Khanh Hoa Province Research Articles

Simple clinical and laboratory predictors to improve empirical treatment strategies in areas of high scrub typhus and dengue endemicity, central Vietnam.

BackgroundDengue fever is highly endemic in Vietnam, but scrub typhus—although recognized as an endemic disease—remains underappreciated. These diseases together are likely to account for more than half of the acute undifferentiated fever burden in Vietnam. Scrub typhus (ST) is a bacterial disease requiring antimicrobial treatment, while dengue fever (DF) is of viral etiology and does not. The access to adequate diagnostics and the current understanding of empirical treatment strategies for both illnesses remain limited. In this study we aimed to contribute to the clinical decision process in the management of these two important etiologies of febrile illness in Vietnam.MethodsUsing retrospective data from 221 PCR-confirmed scrub typhus cases and 387 NS1 protein positive dengue fever patients admitted to five hospitals in Khanh Hoa province (central Vietnam), we defined predictive characteristics for both diseases that support simple clinical decision making with potential to inform decision algorithms in future. We developed models to discriminate scrub typhus from dengue fever using multivariable logistic regression (M-LR) and classification and regression trees (CART). Regression trees were developed for the entire data set initially and pruned, based on cross-validation. Regression models were developed in a training data set involving 60% of the total sample and validated in the complementary subsample. Probability cut points for the distinction between scrub typhus and dengue fever were chosen to maximise the sum of sensitivity and specificity.ResultsUsing M-LR, following seven predictors were identified, that reliably differentiate ST from DF; eschar, regional lymphadenopathy, an occupation in nature, increased days of fever on admission, increased neutrophil count, decreased ratio of neutrophils/lymphocytes, and age over 40. Sensitivity and specificity of predictions based on these seven factors reached 93.7% and 99.5%, respectively. When excluding the “eschar” variable, the values dropped to 76.3% and 92.3%, respectively.The CART model generated one further variable; increased days of fever on admission, when eschar was included, the sensitivity and specificity was 95% and 96.9%, respectively. The model without eschar involved the following six variables; regional lymphadenopathy, increased days of fever on admission, increased neutrophil count, increased lymphocyte count, platelet count ≥ 47 G/L and age over 28 years as predictors of ST and provided a sensitivity of 77.4% and a specificity of 90.7%.ConclusionsThe generated algorithms contribute to differentiating scrub typhus from dengue fever using basic clinical and laboratory parameters, supporting clinical decision making in areas where dengue and scrub typhus are co-endemic in Vietnam.

Analysis of RT-PCR examination from 60 patients contracted Covid-19 in Khanh Hoa province in the year 2020

Background: Covid-19 Pandemic that started in the end of year 2019 has brought the world into an ever seen long lasting health and socio-economic crisis. This study aimed to explore primary characteristics of RT-PCR examination in Covid-19 adult patients who were treated in Khanh Hoa Province in 2020. Materials and method: This study collected laboratory examination data and related factors of 60 adult patients who contracted Covid-19 in the year of 2020 in Khanh Hoa province, Vietnam. Results: The results showed median (IQR) of number of RT-PCR tests taken per patient was 10 (6-12) and there exist differences in this number per patient among four hospitals in the province. Further, the test results in each patient showed repeated positivity as well as consecutive positivity, and a high percentage (53.2%) of recurrent positivity (after the first negative test). Conclusions: The numbers of test per patient were rather different among patients as well as among four hospitals. The results of numerous and consecutive positivity as well as recurrent positivity suggested a persistent existence of SARS-CoV-2 in the patients’ respiratory system. Key words: SARS-CoV-2, Covid-19, recurrent positivity, RT-PCR, Khanh Hoa province

Study on the year-round fluctuation of total lipid content and lipid classes composition in soft coral \(\textit{Sinularia flexibilis}\) from Nha Trang, Khanh Hoa coastal

Samples of soft coral Sinularia flexibilis were collected for one year, from January to December, in the Nha Trang coastal area, Khanh Hoa province, to assess the month-by-month fluctuation of total lipid content and lipid classes composition in this species. Full lipid content reached the highest value from March to May, lower in the period of June-September, and bottomed in October and November. There was a significant decrease in this content between May and June, September and October; the content increased from February to March but was not stable from October to February. The lipid classes composition of Sinularia flexibilis includes polar lipids (PL), sterols (ST), triacylglycerol (TAG), monoalkyldiacyl-glycerol (MADAG), wax (W), and free fatty acids (FFA). The concentration of PL in summer (April-August) was lower than that in winter (September-February); this content increased significantly during November-December; meanwhile, it was observed to decrease in April-May, December-January. The content of ST increased from October to March and declined from April to September. The remaining classes, including W, MADAG, and TAG, tend to grow in the summer and decline in the other months. The fluctuation of lipid class composition throughout the year is closely related to zooxanthellae microalgae in corals at different times of the year and is directly influenced by environmental conditions, especially seawater temperature. Besides, this coral’s maturation and reproduction effect with the increase or release of reproductive materials was also observed.

