Annual risk of tuberculosis infection among tribal population of central India.

OBJECTIVE: To estimate the annual risk of tuberculosis infection (ARTI) among tribal children of Madhya Pradesh, central India. METHODS: Community-based, cross-sectional tuberculin survey among children aged 1-9 years in the tribal population of Madhya Pradesh. Multistage stratified cluster sampling was used to select a representative random sample of villages predominated by tribal population from selected districts. A total of 4802 children were tuberculin-tested with 1TU of PPD RT 23 and the reaction sizes read after 72 h. RESULTS: A total of 3062 (64%) children had no BCG scar. The frequency distribution of children by reaction sizes indicated a fair mode at 18 mm in the right hand side of the distribution. By mirror-image technique, the prevalence of infection among children with no recognizable BCG scar was estimated as 6.8% (95% CI: 4.8-8.9%). The ARTI was computed as 1.3% (0.9-1.7%). The corresponding figures for children irrespective of scar status were 7.1% (95% CI: 5.5-8.8%) and 1.3% (1.0-1.7%) respectively. CONCLUSIONS: The risk of tuberculosis infection in tribal population of Madhya Pradesh, central India is not different from other areas of the country. There is, however, a need to further intensify tuberculosis control measures on a sustained and long-term basis.

Tuberculous infection in Saharia, a primitive tribal community of Central India.

A cross-sectional tuberculin survey was carried out to estimate the prevalence of tuberculous infection and the annual risk of tuberculosis infection (ARTI) among children of Saharia, a primitive ethnic group in Madhya Pradesh, Central India. A total of 1341 children aged 1-9 years were subjected to tuberculin testing with 1 TU of PPD RT 23 and the reaction sizes were read after 72 h. The proportion of BCG scar-positive children was 34.6%. The frequency distribution of children by reaction sizes indicated a clear-cut anti-mode at 11 mm and a mode at 18 mm at the right-hand side of the distribution. The prevalence of infection among children irrespective of BCG scar was estimated as 20.4% (95% CI 18.2-22.5%) and the ARTI was 3.9% (95% CI 3.5-4.3%). The corresponding figures were 21.1% (95% CI 18.3-23.8%) and 3.9% (95% CI 3.4-4.5%) among BCG scar-negative children and 19.0% (95% CI 15.4-22.5%) and 4.0% (95% CI 3.2-4.8%) among BCG scar-positive children. The findings of the present study show a high prevalence of tuberculous infection and high ARTI in this primitive ethnic group. There is an urgent need to further intensify tuberculosis control measures on a sustained and long-term basis in this area.

Active community surveillance of the impact of different tuberculosis control measures, Tiruvallur, South India, 1968-2001.

BACKGROUND: Tuberculosis is curable, but community surveys documenting epidemiological impact of the WHO-recommended DOTS strategy on tuberculosis prevalence have not been published. We used active community surveillance to compare the impact of DOTS with earlier programmes. METHODS: We conducted tuberculosis disease surveys using random cluster sampling of a rural population in South India approximately every 2.5 years from 1968 to 1986, using radiography as a screening tool for sputum examination. In 1999, DOTS was implemented in the area. Prevalence surveys using radiography and symptom screening were conducted at the start of DOTS implementation and after 2.5 years. RESULTS: From 1968 to 1999, culture-positive and smear-positive tuberculosis declined by 2.3 and 2.5% per annum compared with 11.9 and 5.6% after DOTS implementation. The 2.5 year period of DOTS implementation accounted for one-fourth of the decline in prevalence of culture-positive tuberculosis over 33 years. Multivariate analysis showed that prevalence of culture-positive tuberculosis decreased substantially (10.0% per annum, 95% CI: 2.8-16.6%) owing to DOTS after only slight declines related to temporal trends (2.1% annual decline, 95% CI: 1.1-3.2%) and short-course chemotherapy (1.5% annual decline, 95% CI: -9.7% to 11.5%). Under DOTS, the proportion of total cases identified through clinical care increased from 81 to 92%. CONCLUSIONS: Following DOTS implementation, prevalence of culture-positive tuberculosis decreased rapidly following a gradual decline for the previous 30 years. In the absence of a large HIV epidemic and with relatively low levels of rifampicin resistance, DOTS was associated with rapid reduction of tuberculosis prevalence.

The prevalence of tuberculosis in different economic strata: a community survey from South India.

