Value of chest radiography in a tuberculosis prevention programme for HIV-infected people, Botswana.

To exclude tuberculosis, WHO/UNAIDS recommends considering medical history, symptom screen, and chest radiograph before starting tuberculosis prevention in people infected with HIV. The value of a chest radiograph for this purpose is unknown. We prospectively assessed 935 HIV-infected outpatients seeking isoniazid preventive therapy. Of 935 patients, 692 (74%) had no signs or symptoms of tuberculosis. Of these 692, 123 (18%) were lost during the chest radiograph process, and one (0.2%) of the remaining 563 was diagnosed with tuberculosis on the basis of the chest radiograph. A screening chest radiograph should not be required routinely for asymptomatic people taking isoniazid as preventive treatment in settings able to screen for signs and symptoms of tuberculosis.

Cost-effectiveness of home-based care versus hospital care for chronically ill tuberculosis patients, Francistown, Botswana.

SETTING: Francistown, Botswana, 1999. OBJECTIVE: To determine the affordability and cost-effectiveness of home-based directly observed therapy (DOT) compared to hospital-based DOT for chronically ill tuberculosis (TB) patients, and to describe the characteristics of patients and their caregivers. DESIGN: Costs for each alternative strategy were analysed from the perspective of the health system and caregivers, in 1998 US dollars. Caregiver costs were assessed using a structured questionnaire administered to a sample of 50 caregivers. Health system costs were assessed using interviews with relevant staff and documentary data such as medical records and expenditure files. These data were used to calculate the average cost of individual components of care, and, for each alternative strategy, the average cost per patient treated. Cost-effectiveness was calculated as the cost per patient compliant with treatment. The characteristics of caregivers and patients were assessed using demographic and socio-economic data collected during interviews, and medical records. RESULTS: Overall, home-based care reduced the cost per patient treated by 44% compared with hospital-based treatment (dollars 1657 vs. dollars 2970). The cost to the caregiver was reduced by 23% (dollars 551 vs. dollars 720), while the cost to the health system was reduced by 50% (dollars 1106 vs. dollars 2206). The cost per patient complying with treatment was dollars 1726 for home-based care and dollars 2970 for hospitalisation. Caregivers were predominantly female relatives (88%), unemployed (48%), with primary school education or less (82%), and with an income of less than dollars 1000 per annum (71%). Of those patients with an HIV test result, 98% were HIV-positive. CONCLUSION: Home-based care is more affordable and cost-effective than hospital-based care for chronically ill TB patients, although costs to caregivers remain high in relation to their incomes. Structured home-based DOT should be included as a component of the National Tuberculosis Control Programme in Botswana.

The validity of HIV testing using sputum from suspected tuberculosis patients, Botswana, 2001.

SETTING: The World Health Organization recommends that sentinel HIV surveillance be conducted on tuberculosis patients. However, serum HIV testing is complicated in the TB clinic context, and may not be acceptable to patients. DESIGN: To determine the utility of the OraQuick HIV-1/2 Assay for the detection of HIV antibodies in sputum, we consecutively enrolled adult in-patients in Botswana who had sputum sent for acid-fast bacilli testing and serum sent for HIV ELISA testing. OraQuick HIV-1/2 Assay was applied to gingival secretions according to manufacturer's guidelines, and was also dipped into sputum specimens. A subset of 60 sputum specimens was also serially tested up to 72 hours after collection. RESULTS: Of 377 patients, 84% were HIV-positive by serum ELISA. Compared with serum ELISA, the OraQuick HIV-1/2 Assay detected HIV in gingival secretions with 98.4% sensitivity and 98.3% specificity (95%CI 97-99 and 92-100, respectively), and 97.1% sensitivity and 98.3% specificity on initial sputum specimens (95%CI 95-99 and 92-100, respectively). OraQuick HIV-1/2 Assay performance on sputum declined slightly when tested up to 72 hours after collection. CONCLUSIONS: When applied to sputum specimens, the OraQuick HIV-1/2 Assay demonstrates sensitivity and specificity comparable to its intended application on gingival secretions. This novel testing method will be valuable in anonymous sentinel HIV surveillance surveys among tuberculosis patients.

