METHODS: Three community-based surveys were conducted from 2011 to 2015. In the first and second surveys (2011 and 2012) a total of 1,118 male respondents comprising 355 regular kratom users, 171 occasional kratom users, 66 ex-users, and 592 non-users aged 25 or above, were recruited from 40 villages. All respondents were followed up in this study. However, not all respondents were successfully followed up throughout the entire set of studies.
RESULTS: Common health complaints were no more common among kratom users than ex- and non-users, but more regular than occasional users claimed kratom to be addictive. Those with high kratom dependence scores were more likely to experience intense withdrawal symptoms, which developed 1-12 h after the last kratom intake. Over half (57.9%) of regular users had experienced intoxication effects compared to only 29.3% of occasional users. Kratom users were less likely to have a history of chronic diseases such as diabetes, hypertension, dyslipidemia than ex- and non-users.
CONCLUSION: Regular long-term chewing of fresh kratom leaves was not related to an increase in common health complaints, but may pose a drug dependence risk. Severe kratom dependents were more likely to suffer from intense withdrawal symptoms. Medical records revealed no death due to traditional kratom use, but the high prevalence of tobacco or/and hand rolled cigarette smoking among kratom users should be of concern.
METHODS: We constructed phylogenetic trees based on ZIKV coding sequences (CDS) and determined the geographical distribution of the representative viruses by genetic relationship and timeline. We determined genetic recombination among ZIKV and between ZIKV and other flaviviruses using similarity plot and bootscan analyzes, together with the phylogeny encompassing the CDS and eight subgenomic regions.
RESULTS: The phylogenetic trees comprising 717 CDS showed two distinct African and Asian lineages. ZIKV in the African lineage formed two sublineages, and ZIKV in the Asian lineage diversified into the Asian and American sublineages. The 1966 Malaysian isolate was designated the prototype of the Asian sublineage and formed a node of only one member, while the newer viruses formed a distinct node. We detected no genetic recombination in the Thailand ZIKV.
CONCLUSION: Five Thailand isolates discovered in 2006 were the second oldest ZIKV after the Malaysian prototype. Our result suggested two independent routes of ZIKV spread from Southeast Asia to Micronesia in 2007 and French Polynesia in 2013 before further spreading to South American countries.