Trends in the prevalence of Pulmonary Tuberculosis over a period of seven and half years in a rural community in south India with DOTS.

Setting: Tiruvallur district In Tamil Nadu where DOTS was implemented by the State Government as the tuberculosis control measure in 1999, and monitored by the National Institute for Research in Tuberculosis for over five years. Objective: To estimate trends in TB prevalence in a rural community with DOTS. Design: Surveys of pulmonary tuberculosis were undertaken in representative samples of subjects aged >15 years (N = 83,000 – 92,000), initially and after two and half, five and seven and half years of implementation of DOTS. Sputa were collected from those with abnormal radiograph and/or presence of chest symptoms, and examined by direct smear and culture. Results: The prevalence of culture-positive tuberculosis was 607, 454, 309 and 388 per 100,000 in the four surveys, and that of smear-positive tuberculosis was 326, 259, 168 and 180. In the first five years; annual decrease was 12.4% (95% CI 10.4 - 14.4%) for culture-positive tuberculosis, and 12.2% (95% CI 8.0–16.2) for smear-positive tuberculosis. This was, however, followed by a significant increase in the next two and half years. The average new smear-positive case-notification rate was 75 per 100,000 during first four years but declined to 49 in subsequent years. There were no methodological differences during this period and information on changes in socio-economic indicators and nutritional standards was unavailable. Conclusion: Despite the average annual success rate (78%) in this tuberculosis unit being lower than the expected rate of 85%, the implementation of DOTS was followed by a substantial decrease in the prevalence of pulmonary tuberculosis over the seven and half year period. Our findings suggest that sustaining the high effectiveness of DOTS programme needs vigilant supervision.

Emergence of drug resistant mutations after single dose nevirapine exposure in HIV-1 infected pregnant women in south India.

Background & objectives: Resistance to nevirapine (NVP) has been described with single dose preventive regimens in other populations. Our aim was to study the pattern and prevalence of HIV drug resistance (DR) at baseline (during pregnancy) and after delivery among antenatal women exposed to single dose NVP for prevention of parent to child transmission (PPTCT). Methods: HIV-infected, ART-naive primigravidae between 18-25 years of age, attending government antenatal clinics in Chennai, Vellore or Madurai were recruited. Drug resistance testing was carried out during pregnancy and after Sd-NVP treatment (one month after delivery) by Viroseq sequencing. HIV-1 testing by DNA PCR was done in newborns at 30 days. Results: Thirty one women were enrolled but only twenty six plasma specimens were analyzable (24 paired and two postnatal only). No major mutations were observed in any drug class at baseline though many polymorphisms were observed in both the reverse transcriptase and protease genes. Mutations to non-nucleoside reverse transcriptase inhibitors (NNRTI) were observed post-delivery in 33 per cent of women who were treated with Sd-NVP. None of the infants were HIV-positive. Interpretation & conclusions: Among pregnant ART-naïve women, baseline HIV drug resistance was not observed. A high rate of development of NNRTI class resistance among women treated with single-dose NVP was observed. Our results emphasize the need to implement more effective PPTCT regimens, minimizing emergence of drug resistance and thereby preserving long-term treatment options for HIV-infected women in India.

CCR2, MCP-1, SDF-1α & DC-sign gene polymorphisms in HIV-1 infected patients with & without tuberculosis.

Background & objectives: Variability in the clinical outcome of persons exposed to and infected with HIV-1 and tuberculosis (TB) is determined by multiple factors including host genetic variations. The aim of the present study was to find out whether chemokine, chemokine receptor and DC-SIGN gene polymorphisms were associated with susceptibility or resistance to HIV and HIV-TB in south India. Methods: CCR2 V64I (G/A), monocyte chemoattractant protein-1 (MCP-1) -2518 A/G, stromal cell derived factor-1α (SDF-1α) 3’UTR G/A and DC-SIGN gene polymorphisms were studied by polymerase chain reaction based methods in HIV-1 infected patients without TB (n=151), with pulmonary TB (PTB) (n=81) and extrapulmonary TB (n=31), 155 PTB patients without HIV and 206 healthy controls. Results: The genotype frequencies of CCR2 V64I, MCP-1 -2518 and DC-SIGN polymorphisms did not differ significantly between the study groups. A significantly increased frequency of GG genotype of SDF-1α polymorphism was observed among HIV+PTB+ patients compared to healthy controls (P=0.009, Pc=0.027). Interpretation & conclusions: Our data suggest that GG genotype of SDF-1α 3’UTR polymorphism may be associated with susceptibility to PTB in HIV-1 infected patients. A better understanding of genetic factors that are associated with TB could help target preventive strategies to those HIV patients likely to develop tuberculosis.

