Epidemic hand, foot and mouth disease caused by human enterovirus 71, Singapore - Research

Emerging Infectious Diseases, Jan, 2003 by Kwai Peng Chan, Kee Tai Goh, Chia Yin Chong, Eng Swee Teo, Gilbert Lau, Ai Ee Ling

Coinfection with a second virus has been suggested as yet another possible pathogenetic factor (6,9), and this theory is supported by the concomitant isolation of a subgenus B adenovirus with an enterovirus from three persons who died during a HFMD outbreak in Sarawak (6). Among the Singaporean patients with HEV71 infection, three had a second virus isolated concurrently. However, the presence of dual viruses did not result in severe disease, although a child with HEV71 and CAV16 coinfection died in Singapore in 1997 (29).

We considered whether any unusual medications, treatments, or dietary exposures contributed to the deaths. No evidence from the fatalities in Singapore suggests this possibility. Conversely, we reviewed whether any particular therapeutic modality improved clinical outcome, but found that this idea cannot be argued conclusively because the HFMD patient with aseptic meningitis recovered well with symptomatic treatment. The child who survived his two younger siblings had no complications from HFMD and was not cared for differently from his siblings before hospitalization. He was given prophylactic intravenous immunoglobulin solely because his siblings died. Whether this treatment, which was not administered to the patients who died, helped prevent severe disease in him is uncertain.

Considering that transmission of enteroviruses is mainly fecal-oral and through the respiratory route (to some extent) (22), we note that spread of the viruses is prevalent in childcare centers. To break the chain of transmission during the epidemic, the HFMD Task Force coordinated a swift, nationwide closure of preschool centers on October 1, 2000, reopening them on October 16, 2000, only when the HFMD reports recorded a declining trend, and no additional severe cases and deaths associated with the disease were reported. Other measures included repeated public health education through the mass media on observance of good personal hygiene, cleaning and disinfection of premises and articles both at home and at preschool centers, and keeping children away from crowds. These interventions may have played a role in bringing the epidemic under control by the end of October, although the outbreak may have also run its natural course by that time.

In September and October 2000, HEV71 caused the largest HFMD epidemic recorded to date in Singapore, an epidemic that involved mainly young children [less than or equal to] 4 years of age. Five deaths occurred, and HEV71 was isolated from four case-patients. Autopsies of four case-patients showed encephalitis, interstitial pneumonitis, and myocarditis. Virulence determinants of HEV71 and the precipitating factors for the epidemic itself unfortunately remain unknown. Based on our experiences during this epidemic, we found that an HFMD epidemic preparedness plan was useful in providing the framework for prompt actions to monitor the situation, identify the causative agent, interrupt virus transmission, and communicate with and solicit the cooperation of the media, parents, physicians, and preschool center personnel.