Alvin G. Tan

Estimating influenza outpatients' and inpatients' incidences from 2009 to 2011 in a tropical urban setting in the Philippines.

Although the public health significance of influenza in regions with a temperate climate has been widely recognized, information on influenza burden in tropical countries, including the Philippines, remains limited. We aimed to estimate influenza incidence rates for both outpatients and inpatients then characterized their demographic features.

Comparison of Three Screening Test Kits for G6PD Enzyme Deficiency: Implications for Its Use in the Radical Cure of Vivax Malaria in Remote and Resource-Poor Areas in the Philippines.

Objective We evaluated a battery of Glucose-6-Phosphate Dehydrogenase diagnostic point-of-care tests (PoC) to assess the most suitable product in terms of performance and operational characteristics for remote areas. Methods Samples were collected in Puerto Princesa City, Palawan, Philippines and tested for G6PD deficiency with a fluorescent spot test (FST; Procedure 203, Trinity Biotech, Ireland), the semiquantitative WST8/1-methoxy PMS (WST; Dojindo, Japan) and the Carestart G6PD Rapid Diagnostic Test (CSG; AccessBio, USA). Results were compared to spectrophotometry (Procedure 345, Trinity Biotech, Ireland). Sensitivity and specificity were calculated for each test with cut-off activities of 10%, 20%, 30% and 60% of the adjusted male median. Results The adjusted male median was 270.5 IU/1012 RBC. FST and WST were tested on 621 capillary blood samples, the CSG was tested on venous and capillary blood on 302 samples. At 30% G6PD activity, sensitivity for the FST was between 87.7% (95%CI: 76.8% to 93.9%) and 96.5% (95%CI: 87.9% to 99.5%) depending on definition of intermediate results; the WST was 84.2% (95%CI: 72.1% to 92.5%); and the CSG was between 68.8% (95%CI: 41.3% to 89.0%) and 93.8% (95%CI: 69.8% to 99.8%) when the test was performed on capillary or venous blood respectively. Sensitivity of FST and CSG (tested with venous blood) were comparable (p>0.05). The analysis of venous blood samples by the CSG yielded significantly higher results than FST and CSG performed on capillary blood (p<0.05). Sensitivity of the CSG varied depending on source of blood used (p<0.05). Conclusion The operational characteristics of the CSG were superior to all other test formats. Performance and operational characteristics of the CSG performed on venous blood suggest the test to be a good alternative to the FST.

Incidence and Risk Factors of Childhood Pneumonia-Like Episodes in Biliran Island, Philippines—A Community-Based Study

Pneumonia is a leading cause of deaths in infants and young children in developing countries, including the Philippines. However, data at the community level remains limited. Our study aimed to estimate incidence and mortality rates and to evaluate risk factors and health-seeking behavior for childhood pneumonia. A household level interview survey was conducted in Biliran Island, the Philippines. Caregivers were interviewed using a semi-structured questionnaire to check if children had symptoms suggesting pneumonia-like episodes from June 2011 to May 2012. Of 3,327 households visited in total, 3,302 (99.2%) agreed to participate, and 5,249 children less than 5 years of age were included in the study. Incidence rates of pneumonia-like episodes, severe pneumonia-like episodes, and pneumonia-associated mortality were 105, 61, and 0.9 per 1,000 person-years, respectively. History of asthma [hazard ratio (HR): 5.85, 95% confidence interval (CI): 4.83–7.08], low socioeconomic status (SES) (HR: 1.11, 95% CI: 1.02–1.20), and long travel time to the healthcare facility estimated by cost distance analysis (HR: 1.32, 95% CI: 1.09–1.61) were significantly associated with the occurrence of pneumonia-like episodes by the Cox proportional hazards model. For severe pneumonia-like episodes, a history of asthma (HR: 8.39, 95% CI: 6.54–10.77) and low SES (HR: 1.30, 95% CI: 1.17–1.45) were significant risk factors. Children who had a long travel time to the hospital were less likely to seek hospital care (Odds ratio: 0.32, 95% CI: 0.19–0.54) when they experienced severe pneumonia-like episodes. Incidence of pediatric pneumonia-like episodes was associated with a history of asthma, SES, and the travel time to healthcare facilities. Travel time was also identified as a strong indicator for health-seeking behavior. Improved access to healthcare facilities is important for early and effective management. Further studies are warranted to understand the causal relationship between asthma and pneumonia.