DOTS Reacdes Socially Marginalized Population in the Community a Study from a Rural Area of South India.

We report here that the Directly Observed Treatment, Short course (DOTS) is reaching all tuberculosis patients in the community irrespective of social classification based on the analysis from the tuberculosis prevalence survey and programme performance during 1999-2003 from a rural area in Tamilnadu, South India. New smear- positive cases treated under a DOTS programme were classified in two groups namely; scheduled caste living in colony and other population. The prevalence of smear- positive cases among the scheduled caste population was 1.9 times higher than the other population and this was reflected in the notification also. The successful treatment outcome was also similar in these two groups (75% and 78% respectively; overall 77%). From these findings it is concluded that people living in colony have equal access to DOTS as those in the village.

Assessment of long term status of sputum positive pulmonary TB patients successfully treated with short course chemotherapy.

Background: Long term status of pulmonary tuberculosis (PTB) patients treated with short course chemotherapy (SCC) regimens remains unknown. Objective: To assess the clinical, bacteriological, radiological status and health related quality of life (HRQoL) of PTB patients 14 -18 years after successful treatment with SCC. Methodology: In a cross-sectional study, cured PTB patients treated during 1986 – 1990 at the Tuberculosis Research Centre (TRC) were investigated for their current health status including pulmonary function tests (PFT). The St Georges respiratory questionnaire (SGRQ) was used to assess the HRQoL Results: The mean period after treatment completion for the 363 eligible participants was 16.5yrs (range 14-18 yrs, 84% coverage) ; 25 (7 %) had been re-treated and 52 (14%) died. Among the investigated, 58 (29%) had persistent respiratory symptoms; 170(86%) had radiological sequelae but none had active disease. Abnormal PFT was observed in 96 (65%) with predominantly restrictive type of disease in 66(45%). The SGRQ scores for activity and impact were high implying impairment in HRQoL. Conclusion: Assessment of long term status of cured PTB patients showed an impairment of lung functions and HRQoL highlighting the need to address these issues in the management of TB that may provide added value to patient care.

Incomplete immunological recovery following anti-tuberculosis.

Background & objectives: Mycobacterium tuberculosis infection has been shown to result in increased HIV replication and disease progression in HIV-infected individuals through increased immune activation. The objective of this study was to correlate plasma levels of immune activation markers with the presence of tuberculosis (TB) in HIV-infected and uninfected individuals, and to study the changes following anti-tuberculosis treatment. Methods: Plasma markers of immune activation - neopterin, beta-2-microglobulin (β2M) and soluble tumour necrosis factor alpha receptor type I (sTNFα-RI) were measured by ELISA in 42 HIV positive TB patients (HIV+TB+) undergoing a six-month course of TB chemotherapy. Thirty seven HIV+ persons without active TB, 38 TB patients without HIV infection, and 62 healthy volunteers served as controls. Results: Plasma levels of all three markers were elevated in HIV+ individuals, more so in those with active TB. When HIV+ individuals were further categorized based on CD4+ T cell counts, HIV+TB+ patients with CD4+ T cells counts < 200 cells/μl were found to have the highest levels at baseline with a steep fall in neopterin and sTNFα-RI during treatment, but in most instances the levels did not drop to normal. β2M levels remained persistently high despite completing TB treatment. Interpretation & conclusions: The fi ndings of the study suggest that both HIV and TB act synergistically to activate the host immune system. Although ATT was effective in clearing M. tuberculosis infection, a high proportion of HIV+ TB patients continued to have levels well above the normal range, indicating that underlying immune activation persists despite TB treatment. None of the markers were specific enough to be used to assess cure of TB.

Pot method for storage & detection of acid-fast bacilli from sputum samples.

