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Biomedical subjects

E L Corbett

Publications and source records attributed to E L Corbett.

At least 19 recordsLinked to original sources
PubMed2006

Human immunodeficiency virus, smoking and self-rated health in Harare, Zimbabwe.

SETTING: Twenty-two urban factories in Harare. OBJECTIVE: To determine the relationship between the human immunodeficiency virus (HIV), smoking and self-rated health in a high HIV prevalence urban workforce. DESIGN: Cross-sectional survey. RESULTS: Of 7482 employees, 6111 (82%) consented to interview and anonymous HIV serology; 88% were male; median age was 34 years. HIV prevalence was 19%. Current (median 6 cigarettes per day) and former smoking were reported by 17% and 7%, respectively. Smoking (current or former) was more common among HIV-positive (27%) than -negative participants (17%; P < 0.001). Factors significantly associated with being a smoker on multivariate analysis were being HIV-infected (OR 1.5, 95% CI 1.4-1.7), older age (P < 0.001), non-Christian (OR 1.6, 95% CI 1.2-2.2) and manual job (OR 1.4, 95% CI 1.2-1.6). Women (OR 0.05, 95% CI 0.03-0.11) and the better educated (OR 0.7, 95% CI 0.5-0.9) were significantly less likely to smoke. HIV-positive smokers had the highest risk of reporting poor health (adjusted OR compared to HIV-negative non-smokers 3.4, 95% CI 2.3-5.0). CONCLUSIONS: Smoking was significantly more common among HIV-positive than -negative employees in this predominantly male workforce. There was evidence of a combined effect on self-rated poor health, a variable shown to be a strong independent predictor of mortality in industrialised countries. Interventions to encourage smoking cessation may be an important component of HIV care in Southern Africa.

Adolescent↗
PubMed2002

A combined medical and surgical approach to hydatid disease: 12 years' experience at the Hospital for Tropical Diseases, London.

BACKGROUND: There is no consensus as to the most appropriate treatment for the varied and often complicated presentations of hydatid disease in Britain. We looked at our own results over a 12-year period to see if a consistent and logical plan had emerged. PATIENTS AND METHODS: 70 patients presenting between 1986 and 1998 were analysed retrospectively, with regard to their presentation, diagnosis, treatment and outcome, with particular reference to the use of chemotherapy, and to the difficulties of post-treatment assessment by serology and imaging. RESULTS: 37 patients had been treated previously. 35 had hepatic cysts and 26 multiple cysts. 4 patients were treated by surgery alone, 44 by chemotherapy and surgery, and 14 by chemotherapy alone. The combined use of albendazole and praziquantel pre-operatively reduced significantly the number of cysts that contained viable protoscolices: 1/25 versus 5/8 that received albendazole alone (P = 0.00013). During the 12-year period, it became our policy to aim for 3 months drug treatment (albendazole throughout with praziquantel for 2 weeks), re-assess and proceed either to surgery or to continue with chemotherapy. CONCLUSIONS: It is possible to construct an algorithm for the management of patients with hydatid disease by chemotherapy and surgery, but the assessment of results by indirect techniques remains difficult.

Adolescent↗
PubMed2001

Polymorphisms in the IkappaB-alpha promoter region and risk of diseases involving inflammation and fibrosis.

The transcription factor NFkappaB regulates inflammatory and other cellular responses. In non-stimulated cells, NFkappaB is linked to its inhibitor IkappaB, which plays a major role in controlling NFkappaB activity. Here, the gene promoter region of the major inducible IkappaB component (IkappaB-alpha) was studied to identify single nucleotide polymorphisms (SNPs), and to test if these are associated with risk of two diseases involving inflammation and fibrosis (trachoma and silicosis). Three SNPs were identified at positions -881, -826 and -297 relative to the transcription start site. The position -297 is close to two NFkappaB binding sites, kappaB2 and kappaB3, but the alleles were not associated with either disease. Alleles at positions -881 and -826 were in complete linkage disequilibrium with each other, and the rare haplotype was significantly less frequent among patients with trachoma compared to controls, although there was no difference in frequencies between silicosis patients and controls.

