Is TB contact screening relevant in a developing country setting? Experiences from eastern Nepal, 1996-1998.

SETTING: A tuberculosis programme run by a non-governmental organisation in eight hill and mountain districts of eastern Nepal. OBJECTIVE: To assess the impact of contact screening on case-finding. DESIGN: A retrospective cohort study of contacts of smear-positive, smear-negative and extra-pulmonary tuberculosis patients diagnosed and registered during 1996-1998 ('index cases'). Contacts, defined as household members identified by index cases, were screened by sputum examination; two positive smears were taken to indicate smear-positive pulmonary disease. RESULTS: Approximately 50% (668) of registered cases identified contacts; 75% (2298) of the contacts identified provided one or more sputum specimens. An overall smear-positive case yield of 0.61% (14) was obtained from contacts tested, all except one of which were contacts of smear-positive index cases. For smear-positive index cases with a smear grading of > or = 2+, the yield was 7.2 times greater (P = 0.04) than for those with a grading of 1+. CONCLUSION: In this setting, sputum examination of household contacts of smear-negative and extrapulmonary tuberculosis cases is not justified. Further assessment is needed to evaluate the utility of testing contacts of smear-positive cases without symptom screening, and whether cost effectiveness can be improved by restricting testing to contacts of cases with high bacterial (> or = 2+) loads.     

Screening for infection and disease as a tuberculosis control measure among indigents in New York City, 1994-1997.

SETTING: Several social service agencies in New York City, and the Chest Clinic of Bellevue Hospital, a large public hospital. OBJECTIVE: To determine the utility of screening as a preventive and control measure among persons at risk for tuberculosis. DESIGN: Persons seeking social services at several private agencies in New York City were screened, and those with a positive skin test or symptoms suggestive of active tuberculosis were referred to the Chest Clinic for evaluation. RESULTS: Of 3828 persons evaluated, 20 had active tuberculosis, and 33% of the screened cohort were tuberculin skin test positive. Of 466 persons with tuberculosis infection who were evaluated, only 55 persons were given isoniazid (INH), and only 20 completed preventive therapy. Most patients who were not given INH had taken it previously, were older than 35 years, or had continuing alcohol use which made physicians reluctant to prescribe isoniazid. CONCLUSION: Screening for tuberculosis may detect a significant number of cases of active disease when the background prevalence of the disease is very high. However, screening for infection as a means to prevent future cases is unlikely to be effective unless rates of administration and completion of isoniazid preventive therapy are increased.     

Time of development of tuberculosis in contacts

The British Thoracic Association has recommended that close contacts of smear-positive cases of tuberculosis be followed up for at least 2 yrs (Tubercle 1978; 59: 245-259) but Selby et al. have recently suggested that a reduction in duration of follow up may be appropriate (Respir Med 1989; 83: 353-355). We have reviewed the results of contact procedures in Leeds to determine whether our experience supports reduction in the duration of follow up of contacts of patients with tuberculosis. In the 5-yr period 1983-87 there were 555 cases of tuberculosis (135 in Asians) of whom 42 (7.6%) were identified by contact procedures. In addition, contact procedures identified 35 children who were given chemoprophylaxis for positive Heaf tests (grade 2 or more). Of the 42 contacts with tuberculosis, 30 (71%) were diagnosed at the first visit, eight (19%) were diagnosed 6 months later and four (10%) were diagnosed 16-24 months after their initial clinic attendance. Five of the 42 contacts with TB were Asian, two of whom were diagnosed late. Seven out of ten non-Asian contacts who were diagnosed late had initial Heaf reactions of grade 1 or 2. All cases diagnosed late were contacts of a sputum-positive source. Poverty, as defined by residence in the Leeds Urban Priority Area, was associated with an increased risk of 3.3-fold for tuberculosis and a sixfold risk for chemoprophylaxis diagnosed by contact procedures.(ABSTRACT TRUNCATED AT 250 WORDS)     

