The association between environmental factors and tuberculosis infection among household contacts.

A cross-sectional study was conducted to determine the association between environmental factors and tuberculosis infection among household contacts aged less than 15 years in Bangkok, Thailand, between May and December 2003. During the study period, 480 household contacts aged under 15 years were identified. The prevalence of tuberculosis infection among household contacts was 47.08% (95% CI = 42.60-51.56). A generalized estimating equation (GEE) indicated that the risk of positive tuberculin skin testing in household contacst was found to increase with household crowding. Children living in a crowded household were five times more likely to have tuberculosis infection (OR = 5.19, 95% CI = 2.65-8.69). The association between environmental factors and tuberculosis infection assists community tuberculosis staff in understanding the risks for tuberculosis infection in the community and planning appropriate preventive actions based on this risk.

Factors associated with the household contact screening adherence of tuberculosis patients.

A cross-sectional study was conducted to explore factors associated with the adherence of tuberculosis patients in bringing their household contacts to a TB clinic in Bangkok, Thailand. During the study period, May to December 2003, 325 sputum-smear-positive tuberculosis patients were recruited into the study. Of the 325 eligible tuberculosis patients, 169 (52.00%, 95% Cl = 47.00-57.00) brought their household contacts to the TB clinic. Psychosocial and cues to action factors were examined as indicators of the household contact screening adherence of tuberculosis patients. The results reveal that the household contact screening adherence of tuberculosis patients was significantly associated with a higher perceived susceptibility (Adjusted OR = 2.90, 95% Cl = 1.18-7.16), lower perceived barriers (Adjusted OR = 4.60, 95% CI = 1.99-10.60), a higher intention to bring the contacts to the TB clinic (Adjusted OR = 3.35, 95% Cl = 1.44-7.76), and a short distance from home to the TB clinic (Adjusted OR = 11.47, 95% Cl = 4.57-28.79). The results from this study provide information for TB clinic staff for developing an appropriate intervention program. Through effective intervention and active policy enforcement, a higher percentage of household contact screening adherences can be achieved.

Factors associated with the development of tuberculosis in BCG immunized children.

In this hospital-based case-control study, children attending Siriraj Hospital and Queen Sirikit National Institute of Child Health from 1 December 2002 to 30 June 2003 were studied to define factors associated with TB in BCG immunized children (n = 260). Subjects of the same age and sex were divided into case and control groups by tuberculosis status. Caregivers were interviewed with a structured questionnaire. Data were analyzed by univariate analysis and multivariate analysis for biological factors (birth weight, health status, nutritional status), socioeconomic factors (parental education, education of caregiver, parental occupation, household incomes, and stability of household incomes), and environmental factors (history of contact with a tuberculosis patient, housing ventilation, child's bedroom ventilation, biomass smoke, passive smoking, crowded family and crowded in child's bedroom). Our findings show that children who had contact with TB patients had a very high risk of tuberculosis, even though they were vaccinated at birth. The risks vary according to the closeness level: very close (OR 85.67, 95%CI = 11.33-647.79), close (OR 31.11, 95%CI = 3.93-246.22) and not close (OR 32.70, 95%CI = 4.18-255.94). In order to identify the effect of others variables, the data was reanalyzed only in the group with no history of TB patient contacts (n = 192). Living in a crowded family, which was reflected by an average of 5 or more persons per room, also increased the risk (OR 11.18, 95%CI = 2.35-53.20). The other factor that increased the risk for tuberculosis was passive smoking. Children who were exposed to passive smoking had a 9.31 times increased risk of getting tuberculosis (95%CI = 3.14-27.58). These findings suggest that the public health department must develop a TB surveillance system in high TB prevalence areas, and in high density communities, and encourage smokers in every family to avoid smoking near children. Latent tuberculosis treatment recommendations for TB control cluster, as set by the Bureau of AIDS/TB and STIs, must be implemented in all health centers and an effective TB control program must be reinforced.

Risk factors for tuberculosis infection among household contacts in Bangkok, Thailand.

A cross-sectional study was conducted to determine the prevalence of tuberculosis infection and risk factors for tuberculosis infection among household contacts aged less than 15 years in Bangkok, Thailand, between August 2002 and September 2003. During the study period, 342 index cases with sputum smear positive pulmonary tuberculosis patients were recruited into the study and their 500 household contacts aged under 15 years were identified. The prevalence of tuberculosis infection among household contacts was found to be 47.80% (95%CI = 43.41-52.19). In multivariate analysis, a generalized estimating equation (GEE) was used to determine the risk factors for tuberculosis infection among household contacts. The results indicated that the risk of tuberculosis infection was significantly associated with close contact (adjusted OR = 3.31, 95%CI = 1.46-7.45), exposure to female index case (adjusted OR = 2.75, 95%CI = 1.25-6.08), exposure to mother with tuberculosis (adjusted OR = 3.82, 95%CI = 1.44-10.14), exposure to father with tuberculosis (adjusted OR = 2.55, 95%CI = 1.19-5.46), exposure to index case with cavitation on chest radiograph (adjusted OR = 4.43, 95%CI = 2.43-8.05), exposure to index case with 3+ sputum smear grade (adjusted OR = 3.85, 95%CI = 1.92-7.70), and living in crowded household (adjusted OR = 2.63, 95%CI = 1.18-5.85). The distribution of tuberculosis infection and risk factors among contact cases are significant for health care staff in strengthening and implementing tuberculosis control programs in Thailand.