Base Sequence↗
PubMed2001

Persistent radiological changes following miliary tuberculosis in miners exposed to silica dust.

SETTING: Silicosis leads to increased susceptibility to tuberculosis, but it has also been suggested that tuberculosis may interact with intra-pulmonary silica to exacerbate fibrotic lung disease. OBJECTIVES: To investigate the possibility that silicosis developed due to or was exacerbated by tuberculosis. METHODS: In a case series of 15 miners presenting with culture-positive miliary tuberculosis, serial radiographs taken premorbidly, at presentation, and after 2 and 6 months of standard anti-tuberculosis treatment were graded for nodularity using the International Labour Organization system. RESULTS: Increased nodule profusion (compared to premorbid film) remained in 13 (87%) and eight (53%) patients after 2 and 6 months of treatment, respectively, despite clinical improvement in all and documented bacteriological cure in eight (53%). These phenomena, observed irrespective of human immunodeficiency virus (HIV) status, were most pronounced in men with minor premorbid changes. Abnormal pulmonary collagenisation related to silica particles was apparent at post-mortem in two men who died of HIV-associated cryptococcosis after completing TB treatment. CONCLUSIONS: Previous silica exposure appears to result in delayed and potentially incomplete radiological resolution of miliary TB. We postulate that the immune response in tubercles may evoke a 'bystander' fibrotic response, as cytokines play a central role in the pathogenesis of both TB and silicosis.

AIDS-Related Opportunistic Infections↗
PubMed2000

HIV infection and silicosis: the impact of two potent risk factors on the incidence of mycobacterial disease in South African miners.

OBJECTIVE: To investigate the combined effects of HIV infection and silicosis on mycobacterial disease. DESIGN AND SETTING: A retrospective cohort of 1374 HIV-positive and 2648 HIV-negative miners who attended a South African gold mining hospital and primary health clinics. PARTICIPANTS: Miners who had been tested for HIV, with consent, at primary health clinics during 1991-1996, predominantly because of a symptomatic sexually transmitted disease. RESULTS: Tuberculosis (TB) incidence was 4.9 and 1.1 per 100 person-years in HIV-positive and HIV-negative miners respectively. The incidence of Mycobacterium kansasii disease was also high (0.32 and 0.10 per 100 person-years, respectively). Silicosis was highly prevalent, implying inadequate dust control, and was a significant TB risk factor among both HIV-positive and HIV-negative men (adjusted incidence rate ratios 1.4-2.5 according to radiological severity). The data were consistent with the risks of silicosis and HIV combining multiplicatively, but did not fit an additive model. The incidence of HIV-associated TB increased significantly during the study, with no corresponding change in HIV-negative rates, to reach 16.1 per 100 person-years among HIV-positive silicotics. CONCLUSIONS: The risks of silicosis and HIV infection combine multiplicatively, so that TB remains as much a silica-related occupational disease in HIV-positive as in HIV-negative miners, and HIV-positive silicotics have considerably higher TB incidence rates than those reported from other HIV-positive Africans. The increasing impact of HIV over time may indicate epidemic TB transmission with rapid disease development in HIV-infected miners. Similar but currently unrecognized interactions may be contributing to TB control problems in other industrializing countries affected by the HIV epidemic.

AIDS-Related Opportunistic Infections↗
PubMed2000

Drug-resistant tuberculosis in South African gold miners: incidence and associated factors.