The value of contact procedures for tuberculosis in Edinburgh

We have reviewed the value of routine contact procedures (CP) in screening for tuberculosis in the Edinburgh area. Nine hundred and forty-seven index cases were notified during the 5-year period 1977-81; of these, 131 (14%) were detected by CP, 78 had previously undetected tuberculous disease and a further 53 required chemoprophylaxis (CPX). None had presented with symptoms, and disease was consequently detected at an earlier stage with fewer being sputum smear positive (10% vs 29% P less than 0.01). The 131 cases were found by CP during the screening of 4445 contacts, an overall yield of 2.9%. The highest yield was 18% for close contacts of sputum smear positive index cases, the yield for the casual contact being only 3%. The overall yield for contacts of smear negative respiratory and non-respiratory index cases was less than 2% in each group. Young contacts were particularly vulnerable and the yield in Asian children was 10.2%, twice that of the 4.9% in non-Asian children (P less than 0.001). The incidence of new cases in contacts who had previous BCG vaccination was significantly lower than that in non-vaccinated contacts (1.15% vs 3.06% P less than 0.001) suggesting a protective effect of 62%. One hundred and twenty-five (95%) of the 131 new cases were diagnosed within 3 months of first attendance, the remaining 5% at 6 months. The workload involved in screening contacts in this series could have been halved by restricting CP to all contacts of sputum smear positive index cases and only the close contacts of all other index cases. This would have resulted in missing 18% of the new cases, or three cases of tuberculosis and two cases requiring CPX per year, in a population of 608 000. Seventy-two (7.6%) of the 947 index cases were of Asian origin. Their disease occurred more in young adults, especially women, and was more frequently extrapulmonary in site (25% vs 12% in non-Asians P less than 0.01). We conclude that contact procedures remain valuable in the detection of new, asymptomatic cases of tuberculosis in Edinburgh and, by implication, in other urban areas of the United Kingdom. Particular efforts should be directed towards children, Asians and those without BCG vaccination, especially if they have been in contact with sputum smear positive index cases.     

Mycobacterial culture results of smear-positive patients with suspected pulmonary tuberculosis in Liverpool.

The aim of this study was to assess the final mycobacterial culture results of patients with smear-positive sputum or bronchial washings and to investigate the efficiency of local tuberculosis (TB) contact-tracing. Retrospective analysis of mycobacterial cultures and contact-tracing was performed in every patient with smear-positive sputum or bronchoalveolar lavage (BAL) in two Liverpool teaching hospitals (1996-1998). Of these patients 116 with smear-positive sputum or BAL were identified. Mycobacterium tuberculosis (M. tuberculosis) was cultured in 57 (49%), environmental mycobacteria in 37 (32%) and cultures were negative in 22 (19%) of the patients. Contact-tracing information was available in 107 of the 116 (92%) patients. A total number of 1,357 contacts were screened for possible tuberculosis. Of these, 420 (31%) were contacts of patients who cultured environmental organisms or had negative cultures. In this study, 51% of smear-positive patients in Liverpool did not have tuberculosis. Inefficiencies in current contact-tracing procedures have been identified which result from screening contacts of index cases that are subsequently found not to have cultured Mycobacterium tuberculosis. The authors believe that there are clear grounds for using rapid tests to identify and type mycobacteria more quickly than current solid or liquid media methods. It is also suggested that regional variations in the frequency of infection with environmental mycobacteria should be considered when formulating tuberculosis contact-tracing procedures.     

Clinical analysis of pulmonary tuberculosis found by mass screening medical examination