A cross-sectional socio-economic survey to assess the standard of living index (SLI) of a rural population in South India was undertaken along with a tuberculosis (TB) prevalence survey during 2004-2006. Of 32,780 households, the SLI was low, medium and high in 22%, 36% and 42%, and TB prevalence was 343, 169 and 92 per 100,000 population, respectively, a significant decrease in trend (P < 0.001); 57% of the TB patients had a low SLI and the prevalence of TB was higher amongst the landless (P < 0.001), those living below the poverty line (P < 0.01) and in katcha houses (P < 0.001), suggesting that TB disproportionately affects those with a low SLI.

Coincident filarial, intestinal helminth, and mycobacterial infection: helminths fail to influence tuberculin reactivity, but BCG influences hookworm prevalence.

The prevalence of helminth and tuberculosis infections is high in South India, whereas Bacille-Calmette-Guerin (BCG) vaccine efficacy is low. Our aim was to determine whether concurrent helminth infection alters the ability to mount a delayed-type hypersensitivity response to tuberculin. In a cross-sectional study in southern India, individuals 6-65 years of age were screened for intestinal helminths, circulating filarial antigenemia, tuberculin reactivity, active tuberculosis, and history of BCG vaccination; 54% were purified protein derivative (PPD) positive, 32% had intestinal helminth infection, 9% were circulating filarial antigen positive, and 0.5% had culture-confirmed active tuberculosis. Only age and BCG vaccination were significantly associated with PPD reactivity; however, BCG vaccination was associated with a lower prevalence of hookworm infection relative to those without prior BCG vaccination. Neither intestinal helminth infection nor filarial infection was associated with diminished frequencies of PPD positivity. Our findings suggest that preceding helminth infection does not influence significantly the delayed-type hypersensitivity response to tuberculin.

Yield of pulmonary tuberculosis cases by employing two screening methods in a community survey.

OBJECTIVE: To compare the yield of tuberculosis (TB) cases by two screening methods. SETTING: Two disease surveys conducted in Tiruvallur, south India. RESULTS: Of bacteriologically confirmed cases, 60% were identified by symptom inquiry alone whereas 82% were identified using chest radiography (CXR). CONCLUSION: The prevalence of TB was underestimated by both methods. The total cases in this community can be estimated by multiplying the number of identified cases by a correction factor (CF) of 1.7 when symptom inquiry alone is used or 1.2 when CXR is used. The CF may be different in other settings.

Predictors of relapse among pulmonary tuberculosis patients treated in a DOTS programme in South India.

OBJECTIVE: To identify risk factors associated with relapse among cured tuberculosis (TB) patients in a DOTS programme in South India. DESIGN: Sputum samples collected from a cohort of TB patients registered between April 2000 and December 2001 were examined by fluorescence microscopy for acid-fast bacilli and by culture for Mycobacterium tuberculosis at 6, 12 and 18 months after treatment completion. RESULTS: Of the 534 cured patients, 503 (94%) were followed up for 18 months after treatment completion. Of these, 62 (12%) relapsed during the 18-month period; 48 (77%) of the 62 relapses occurred during the first 6 months of follow-up. Patients who took treatment irregularly were twice more likely to have a relapse than adherent patients (20% vs. 9%; adjusted odds ratio [aOR] 2.5; 95% CI 1.4-4.6). Other independent predictors of relapse were initial drug resistance to isoniazid and/or rifampicin (aOR 4.8; 95% CI 2.0-11.6) and smoking (aOR 3.1; 95% CI 1.6-6.0). The relapse rate among non-smoking, treatment adherent patients with drug-sensitive organisms was 4.8%. CONCLUSIONS: The relapse rate under the DOTS programme may be reduced by ensuring that patients take their treatment regularly and are counselled effectively about quitting smoking.

A baseline survey of the prevalence of tuberculosis in a community in south India at the commencement of a DOTS programme.

OBJECTIVE: To determine the baseline prevalence of culture-positive and smear-positive tuberculosis and the annual risk of tuberculous infection (ARTI) in a community in south India where DOTS is being implemented. METHODS: Using cluster sampling, 50 rural panchayats (villages) and three urban units in Tiruvallur district were selected randomly. All adults aged > or = 15 years underwent symptom and radiographic examination, and those with abnormal shadows and/or chest symptoms had sputum smear and culture examination. In another cluster sample of 73 villages and three urban units, all children aged < 10 years were tuberculin tested. RESULTS: The prevalence of culture-positive and smear-positive tuberculosis was respectively 605 and 323/100,000. Both increased appreciably with age, and were substantially higher in males than in females at all ages; the overall male:female ratio was 5.5 for culture-positive and 6.5 for smear-positive tuberculosis. The ARTI in children aged under 10 years was 1.6%, and was unaffected by sex. Over three decades there was an overall decline of 1.8% per annum in the prevalence of culture-positive and 2.1% for smear-positive tuberculosis. CONCLUSION: Tuberculosis is a major problem in this rural community in south India, with a prevalence of 605/100,000 for culture-positive tuberculosis and 323/100,000 for smear-positive tuberculosis.

