Evaluation of Different Clinical Sample Types in Diagnosis of Human Enterovirus 71-Associated Hand-Foot-and-Mouth Disease

Abstract

Human enterovirus 71 and coxsackievirus A16 are important causes of hand-foot-and-mouth disease (HFMD). Like other enteroviruses, they can be isolated from a range of sterile and nonsterile sites, but which clinical sample, or combination of samples, is the most useful for laboratory diagnosis of HFMD is not clear. We attempted virus culture for 2,916 samples from 628 of 725 children with HFMD studied over a 3 1/2-year period, which included two large outbreaks. Overall, throat swabs were the single most useful specimen, being positive for any enterovirus for 288 (49%) of 592 patients with a full set of samples. Vesicle swabs were positive for 169 (48%) of 333 patients with vesicles, the yield being greater if two or more vesicles were swabbed. The combination of throat plus vesicle swabs enabled the identification of virus for 224 (67%) of the 333 patients with vesicles; for this patient group, just 27 (8%) extra patients were diagnosed when rectal and ulcer swabs were added. Of 259 patients without vesicles, use of the combination of throat plus rectal swab identified virus for 138 (53%). For 60 patients, virus was isolated from both vesicle and rectal swabs, but for 12 (20%) of these, the isolates differed. Such discordance occurred for just 11 (10%) of 112 patients with virus isolated from vesicle and throat swabs. During large HFMD outbreaks, we suggest collecting swabs from the throat plus one other site: vesicles, if these are present (at least two should be swabbed), or the rectum if there are no vesicles. Vesicle swabs give a high diagnostic yield, with the added advantage of being from a sterile site.

Comparison of the Detection Rates of RT-PCR and Virus Culture Using a Combination of Specimens from Multiple Sites for Enterovirus-Associated Encephalomyelitis during Enterovirus 71 Epidemic

“…We evaluated the patients with herpangina and HFMD from pediatric clinics, and found a significant risk of neurological complications in patients with HFMD (20). Although the common benign forms of EV diseases are well recognized by clinicians, the early identification of herpangina and HFMD can help predict and prevent morbidities from EV71 infections (21,22). In addition, early recognition of the pathogen during EV71 epidemics using different methods and specimens collected from different sites helps the clinical physicians to get more information for making decisions.…”

“…This may imply that both the oral-oral route and the fecal-oral route are the main transmission routes for acute EV71 illness. Moreover, RT-PCR is more sensitive in identifying cases of EV71 than VC using specimens from each site, which may imply the practical utility in the identification of acute EV71 illness (21).…”

“…Various cell lines can be used to identify cytopathic effects. However, typing by immunofluorescence is laborious, and the results are reliable only during the acute phase of the illness, which results in low positivity even when combining specimens collected from different sites (21). Once a virus is detected from a patient's specimen, there is no question regarding whether the result is truly positive.…”

“…Studies of EV infections complicated with CNS infections show that the yields are frequently lower in CSF and blood (9,21). Possible explanations include the virus being transiently present in CSF and blood and a lower amount of virus being present in CSF and blood, making detection difficult.…”

Hand, Foot and Mouth Disease: A case report

“…Throat and vesicle (if available) swab samples in virus transportation medium can be used for varied of molecular technique, cell culture for virus isolation using PCR and several other technique [19,20]. This become important in patients presenting with other manifestations of EV71, such as CNS disease or cardiovascular collapse, rapid virological diagnosis is even more helpful because of the broad differential for those conditions and the specific treatments available.…”