Five hundred twenty-one patients with pulmonary tuberculosis were diagnosed in our three affiliated hospitals during past 10 years. Among them, 43 cases (22 men and 21 women; mean age 54.8 years) who were detected by active case-finding were clinically evaluated. Most of them were detected in an annual mass screening examination, but seven cases were found by contacts examination which was performed on subjects who were contacted with newly diagnosed patients with pulmonary tuberculosis. Fifteen of them were socially jobless on admission. Eighteen cases (41.9%) had underlying diseases, and gastrointestinal diseases and diabetes mellitus were most frequently observed. The final diagnosis was confirmed through bronchoscopic specimens in 18 cases in which Mycobacterium tuberculosis could not be detected from the sputum. Regarding radiological findings according to the criteria of the Japanese Society of Tuberculosis, most cases had unilateral distribution, and were classified as type III (active, non-cavitary) for characteristics and 1 (minimal) for the extent of lesions. Treatment using combination therapy with four drugs including pyrazinamide was performed for over half of these cases and subsequently the clinical efficacy was good except in one case who died due to worsening of the underlying disease. Anti-tuberculous drugs were generally administered to cases suspected of having pulmonary tuberculosis on chest X-ray. However, early diagnosis using bronchoscopy and early treatment seems to be useful, when Mycobacterium tuberculosis is not detected in the sputum.     

Human T-cell lymphotropic virus-III (HTLV-III) seropositivity and related disease among 71 consecutive patients in whom tuberculosis was diagnosed. A prospective study

The incidence of tuberculosis has recently risen in Southeast Florida. In order to determine the number and proportion of tuberculosis cases and the characteristics of tuberculosis that might be related to human T-cell lymphotrophic virus-III (HTLV-III) infection, all patients seen by the Dade County Florida Public Health Department-Tuberculosis Clinic during a 6-month period were medically evaluated and screened for HTLV-III antibody by an enzyme-linked immunosorbent assay. Of 71 consecutive patients confirmed to have tuberculosis (70 by culture) during the study period, 22 (31%) were seropositive and 49 (69%) were seronegative for HTLV-III antibody. The seropositive group had a significantly higher proportion of patients who were black, Haitian, and within the age group of 25 to 44 yr. The seropositive group also had a significantly higher rate of mild-to-moderate serum aspartate transaminase elevations (less than or equal to 5 times normal), tuberculin skin test false negativity, extrapulmonary tuberculosis (especially lymphatic), and pulmonary tuberculosis with an atypical radiographic picture. The seropositive group had a significantly lower proportion of patients with sputum cultures positive for M. tuberculosis. There was no significant difference between the groups with respect to the proportion of patients with positive sputum smears when sputum cultures were positive, serious antituberculosis drug reactions (requiring discontinuation of therapy), or percent of home contacts who were tuberculin skin tested and found to be positive. At the time of the diagnosis of tuberculosis, only 6 (27%) of the seropositive patients with tuberculosis had clinical evidence of AIDS or AIDS-related complex (unexplained thrush).(ABSTRACT TRUNCATED AT 250 WORDS)     

Inner-city survey for tuberculosis: evaluation of diagnostic methods

A total of 1,271 persons living in a socially and economically depressed, inner-city area of Vancouver, British Columbia, voluntarily attended a tuberculosis case-finding campaign. Chest x-ray, on-the-spot specimen of sputum, and tuberculin skin test were offered at the time of the first attendance. All 3 diagnostic methods were found to be well accepted, with 93% of the participants having an x-ray, over 95% producing a sputum specimen, and almost 95% having a tuberculin test (a quarter of these did not, however, report for reading of the test). Eight cases of bacteriologically confirmed pulmonary tuberculosis were found: 6 suspected on x-ray (the remaining 2 films were abnormal but not diagnostic of tuberculosis), and 6 being positive on smear and/or culture of the initial on-the-spot sputum specimen. Examination of a second specimen of sputum diagnosed all of the 8 active cases identified by the survey. These results suggest that, in this particular setting, a chest radiogram taken by a transportable chest x-ray apparatus or examination of 2 sputum specimens might be equally successful at detecting all cases of active pulmonary tuberculosis within the time required for sputum culture. Examination of the sputum smear immediately identifies all the more infectious cases of pulmonary tuberculosis. The prevalence rate of 629 per 100,000 among those presenting themselves to this campaign illustrates the high-yield which might be achieved by active case-finding projects in known high-incidence segments of a generally low-incidence population.     

Outbreak of tuberculosis in a homeless population involving multiple sites of transmission.