Antimicrobial activity of fungi isolated from Tan Dao mangrove forest in Khanh Hoa

Mangrove-derived fungi are the potential source of novel metabolites, comprising unique molecular structures with diverse bioactivities. In this study, 32 fungal strains isolated from the Tan Dao mangrove forest in Khanh Hoa province were investigated for their ability to produce antimicrobial agents using the disc diffusion method. Seventy-eight percent of obtained fungi (25 out of 32 isolates) exhibited antimicrobial activity against at least two test pathogens. Of them, bacteria Bacillus cereus and Streptococcus faecalis were the most susceptive to the antimicrobial activity of all fungal isolates with inhibition zones ranging from 8 to 36 mm, respectively, followed by Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Pseudomonas aeruginosa. There were only three fungal isolates that showed antimicrobial activity towards Candida albicans with the inhibition zone of 8−17 mm diameter. The strain LM.8.1 showing significant activity against all test microorganisms was identified as Penicillium sp. LM.8.1. The effect of culture conditions including pH, salinity, and incubation time on the production of antibacterial compounds of fungus Penicillium sp. LM.8.1 was also studied. The results indicated that fungi isolated from the Tan Dao mangrove forest possess potent antimicrobial properties and should be further investigated.

Effects of jig location and soak time on catch rates of a novel fishing gear design of squid longline fisheries

The use of handline jigging with artificial light is typical for the nighttime harvesting of cephalopod species in Vietnam. However, this fishing method requires great manpower and consumes a large amount of fuel for the electric generator. Therefore, developing an alternative fishing gear is needed. In this study, fishing experiments were conducted along the coast of Khanh Hoa province to compare the catch rate and size selectivity of a novel fishing gear design – squid horizontal longline – at different jig locations in the water where jigs actually work and to determine how soak time affected the catch rate and size selectivity. Our results showed that the effect of the squid longline on catch rates and size distribution depended on jig height from the seabed and soak time. The squid longline fished at 3 m higher off the seabed produced significantly higher catch rates than those fished at 7 m higher off the seabed. More large individuals were also caught at a depth of 3 m from the seabed. The catch rate increased with soak time, but peaked at 5 h of soaking. The new fishing method reduced the fuel consumption and crewmember as much as 60% and 38%, respectively compared to the traditional fishing technique. This study shows that squid longlines can promisingly replace conventional handline jigging with artificial light in harvesting squid species, which provides socioeconomic and environmental benefits.

Stress, lo âu, trầm cảm và một số yếu tố liên quan ở nhân viên Cảng hàng không quốc tế Cam Ranh, tỉnh Khánh Hòa năm 2020

This cross-sectional study, applying quantitative method, was carried out at Cam Ranh International Airport, Khanh Hoa province from April to October 2020. The study aimed at indentifying the risk of stress, anxiety and depression among staffs and associated factors. Quantitative data, applying DASS-21, was collected through 422 self-administrative questionnaires and analyzed by SPSS 20.0. Results showed that the risk of stress, anxiety and depression among staffs working at Cam Ranh International Airport was 55.9%, 47.4%, and 21.3%. Associated factors were as following: years of working, monthly income, number of children, caregiver to elderly, work characteristic, working time, amount of work, reward, and woking condition. Key words: mental health, airport, DASS-21

Investigating Sea Surface Temperature and Coral Bleaching in the Coastal Area of Khanh Hoa Province

Khanh Hoa Coastal area is considered the area with the most diverse coral reefs in the west of the East Sea. With the trend of increasing global temperature, the coral reefs here are affected, including the phenomenon of bleaching. This paper uses a Multi-scale Ultra-high Resolution Sea Surface Temperature (MUR SST) data source to evaluate the possible relationship between sea surface temperature and coral bleaching in the period 2010-2019 in Khanh Hoa coastal area is based on two parameters: Hot Spot (HS) and Degree Heating Months (DHM). Research results show that in the past 10 years, corals in Khanh Hoa coastal area may experience heat stress in 6 years, including 2010, 2013 and the years from 2016 to 2019. The phenomenon of heat stress starts to occur in May of each year, and the level of heat stress in 2010 was stronger than in other years. Within 6 years, there have been heat stress, coral bleaching events due to temperature only occurred in 2010; while in 2013, 2016, 2017, 2018 and 2019, corals suffered from heat stress in the watch level, meaning an increase in temperature is not yet capable of causing coral bleaching. The cause of coral bleaching in 2010 was the combined effect of the increase in sea surface temperature and the suppression of upwelling during the southwest monsoon.

