SummaryAn integrated epidemiological study of Opisthorchis viverrini consisting of risk factors analysis and parasitation prevalence determination in humans, as well as the assessment the roles of host reservoirs (dogs and cats) and intermediate hosts (cyprinid fi sh) was carried out in the vicinity of Huay Luang dam, Udon Thani province, in the north east of Thailand. The survey was conducted from June 2014 to July 2016 in three sub-districts. Fecal samples were collected from 5,347 participants in 22 villages and the overall prevalence of O. viverrini was found to be 31.5 %. Risk factors for liver fl uke infection were determined from questionnaires analysis which sought demographic data and information about the eating behaviors of the participants. The behavior of raw fi sh consumption correlated signifi cantly with parasitation in the studied areas. The risk factors for O. viverrini infection in humans were associated signifi cantly with age, education, and habitation within a two kilometer range from nearby water and food sources. Questionnaires showed that the drug treatments were not always appropriate. The stools of domestic dogs (n = 468) and cats (n = 262) collected for parasitological analysis and results showed that the zoonotic role of dogs should not be underestimated as has been done previously/in past. The incidence of O. viverrini metacercariae in four cyprinid fi shes Barbonymus gonionotus (n = 124), Cyclocheilichthys repasson (n = 843), Hampala dispar (n = 276) and Henicorhynchus siamensis n = 946), were determined and overall values ranged from 2.4 % to 23.1 %. There was a seasonal variation in metacercariae intensity which ranged from 1 -125 metacercariae per fi sh. The study concluded that transmission ecology should be taken into consideration in developing of control strategies against opisthorchiasis.

Leaf rolling is a common response to drought among members of the grass family. A detailed understanding of the structural changes that occur when rice leaves roll in response to drought may assist in determining the physiological mechanisms underlying this feature and determining its potential utility in plant breeding. The anatomical characteristics of rice cultivars native to northeastern Thailand in response to drought stress were evaluated in this study. Polyethylene glycol (PEG) treatments were applied to seedlings of 28 native rice cultivars and two rice breeding cultivars for 10 d. When cultivated in drought-prone environments, the native rice cultivars had a leaf rolling index between 4 and 7, which was classified as moderate to high leaf rolling. Rice leaf anatomy exhibited profound changes in response to drought, with smaller bulliform cells (36.8%), thicker epidermis (10.98%), smaller vascular bundles (7.41%), and smaller bundle sheath cells (11.95%). Decision trees were used to explore the association between the degree of leaf rolling and anatomical traits. According to the decision tree models generated on the basis of the gain ratio, information gain, and Gini index, the epidermis, leaf thickness, and bulliform cells were the major factors of the root nodes, and the maximum accuracy of the models was 70.90%. Overall, the models indicated that rice leaves with a thin epidermis, large bulliform cells, thin leaves, and small vascular bundles are more likely to display high leaf rolling adaptations under drought stress conditions.

Drought isa major constraint in many rainfed areas and affects rice yield. We aimed to characterize the physiological changes in rice in response to drought using Fourier transform infrared (FTIR) spectroscopy. Eighty rice landrace seedlings were subjected to drought in the greenhouse using a PEG 6000. Physiological parameters, including total chlorophyll content, relative water content, electrolyte leakage, and biochemical changes were evaluated. Based on the FTIR results, the landraces were divided into three main groups: tolerant, moderately tolerant, and susceptible. Principal component analysis revealed spectral differences between the control and drought stress treatment groups. Lipid, pectin, and lignin content increased after drought stress. The biochemical components of plants at different drought tolerance levels were also compared. The lipid (CH2 and CH3), lignin (C=C), pectin (C=O), and protein (C=O, N–H) contents were the highest in the drought-tolerant cultivars, followed by the moderately tolerant and susceptible cultivars, respectively. Cultivar 17 and 49 were the most tolerant, and the functional groups were identified and characterized using FTIR. Overall, these results will be useful in selecting parental cultivars for rice breeding programs.