SETTING: During 2002-2003, a large outbreak of tuberculosis (TB) occurred among persons using multiple homeless facilities in King County, Washington. OBJECTIVE: To control the transmission of TB in multiple settings. DESIGN: In 2002, contacts exposed to patients in homeless facilities were screened using tuberculin skin tests (TSTs) and symptom review. Based on these screening results, sites of transmission were identified and prioritised, and exposed cohorts at these sites were offered intensive screening tests in 2003 (e.g., symptom review, TST, chest radiograph [CXR], sputum examination and culture). Mycobacterium tuberculosis isolates from patients were genotyped using PCR-based methods to identify outbreak-associated patients quickly. RESULTS: During 2002-2003, 48 (15%) of 313 patients diagnosed in King County were outbreak-associated; 47 culture-positive patients had isolates that matched the outbreak strain by genotyping. Three facilities visited by >12 patients in 2002 had a higher prevalence of TST positive results (approximately 30%) among clients compared with the background rate (7%) in the homeless community. Screening contacts with one sputum culture was as sensitive as CXR in detecting TB disease (77% vs. 62%, respectively). CONCLUSIONS: A comprehensive, resource-intensive approach likely helped to control transmission. This outbreak highlights the vulnerability of homeless populations and the need to maintain robust TB programs in urban settings.     

广东省2005—2008年非结防机构网络直报肺结核病人转诊与追踪情况分析

目的分析广东省2005—2008年非结防机构网络直报肺结核病人转诊和追踪情况,探讨提高病人发现水平的措施。方法收集广东省2005—2008年中国结核病控制工作月报表、季报表进行分析。结果2005—2008年广东省各非结防机构网络直报肺结核/疑似肺结核病人的转诊到位率和追踪到位率分别为42.5%和39.0%,总体到位率为64.9%。追踪到位的疑似病人中52.8%被确诊为肺结核。网络直报病人中菌阳、菌阴和未查痰病人的转诊到位率分别为66.9%、58.0%和37.9%;结防机构追踪到位的疑似病人中菌阳、菌阴和未查痰病人的肺结核确诊率分别为97.6%、79.8%和43.6%。结论非结防机构在肺结核病人的发现中起重要作用。建立规范化的结核病登记、报告及转诊工作制度,提高网络直报病人的查痰率,将提高肺结核病人发现水平。     

2018年济南市学校肺结核患者密切接触者筛查结果分析

目的调查2018年济南市学校肺结核患者密切接触者的筛查情况,对全市学校肺结核疫情和处置情况进行分析。方法建立2018年济南市学校肺结核的发病情况和处置结果数据库,包括济南市市、县两级监测到《传染病报告信息管理系统》中报告的患者、学校方告知患者及外地单位反馈的学校患者。2018年全市共发现学生或教师肺结核患者197例,除去实习、毕业或近期接受过筛查等原因的10例患者,对187例肺结核患者开展个案流行病学调查,确定密切接触者共11617名。对其中24例病原学阳性肺结核患者确定密切接触者2138名,实际筛查2104名;163例病原学阴性及无病原学结果的肺结核患者确定密切接触者9479名,实际筛查9384名。密切接触者采用全市统一配发的卡介菌纯蛋白衍生物(BCG-PPD)试剂进行结核菌素皮肤试验(简称"PPD试验")筛查。结果2018年济南市学校肺结核患者以大学生为主81.28%(152/187)。11488名密切接触者的PPD试验结果中,阴性8898名(77.45%),一般阳性1434名(12.48%),中度阳性651名(5.67%),强阳性505名(4.40%)。24例病原学阳性患者的密切接触者PPD试验强阳性率(7.41%,156/2104)明显高于163例非病原学阳性患者密切接触者PPD试验的强阳性率(3.72%,349/9384),差异有统计学意义(χ^2=55.84,P<0.001)。通过筛查共发现肺结核患者31例。结论通过对学校肺结核患者密切接触者的筛查,可发现部分结核病患者;落实肺结核患者密切接触者的结核病筛查工作,可减少结核病在学校中的传播。     

Investigation of the cases due to Mycobacterium kansasii in our hospital]