Blood cells and some hematological parameters of red drum (Linnaeus, 1766) in Vietnam.

This research focuses on hematological characteristics, erythrocyte morphology and some biochemical parameters of red drum Sciaenops ocellatus (Perciformes: Sciaenidae), cultured in natural water environment in areas near river mouth (L1), estuaries (L2) in Ha Tinh province and coastal areas (L3) in Nha Trang city, Khanh Hoa province of Vietnam. A total of 18 speciments were examined in research, six in each location. Blood was drawn from the tail vein, using a microscope to research morphology and automated gauges to determine blood biochemical parameters. Analysis of blood samples showed that the rate of red drum's erythrocyte morphology disorders in all three locations was quite high. The two main types of disorders were nuclear deformity and nuclear-matter distribution. Changes in erythrocyte size, shape and nuclear were related to salt concentration at culture locations. Blood hemoglobin content was stable in all three regions. Other hematological parameters such as the number of erythrocytes, blood biochemical parameters (glucose, SGOT, SGPT, urea, creatine, plasma iron, albumin, and protein) have differences among the locations, which showed the different reactions of the same species with different environmental conditions.

Primulinascutellifolia, a new species of Gesneriaceae from southern Vietnam.

Primulinascutellifolia is described as a new species from Khanh Hoa Province, southern Central Vietnam. It is distinct in the genus in having scutellate leaves that make it a highly potential ornamental plant. The new species looks like P.annamensis in general shapes, sizes and colours of habit, inflorescence, flower, and leaf but is distinguishable by adaxially glabrous and abaxially strigose leaves with serrate margins, scutellate leaf blade and appressed downwards tomentose petiole, sparsely glandular hairs on apical 1/2 of the gynoecium and trapeziform one-lipped stigma with slightly emarginated apex.

More about the biodiversity of parasites in Vietnam: a first report of microsporidia (opistosporidia, microsporidia) in coral fish

This is the first report of microsporidia infection in marine fish from Vietnam. Microsporidia (Opistosporidia, Microsporidia) were identified in 4 species of coral fish Cheilinus chlorourus (Labridae), Abudefduf bengalensis (Pomacentridae), Pomacentrus brachialis (Pomacentridae), Atule mate (Carangidae) from Nha Trang Bay (East Sea), Khanh Hoa Province, Vietnam, in 2018 and 2019. Dry smears of blood, intestine and liver were stained using the Giemsa method. Gut and liver were fixed in Bouin’s fluid, processed for routine paraffin infiltration, and sections were stained with Hematoxylin and Eosin. Strong microsporidia infections were the same for all three species revealed in 1 of every 6 fish samples (prevalence 16.7%) of C. chlorourus, A. bengalensis, and P. brachialis. In C. chlorourus there were meronts, sporogonial plasmodia, and sporoblasts found in all layers of intestine (enterocytes, myocytes, mesotheliocytes), pancreas and liver. In A. bengalensis parasites were found in enterocytes of the small intestine and liver. In P. brachialis meronts, sporogonial plasmodia and sporoblasts were in enterocytes of the small intestine. Intracellular parasites are located in parasitophorous vacuoles covered with additional shell, which appeared to be in the process of forming xenoma. Microsporidia infection was revealed in 1 of 31 fish samples of A. mate (prevalence 3 %). Up to 30 of round and oval white xenomas were detected in the gills of fresh samples by microscopy. We tentatively assign the microsporidia to Glugeidae due to host affiliation (fish), localization (digestive system) and xenoma formation. They differ from Pleistophoridae by localization in non-muscular cells.