BACKGROUND & OBJECTIVES: Sputum acid-fast bacilli (AFB) microscopy services are not available in all health facilities. Alternative procedures are needed to transport sputum samples to the diagnostic centres for detection of AFB. The objective of the present study was to evaluate sputum smears made by pot-method with the direct smears made immediately after sputum collection by Ziehl-Neelsen (ZN) method. METHODS: Ninety three sputum samples from 49 pulmonary tuberculosis suspects were studied. Their direct smears (ZN smears) were stained by hot ZN method. The samples were then mixed with phenol ammonium sulphate basic fuchsin solution and stored at ambient conditions. The smears (pot smears), made on day 7, were then, decolourized and counter-stained for detection of AFB (pot method). The ZN and pot smears were read blind. After excluding 18 samples for various reasons, the results of pot and ZN smears of 63 samples from smear positive (2 of 3 direct smears were positive) and 12 from smear negative (3 of 3 direct smears were negative) patients were analysed. ZN method was the gold standard. RESULTS: Pot and ZN smears were positive in 61 of 63 samples from smear-positive patients and negative in 11 of 12 smear-negative patients (kappa = 0.87). The sensitivity and specificity of pot method were 96.8 and 91.7 per cent respectively. INTERPRETATION & CONCLUSION: Sputum samples can be stored for up to seven days in the sputum container with phenol ammonium sulphate basic fuchsin solution. However, a comprehensive study needs to be done confirm the accuracy of the pot method for storage and transportation of sputum to microscopy centres for detection of AFB.

DOTS reaches socially marginalized population in the community: a study from a rural area of South India.

We report here that the Directly Observed Treatment, Short course (DOTS) is reaching all tuberculosis patients in the community irrespective of social classification based on the analysis from the tuberculosis prevalence survey and programme performance during 1999-2003 from a rural area in Tamilnadu, South India. New smear- positive cases treated under a DOTS programme were classified in two groups namely; scheduled caste living in colony and other population. The prevalence of smear- positive cases among the scheduled caste population was 1.9 times higher than the other population and this was reflected in the notification also. The successful treatment outcome was also similar in these two groups (75% and 78% respectively; overall 77%). From these findings it is concluded that people living in colony have equal access to DOTS as those in the village.

Phenol ammonium sulphate basic fuchsin staining of sputum in pot for the detection of acid-fast bacilli.

BACKGROUND & OBJECTIVES: Improper practices of making direct smears of sputum for detection of acid-fast bacilli (AFB) and of disposing sputum cups are hazardous. The present study was undertaken with the objective to stain sputum samples in their containers by 'phenol (10%) ammonium sulphate (4%) basic fuchsin (2%) solution' and to decolourize and counterstain their smears for detection of AFB- (henceforth called pot method) and to compare the smear results of pot method with the standard Ziehl-Neelsen (ZN) method. METHODS: A total of 575 selected sputum samples from pulmonary tuberculosis patients were stained by the standard ZN and pot methods and the proportions of AFB positive smears were compared. RESULTS: Of the 575 samples, 126 were AFB positive for both the staining methods and the difference was not statistically significant. Pot method missed 9 ZN positive smears (8 scanty and one 1+) and ZN method missed 9 pot positive smears (9 scanty) and the difference was not significant. High grade smears (3+) were seen more in pot method (42) than in ZN method (25) and the difference was significant. INTERPRETATION & CONCLUSION: Our findings showed that pot method was comparable to standard ZN method and had many advantages. Pot method can be explored further for the detection of AFB in sputum samples obtained from pulmonary tuberculosis suspects.

Annual risk of tuberculosis infection in Chennai city.

AIM: To study the proportion of children infected with Mycobacterium Tuberculosis in Chennai city. METHODOLOGY: A cluster sampling methodology was adopted to select an estimated sample size of 7000 children from five corporation zones selected systematically from ten zones of the city. A total of 7098 children aged 1-9 years were subjected to Mantoux and test read; 1897 (27%) from slum area and 5201 (73%) from non-slum area. RESULTS: The prevalence of infection among children without BCG scar was estimated to be 10.5 % (ARTI of 2.0%) and was similar to that among children irrespective of scar status. The prevalence of infection was higher among children in slum areas (11.1%; ARTI 2.1%) compared to non-slum areas (8.9%; ARTI 1.7%); but the difference was not statistically different. CONCLUSION: The tuberculosis situation in Chennai as measured by risk of infection was higher in urban city area than rural areas and comparable to that found in other cities as reported from earlier studies. This information can be used as baseline information for monitoring the epidemiological trends in Chennai city in future.

Evaluation of different types of chest symptoms for diagnosing pulmonary tuberculosis cases in community surveys.