Survey for tuberculosis in a tribal population in North Arcot District.

SETTING: Tribal villages in the jungles of the Jawadhu hills, South India. OBJECTIVE: To estimate the prevalence of tuberculosis (TB) infection and disease in a remote tribal population. DESIGN: A cross-sectional survey with two-stage screening for identification of cases. A stratified probability proportional sample with the hamlet as the unit. METHODS: Among 56 revenue divisions with a population of about 66,000, 24 revenue divisions were selected. Among 26,320 persons registered, children < 10 years were tuberculin tested and reactions were read after 72 hours. Those over 15 were X-rayed, and tuberculosis symptoms were investigated. Sputum was collected from those with abnormal X-ray or symptoms and examined for smear and culture positivity and sensitivity. RESULTS: Of the 6952 children tested and read, 5% had BCG scars and the prevalence of infection was 5%. The annual risk of infection was 1.1. Among adults, the prevalence of bacillary cases was 8/1000 and X-ray cases 29/1000. The prevalence of bacillary disease was higher among males, particularly with increasing age. Thirty symptomatic cases had normal X-rays and 63 X-ray cases had no symptoms. Thus prevalence would have been underestimated if either method had been used alone for screening. Isoniazid resistance was seen in 12% of patients, two of whom also had rifampicin resistance (2.6%). CONCLUSIONS: The prevalence and pattern of tuberculosis in this tribal group is similar to that observed in non-tribal areas.

External validation of prognostic model of one-year mortality in patients requiring prolonged mechanical ventilation.

BACKGROUND: External validation of prognostic model for one-year mortality in patients ventilated for 21 days or more. A measure that identifies patients who are at high risk of mortality after prolonged ventilation will help physicians communicate prognoses to patients or surrogate decision makers. Our objective was to validate a prognostic model developed by Carson et al in a different setting. METHODS: An observational study was conducted from September 2002 to September 2007 in 30 beds Medical/Surgical Intensive Care Unit (ICU) at Mercy Fitzgerald Hospital (MFH) and 20 beds Medical/Surgical ICU at Mercy Philadelphia Hospital (MPH). One hundred and fifty medical and surgical patients requiring mechanical ventilation after acute illness for at least 21 days after initial intubation were enrolled. RESULTS: One year mortality was 45.4%. Area under the receiver operating characteristic curve for three month mortality was 0.90 and for one year mortality was 0.92. For identifying patients who had ≥90% risk of death at 3 month had sensitivity of 40% and specificity of 95% and risk of death at 1 year had sensitivity of 70% and specificity of 99%. Four predictive variables, requirement of vasopressors, hemodalysis, platelet count ≤ 150 x 10 9/L and age ≥50 yrs can be used as a simple prognostic score that clearly identifies low-risk patients and high-risk patients. CONCLUSIONS: Simple clinical variables measured on day 21 of mechanical ventilation can identify patients at highest and lowest risk of death from prolonged mechanical ventilation.

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.

Feasibility of involving literate tribal youths in tuberculosis case-finding in a tribal area in Tamil Nadu.

SETTING: Tribal area in South India with a population of 96,000, where the tuberculosis case-finding activity was very poor. OBJECTIVES: To investigate the feasibility of (1) involving literate (who can read and write) tribal youth volunteers for detecting cases of pulmonary tuberculosis (PT) in their respective hamlets; and (2) antituberculosis drug delivery to sputum-positive patients at their homes by village health nurses (VHNs). DESIGN: One volunteer from each of 61 hamlets was selected and trained in the detection of subjects with chest symptoms, sputum collection and transportation to the Primary Health Centre for smear examination. All smear-positive patients were treated with 2RHZ/6TH and the drugs were supplied by VHNs fortnightly at their homes. RESULTS: During a period of 1 year (1992-93), the total population screened was 9383 persons; of these 5755 were aged 15 years and above. A total of 338 symptomatic subjects were identified; 12 sputum-positive cases were detected and started on treatment. Antituberculosis drugs were supplied by VHNs to patients for the first 9 months of the study and by literate youths for the next 3 months. Spot drug checks revealed that 11 of the 12 patients were regular in drug consumption. CONCLUSION: It is feasible to train literate tribal youth volunteers within a short time to detect subjects with chest symptoms in the community and thereby cases of pulmonary tuberculosis. They can serve as an excellent model for community participation in difficult areas.