Физико-химические свойства почв мангровых лесов Вьетнама

Recently the area of mangrove (evergreen) forests growing along the coast of Vietnam has been significantly increased by artificial afforestation under the recognition of their ecological role and economic importance. Protection mangrove forests are the largest among all mangrove forests in Vietnam. They act as a belt to prevent coastal roads from erosion and damage due to tides, storms, and tsunamis. However, their role in coastal soil formation is still poorly studied. Soil formation in mangrove forests is influenced by many factors including the following: woody vegetation, tidal saltwater, precipitation, and mountain runoff. The ability of soil to retain water, nutrients, ions, and some other physical and chemical properties is closely related to the soil texture. Long-term monitoring of the soil texture and the content of nutrients in the soil of mangrove forests in the Dam Bay area of the Nha Trang Bay allowed us to distinguish 2 groups of soil phases: typical laterite soil in natural mangrove forests and in rhizophore plantings of 2004 and poorly developed laterite soil in cultural cenoses of 2007 and 2013 and in the littoral zone. These two groups have differences in the soil texture depending on the time of stand formation. The total amount of gravel, aleurite, and silt in the first group of soils is higher than that in the second group. The concentrations of nutrients (phosphorus and nitrogen content) in the soil of mangrove forests is quite high, though it gradually decreases from the soil of natural mangrove forests to the littoral zone. In order to effectively prevent erosion of soils and improve their physical and chemical properties, artificial mangrove forests should continuously be grown along the coast lines of the Nha Trang Bay in the Khanh Hoa province, Vietnam. For citation: Phan T.H., Kovyazin V.F., Zvonareva S.S., Nguyen T.H.T., Nguyen T.L. Physical and Chemical Soil Properties of Mangrove Forests in Vietnam. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 9–21. DOI: 10.37482/0536-1036-2021-5-9-21

Phytoplankton composition of the mangrove ecosystem in Khanh Hoa province, Vietnam

The objective of this study was to clarify the structureof phytoplankton in the natural mangroves of Nha Phu lagoon in Khanh Hoa province, Vietnam, and their correlation with other environmental factors. The outcome of the surveys in the area showed that there was a high diversity of phytoplankton species with about 139 ones, particularly Silic algae dominance. The biomass of phytoplankton here is not high, ranging from 25 260 to 58686 cells/liter. The environmental parameters show that the area has a favorable environment for the growth of phytoplankton. The salinity of water was from 18 %o to 35 %o the temperature was between 29.4 °C and 30.1 °C, and the pH index varied from 7.03 to 7.98. Analysis of the relationship between the abundance of phytoplankton species and environmental factors pointed out that the number of phytoplankton species has an inverse linear proportion to the content of Chlorophyll-a but a direct one to the salinity and the total content of Phosphorus in seawater. Also, the biomass of phytoplankton has an inverse linear proportion to salinity and pH but follows the opposite one to the environmental temperature and the content of Chlorophyll-a.

Asplenium quangbinhense sp. nov. and three new records of Asplenium (Aspleniaceae) from Vietnam

We describe a new species of Asplenium (Aspleniaceae) from Vietnam as A. quangbinhense. Morphologically, it is most similar to A. oldhamii. The new species is closely related to A. pseudopraemorsum, and a morphological comparison is presented between the two species. Three species, A. cyrtosorum, A. maguanense, and A. pseudopraemorsum, are reported as new records for Vietnam based on newly collected specimens from Quang Binh, Ha Giang, and Khanh Hoa provinces, Vietnam, respectively.

Ecological and behavioural risk factors of scrub typhus in central Vietnam: a case-control study

BackgroundThe risk factors for scrub typhus in Vietnam remain unknown. Scrub typhus caused by Orientia tsutsugamushi often presents as an undifferentiated febrile illness and remains under appreciated due to the limited availability of diagnostic tests. This tropical rickettsial illness is increasingly recognized as an important cause of non-malaria acute undifferentiated fever in Asia. This study aimed to investigate behavioural and ecological related risk factors of scrub typhus to prevent this potentially life-threatening disease in Vietnam.MethodsWe conducted a clinical hospital-based active surveillance study, and a retrospective residence-enrolment date-age-matched case–control study in Khanh Hoa province, Vietnam, from August 2018 to March 2020. Clinical examinations, polymerase chain reaction and enzyme-linked immunosorbent assay IgM tests were applied to define cases and controls. All enrolled participants filled out a questionnaire including demographic socio-economic status, personal behaviors/protective equipment, habitat connections, land use, and possible exposure to the vector. Multivariable conditional logistic regression was used to define the scrub typhus associated risk factors.ResultsWe identified 44 confirmed cases and matched them with 152 controls. Among cases and controls, the largest age group was the 41–50 years old and males accounted for 61.4% and 42.8%, respectively. There were similarities in demographic characteristics between the two groups, with the exception of occupation. Several factors were significantly associated with acquisition of scrub typhus, including sitting/laying directly on household floor [adjusted OR (aOR) = 4.9, 95% CI: 1.6–15.1, P = 0.006], household with poor sanitation/conditions (aOR = 7.9, 95% CI: 1.9–32.9, P = 0.005), workplace environment with risk (aOR = 3.0, 95% CI: 1.2–7.6, P = 0.020), always observing mice around home (aOR = 3.7, 95% CI: 1.4–9.9, P = 0.008), and use of personal protective equipment in the field (aOR = 0.4, 95% CI: 0.1–1.1, P = 0.076).ConclusionsEcological and household hygiene-related factors were more associated with scrub typhus infection, than individual-level exposure activities in the hyper-endemic area. These findings support local education and allow people to protect themselves from scrub typhus, especially in areas with limitations in diagnostic capacity.Graphical abstract

