healthy subject. However, beyond this limit or when the time of infection is unknown, the most objective decisional analysis still demonstrates the clear-cut benefit of chemoprophylaxis in proportion to its side effects for all young subjects aged less than 35 years.
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PMID:[Indications for chemoprophylaxis of tuberculosis. Arguments for]. 843 36

This study determines risk factors for tuberculosis (TB) and identifies groups among South African gold miners at high risk for contracting TB. A retrospective cohort analysis was conducted with hospital and personnel databases on a randomly selected sample of the labor force of Freegold Mines. A person-years analysis was carried out to examine incidence ratios between different age groups, period, cumulative service, mining occupation, and silicosis status, with a separate analysis on a subgroup of men with known HIV status. Findings reveal that TB was associated with age, with a rate ratio of 21 for the oldest age group compared with the youngest, after adjustment for period, cumulative service, occupation, and silicosis status. There was also a significant relationship between TB and occupation, such as drilling, with a rate ratio of 2.3, compared with workers of low dust surface maintenance, after adjustment for age, period, cumulative service, and silicosis. Analysis of the HIV-tested subjects indicated that these findings are unlikely to be the result of confounding due to HIV infection. Prevalence of HIV infection in this group has been increasing sharply since 1991, but the increase was slowing towards the end of the study period. In conclusion, age, mining occupation, silicosis status, and HIV infection with predicted rates of 100/1000 person-years can define a profile of miners who are at high risk of developing TB. TB screening programs should therefore take special cognizance of high-risk groups of gold miners.
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PMID:Variation in incidences of tuberculosis in subgroups of South African gold miners. 942 75

The tuberculin reaction following the intradermal injection of PPD appears 48-72 hours after injection. The positivity is shown by an > 5 mm area of induration of the skin. Tuberculin reaction is an invaluable instrument of epidemiologic investigation. Clinically, the value of tuberculin test, though remarkable, is limited by the fact that its positivity is not necessarily a sign of active tuberculosis. The three control strategies of tuberculosis are: prompt identification and correct management of cases, vaccination, prophylaxis. The latter, that in most cases is performed with isoniazid (300 mg/daily for 12 months) is indicated in the following situations: subjects with > 5 mm tuberculin test; recent contacts with patients with infective tuberculosis; chest X-ray indicative for old fibrotic lesions, HIV infection; subjects with > 10 mm tuberculin test: HIV-negative drug-addicts; clinical conditions at high risk for tuberculosis (e.g. silicosis, hematologic malignancy, iatrogenic immunosuppression).
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PMID:Tuberculin skin test and chemoprophylaxis of tuberculosis. 967 47

Pulmonary mycobacterial disease is common in miners. Risk factors for nontuberculous pulmonary mycobacterial (NTM) disease and tuberculosis (TB) in gold miners were identified in a retrospective case-control study that included 206 NTM patients and 381 TB patients of known human immunodeficiency virus (HIV) status diagnosed between 1993 and 1996. A total of 180 HIV-tested trauma/surgical inpatients were selected as control patients. Both HIV infection (odds ratio [OR] 3.6 for NTM and 4.5 for TB patients) and higher grades of silicosis (OR 5.0 for NTM and 4.9 for TB patients) were significantly more common in NTM and TB patients than in control patients. HIV prevalence rose in the control and both case groups during the study period. The overall HIV prevalence was 13.1% in NTM patients, 14.2% in TB patients, and 5.6% in control patients. Previous TB (OR 9.6), premorbid focal radiological scarring (OR 7.4) and a dusty job at diagnosis (OR 2.4) were additional significant risk factors for NTM disease. These findings suggest that the historically high incidence of NTM disease in miners is largely attributable to chronic chest disease from silica dust inhalation and prior TB. HIV infection has recently become an additional risk factor for mycobacterial disease in miners and is likely to become increasingly important as the HIV epidemic progresses.
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PMID:Risk factors for pulmonary mycobacterial disease in South African gold miners. A case-control study. 987 24

The impact of human immunodeficiency virus (HIV) infection on Mycobacterium kansasii disease in miners was investigated with a retrospective study covering a single workforce. M. kansasii, isolated from 43 HIV-positive and 202 HIV-negative miners, was the most common nontuberculous mycobacterial (NTM) species in both HIV groups. CD4 counts were unusually high for M. kansasii disease (mean 490 x 10(6)/L, from 14 HIV-positive men). Treatment outcomes were similar: mortality during treatment was higher in HIV-positive than in HIV-negative men (9% and 2%, respectively), but not significantly so. The majority of a sample of 31 HIV-positive and 92 HIV-negative men had radiological silicosis and/or old tuberculosis scarring prior to M. kansasii disease. A normal premorbid radiograph was more common in HIV-positive men (45% versus 24%; odds ratio [OR], 2.62; 95% confidence interval [95% CI], 1.01 to 6.67). New cavitation was less common (55% versus 78%; OR, 0.34; 95% CI, 0.13 to 0.88) and new hilar adenopathy more common (OR, 5.07; 95% CI, 1.24 to 21.9) in HIV-positive than in HIV-negative men. Miners, who have additional NTM risk factors, develop M. kansasii disease that occurs at an earlier stage of HIV infection and more closely resembles disease in HIV-negative men than has been found for HIV-associated M. kansasii disease in other settings.
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PMID:The impact of HIV infection on Mycobacterium kansasii disease in South African gold miners. 1039 Mar 73