SETTING: A gold mining company in the Free State Province of South Africa. OBJECTIVE: To document the incidence of and factors associated with drug-resistant tuberculosis (TB) in South African gold miners. DESIGN: Review of Mycobacterium tuberculosis drug susceptibility records for the period from 1 July 1993 to 30 June 1997. RESULTS: Over the study period, 2241 miners had culture-positive M. tuberculosis pulmonary disease where isolates were tested for drug susceptibility to the four primary anti-tuberculosis drugs. The proportions of primary and acquired drug resistance were respectively 7.3% and 14.3% for isoniazid and 1.0% and 2.8% for resistance to at least isoniazid and rifampicin (multidrug resistance). Resistance to streptomycin and ethambutol was uncommon, and rifampicin monoresistance was rare. No significant factors for primary drug resistance were identified. Patients with retreatment pulmonary TB who failed primary TB treatment (versus cure) were significantly more likely to have TB with resistance to any TB drug or MDR (odds ratios respectively 9.82, 95%CI 2.97-33.5, and 18.74, 95%CI 1.76-475). Human immunodeficiency virus (HIV) infection was not significantly associated with primary or acquired drug resistance, and there was no trend of increasing resistance over time. CONCLUSION: Anti-tuberculosis drug resistance has remained stable despite the HIV epidemic and increasing TB rates. Directly observed therapy may have contributed to containing the level of drug resistance. Adherence to and completion of treatment are essential to prevent drug resistance and treatment failure, including in situations with high HIV prevalence.

Adult↗
PubMed2000

The impact of HIV infection on recurrence of tuberculosis in South African gold miners.

UNLABELLED: DESIGN AND OBJECTIVES: Potential risk factors for recurrence of tuberculosis (TB) were investigated in a retrospective cohort study of 305 human immunodeficiency virus (HIV) positive and 984 HIV-negative South African gold miners treated for TB with directly-observed, rifampicin-based regimens. Standard treatment changed from rifampicin, isoniazid and pyrazinamide (RHZ) to RHZ plus ethambutol (RHZE) during the study period. RESULTS: Recurrence occurred in 37 HIV-positive and 46 HIV-negative men. HIV infection was associated with a significantly higher recurrence rate (8.2 vs 2.2 per 100 person-years; multivariate-adjusted incidence rate ratio [IRR] 4.9, 95% confidence interval [CI] 3.0-8.1), as were post-tuberculous scarring (multivariate-adjusted IRR 1.6 for one or two scarred lung zones, 4.0 for three or more zones; test for trend P < 0.001) and drug resistance (multivariate-adjusted IRR 2.7, 95%CI 1.01-7.4). The recurrence rate was significantly higher following treatment with RHZ than RHZE (multivariate-adjusted IRR 2.1, 95%CI 1.1-4.0). The difference between regimens needs to be interpreted with caution, however, as allocation was not randomised. CONCLUSION: The high recurrence rate among HIV-positive men requires further investigation to distinguish relapse from re-infection as the predominant cause, leading to consideration of further intensification of the initial regimen or use of secondary prophylaxis.

AIDS-Related Opportunistic Infections↗
PubMed2000

Factors associated with an increased case-fatality rate in HIV-infected and non-infected South African gold miners with pulmonary tuberculosis.

SETTING: A gold mining company in the Free State Province, South Africa. AIM AND DESIGN: A retrospective cohort study to investigate factors associated with an increased case-fatality rate (CFR) at 6 months in human immunodeficiency virus (HIV) positive and negative tuberculosis (TB) patients. RESULTS: Between April 1993 and March 1997, there were 2236 men with culture-confirmed pulmonary TB in whom HIV status and treatment outcome were known. The overall CFR within the first 6 months of therapy was low (3.6%). After adjusting for confounding factors, HIV infection (OR 15.0, 95%CI 7.4-30.6), self-presentation compared to detection by the active radiological screening programme (OR 5.6, 95%CI 2.6-12.2) and presence of silicosis (OR 3.0, 95%CI 1.4-6.3) were significantly associated with an increased CFR. Opportunistic infections accounted for 56.2% (36/64) of deaths in HIV-positive men. Cryptococcal disease accounted for 75% (27/36) of deaths from opportunistic infections. CONCLUSION: HIV infection and silicosis are both powerful risk factors for TB and are associated with an increased risk of death. Strategies aimed at reducing these two risk factors within the workforce could reduce TB incidence and mortality. In settings with functional DOTS programmes and sufficient resources, expanding the DOTS programme to include active case detection should be explored as a means of reducing TB prevalence and mortality.