Control of anti-tuberculosis drug resistance in Botswana.

SETTING: Botswana, where in 2000 the prevalence of human immunodeficiency virus (HIV) infection among adults was 38%, and the tuberculosis (TB) rate was 591/100,000. A 1995-1996 survey demonstrated low levels of anti-tuberculosis drug resistance. OBJECTIVE: Because TB drug resistance may increase rapidly in HIV-infected populations, a second survey was undertaken in 1999 to determine any increase in anti-tuberculosis drug resistance. DESIGN: Sputum specimens positive for acid-fast bacilli from patients without prior TB treatment (new patients), and all sputum specimens from patients reporting prior TB treatment (retreatment patients) were collected nationwide. Specimens were cultured for Mycobacterium tuberculosis and tested for resistance to isoniazid, rifampicin, ethambutol, and streptomycin. RESULTS: From January to May 1999, 783 patients were consecutively enrolled from all districts. Of these, 483 (61.7%) were male, the median age was 33 years, and 82% were new patients. Drug resistance occurred in 6.3% of new patients (95 % confidence interval [CI] 4.6-8.6) and 22.8% of retreatment patients (95% CI 16.5-30.1). Resistance to at least isoniazid and rifampicin was found in 0.5% of new (95% CI 0.1-1.3) and 9.0% of retreatment patients (95% CI 5.1-14.5). CONCLUSION: Anti-tuberculosis drug resistance remains relatively low in Botswana, probably as a result of a well-functioning TB program. Periodic surveys will be essential to adequately determine any significant trend.

Risk factors for transmission of Mycobacterium tuberculosis from HIV-infected tuberculosis patients, Botswana.

OBJECTIVE: To identify risk factors for transmission of Mycobacterium tuberculosis from patients with tuberculosis and human immunodeficiency virus (HIV) infection in Botswana. DESIGN: Transmission was studied in 210 children aged <10 years (contacts) of unknown HIV status exposed to 51 adults with tuberculosis (index cases), including 41/49 (83.7%) with HIV infection. METHODS: Data collected on index cases included demographics, clinical and social characteristics, sputum, HIV, and CD4 lymphocyte results. Tuberculin skin testing was performed on contacts, and their parent or guardian was interviewed. A positive test was defined as > or = 10 mm induration. Skin test results were compared with results obtained from a population survey of children of similar age from the same community. RESULTS: A positive skin test was found in 12.1% of exposed children compared with 6.2% in the community (P = 0.005). Of the infected children, 22 (78.6%) were contacts of a close female relative. The risk of transmission increased with the degree of sputum smear positivity for acid-fast bacilli among female index cases (10.8% if smear 0+, 9.3% if smear 1+,29.4% if smear 2+, 44% if smear 3+, P < 0.001). In multivariate analysis, severe immunodeficiency (CD4 lymphocyte count <200 cells/mm3) among HIV-infected index cases was protective against transmission (OR 0.08, 95%CI 0.01-0.5, P = 0.006). CONCLUSION: The intensity of exposure to tuberculosis patients and the degree of sputum smear positivity for acid-fast bacilli remain important risk factors for transmission of M. tuberculosis during the era of HIV. However, tuberculosis patients with advanced AIDS may be less infectious than patients in earlier stages of AIDS.

Molecular and conventional epidemiology of Mycobacterium tuberculosis in Botswana: a population-based prospective study of 301 pulmonary tuberculosis patients.

Little is known about patterns of tuberculosis (TB) transmission among populations in developing countries with high rates of TB and human immunodeficiency virus (HIV) infection. To examine patterns of TB transmission in such a setting, we performed a population-based DNA fingerprinting study among TB patients in Botswana. Between January 1997 and July 1998, TB patients from four communities in Botswana were interviewed and offered HIV testing. Their Mycobacterium tuberculosis isolates underwent DNA fingerprinting using IS6110 restriction fragment length polymorphism, and those with matching fingerprints were reinterviewed. DNA fingerprints with >5 bands were considered clustered if they were either identical or differed by at most one band, while DNA fingerprints with < or =5 bands were considered clustered only if they were identical. TB isolates of 125 (42%) of the 301 patients with completed interviews and DNA fingerprints fell into 20 different clusters of 2 to 16 patients. HIV status was not associated with clustering. Prior imprisonment was the only statistically significant risk factor for clustering (risk ratio, 1.5; 95% confidence interval, 1.1 to 2.0). In three communities where the majority of eligible patients were enrolled, 26 (11%) of 243 patients overall and 26 (25%) of 104 clustered patients shared both a DNA fingerprint and strong antecedent epidemiologic link. Most of the increasing TB burden in Botswana may be attributable to reactivation of latent infection, but steps should be taken to control ongoing transmission in congregate settings. DNA fingerprinting helps determine loci of TB transmission in the community.

