Epidemiological and etiological characteristics of hand, foot, and mouth disease in Ningbo, China, 2008-2011

Department of Viral Research, Ningbo Center of Disease Control and Prevention, Ningbo 315010, China.
Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology (Impact Factor: 3.02). 05/2012; 54(4):342-8. DOI: 10.1016/j.jcv.2012.04.021
Source: PubMed


Outbreaks of hand, foot, and mouth disease (HFMD) in central China have caused public health concerns since 2007. It is of particular public health significance to update epidemiology of HFMD in port cities.
To investigate epidemical, etiological and clinical characteristics of HFMD in Ningbo, China, from 2008 to 2011.
From May 2008 to December 2011, a total of 37,404 HFMD cases including 196 severe and 12 fatal cases were investigated. Human enteroviruses from 2360 cases were determined by real-time RT-PCR. The VP1 gene of EV71 from 78 cases and CA16 from 21 cases, the VP4 gene from 28 cases, and full-length genomes of 10 isolates were analyzed. Neutralizing antibodies were evaluated in 258 healthy subjects. Parameters associated with severe HFMD were evaluated.
Annual incidence of HFMD was 3066.8/100,000 in the population of ≤5 years. EV71 C4a, CA16 B1, and other enteroviruses accounted for 63.7%, 24.0% and 12.3%, respectively. The genomes of EV71 from fatal and non-fatal cases were nearly identical. The positive rates of neutralizing antibody to EV71 increased from 13.5% to 67.6% in 1- to 5-year healthy groups. The neutralizing antibody to CA16 B1 isolate was negative. EV71, exposure history and certain early manifestations including fever, vomiting, limb exanthema and peripheral neutrophil ratio were significantly associated with HFMD severity.
HFMD mainly caused by EV71 C4a and CA16 B1 is seriously epidemic in Ningbo. Future emphasis should be paid on EV71 immuno-prophylaxis and early identification of severe cases upon the etiological and clinical characteristics.

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    • "Viral RNA was extracted from clinical specimens and viral cultures using a QIAamp Viral RNA Mini Kit (Qiagen, Germany) according to the manufacturer's instructions. All RNA samples were examined by real time reverse-transcription PCR (rt RT-PCR) using a set of Pan-EV (EV universal primer) probe and primers; positive samples were tested by rt RT-PCR for EV71 and CA16 using specific primers and probes [17]. Rt RT-PCR was performed using AgPath-ID™ One-Step RT-PCR reagents (Applied Biosystems, Foster, CA, USA). "
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    • "Inter-typic and intra-typic recombination events were frequently detected in EV71 strains circulating in the Asia-Pacific region (24, 36–38). In recent years, recurring HFMD outbreaks caused by EV71 of subgenotype C4 (‘double-recombinant’ belonging to a novel genotype D) have been reported in Hong Kong and different provinces in China (11–16, 39). In this review, we provide an update on the epidemiology and genetic evolution of EV71. "
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