AIDS-Related Opportunistic Infections↗
PubMed1999

Risk factors for pulmonary mycobacterial disease in South African gold miners. A case-control study.

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.

Adult↗
PubMed1999

The impact of HIV infection on Mycobacterium kansasii disease in South African gold miners.

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.

AIDS-Related Opportunistic Infections↗
PubMed1999

Nontuberculous mycobacteria: defining disease in a prospective cohort of South African miners.

A gold mining work force was followed prospectively over 1 yr for sputum nontuberculous mycobacterial (NTM) isolates. NTM were isolated from 118 men, of whom 32 (27%) met the American Thoracic Society (ATS) case-definitions for pulmonary NTM disease (23 M. kansasii, seven M. scrofulaceum, one M. avium, and one M. abscessus). Determining isolate significance was difficult because most men had been started on presumptive TB treatment before isolate identification (70%). Histologic criteria were considered inappropriate for this high M. tuberculosis incidence population, particularly for patients who had stabilized on presumptive TB treatment. Among men not meeting case-definitions, indicators of disease were significantly more prevalent for M. kansasii than for M. fortuitum, the local laboratory contaminant (ORs: 6.5 for cough, 7. 2 for smear-positivity, 36.0 for radiologic changes, and 14.3 for presumptive TB treatment), suggesting underdiagnosis of M. kansasii disease. Of 53 men with definite or possible M. kansasii disease, 18 (34%) were HIV-positive. HIV-associated M. kansasii disease occurred at an early stage of immunosuppression (median CD4 count, 381 x 10(6)/L) with a good outcome (83% cured after 12 mo of treatment). ATS case-definitions for NTM disease are difficult to apply in this population, and treatment decisions should be guided by the pathogenic potential of the isolate.

Adult↗
PubMed1999

Use of miniradiographs to detect silicosis. Comparison of radiological with autopsy findings.

Radiological and routine autopsy findings from 241 South African gold miners were compared, using pathology as the "gold standard." Previous annual screening miniradiographs were read independently by two readers, using the International Labor Office (ILO) grading system, without reference to personal identifiers. Individual and consensus silicosis grades were recorded for each subject. When pathological and radiological silicosis were defined as any abnormal grade, the sensitivity and specificity of the radiological diagnosis was 67.5% and 80%, with positive and negative predictive values of 63% and 83%. Most undetected autopsy silicosis was early-grade. Using higher pathological and radiological grades to define silicosis (5 nodules or more and ILO grades 1/1 and above), sensitivity and specificity increased to 71% and 96%, and positive and negative predictive values increased to 76% and 95%, respectively. Use of a consensus grade made little difference to results from individual readers. For each radiological definition, sensitivity was considerably higher than, but specificity was similar to, that found in a previous study of South African gold miners which used the same pathology source and standard sized films. The difference between these two study findings, and unexpected demonstration of higher sensitivity from miniradiographs, suggests that further research is required into factors affecting radiological interpretation before silicosis grading can be considered to be adequately standardized.

Adult↗
PubMed1999

Mycobacterium kansasii and M. scrofulaceum isolates from HIV-negative South African gold miners: incidence, clinical significance and radiology.

