Epidemiological and molecular characterization of Coxsackievirus A6 causing hand, foot, and mouth disease in the Philippines, 2012-2017.

Coxsackievirus A6 (CVA6) is emerging as the dominant serotype among enteroviruses (EVs) responsible for hand, foot, and mouth disease (HFMD) outbreaks in multiple countries. However, details regarding this serotype in the Philippines are limited. In this study, we investigated the epidemiological and molecular characteristics of laboratory-confirmed CVA6 HFMD cases in the Philippines between 2012 and 2017. Data collected from case report forms submitted to the National Reference Laboratory for Poliovirus and other Enteroviruses were used to determine the distribution and clinical findings of laboratory-confirmed CVA6 HFMD. Phylogenetic analyses of the complete viral protein 1 (VP1) and partial 3D polymerase (3Dpol) gene sequences were performed to determine the genotype and recombinant (RF) form of the selected samples. An increase in the detection rate of CVA6 among enterovirus-positive HFMD cases was observed from 61.9% (140/226) in 2012 to 88.1% (482/587) in 2017, with most cases coming from the Luzon island group. Among the detected cases, the majority were children, with a median age of 2 years old (interquartile range: 1.17-3.40). Respiratory-related morbidities were the commonly reported complications (7.9%; 72/907). Based on the VP1 and 3Dpol gene sequence analysis, the CVA6 strains in this study were classified as genotype D3b and RF-A group, respectively. This study elucidated that CVA6 was the most prevalent enterovirus serotype causing HFMD in the Philippines in 2012-2017, with genotype D3b/RF-A circulating within this period. This study highlights the importance of viral surveillance and molecular epidemiological analysis to broaden our understanding of HFMD in the Philippines.

Genotyping of respiratory syncytial virus among influenza-like illness and severe acute respiratory infection cases of children in the Philippines from 2006 to 2016.

OBJECTIVE: Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory infection, and therefore, a major threat to global health. This study determined the epidemiological and molecular characteristics of RSV among cases of influenza-like illness (ILI) and severe acute respiratory infection (SARI) among children in the Philippines. METHOD: The study included archived nasopharyngeal swab and oropharyngeal swab samples collected from patients under the age of five who are presented with ILI or SARI for the period of 2006-2016. Swabs were examined for RSV subgroup by multiplex real-time qRT-PCR. Partial genome sequencing and phylogenetic analyses of the second hypervariable region (HVR) of the G gene were used to determine the genotype of RSV isolates. RESULTS: A total of 1036 representative samples from all sites were selected and tested. Of these samples, 122 were RSV-positive at 11.8% prevalence rate, and 58.2% (71/122) were classified as RSV-A. Six genotypes were identified, which include NA1 (27/122, 22.1%), ON1 (5/122, 4.1%), GA2 (1/122, 0.8%), and GA5 (1/122, 0.8%) for RSV-A; and BA2 (13/122, 10.7%) and BA9 (1/122, 0.8%) for RSV-B. Most RSV-related cases were significantly associated with clinical characteristics such as runny nose (88.1% RSV vs. 11.9% non-RSV: p value = 0.021), pneumonia (80.6% RSV vs. 19.4% non-RSV; p value = 0.015), and bronchitis (71.7% RSV vs. 28.3% non-RSV; p value < 0.001). Increased RSV-related cases were observed among children below 24 months old. CONCLUSION: The RSV trend and genetic variability in the Philippines resembles a similar pattern of transmission globally.

Serotype Identification of Human Adenoviruses Associated with Influenza-Like Illnesses in the Philippines from 2006-2012 by Microneutralization and Molecular Techniques.

OBJECTIVES: Human adenoviruses (HAdV) are known to cause a wide range of diseases including acute respiratory infections, conjunctivitis, and acute gastroenteritis. In this study, we aimed to determine the serotypes of HAdV in patients with influenza-like illness (ILI) in the Philippines from 2006-2012 and to describe the demographic and epidemiological characteristics of patients who tested positive for HAdV. METHODS: Between 2006 and 2012, the Philippine National Influenza Centre detected HAdV in 1294 samples of patients with ILI. Serotype determination was done in select samples using microneutralization, polymerase chain reaction (PCR), and sequencing methods. RESULTS: A total of 8 serotypes were identified (HAdV 1-7 and 11), with HAdV-2 (27.8%), and HAdV-3 (27.8%) being the most prevalent. The majority of HAdV infections were found in children below 5 years of age (79.9%). CONCLUSIONS: The identification of HAdV circulating serotypes may serve as guide for designing disease intervention and control strategies and will provide important information regarding the contribution of this virus to respiratory infections, particularly in children, which remain a public health burden in the Philippines.