A clinical study of 23 patients with Mycobacterium kansasii infection of the lung encountered at National Chiba Higashi Hospital from 1988 to 1990 was carried out. All 23 cases were male, aged from 25 to 81 years-old. Diagnoses were confirmed by sputum culture. The cases consisted of 15 primary infections and 8 secondary infections. Out of the 23 cases, 11 were detected by mass screening with chest X-ray findings, 10 cases were discovered when visiting the hospital because of chest complications and two cases were diagnosed during the observation of other diseases. On admission, sputum smear examinations were positive for 15 patients and negative for 8 patients. Chest X-ray findings using the roentgenological classification criterion for pulmonary tuberculosis established by the Japanese Society for Tuberculosis, 20 cases revealed a Type II shadow and three cases revealed a Type III shadow. One patient has died from another disease, two are undergoing chemotherapy, two have ceased chemotherapy treatment, and 18 patients have completed the treatment, Sputum cultures rapidly turned to negative for mycobacterium detection after chemotherapy treatment. The prognosis is considered to be quite good.     

Cost-effectiveness of polymerase chain reaction versus Ziehl-Neelsen smear microscopy for diagnosis of tuberculosis in Kenya.

BACKGROUND: Laboratory services, particularly in large sub-Saharan cities, are overstretched, and it is becoming difficult both for patients and health staff to adhere to the diagnostic procedures for tuberculosis. Alternative techniques would be welcome. The polymerase chain reaction (PCR) has the potential to be cost-effective. We compared the cost-effectiveness of two diagnostic strategies, Ziehl-Neelsen (ZN) on three specimens followed by chest X-ray (CXR), and AMPLICOR MTB PCR on the first specimen only. METHODS: Three sputum samples were collected from tuberculosis (TB) suspects attending the Rhodes Chest Clinic, Nairobi. All samples were subjected to ZN, PCR and L?wenstein-Jensen culture used as gold standard. CXR was used to diagnose smear-negative TB. Cost analysis included health service and patient costs. RESULTS: Costs per correctly diagnosed case were US dollar 41 and dollar 67 for ZN and PCR, respectively. When treatment costs were included, including treatment of culture-negative cases, PCR was more cost-effective: dollar 382 vs. dollar 412. CONCLUSION: PCR may be an alternative in settings with many patients. PCR is patient friendly, CXR is not necessary and, unlike ZN, its performance is hardly affected by the human immunodeficiency virus. PCR can handle large numbers of specimens, with results becoming available on the same day.     

Prevalence and risk factors associated with tuberculin skin test positivity among household contacts of smear-positive pulnionary tuberculosis cases in Umerkot, Pakistan.

STUDY POPULATION AND SETTING: Household contacts of acid-fast bacilli (AFB) sputum smear-positive tuberculosis patients in the Umerkot Taluka, Sindh, Pakistan. OBJECTIVE: To estimate the prevalence of and identify risk factors associated with tuberculin skin test (TST) positivity among household contacts of acid-fast bacilli (AFB) sputum smear-positive pulmonary tuberculosis cases. DESIGN: A cross-sectional study of household contacts of AFB sputum smear-positive tuberculosis cases, registered at the Umerkot Anti-Tuberculosis Association clinic from August 1999 to September 1999. The contact's Mycobacterium tuberculosis infection status was assessed using TST. On the day of the TST, a pre-designed questionnaire was administered to collect data on putative risk factors for TST positivity among contacts. The data were analysed using a marginal logistic regression model by the method of generalised estimating equations (GEE) to determine risk factors independently associated with TST positivity. RESULTS: The prevalence of TST positivity among household contacts of AFB sputum smear-positive index patients was 49.4%. The final multivariate GEE model showed that contact's age and sleeping site relative to the index case, the intensity of the index case's AFB sputum-smear positivity and the contact's BCG scar status were independent predictors of TST positivity among household contacts of AFB sputum smear-positive index cases. CONCLUSIONS: The results suggest that the household contacts of AFB sputum smear-positive tuberculosis patients in a poor neighbourhood of rural Sindh had a high prevalence of M. tuberculosis infection as determined by TST. Poor housing conditions seem to contribute to the spread of M. tuberculosis infection. Early diagnosis of pulmonary TB through evaluation of TST-positive household contacts, followed by appropriate therapy, may prevent further spread of M. tuberculosis infection. We recommend an awareness programme to prevent household contacts from acquiring M. tuberculosis infection from smear-positive pulmonary TB cases.     

