In 2012, a mysterious illness killed dozens of children in Cambodia. The World Health Organization (WHO) and the Cambodian Health Ministry later found out that a virus that causes hand, foot, and mouth disease (HFMD) is responsible for the deaths of children in Phnom Penh.

Reuters reported that out of the 59 cases, 52 tested positive for Enterovirus A71 (EV-A71), which causes HFMD. According to the WHO, HFMD usually targets infants and children and appears as a rash on infected palms, soles, and buttocks, along with painful lesions on the tongue, gums, and insides of the cheeks. Transmission occurs through direct contact with the mucus, saliva, or feces of an infected person.

Between November 2011 and February 2012, the Centers for Disease Control and Prevention (CDC) also received reports of 63 people with symptoms of HFMD in Alabama, California, Connecticut, and Nevada.

In the Philippines, the National Polio Laboratory (NPL) of the Research Institute for Tropical Medicine (RITM) was designated in 2012 by the Department of Health (DOH) as the reference laboratory for HFMD referred samples, following the deadly outbreak in Cambodia.

Fast forward to 2019, Science Research Specialist I Maria Melissa Ann Jiao from the RITM-NPL presented their study at the 38th Anniversary Research Forum entitled “Molecular Detection of Enteroviruses from Hand, Foot, and Mouth Disease Surveillance Cases in the Philippines, 2012 to 2017.” Along with Supervising Science Research Specialist and Section Head of the RITM-NPL Dr. Lea Necitas Apostol, the study characterized and determined the EV-A71, CVA6 and CVA16 genogroups circulating in the Philippines through conventional, multiplex targeting VP1 assay and complete VP1 gene sequencing. The three genotypes listed above were selected because they are the most common causes of HFMD globally.

Through nested, pan enterovirus screening assay, VP1 gene sequencing, a mapping distribution of enterovirus positives were generated, where it showed a nationwide spread of EV infection. In 2012, HFMD cases were particularly high in NCR, Region IV-A, and Region VI respectively.

Meanwhile, a phylogenetic analysis of EV-A71 from Acute Flaccid Paralysis cases, HFMD cases, and healthy Filipino children, revealed that the C2 strain is the circulating genogroup of EV-A71 in the country since 2000 to 2017. Furthermore, from 2012 to 2017, the study also found that CVA 6 is the most common cause of HFMD in the Philippines.

The study conducted by the RITM-NPL was the first nationwide prevalence and molecular epidemiology study of HFMD in the Philippines. Together with the DOH Epidemiology Bureau, the RITM TOHOKU Collaborating Center, and the Picornavirus and other CNS Study Group, the study aimed to: (1) provide understanding on the changing patterns of the disease incidence; (2) provide understanding on the changing patterns of the disease incidence; and (3) provide vaccine strategies in the future, especially with EV-A71.

Currently, China has a licensed vaccine for EV-A71, which was found effective in producing cross protective antibody to other EV-A71 genogroup except for the C2-like and C1 strains. The Philippines is yet to include EV-A71 vaccination on its country plan for the Expanded Programme on Immunization.

by Ma. Patricia Lansang, Communication and Engagement Office