Completeness and timeliness of treatment initiation after laboratory diagnosis of tuberculosis in Gaborone, Botswana.

SETTING: Gaborone, the capital of Botswana. OBJECTIVE: To determine the time from positive sputum smear microscopy for acid-fast bacilli (AFB) to initiation of therapy, and to identify risk factors for delays. DESIGN: Retrospective cohort study of medical records and surveillance data for patients with positive smear microscopy and newly diagnosed tuberculosis (TB) from January to May 1997. Treatment delay was defined as more than 2 weeks from the first positive sputum smear to the initiation of TB treatment. RESULTS: Of 127 patients identified, 15 (11.8%) had treatment delay, 13 (10.2%) had an incomplete workup (only one smear performed) and were not registered for TB treatment, and six (4.5%) had two or more positive smears but were not registered for TB treatment. Risk factors for treatment delay or non-registration included TB patients who had been diagnosed in a hospital outpatient setting vs. a clinic (RR 2.9, 95% CI 1.2-3.6, P = 0.02), or in a high volume vs. low volume clinic (RR 2.2, 95% CI 1.2-5.3, P = 0.01). CONCLUSION: More than a quarter of the smear-positive TB patients identified had treatment delay or no evidence of treatment initiation. Proper monitoring of laboratory sputum results and suspect TB patient registers could potentially reduce treatment delays and patient loss.

Transmission of Mycobacterium tuberculosis among employees in a US government office, Gaborone, Botswana.

SETTING: A US government office located in Botswana where two office employees, one negative and one positive for the human immunodeficiency virus (HIV), were diagnosed with pulmonary tuberculosis (TB) in January 1998. One employee had been symptomatic with untreated laryngeal TB for 8 months. OBJECTIVE: To determine the extent of and risk factors for TB transmission in the office. METHODS: Office contacts were interviewed and a tuberculin skin test (TST) was performed. A positive TST was defined as > or = 10 mm induration for employees from countries where TB is highly endemic, and as > or = 5 mm induration for those from low prevalence counties. RESULTS: Of 79 office contacts investigated, 54/57 (94.7%) born in high TB prevalence countries had a positive TST compared with 4/22 (18.2%) from low prevalence countries (RR 5.1, 95% CI 2.1-12.7, P < 0.001). Of 20 US-born contacts, three (15%) had documented TST conversion, two of whom were co-workers of the employee with laryngeal TB. Isolates of Mycobacterium tuberculosis from the TB cases had matching DNA fingerprints. CONCLUSION: Delayed diagnosis in a setting of high TB prevalence may have contributed to transmission within a US government office located in Botswana. Transmission may have been underestimated due to the high background prevalence of tuberculous infection in the population. Recent tuberculous transmission to persons living with HIV infection may be playing an important role in the escalating TB epidemic in Africa.

Validation of the surveillance system for tuberculosis in Botswana.

SETTING: Gaborone and Francistown, Botswana, where surveillance data in the 1997 Electronic Tuberculosis (TB) Register suggest that 39% of pulmonary TB patients did not have pre-treatment sputum smear microscopy performed. OBJECTIVE: To determine the proportion of patients with reportedly missing pre-treatment sputum smear results in 1997 who had smears examined, and to identify stages in the system where results were lost. METHODS: Patients with pulmonary TB in 1997 who were missing pre-treatment sputum smear results in the Electronic TB Register were cross-matched with laboratory records; medical records were reviewed. RESULTS: Of 374 patients with pre-treatment sputum smear results missing, 224 (60%) actually had had a sputum smear examined in the laboratory. The proportion of pulmonary TB patients in Gaborone and Francistown who did not have sputum examined was therefore 16% instead of 39%. Most missing results (69%) had not been transcribed from the laboratory results onto the TB Treatment Card. Patients who had a negative smear result or who sought care at a clinic that was different from where their diagnostic evaluation had been initiated were more likely to have missing results. CONCLUSIONS: The actual performance of the Botswana National TB Programme with respect to sputum microscopy examination is much better than surveillance indicators suggest. In addition to sputum collection, proper recording of results needs reinforcement among health care workers to improve routine performance indicators.