Health problems of gold miners who worked underground include decreased life expectancy; increased frequency of cancer of the trachea, bronchus, lung, stomach, and liver; increased frequency of pulmonary tuberculosis (PTB), silicosis, and pleural diseases; increased frequency of insect-borne diseases, such as malaria and dengue fever; noise-induced hearing loss; increased prevalence of certain bacterial and viral diseases; and diseases of the blood, skin, and musculoskeletal system. These problems are briefly documented in gold miners from Australia, North America, South America, and Africa. In general, HIV infection or excessive alcohol and tobacco consumption tended to exacerbate existing health problems. Miners who used elemental mercury to amalgamate and extract gold were heavily contaminated with mercury. Among individuals exposed occupationally, concentrations of mercury in their air, fish diet, hair, urine, blood, and other tissues significantly exceeded all criteria proposed by various national and international regulatory agencies for protection of human health. However, large-scale epidemiological evidence of severe mercury-associated health problems in this cohort was not demonstrable.
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PMID:Health risks of gold miners: a synoptic review. 1297 Dec 53

Occupational settings offer an ideal opportunity to provide preventive health services for HIV-infected workers. A specialized clinic was established in a mining hospital in the Free State, South Africa, with the primary aim of delivering preventive therapy such as isoniazid to those at high risk of tuberculosis (individuals with HIV infection or silicosis), and cotrimoxazole to those at highest risk for opportunistic infections. The clinic design has taken regard of the importance of minimizing stigma, protecting confidentiality, monitoring potential side effects, supporting adherence and identification of prophylaxis failure. The clinic opened in April 1999 and, by August 2001, 1773 patients had attended at least once; 1762 are HIV-infected and 11 have silicosis. Of those with HIV infection, most were asymptomatic at their first visit. The clinic has achieved high acceptability: 99% of persons who were actively recruited to the service agreed to attend. The number still attending after a median of 13 months from recruitment was 1,270 (72%) and only 48 (2.7%) have declined continued attendance. Most losses were due to termination of employment unrelated to a medical condition. The clinic has already been successfully replicated in two other regions of the mining health service in South Africa and provides a model for workplace HIV clinical services that could be used for implementation of further interventions such as antiretroviral therapy.
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PMID:Feasibility and acceptability of a specialist clinical service for HIV-infected mineworkers in South Africa. 1466 Jan 43

Silicosis and tuberculosis (TB) are significant mining-related illnesses in developing countries. The purpose of this study was to examine annual cases of these diseases in Zambian miners, including comparison of periods before (1960-1970) and after (1992-2002) the arrival of the HIV/AIDS pandemic. The Occupational Health and Safety Research Bureau of Zambia reported 2114 cases from 1945 to 2002. Of these, 22.7% were silicosis, 65.4% TB, and the remaining 11.9% silicotuberculosis. While silicosis cases decreased from 28.6% to 12.4% with the arrival of HIV/AIDS, there was a large increase in tuberculosis cases (37.1% to 86.1%), with a corresponding decrease in silicotuberculosis cases (34.3% to 1.6%). Although silicosis remains an occupational health issue in Zambian miners, the most significant problem appears to be the marked increase in cases of TB.
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PMID:Silicosis and tuberculosis in Zambian miners. 1613 Sep 67

Pulmonary TB should be suspected in patients with respiratory symptoms longer than 2-3 weeks. Immunosuppression may modify clinical and radiological presentation. Chest x-ray shows very suggestive, albeit sometimes atypical, signs of TB. Complex radiological tests (CT scan, MR) are more useful in extrapulmonary TB. At least 3 serial representative samples of the clinical location are used for diagnosis whenever possible. Bacilloscopy and liquid medium cultures are indicated in all cases. Genetic amplification techniques are coadjuvant in moderate or high TB suspicion. Administration of isoniazid, rifampicin, ethambutol and pyrazinamide (HREZ) for 2 months and HR for 4 additional months is recommended in new cases of TB, except in cases of meningitis in which treatment should continue for up to 12 months and up to 9 months in spinal TB with neurological involvement, and in silicosis. Appropriate adjustments with antiretroviral treatment should be made in HIV patients. Combined therapy is recommended to avoid development of resistance. An antibiogram to first line drugs should be performed in all the initial isolations of new patients. Treatment control is one of the most important activities in TB management. The Tuberculin Skin Test (TST) is positive in TB infection when >or=5mm, and Interferon-Gamma Release Assays (IGRA) are recommended in combination with TT. The standard treatment schedule for infection is 6 months with isoniazid. In pulmonary TB, respiratory isolation is applied for 3 weeks or until 3 negative bacilloscopy samples are obtained.
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PMID:[Consensus document on the diagnosis, treatment and prevention of tuberculosis]. 2629 96


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