BACKGROUND: Prevalence of tuberculosis (TB) is an important epidemiological index to measure the load of the disease in a community. A series of disease surveys were undertaken in rural community in Tiruvallur district in Tamilnadu, south India OBJECTIVE: To investigate the yield of pulmonary tuberculosis (TB) cases by different symptoms status and suggest predominant symptoms for detection of cases in the community based surveys. METHODS: Three disease surveys were conducted during 1999-2006, in a random sample of 82,000 adults aged > or = 15 years to estimate the prevalence and incidence of pulmonary TB. All subjects were screened for chest symptoms and chest radiography. Sputum examination was done among those who were either symptomatic or abnormal on X-ray or both. Cases observed through symptom inquiry were included for analysis. RESULTS: In survey-I, 65.6% had cough of > or = 14 days and yielded 79.1% of the total cases. In surveys II and III, symptomatic subjects with cough contributed 69.5% and 69.2% of the cases respectively. In survey I, 26.8% had symptoms without cough but with at least chest pain > or = 1 month contributed 8.4% of total cases. The corresponding proportions in subsequent surveys were 29.3, 11.5%; and 23.4, 11.2% respectively. The number of symptomatics without cough and chest pain but with fever > or = 1 month was negligible. CONCLUSION: The relative importance of cough as a predominant symptom was reiterated. The yield of pulmonary TB cases from symptomatics having fever of > or = 1 month was negligible. Fever may be excluded from the definition of symptomatics for screening the population in community surveys.

Increased yield of smear positive pulmonary TB cases by screening patients with > or =2 weeks cough, compared to > or =3 weeks and adequacy of 2 sputum smear examinations for diagnosis.

BACKGROUND: RNTCP recommends examining three sputum smears for AFB from Chest Symptomatics (CSs) with cough of > or =3 weeks for diagnosis of Pulmonary TB (PTB). A previous multi-centric study from Tuberculosis Research centre (TRC) has shown that the yield of sputum positive cases can be increased if duration of cough for screening was reduced to > or =2 weeks. Other studies have shown that two smear examinations are adequate for diagnosis of smear positive PTB . To validate the above findings, a cross sectional multi-centric study was repeated in different settings in five geographical areas in India. METHODS: Three primary and secondary level health facilities with high out-patient attendance were selected from two Tuberculosis Units (TU) in each of the 15 selected districts to screen about 10,000 new adult outpatients from each state. For patients who did not volunteer history of cough, symptoms were elicited using a structured simple questionnaire. All the CSs were referred for sputum examination. RESULTS: A total of 96,787 out-patients were registered. Among them 69,209 (72%) were new adult out-patients. Using > or =2 weeks of cough instead of 3 weeks as the criterion for screening, there was an overall increase of 58% in CS and 23% increase in the detection of smear-positive cases. Among 211 patients, 210 were positive at least by one smear from the initial two specimens. Increase in the work-load if 2 smears were done for patients with cough of > or =2 weeks cough were 2 specimens (i.e. 13 to 15) per day for an adult OPD of 150. CONCLUSION: The yield of sputum positive PTB cases can be improved by screening patients with > or =2 weeks cough and two specimens are adequate for diagnosis.

Impact of improved treatment success on the prevalence of TB in a rural community based on active surveillance.

OBJECTIVE: To study the impact of improved treatment outcome of a cohort of patients treated under DOTS strategy on the prevalence of pulmonary tuberculosis (TB) in the community. DESIGN: The data from TB register of one Tuberculosis Unit (TU) in Tiruvallur district of Tamilnadu, and two TB disease surveys conducted in the same area during 1999-2003 were analysed. The successful treatment outcome was compared to the prevalence of TB in the subsequent cohort. RESULTS: The proportion of patients who completed treatment successfully was 75.3% in the first cohort period. This higher proportion of treatment success among patients treated under DOTS in the first cohort period (1999-2001) compared to the 51-55% reported during SCC, resulted in a lower prevalence of smear-positive cases, irrespective of culture results observed in the survey conducted during 2001-2003 compared to that in the survey conducted during 1999-2001 (252 vs. 323 per 100,000; annual decline of 9%). Similarly, a decline in culture-positive cases, irrespective of smear results, was also observed (443 vs. 605; annual decline 11%). CONCLUSION: The higher proportion of successful completion of treatment after DOTS implementation was associated with a substantial decline in the prevalence of TB. These findings showed that we are in the direction towards achieving the Millennium Development Goals (MDGs).