Knowledge, attitudes and beliefs regarding tuberculosis preventive therapy for HIV-infected persons, Botswana, 1999.

SETTING: Botswana, 1999. OBJECTIVE: To measure knowledge, attitudes and beliefs about tuberculosis (TB) preventive therapy (PT) for persons infected with the human immunodeficiency virus (HIV). DESIGN: A systematic sample of adult clinic attendees, using a standardised questionnaire. RESULTS: A total of 275 patients at 38 clinics in five districts were interviewed. The majority were female (65%) and unmarried (84%). Knowing someone with TB or AIDS was common (78% and 53%, respectively). Respondents perceived a relationship between TB and HIV (80%), and the majority were willing to undergo tuberculin skin testing (92%). Of those, most were willing to undergo evaluation for active TB (98%), and to take PT, although willingness to take PT declined with proposed duration (97% 6 months, 90% 1 year, 81% lifetime, P < 0.01). Previous HIV testing was reported by 13%; those who had not undergone testing reported that they would if doctors could improve the quality (95%) or duration (93%) of life of persons with AIDS. The majority favoured receiving HIV test results on the day they were tested (60%). CONCLUSIONS: Most clinic attendees in Botswana were willing to undergo HIV testing if it were beneficial to do so, such as by receiving PT. Pilot PT projects should be initiated. Voluntary HIV counselling and testing services should consider rapid HIV testing methods.

Former migrant mineworkers with respiratory disease: the South African compensation system, and implications for neighbouring countries.

In the region of Southern Africa, substantial numbers of people, primarily males, have been employed in the South African mining industry. Migrant workers from neighbouring countries have constituted a large part of the work force. Until recently, there has been little or no attention directed toward the state of health of these individuals, despite the fact that their work involves a high health risk, especially in regard to mine-related lung diseases. In addition, the South African workers' compensation programme has seldom been utilised by the migrant worker who is a victim of occupational disease. However, recent experiences from Botswana show that compensation claims can be successfully made from the neighbouring countries where the migrant workers originate. Efforts are being made to address the problem systematically, and the government of Botswana is actively involved. The major occupational lung disorders are described briefly, and differential diagnostic problems with pulmonary TB are discussed. Furthermore, a survey of the compensation system in South Africa is presented, and practical steps for medical examinations involving compensation claims are described.

Survey of physician use of radiography and sputum smear microscopy for tuberculosis diagnosis and follow-up in Botswana.

SETTING: National survey of physician knowledge, attitudes, and practices for tuberculosis (TB) diagnosis and monitoring in Botswana. OBJECTIVE: To assess adherence to national guidelines for TB diagnosis and monitoring. DESIGN: Questionnaires were mailed to all physicians registered with the Ministry of Health. RESULTS: The response rate was 69%. Diagnostic and follow-up practices differed substantially from national recommendations. Senior District Medical Officers (SDMOs) were the most likely to adhere to guidelines on use of sputum examination for diagnosis (87%) and follow-up (50%); private practitioners were the least likely to follow the same guidelines (53% and 10%, respectively). SDMOs were also less likely to use radiographs for diagnosis (27%); the greatest use was seen in government hospital-based physicians (86%). While most SDMOs had received an introduction to the TB programme and had access to the programme manual and recent information on TB, the majority of other practising physicians in the country did not. CONCLUSION: Recommended diagnostic procedures for TB were not being followed by a substantial percentage of physicians. Efforts are being made to inform hospital-based physicians and private practitioners about TB programme policies. Adherence to programme recommendations is vital to strengthen TB control efforts.