1.Causative agents of hand, foot and mouth disease in University Malaya Medical Centre, Kuala Lumpur, Malaysia in 2012-2013
Aw-Yong, K.L. ; Sam, I.C. ; Chan, Y.F.
Tropical Biomedicine 2017;34(1):240-248
Hand, foot and mouth disease (HFMD) is a childhood illness, commonly caused by
enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16). In recent years, unusual HFMD
outbreaks caused by coxsackievirus A6 (CV-A6) have been reported. From May 2012 to
September 2013, enteroviruses were detected in 25 HFMD patients in University Malaya
Medical Centre, Kuala Lumpur, Malaysia. The predominant serotypes were EV-A71 (48%) and
CV-A6 (48%), followed by CV-A16 (4%). CV-A6 patients (mean age, 2.1) were significantly
younger than EV-A71 patients (mean age, 3.3). There were no significant differences observed
in clinical features between EV-A71 and CV-A6 patients. Since enteroviruses are difficult to
differentiate clinically, the conserved 5’ untranslated region (5’ UTR) was used to identify
enterovirus serotypes. Phylogenetic analysis of 5’ UTR showed distinct clustering of viruses
as EV-A71, CV-A16 and CV-A6. Further genotyping with capsid genes showed that all the EVA71
sequences belonged to subgenotype B5, while the CV-A16 sequence belonged to
subgenotype B2b. CV-A6 sequences were clustered into genotypes D1 and D2, with recent
isolates from Seri Kembangan, Malaysia and China. In summary, 59.5% of HFMD cases in our
centre in 2012-2013 were caused by EV-A71, CV-A16 and the newly emerging CV-A6. This
study also demonstrated that 5’ UTR is suitable for preliminary identification of enteroviruses
during HFMD outbreaks, but specific capsid genes such as VP1 and VP4/VP2 are required for
further genotyping. Apart from measures to control the spread of the virus during an outbreak
of HFMD, identification of EV-A71 as the etiological agent is important as EV-A71 is a major
cause of severe neurological complications and potentially fatal.
2.Diagnosis of human enterovirus A71 infection in Malaysia using a commercial IgM-capture enzyme-linked immunosorbent assay and an IgM-colloidal gold immunochromatographic assay
Aw-Yong, K.L., Tan, C.W., Sam, I.C. and Chan, Y.F.
Tropical Biomedicine 2016;33(2):238-245
Hand, foot and mouth disease (HFMD) is a common childhood infection caused by
many enteroviruses, including enterovirus A71 (EV-A71). As EV-A71 is associated with severe
neurological disease, early diagnosis is critical for clinical and public health management. In
developing countries such as Malaysia, laboratory capacity to carry out EV-A71 IgM detection
is greater than that of the gold standard methods of virus culture or molecular detection. This
study evaluated two diagnostic kits, EV-A71 IgM-capture enzyme-linked immunosorbent
(ELISA) and EV-A71 IgM-colloidal gold immunochromatographic assay (GICA), which had
previously only been assessed in China. The assays were tested with 89 serum samples from
patients with suspected HFMD. The sensitivity, specificity, positive predictive value, and
negative predictive value rates were 78.4%, 80.8%, 74.4%, and 84.0%, respectively, for the
IgM-capture ELISA, and 75.7%, 76.9%, 70.0%, and 81.6% for the IgM GICA. These performance
measures were similar between the two assays. Concordance between the two assays was
91.1%. The sensitivity rates were lower than those previously reported, likely because the
multiple circulating EV-A71 genotypes in Malaysia differ from the C4 subgenotype found in
China and used in the assays. Both assays had low false positive rates (12.5% and 16.7% for
ELISA and GICA, respectively) when tested on sera from patients confirmed to have
enteroviruses. Both diagnostic kits are suitable for early diagnosis of HFMD caused by EV-
A71 in Malaysia, but confirmation with culture or PCR is still important.