Contact examination for tuberculosis in Hong Kong is useful.

SETTING: The tuberculosis programme of the Hong Kong Government Tuberculosis and Chest Service. OBJECTIVE: To determine the outcome of examination of household contacts in Hong Kong. DESIGN: A retrospective cohort study of all household contacts of 970 randomly selected index cases from a total of 5757 registered for treatment with the Chest Service. RESULTS: Of 2678 household contacts (three/index case) identified, 90% were examined; 41 active cases were found, at a rate of 1720/100000 (95%CI 1238-2329). The rate was highest among two extremes of age, 3604/100000 (95%CI 990-3615) in children < or = 5 years and 3347/100000 (95%CI 1456-6489) in those >60 years of age. Contacts of index cases whose sputum smear and culture were positive had the highest rate of disease, 2904/100000 (95%CI 1669-4673); but contacts with negative bacteriology also had a high rate of 1478/100000 (95%CI 678-2789). Active cases identified through contact tracing could be source cases rather than secondary cases. Eight per cent of children aged < or = 5 years had positive tuberculin reactions; as BCG vaccination is given to all newborns, with 99% coverage in Hong Kong in the past 30 years, it was difficult to estimate the rate of infection in these children. CONCLUSION: In Hong Kong, an area with an intermediate burden of tuberculosis, contact investigation is a very useful procedure for active case finding.     

Timing of quantiferon TB-G test for the contact examination of tuberculosis

PURPOSE: To investigate the timing when Quanti FERON TB-Gold test (QFT-G) for the contact examination of tuberculosis should be done. METHOD: We examined QFT-G test for the 25 family contacts of sputum smear positive tuberculosis cases diagnosed at Fukujuji Hospital 5 times (soon after the diagnosis of the index case, 2 months later, 3 months later, 4 months later and 6 months later). And we calculated the positivity at these examinations. RESULTS: Among 25 contacts, 8 persons became QFT-G positive. The positivity was higher among the contacts of cases with longer delay in diagnosis. 2 contacts were positive soon after the diagnosis of index cases, 5 cases became positive 2 months after the diagnosis and 1 case became positive after 3 months. CONCLUSION: 3 months interval from the diagnosis of the index case will be enough for the final decision of the infection of contacts.     

Evaluation of active tuberculosis case finding through symptom screening and sputum microscopy of close contacts in Shandong, China

Objectives To evaluate the effect of active case finding through symptom screening and sputum microscopy of close contacts in a Fidelis (Fund for Innovative DOTS Expansion through Local Initiatives to Stop TB) project. Methods Secondary data from all 35 counties were collected during implementation and used. They comprised new cases identified, number of close contacts screened and their relationships. Fifty‐four in‐depth interviews were conducted with staff from key stakeholders. Results A total of 13 310 symptomatic contacts of 5255 index cases were screened, and 90 new smear‐positive cases were detected with a yield rate of 0.7%. The yield rate of close contacts was positively associated with smear grades of the index cases (P < 0.01). Close contacts of cases, such as classmates and workmates, who lived in a closed contained setting, had a higher yield rate than family members (P < 0.001). Gaps in project implementation such as training, incentives and sputum collection were identified through in‐depth interviews. Conclusions The yield rate of close‐contact screening of 0.7% was similar to other findings in China. There was a higher yield from screening of close contacts in congregated settings like schools and workshops. Future active case finding projects should provide clear operational guidelines and adequate training.     

An incremental cost-effectiveness analysis of the first, second and third sputum examination in the diagnosis of pulmonary tuberculosis.