Seasonality of Influenza and Respiratory Syncytial Viruses and the Effect of Climate Factors in Subtropical-Tropical Asia Using Influenza-Like Illness Surveillance Data, 2010 -2012.

Introduction The seasonality of influenza and respiratory syncytial virus (RSV) is well known, and many analyses have been conducted in temperate countries; however, this is still not well understood in tropical countries. Previous studies suggest that climate factors are involved in the seasonality of these viruses. However, the extent of the effect of each climate variable is yet to be defined. Materials and Methods We investigated the pattern of seasonality and the effect of climate variables on influenza and RSV at three sites of different latitudes: the Eastern Visayas region and Baguio City in the Philippines, and Okinawa Prefecture in Japan. Wavelet analysis and the dynamic linear regression model were applied. Climate variables used in the analysis included mean temperature, relative and specific humidity, precipitation, and number of rainy days. The Akaike Information Criterion estimated in each model was used to test the improvement of fit in comparison with the baseline model. Results At all three study sites, annual seasonal peaks were observed in influenza A and RSV; peaks were unclear for influenza B. Ranges of climate variables at the two Philippine sites were narrower and mean variables were significantly different among the three sites. Whereas all climate variables except the number of rainy days improved model fit to the local trend model, their contributions were modest. Mean temperature and specific humidity were positively associated with influenza and RSV at the Philippine sites and negatively associated with influenza A in Okinawa. Precipitation also improved model fit for influenza and RSV at both Philippine sites, except for the influenza A model in the Eastern Visayas. Conclusions Annual seasonal peaks were observed for influenza A and RSV but were less clear for influenza B at all three study sites. Including additional data from subsequent more years would help to ascertain these findings. Annual amplitude and variation in climate variables are more important than their absolute values for determining their effect on the seasonality of influenza and RSV.

Epidemiological characterization of influenza A(H1N1)pdm09 cases from 2009 to 2010 in Baguio City, the Philippines.

Background Baguio City, Philippines experienced its first influenza A(H1N1)pdm09 [A(H1)pdm09] case in May 2009. In spite of numerous reports describing the epidemiological and clinical features of A(H1)pdm09 cases, there are no studies about A(H1)pdm09 epidemiology in the Philippines, where year-round influenza activity was observed. Objectives We aimed to investigate the epidemiological and clinical features of A(H1)pdm09 in pandemic and post-pandemic periods. Methods Data were collected under enhanced surveillance of influenza-like illness (ILI) and severe acute respiratory infection (SARI) from January 2009 to December 2010. RT-PCR was used to detect A(H1)pdm09, following the protocol of the United States Centers for Disease Control and Prevention. The reproduction number was computed as a simple exponential growth rate. Differences in proportional and categorical data were examined using chi-square test or Fishers’ exact test. Results and Conclusions The outbreak was observed from week 25 to 35 in 2009 and from week 24 to 37 in 2010. The highest proportion of cases was among children aged 5–14 years. The number of ILI outpatients was 2.3-fold higher in 2009 than in 2010, while the number of inpatients was 1.8-fold higher in 2009. No significant difference in gender was observed during the two periods. The clinical condition of all patients was generally mild and self-limiting, with only 2 mortalities among inpatients in 2009. The basic reproduction number was estimated as 1.16 in 2009 and 1.05 in 2010 in the assumption of mean generation time as 2.6 days. School children played a significant role in facilitating influenza transmission.

Estimates of influenza and respiratory syncytial virus incidences with fraction modeling approach in Baguio City, the Philippines, 2012‐2014

Estimation of the incidences of influenza and respiratory syncytial virus (RSV) infection is important for disease control. Previous estimate in the city showed a substantial burden of influenza in both outpatients and inpatients while it did not account for individuals who do not seek medical attention nor RSV.

Local persistence and global dissemination play a significant role in the circulation of influenza B viruses in Leyte Island, Philippines.