Identification & differentiation of Mycobacterium avium & M. intracellulare by PCR- RFLP assay using the groES gene.

BACKGROUND & OBJECTIVE: We report a new polymerase chain reaction (PCR) - restriction fragment length polymorphism (RFLP) assay using mycobacterial groES as a target to identify Mycobacterium avium and M. intracellulare in clinical samples. METHODS: The assay was standardized using M. avium and M. intracellulare standard strains obtained from ATCC and was tested with 45 M. avium-M. intracellulare complex (MAC) clinical isolates (Of which 31 were from HIV(+) individuals). The standard and clinical strains were typed with HPLC based mycolic acid fingerprinting. RESULTS: Three polymorphisms (BamHI, BstNI and HgaI) were identified for inter-species differentiation among standard strains; of which, only HgaI was found to be useful in clinical isolates. Of the 45 isolates, 25 were M. avium and 20 were M. intracelluare. MAC isolates, which could not be differentiated by HPLC analysis, were also typed by this method. INTERPRETATION & CONCLUSION: The use of mycobacterial groES as a PCR-RFLP target for M. avium and M. intracellulare is a simple and rapid method that can complement HPLC in their differentiation.

Sputum conversion at the end of intensive phase of Category-1 regimen in the treatment of pulmonary tuberculosis patients with diabetes mellitus or HIV infection: An analysis of risk factors.

BACKGROUND & OBJECTIVE: New smear-positive pulmonary tuberculosis (PTB) patients in the Revised National Tuberculosis Control Programme (RNTCP) are treated with a 6-month short-course chemotherapy (SCC) regimen irrespective of co-morbid conditions. We undertook this retrospective analysis to compare sputum conversion rates (smear, culture) at the end of intensive phase (IP) of Category-1 regimen among patients admitted to concurrent controlled clinical trials: pulmonary tuberculosis alone (PTB) or with type 2 diabetes mellitus (DM-TB) or HIV infection (HIV-TB), and to identify the risk factors influencing sputum conversion. METHODS: In this retrospective analysis sputum conversion rates at the end of intensive phase (IP) in three concurrent studies undertaken among PTB, DM-TB and HIV-TB patients, during 1998 - 2002 at the Tuberculosis Research Centre (TRC), Chennai, were compared. Sputum smears were examined by fluorescent microscopy. HIV infected patients did not receive anti-retroviral treatment (ART). Patients with DM were treated with oral hypoglycaemic drugs or insulin (sc). RESULTS: The study population included 98, 92 and 88 patients in the PTB, DM-TB and HIV-TB studies. At the end of IP the smear conversion (58, 61, and 62%) and culture conversion (86, 88 and 92%) rates were similar in the three groups respectively. The variables associated with lack of sputum smear or culture conversion were age >45 yr, higher pre-treatment smear and culture grading, and extent of the radiographic involvement. INTERPRETATION & CONCLUSION: Our findings confirm that the current policy of the control programme to treat all pulmonary TB patients with or with out co-morbid conditions with Category-I regimen appears to be appropriate.

Status of smear-positive TB patients at 2-3 years after initiation of treatment under a DOTS programme.

OBJECTIVE: To describe the status of cases 2-3 years after the initiation of treatment under DOTS. SETTING: After DOTS implementation in Tiruvallur district, south India, we followed up a cohort of smear-positive TB patients registered during 2002-03 after initiation of treatment. RESULTS: The overall mortality rate was 15.0% and among the remaining 18.6% had active disease. In multivariate analysis, a higher mortality rate was independently associated with age, sex, occupation, treatment outcome and initial body weight of patients. CONCLUSION: The mortality and morbidity rates are still high during follow-up and needs to be curtailed by addressing these issues effectively in TB control programme.

Evaluation of an intermittent six-month regimen in new pulmonary tuberculosis patients with diabetes mellitus.