SETTING: St. Francis Hospital in Katete District, Eastern Province, Zambia. OBJECTIVE: To compare the incremental cost-effectiveness of examining serial sputum smears for screening suspects for pulmonary tuberculosis at a rural district hospital in Zambia. DESIGN: An incremental cost-effectiveness analysis of serial sputum smear examinations for diagnosing pulmonary tuberculosis based on laboratory results collected during 1997 and 1998 in a rural district hospital in Zambia. The cost analysis took a health service provider perspective, and used the ingredients approach. The cost-effectiveness is expressed in terms of the incremental cost per tuberculosis case diagnosed. Relevant information was obtained from various sources, including administrative records, interviews and direct observation. RESULTS: Of a total of 166 acid-fast bacilli positive suspects who had three sputum smears examined sequentially, 128 (77.1%) were found on the first smear, a further 25 (15%) on the second smear and 13 (7.9%) additional cases were identified on the third smear. The economic analysis shows that the incremental cost of performing a third test, having already done two, increases rapidly with only a small gain in terms of additional cases of tuberculosis identified. CONCLUSION: A policy of examining two samples should be considered in resource-poor settings, if the remaining steps of the national diagnostic algorithm can be adhered to with respect to smear-negative suspects.     

A preliminary study of the influence of HIV infection in the transmission of tuberculosis

The human immunodeficiency virus (HIV) epidemic has had a profound influence on the epidemiology of tuberculosis (TB). The potential for HIV-associated TB cases to transmit M. tuberculosis and to produce a secondary increase in TB morbidity is unknown. A cross-sectional study was carried out to compare the prevalence of M. tuberculosis infection among the household contacts of HIV-positive and HIV-negative pulmonary tuberculosis (PTB) patients. Records of tuberculin (Mantoux) tests administered during routine contact investigations at the Chest Clinic, Hospital Kota Bharu, from 1999 to 2000 were reviewed. The HIV status of the patients was based on the results of ELISA tests while information on household contacts was gathered during visits to their houses. Ninety-four contacts of 39 HIV-negative patients and 44 contacts of 17 cases of HIV-positive patients were included in this preliminary study. 30% (12/40) of the contacts of HIV-positive PTB had a positive tuberculin compared with 52.8% (47/ 94) of the contacts of HIV-negative patients [OR = 0.41, 95% Confidence interval (CI) 0.17 - 0.97; p = 0.016]. The difference was still significant after performing multivariate logistic regression analysis to adjust for variables associated with infectiousness of TB (adjusted OR = 0.24, 95% CI 0.07 - 0.87; p = 0.03). This study has shown that HIV-infected PTB patients are less infectious to their contacts than HIV-negative patients. The presence of MV in the community may not necessitate a change of the current policy of the management of contacts.     

Under-diagnosis of smear-positive pulmonary tuberculosis in Nairobi, Kenya.

SETTING: Nairobi City Council Chest Clinic, Nairobi, Kenya. OBJECTIVE: To determine if under-reading of sputum smears is a contributing factor in the disproportionate increase in smear-negative tuberculosis in Nairobi, Kenya. METHODOLOGY: Between October 1997 and November 1998, patients fulfilling the local programme definition of smear-negative presumed pulmonary tuberculosis were enrolled in the study. Two further sputum specimens were collected for examination in a research laboratory by fluorescence microscopy. RESULTS: Of 163 adult subjects enrolled, 55% were seropositive for the human immunodeficiency virus type 1 (HIV-1). One hundred subjects had had two pre-study sputum smears assessed before recruitment and produced two further sputum specimens for re-examination in the research laboratory; of these 19 (19%) were sputum smear-positive on re-examination and a further seven (7%) became smear-positive on second re-examination. CONCLUSIONS: Of those patients with smear-negative presumed pulmonary tuberculosis by the local programme definition, 26% were smear-positive when reexamined carefully with two repeat sputum smears. This suggests that the high rates of smear-negative tuberculosis being seen may in part be due to under-reading. This is probably as a result of the overwhelming burden of tuberculosis leading to over rapid and inaccurate sputum examination. Retraining of existing technicians and training of more technicians is likely to reduce underreading and increase the yield of smear-positive tuberculosis. This finding also stresses the need for regular quality assurance.