Respiratory syncytial virus-associated lower respiratory tract infection in under-5-year-old children in a rural community of central Thailand, a population-based study.

The population-based cohort study on the epidemiology of respiratory syncytial virus (RSV)-associated lower respiratory tract infection (LRI) (RSV-LRI) was conducted in Takhli district from November 1998 to February 2001. The incidence of RSV-LRI was 12.6/1,000 child-year and 5.8/ 1,000 child-year during the first and second year, respectively. RSV accounted for 35.8 per cent of all LRI cases during the first year and significantly decreased to 17.5 per cent during the second year. Three-quarters of RSV-LRI occurred among children under 2 years old (76.6% during the first year and 62.2% during the second year). Most of RSV-LRI in both years occurred from July to October. Risk factor for morbidity of RSV infections were age less than or equal to 2 years (OR = 2.38, 95% CI = 1.22-4.67 p = 0.009) and sleeping with more than 3 persons in the patient's bedroom (OR = 2.92,95% CI = 1.42-6.00, p = 0.002). Most RSV-LRI (63.9%) were clinically diagnosed as having pneumonia. No RSV-LRI deaths were detected. During the first year, RSV subtype B was predominate, in contrast to the second year when subtype A was more predominate. Further research to determine the annual change in subtype of RSV-LRI and correlation of severity of disease with specific subtypes needs to conducted in order to prepare for the future introduction of a vaccine.

Wheezing--associated lower respiratory infections in under 5-year-old children: study in Takhli District Hospital.

Wheezing was detected in 251 of the 421 (59.6%) children under 5 years old suffering from acute lower respiratory infections (LRI) treated at the Takhli Hospital, Nakhon Sawan Province from November 1998 to October 2000. Bronchitis and pneumonia accounted for 55.0 per cent and 40.6 per cent of LRI with wheezing. Most of the patients, 162 of 251 (64.5%) cases were children under 2 years old. The wheezing symptom declined significantly in children older than 4 years of age. In this study, LRI with wheezing was found all year round but was more frequent in the rainy season similar to other respiratory infections. As the respiratory syncytial virus (RSV) infections were mainly found during the rainy season (July-October), the association of wheezing and RSV infections in the rainy season was evaluated. RSV causing LRI with wheezing in the rainy season revealed 54.7 per cent and 39.4 per cent in the first and second studied year, respectively. The two-year follow-up of 121 cases of LRI with wheezing showed that 37 cases (30.5%) had repeated episodes of wheezing. In conclusion, LRI with wheezing caused by RSV was commonly found in children under 2 years old. The occurrence was all the year round but predominantly in the rainy season.

Acute viral lower respiratory infections in children in a rural community in Thailand.

The present study was conducted as a population based cohort in a rural community of Amphoe Takhli, Nakhon Sawan province for the determination of the prevalence of acute viral lower respiratory infection (ALRI) in pediatric cases under 5 years of age from November 1998 to February 2001. There were 472 ALRI episodes during the study period; and there were 5 cases who contracted ALRI twice. The etiologic agents were determined by indirect immunofluorescence (IIF) test using specific monoclonal antibodies for the staining of exfoliated cells in nasopharyngeal aspirate (NPA) samples. The slides of fixed cells were prepared by Takhli Hospital and posted in ambient temperature to the Virology Laboratory, Siriraj Hospital where they were stained and examined. Among 472 episodes of ALRI, 170 (36.0%) viral agents were found. Viral agents were associated with 41.4 per cent of all pneumonic cases. Respiratory syncytial virus (RSV) was the most common virus observed in the present study; and it was also the most common virus associated with pneumonia and bronchitis. RSV subgrouping was performed directly in NPA samples by IIF test using a panel of subgroup specific monoclonal antibodies. RSV subgroup B predominated over subgroup A in the first study year, and it was vice versa in the second year. Overall, more cases of subgroup B were found which was in contrast to what the authors had reported in the previous study. Prevalence of RSV was seasonal dependent, the epidemic was seen during the rainy season with peaks in August or September of each year. As the method of viral identification was limited to IIF only, therefore, fewer viruses were detected. Parainfluenza viruses were detected as the second most common viral agent, the viruses spread during early summer with peaks in February or March of each year. However, its association with croup could not be demonstrated which may be due to the insensitivity of IIF in the diagnosis of non-RSV infection. Nevertheless, in terms of feasibility to investigate the disease in a rural area, IIF is economic, convenient and rapid; and gives enough information for the nationwide plan of a health care development system.