Pandemic influenza H1N1 2009 in Thailand

Background: Developing a quantitative understanding of pandemic influenza dynamics in South-East Asia is important for informing future pandemic planning. Hence, transmission dynamics of influenza A/H1N1 were determined across space and time in Thailand. Methods: Dates of symptom onset were obtained for all daily laboratory-confirmed cases of influenza A/H1N1pdm in Thailand from 3 May 2009 to 26 December 2010 for four different geographic regions (Central, North, North-East, and South). These data were analysed using a probabilistic epidemic reconstruction, and estimates of the effective reproduction number, R(t), were derived by region and over time. Results: Estimated R(t) values for the first wave peaked at 1.54 (95% CI: 1.42-1.71) in the Central region and 1.64 (95% CI: 1.38-1.92) in the North, whilst the corresponding values in the North-East and the South were 1.30 (95% CI: 1.17-1.46) and 1.39 (95% CI: 1.32-1.45) respectively. As the R(t) in the Central region fell below one, the value of R(t) in the rest of Thailand increased above one. R(t) was above one for 30 days continuously through the first wave in all regions of Thailand. During the second wave R(t) was only marginally above one in all regions except the South. Conclusions: In Thailand, the value of R(t) varied by region in the two pandemic waves. Higher R(t) estimates were found in Central and Northern regions in the first wave. Knowledge of regional variation in transmission potential is needed for predicting the course of future pandemics and for analysing the potential impact of control measures.

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.

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.

Gender difference in treatment seeking behaviors of tuberculosis cases in rural communities of Bangladesh.

This descriptive cross-sectional study was conducted to investigate gender differences in the epidemiological factors associated with the treatment seeking behaviors of TB cases in the rural communities of Bangladesh. The study reveals that there is significant gender difference in treatment seeking behaviors of rural TB cases and the majority of them (52%) have taken prior treatment from various traditional healers, 70% of them are females who attended health centers (UZHCs) as the other choice (adjusted OR: 4.2, 95% CI: 2.0-8.4). It was found that the mean patient delay was 63 days (range 14-210 days) where half of the females delayed more than 60 days while they were spreading their disease. The study findings reveal gender differences in treatment seeking behaviors associated with socio-cultural barriers, particularly among females in their access to TB care. Fifty-five percent of cases wanted the diagnosis of TB remain confidential to avoid being labeled as TB patients, where 82.7% were female, 85.6% of female TB patients had problems in their relationships with their spouse (61%) and family members (58%) after being diagnosed with TB. The results of the TB service factors found that 39% of females were not satisfied with their provider's behaviors, which was significantly associated with treatment seeking behavior (adjusted OR: 2.6, 95% CI: 1.0-6.6). The study findings strongly suggest that there was a significant gender difference in treatment seeking behavior in rural Bangladesh. Based on the study findings, we recommend developing an appropriate gender strategy for developing a TB control program, comprised of operational, socio-cultural and community awareness interventions aimed at treating undiscovered reservoirs of female TB cases in rural Bangladesh.

Cigarette smoking and its relation to pulmonary tuberculosis in adults.

The purpose of this hospital-based case-control study is to determine the effect of passive and active smoking on pulmonary TB in adults. The study subjects were 100 new pulmonary TB cases diagnosed at TB Division, and age-sex matched 100 non-TB cases from patients admitted to Taksin Hospital and healthy subjects who came for annual physical check-up at either the outpatient clinic of the TB division or Taksin Hospital, during May 2001 to October 2001. All subjects had blood tests and only persons who were HIV-negative, DM-negative and free of other lung diseases were included. Data were collected by direct interview using questionnaires. Multivariate analysis of cigarette smoking related to pulmonary TB in adults was performed. The factors related to pulmonary TB in adults were current active smoking regardless of passive smoking exposure. There was a significant association between early age at initiation of smoking and TB. Active (current + ex-active) smokers who started smoking at age 15-20 years had a higher risk of pulmonary TB compared to others (OR = 3.18, 95% CI = 1.15-8.77); as well as the long duration of smoking: persons who had smoked >10 years had a higher risk of pulmonary TB (OR = 2.96, 95% CI = 1.06-8.22). There was a relationship between pulmonary TB and the amount of smoking exposure. Those who smoked >10 cigarettes/day (OR = 3.98, 95% CI = 1.26-12.60) or >3 days/week (OR = 2.68, 95% CI = 1.01-7.09) had higher risk of pulmonary TB compared to non-smokers. Passive smokers who were exposed to tobacco smoke >3 times/week outside the home had a higher risk of pulmonary TB than those with exposure < or =3 times/week (OR = 3.13, 95% CI = 1.07-9.17). It was also found that the effects of passive smoking in the office and/or neighborhood were strong. Persons with such exposures had a higher risk of pulmonary TB than no exposure or exposure < or =3 times/week from either or both places (OR = 4.62, 95% CI = 1.68-14.98). Therefore, an effective anti-smoking campaign is expected to have a positive repercussion on TB incidence. Smoking cessation must be considered and promoted by all levels of health care providers.