SETTING: A South African gold mining hospital. OBJECTIVE: To investigate the clinical significance of non-tuberculous mycobacteria (NTM) isolates, and estimate NTM disease incidence in human immunodeficiency virus (HIV) negative miners. DESIGN: Retrospective case series describing clinical and radiological features associated with NTM sputum isolates from HIV-negative miners between January 1993 and July 1996, and a comparison group with Mycobacterium tuberculosis infection. RESULTS: Of miners with NTM isolates, 90% had been HIV-tested and 81% were HIV-negative. M. kansasii and M. scrofulaceum accounted for 202 (68%) and 41 (14%) isolates respectively. More than 80% of miners with M. kansasii or M. scrofulaceum were smear positive, and new cavitation was present in 78% and 74% respectively. Treatment failure occurred in 3% of M. kansasii and 12% of M. scrofulaceum patients. A normal pre-morbid radiograph was significantly less common in NTM than M. tuberculosis patients (odds ratio 0.26 and 0.10 for M. kansasii and M. scrofulaceum, respectively). NTM disease incidence, defined as NTM isolate plus new cavitation, was estimated at 66 and 12 per 100000 person-years for M. kansasii and M. scrofulaceum, respectively. CONCLUSIONS: M. kansasii and M. scrofulaceum disease are common in HIV-negative South African gold miners. Most isolates are associated with new cavitation against a background of silicosis or old TB scarring.

Adult↗
PubMed1999

Mycobacterial disease in South African gold miners in the era of HIV infection.

SETTING: Mining company tuberculosis (TB) clinic, Freestate Province, South Africa. OBJECTIVES: To investigate the impact of the human immunodeficiency virus (HIV) on tuberculosis case rates and case detection methods in miners. DESIGN: Demographic and clinical data were extracted from the central computerised TB database for the period 1990-1996. RESULTS: A total of 7450 miners had TB, which was smear- or culture-positive in 81% of pulmonary cases. Incidence rates more than doubled between 1990 and 1996, from 1174 to 2476 per 100000 per year. Non-tuberculous mycobacteria, predominantly Mycobacterium kansasii, were isolated more commonly from retreatment than from new cases (19.5% and 11.5% respectively, P < 0.001). HIV prevalence in TB patients increased from 15% in 1993 to 45% in 1996 (P < 0.001). There was no significant association between HIV and smear status, but HIV-positive patients were more likely than HIV-negative patients to present passively with symptoms rather than through the active radiological screening programme (OR 1.9, P < 0.0001). The overall proportion of patients presenting passively increased from 23% in 1990 to 51% in 1996 (P < 0.001). CONCLUSION: The HIV epidemic has lead to increased TB incidence in South African miners to very high rates, and appears to be impacting on the efficacy of the active radiological screening programme.

Adult↗
PubMed1998

Mycobacterium kansasii and human immunodeficiency virus co-infection in London.

OBJECTIVES: although Mycobacterium kansasii infection has long been endemic in the U.K., the disease burden and characteristics of infection in the HIV-seropositive population has not been well documented. This study addresses these issues in an inner city population that comprises a quarter of all cases of acquired immunodeficiency syndrome (AIDS) reported in the U.K. METHODS: retrospective review of case notes from two inner London specialist HIV Units. RESULTS: twenty-nine cases of M. kansasii infection were identified, with case notes available for review in 26. Ten had pulmonary disease and nine had disseminated infection: a further seven patients appeared simply to be colonized (two respiratory and five gastrointestinal): M. kansasii was isolated from stool in over a third (nine of 26) of cases. Disseminated M. kansasii infection occurred in 0.44% of AIDS cases seen in our two units and all isolates were resistant to isoniazid ion vitro. A clinical response achieved in 11 of the 13 patients with M. kansasii-related disease who received anti-mycobacterial therapy. All four patients who relapsed following initial clinical response to therapy had received sub-optimal treatment. CONCLUSIONS: the incidence of disseminated M. kansasii infection in HIV-infected individuals in the U.K. is similar to that seen in those from high prevalence regions of the U.S.A., and anti-mycobacterial therapy leads to a clinical response in the majority of patients with HIV and M. kansasii co-infection. The frequent isolation of M. kansasii from the stool suggests that the gastrointestinal tract may be a significant source of disseminated infection.

Adult↗