IMPORTANCE: EV-A71 is one of many viruses that cause HFMD, a common syndrome that largely affects infants and children. HFMD usually causes only mild illness with no long-term consequences. Occasionally, however, severe infection may arise, especially in very young children, causing neurological complications and even death. EV-A71 is highly contagious and is associated with the most severe HFMD cases, with large and frequent epidemics of the virus recorded worldwide. Although major advances have been made in the development of a potential EV-A71 vaccine, there is no current prevention and little is known about the patterns and dynamics of EV-A71 spread. In this study, we utilize full-length genome sequence data obtained from HFMD patients in Viet Nam, a geographical region where the disease has been endemic since 2003, to characterize the phylodynamics of this important emerging virus.
METHODS: We established a sentinel surveillance programme for hand, foot and mouth disease in Sarawak, Malaysia, in March 1998, and the observations of the first 7 years are described here. Virus isolation, serotyping and genotyping were performed on throat, rectal, vesicle and other swabs.
RESULTS: During this period Sarawak had two outbreaks of human enterovirus 71, in 2000 and 2003. The predominant strains circulating in the outbreaks of 1997, 2000 and 2003 were all from genogroup B, but the strains isolated during each outbreak were genetically distinct from each other. Human enterovirus 71 outbreaks occurred in a cyclical pattern every three years and Coxsackievirus A16 co-circulated with human enterovirus 71. Although vesicles were most likely to yield an isolate, this sample was not generally available from most cases and obtaining throat swabs was thus found to be the most efficient way to obtain virological information.
CONCLUSION: Knowledge of the epidemiology of human enterovirus 71 transmission will allow public health personnel to predict when outbreaks might occur and to plan interventions in an effective manner in order to reduce the burden of disease.
MATERIALS AND METHODS: Seventy-six participants (58 males, 18 females) were recruited to participate in the study. Bilateral weight-bearing lateral radiographs of the right foot were taken from each participant. Navicular heights (NH), medial cuneiform height (MCH), calcaneal inclination angle (CIA) and calcaneal-first metatarsal angle (C1MA) were measured to represent the medial arch. The lateral arch was represented by cuboid height (CH) and calcaneal-fifth metatarsal angle (C5MA) whereas; MCH and CH represented the transverse arch. Mean difference of variables between males and females was compared using independent t-test while the correlation between the variables was determined using Pearson correlation.
RESULTS: All the variables were not significantly related to gender. Significant moderate to excellent linear correlations were observed between the variables. CIA showed the strongest correlation with C1MA (r = -0.90) and C5MA (r = -0.84) whereas, CH had the least correlation with other variables.
CONCLUSIONS: The moderate to excellent correlations between the variables indicate that deformation or elevation of the medial arch may consequently result in similar movements of the lateral and transverse arches and vice versa.