BACKGROUND: The treatment of tuberculosis (TB) with category I regimen of the Revised National Tuberculosis Control Programme (RNTCP) for patients with diabetes mellitus (DM) needs evaluation. OBJECTIVE: To assess the cure and relapse rates in 3 years, among the new smear-positive TB patients with Type-2 DM (DMTB) treated with CAT-I regimen (2E3H3R3Z3/4R3H3) of RNTCP. METHODOLOGY: TB suspects attending the diabetology units and the TB research centre (TRC) Chennai, were investigated. Eligible DMTB cases were enrolled. Baseline estimation of cardiac, renal, liver function tests and glycosylated-HBA1c were undertaken. All patients received 2E3H3R3Z3/4R3H3 under supervision at TRC. Clinical and sputum (smear and culture) examinations and monitoring of diabetic status were undertaken every month up to 24 months, then once in 3 months up to 36 months. RESULTS: Of 100 patients admitted, 7 were excluded for various reasons from analysis. Of 93 patients, 87 (94%) had a favourable response at the end of treatment. Pre and post treatment mean glycosylated-HBA1c were 9.7% and 8.4% (>7% poor control). During follow-up period, 6 died and one lost to follow-up. Of the remaining, four relapsed. CONCLUSION: Category-I regimen, recommended for all the new smear-positive patients in the Indian TB programme, is effective in the treatment of DMTB patients, despite poor control of diabetes.

Interleukin-12B & interleukin-10 gene polymorphisms in pulmonary tuberculosis.

BACKGROUND & OBJECTIVE: Cytokines play an important role in anti-tuberculosis immune response. Skewing of immunity from protective to pathogenic may involve a shift in Th1-Th2 paradigm. Cytokine gene polymorphism is known to be associated with functional differences in cytokine regulation and altered clinical performance in a variety of diseases. The aim of this study was to know whether Interleukin-12B 3' UTR (Taq1) (A/C) and Interleukin-10 (-1082 G/A) gene polymorphisms were associated with susceptibility to pulmonary tuberculosis. METHODS: IL -10 (-1,082 G/A) and IL-12B gene polymorphisms were studied in 132 pulmonary TB (PTB) patients and 143 normal healthy subjects (NHS), using DNA based polymerase chain reaction (PCR) with sequence specific primers and restriction digestion. RESULTS: The allelic as well as genotypic frequencies of Interleukin -10 (-1082) and Interleukin -12B (3'UTR Taq 1) did not differ significantly between the patients and controls. INTERPRETATION & CONCLUSION: Our findings suggested that IL -10 (-1082 G/A) and IL -12B 3'UTR (Taq I) (A/C) gene polymorphisms were not associated either with susceptibility or resistance to pulmonary tuberculosis in the south Indian population.

Reasons for non-compliance among patients treated under Revised National Tuberculosis Control Programme (RNTCP), Tiruvallur district, south India.

OBJECTIVES: To elicit reasons for treatment default from a cohort of TB patients under RNTCP and their DOT providers. METHODS: A total of 186 defaulters among the 938 patients registered during 3rd and 4th quarters of 1999 and 2001 in one Tuberculosis Unit (TU) of Tiruvallur district, Tamil Nadu and their DOT providers were included in the study. They were interviewed using a semi-structured interview schedule. RESULTS: Sixteen (9%) had completed treatment, 25 (13%) died after defaulting, and 4 (2%) could not be traced. Main reasons given by the remaining 141 patients and their DOT providers were: drug related problems (42%, 34%), migration (29%, 31%), relief from symptoms (20%, 16%), work related (15%, 10%), alcohol consumption (15%, 21%), treatment from other centers (13%, 4%), respectively. Risk factors for default were alcoholism (P<0.001), category of treatment (P<0.001), smear status (P<0.001), type of disease (P<0.001) and inconvenience for DOT (P<0.01). CONCLUSION: This study has identified group of patients vulnerable to default such as males, alcoholics, smear positive cases, and DOT being inconvenient. Intensifying motivation and counselling of this group of cases are likely to improve patient compliance and reduce default.

Comparison of tuberculin reaction sizes at 48 and 72 hours among children in Tiruvallur district, south India.

SETTING: A rural population in Tiruvallur district, south India. OBJECTIVE: To study the variability of skin test reaction sizes between 48 and 72 hours. METHODS: A tuberculin test survey was conducted among children aged less than 10 years. The reaction sizes were read by the same reader at 48 hours and 72 hours independently. The results of the tuberculin test were compared. RESULTS: Of 957 children aged below 10 years were included in the study; the male and female ratio was 1: 1.1. There were no significant differences between the readings of reaction size at 48 and 72 hours. CONCLUSION: The tuberculin test results can be read either at 48 hours or 72 hours without compromising the validity.