Background: Few studies have investigated the viral isolation characteristics for severe complicated enterovirus infection (SCEI). This study evaluated the seasonality and contribution of circulated viruses to the chronologic trend and weekly reported SCEI epidemic.
Methods: Enterovirus infection surveillance and virology laboratory data in 2000 to 2008 obtained from the Centers for Disease Control in Taiwan were analyzed. We measured the monthly and weekly virology isolation rates by viral types. The virus-specific and the season-specific relative risks for SCEI and 95% confidence intervals (CI) associated with the isolated circulating viruses and weather status was evaluated.
Results: Among 1539 virology confirmed SCEI cases, the mean annual incidence rates ranged from 0.72/100,000 to 32.5/100,000 in children aged 5 years and less; rates were higher in warm months with cases peaking in June (12.6%). The untypeable nonpolio enterovirus was the most frequently isolated type among the monitored specimens (6.07%), followed by coxsackievirus A (3.99%), EV71 (1.77%), coxsackievirus B (1.56%), and echovirus (1.23%). However, these SCEI cases had very strong associations with the isolation of EV71 and coxsackievirus A and B. The corresponding relative risks were 1.14 (95% CI, 1.11–1.17), 1.03 (95% CI, 1.01–1.04), and 1.09 (95% CI, 1.07–1.12), respectively, for 1% increase in weekly isolation rate.
Conclusions: Isolation rates for EV71 and coxsackieviruses A and B can predict the development of SCEI cases, particularly in warm months.
From the *Department of Bioenvironmental Engineering, Chung Yuan Christian University College of Engineering, Chung Li, Taiwan; †Institute of Environmental Engineering, National Chiao Tung University, Hsinchu City, Taiwan; ‡Institute of Preventive Medicine, National Taiwan University College of Public Health, Taipei, Taiwan; §Global Change Research Center, National Taiwan University, Taipei, Taiwan; ¶Institute of Ecology and Evolutionary Biology, China Medical University College of Life Sciences, Taichung, Taiwan; and ∥Institute of Environmental Health, China Medical University College of Public Health, Taichung, Taiwan.
Accepted for publication September 23, 2009.
Supported by Executive Yuan Department of Health (grant number DOH94-DC-1107) 2005 and National Science Council (NSC 95–2625-Z-039–002) 2006 and (96–2625-Z039–003) 2007.
The interpretation and conclusions contained herein do not represent these agencies.
Address for correspondence: Fung-Chang Sung, PhD, MPH, Institute of Environmental Health, China Medical University College of Public Health, 91 Hsueh-Shih Rd, Taichung 404, Taiwan. E-mail: email@example.com or firstname.lastname@example.org.