The local and global transmission dynamics of influenza B virus is not completely understood mainly because of limited epidemiological and sequence data for influenza B virus. Here we report epidemiological and molecular characteristics of influenza B viruses from 2010 to 2013 in Leyte Island, Philippines. Phylogenetic analyses showed global dissemination of the virus among both neighboring and distant areas. The analyses also suggest that southeast Asia is not a distributor of influenza B virus and can introduce the virus from other areas. Furthermore, we found evidence on the local persistence of the virus over years in the Philippines. Taken together, both local persistence and global dissemination play a significant role in the circulation of influenza B virus.

Smoking-attributable burden of lung cancer in the Philippines.

Background In the Philippines, smoking is highly prevalent and tobacco control policies fail to fully implement the WHO Framework Convention on Tobacco Control provisions. To aid in policy change, intervention implementation, monitoring and evaluation, this study aimed to provide the first internally consistent and latest Philippine estimates of the following: disability-adjusted life-years (DALYs) lost due to lung cancer; population-attributable fractions (PAFs) of smoking; and smoking-attributable lung cancer DALYs. Methods This study applied the Global Burden of Disease and Comparative Risk Assessment frameworks to secondary data, supplemented by expert opinion. A comprehensive internally consistent assessment of disease epidemiology was conducted using DISMOD II and disease impact was quantified as DALYs. PAFs were calculated using the smoking impact ratio and Monte Carlo uncertainty analyses were conducted. Results For 2008, lung cancer incidence and mortality estimates were 10 871 cases and 9871 deaths respectively. Lung cancer accounted for an estimated 267 787 DALYs lost, 99% of which were due to years of life lost. Overall, the PAF of smoking was 65% and a total of 173 103 DALYs were smoking-attributable. There were increasing trends in incidence, mortality and DALY rates with age. The majority of incidence (72%), mortality (71%) and disease burden (72%) occurred among men, who also had higher PAF estimates. Conclusions Considerable health gains could be achieved if smoking exposure were reduced in the Philippines. Strong enforcement of measures like increasing taxation to the WHO-endorsed rate, expanding smoke-free environments, and requiring large graphic warnings within a comprehensive tobacco control programme is recommended.

Association Between Preceding Viral Respiratory Infection and Subsequent Respiratory Illnesses Among Children: A Prospective Cohort Study in the Philippines

A prospective cohort study on acute respiratory infections of children in the Philippines found that the risk for subsequent respiratory infections was significantly enhanced after infections with adenovirus, influenza A virus, parainfluenza virus type 4, and rhinovirus species C.

Smoking-attributable burden of lung cancer in the Philippines: a comparative risk assessment

Abstract Background Smoking is highly prevalent in the Philippines. Tobacco control policies fail to fully implement the WHO Framework Convention on Tobacco Control provisions, especially with respect to taxation, smoking bans, sales and marketing restrictions, and cessation support. To aid in policy change and intervention implementation, monitoring, and evaluation, this study aimed to provide the most recent (2008) estimates for the Philippines of: (1) disability-adjusted life-years (DALYs) lost due to lung cancer; (2) population-attributable fractions (PAFs) for smoking; and (3) smoking-attributable lung cancer DALYs. Methods This study applied the Global Burden of Disease and Comparative Risk Assessment frameworks to secondary data, supplemented by local expert opinion. A comprehensive internally consistent assessment of disease epidemiology was conducted using the DisMod II model, and disease impact was quantified in the form of DALYs. PAFs were calculated using the smoking impact ratio, which indirectly estimates accumulated smoking exposure. Uncertainty analyses to obtain intervals were conducted per age–sex group via Monte Carlo simulations. Findings For the 2008 Philippine population, aggregated lung cancer incidence and mortality estimates were 10 871 cases and 9871 deaths, respectively. Lung cancer accounted for the loss of an aggregated estimate of 104 442 DALYs, 99% of which were due to years of life lost. Overall, the aggregated PAF for smoking was 62%, and an aggregated total of 64 913 DALYs were attributable to smoking. There were increasing trends in incidence, mortality, and DALY losses with age, the majority of which occurred among males, who also had higher PAF estimates. Interpretation Considerable health gains could be achieved if smoking exposure were eliminated or reduced in the Philippines. Prevention of initiation and support for cessation of smoking through strong enforcement of measures, such as increasing taxation to the WHO-endorsed rate, more stringent sales and marketing restrictions, and development and scaling up of smoking cessation programmes is recommended. Funding None.