Hand, Foot, and Mouth Disease in Thailand: A Comprehensive Modelling of Epidemic Dynamics.

Hand, foot, and mouth disease (HFMD) is a highly contagious disease with several outbreaks in Asian-Pacific countries, including Thailand. With such epidemic characteristics and potential economic impact, HFMD is a significant public health issue in Thailand. Generally, contagious/infectious diseases' transmission dynamics vary across geolocations due to different socioeconomic situations, demography, and lifestyles. Hence, a nationwide comprehensive model of the disease's epidemic dynamics can provide information to understand better and predict a potential outbreak of this disease and efficiently and effectively manage its impact. However, there is no nationwide and comprehensive (i.e., the inclusion of reinfections in the model) model of HFDM dynamics for Thailand. This paper has endeavoured to promote nationwide comprehensive modelling of HFMD's epidemic dynamics and comprehend the reinfection cases. We have formulated the SEIRS epidemiological model with dynamic vitals, including reinfections, to explore this disease's prevalence. We also introduced periodic seasonality to reproduce the seasonal effect. The pattern of spread of this disease is uneven across the provinces in Thailand, so we used K-means clustering algorithm to cluster those provinces into three groups (i.e., highly, moderately, and least affected levels). We also analysed health records collected from district hospitals, which suggest significant reinfection cases. For example, we found that 11% (approximately) of infectious patients return for repeat treatment within the study period. We also performed sensitivity analysis which indicates that the basic reproduction number (R 0) is sensitive to the rate of transmission (ß) and the rate at which infected people recover (γ). By fitting the model with HFMD confirmed data for the provinces in each cluster, the basic reproduction number (R 0) was estimated to be 2.643, 1.91, and 3.246 which are greater than 1. Based on this high R 0, this study recommends that this disease will persist in the coming years under identical cultural and environmental conditions.

Human dendritic cells as targets of dengue virus infection.

Dengue virus infections are an emerging global threat. Severe dengue infection is manifested as dengue hemorrhagic fever and dengue shock syndrome, both of which can be fatal complications. Factors predisposing to complicated disease and pathogenesis of severe infections are discussed. Using immunohistochemistry, immunofluorescence, flow cytometry, and ELISA techniques, we studied the cellular targets of dengue virus infection, at both the clinical (in vivo) and the laboratory (in vitro) level. Resident skin dendritic cells are targets of dengue virus infection as demonstrated in a skin biopsy from a dengue vaccine recipient. We show that factors influencing infection of monocytes/macrophages and dendritic cells are different. Immature dendritic cells were found to be the cells most permissive for dengue infection and maybe early targets for infection. Immature dendritic cells exposed to dengue virus produce TNF-alpha protein. Some of these immature dendritic cells undergo TNF-alpha mediated maturation as a consequence of exposure to the dengue virus.

Phylogenetic analysis of Ara+ and Ara- Burkholderia pseudomallei isolates and development of a multiplex PCR procedure for rapid discrimination between the two biotypes.

A Burkholderia pseudomallei-like organism has recently been identified among some soil isolates of B. pseudomallei in an area with endemic melioidosis. This organism is almost identical to B. pseudomallei in terms of morphological and biochemical profiles, except that it differs in ability to assimilate L-arabinose. These Ara+ isolates are also less virulent than the Ara- isolates in animal models. In addition, clinical isolates of B. pseudomallei available to date are almost exclusively Ara-. These features suggested that these two organisms may belong to distinctive species. In this study, the 16S rRNA-encoding genes from five clinical (four Ara- and one Ara+) and nine soil isolates (five Ara- and four Ara+) of B. pseudomallei were sequenced. The nucleotide sequences and phylogenetic analysis indicated that the 16S rRNA-encoding gene of the Ara+ biotype was similar to but distinctively different from that of the Ara- soil isolates, which were identical to the classical clinical isolates of B. pseudomallei. The nucleotide sequence differences in the 16S rRNA-encoding gene appeared to be specific for the Ara+ or Ara- biotypes. The differences were, however, not sufficient for classification into a new species within the genus Burkholderia. A simple and rapid multiplex PCR procedure was developed to discriminate between Ara- and Ara+ B. pseudomallei isolates. This new method could also be incorporated into our previously reported nested PCR system for detecting B. pseudomallei in clinical specimens.