In Taiwan, enterovirus 71 (EV71) has played an important role in severe enterovirus-related cases every year since the devastating outbreak in 1998. Three genogroups A, B, C occur worldwide; with the B and C genogroups being subdivided into B1-B4 and C1-C4 subgenogroups respectively. To understand the mutation of the EV71 genogroup in Taiwan before and after 1998, a total of 54 worldwide strains were studied including 41 Taiwanese strains obtained in 1986 and 1998-2004. A fragment of 207 bp of the VP4 region was amplified and sequenced. Genetic analysis was performed using MEGA software (version 3.0) for the nucleotide sequence alignment and phylogenetic analysis. In Taiwan, the subgenogroup B1 was predominant before 1998 while subgenogroup C2 was the major etiologic group in 1998 outbreak. A minor etiologic group outbreak in 1998, subgenogroup B4, became predominant during the period from 1999 to 2003. In this study, subgenogroup C4 emerged and became predominant in 2004 in Taiwan. The nucleotide differences between B1 and C2, C2 and B4, B4 and C4 were 20%-26%, 19%-27%, 18%-22%, respectively. Nucleotide sequence alignment revealed 67 substitutions. Most of the substitutions (62/67) were silent mutations. This is the first report about the emergence of EV71 subgenogroup C4 in Taiwan.

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Melamine, a widely used chemical found in many products in daily use, became a public health concern due to melamine-associated urinary stone formation in children. In adults, it is still unknown whether low-dose melamine exposure may also cause urolithiasis. To address this question, we studied 211 Taiwanese patients diagnosed with calcium urolithiasis and 211 age- and gender-matched controls. All patients completed a detailed questionnaire and provided blood and urine samples for biochemical analysis. Urinary melamine concentrations were measured by triple-quadrupole liquid chromatography tandem mass spectrometry. Compared with those whose urinary melamine levels were below the detection limit of the method, patients with urinary melamine levels of up to 3.11  ng/ml and those with levels of ≥3.12  ng/ml had 3.01- and 7.64-fold increased risk, respectively, of calcium urolithiasis after adjusting for educational level, fluid intake, cigarette smoking, betel quid chewing, alcohol drinking, urinary uric acid, calcium, creatinine, and estimated creatinine clearance rate. The population attributable risk of calcium urolithiasis averaged 50% when melamine was detected in the urine, after considering other covariates. MALDI-TOF mass spectrometry detected melamine in the stones of nine representative patients who had measurable urinary melamine levels. Thus, low-dose melamine exposure can play an important role in calcium urolithiasis in Taiwanese adults.