Cycloartane triterpenoids and biological activities from the propolis of the stingless bee Lisotrigona furva

AbstractChromatographic separation of ethyl acetate extract of the stingless bee Lisotrigona furva propolis, that collected in Khanh Hoa province, led to isolation of five cycloartane‐type triterpenes including cycloartenone (1), cycloartenol (2), (24E)‐3β‐hydroxycycloart‐24‐en‐26‐al (3), mangiferonic acid (4) and mangiferolic acid (5). Mango plant (Mangifera indica) was suggested to be a resin source of the propolis. The propolis EtOH extract showed good antimicrobial activity on Gram (+) strain E. feacalis and fungus C. albicans. Among the isolated compounds, compound 3 displayed selective activity against three Gram (+) strains and C. albicans over Gram (‐) strains with all MIC values of 64 μg/mL. However, the propolis EtOH extract was not active against LU‐1 and MCF‐7 cancer cell lines. Only compound 5 exhibited moderate activity on LU‐1 cancer cell line with IC50 of 13.33 μg/mL.

New record of the genus <i>Mastoniaeforis</i>(Gastropoda: Triphoridae) from Vietnam

Species of the genus Mastoniaeforis are mainly distributed in the Indo-West Pacific with ten species being recorded in the world. To date this genus was not recorded in Vietnam. Specimens of three species, M. chaperi , M. lifuana and M. speciosa, were collected in two field trips from May, 2019 to October, 2020 in Truong Sa archipelago (Spratly Islands), Khanh Hoa Province, Vietnam. The diagnostic characters, distribution, and illustrations of three Mastoniaeforis species in Vietnam are provided.

Water exchange in Van Phong bay, Khanh Hoa province by hydrodynamic model

The analysis of the average wind field from 1979 to 2018 showed that in the Van Phong bay area, the hydrodynamic process is mainly influenced by tidal currents when the frequency of weak wind accounts for a high proportion and the wind regime is controlled entirely by locality and less likely to alter tidal currents significantly. Based on the shallow water hydrodynamic finite element model (FEM), a two-dimensional hydrodynamic model has been developed for Van Phong bay to study hydrodynamic features, especially exchange capacity of seawater with the open sea. The results show that the daily average daily exchange of water in Van Phong bay is about 1,845.46 × 106 m3/day, equivalent to 34.7% water volume in the bay. In the rainy season, the typical daily average water exchange in Van Phong bay is about 2,136.04 × 106 m3/day, equivalent to 43.19% of the volume of water in the bay. In the dry season, the typical daily average total water exchange in Van Phong bay is about 1,825.56 × 106 m3/day, corresponding to 34.35% of water volume in the bay.

Mosquitoes (Diptera: Culicidae) from Villages and Forest Areas of Rural Communes in Khanh Hoa and Binh Phuoc Provinces, Vietnam.

This study presents the diversity of mosquitoes collected from communes, endemic with malaria and dengue, located in Khanh Hoa and Binh Phuoc Provinces, Vietnam. A total of 10,288 mosquitoes were collected in the village and forested sites using standard larval dippers, cow-baited traps, ultra-violet light traps, and mechanical aspirators. Mosquito taxa were identified morphologically and species complexes/groups were further characterized molecularly. Five genera of mosquitoes were morphologically identified: Anopheles Meigen (21 species), Aedes Meigen (2 species), Culex Linnaeus (5 species), Mansonia Blanchard sp., and Armigeres Theobald sp. The PCR-based identification methods allowed the distinction of members of Maculatus Group, Funestus Group, and Dirus Complex; and DNA barcodes enabled the further identification of the Barbirostris Complex. Data reported here include the first report of An. saeungae Taai & Harbach and An. wejchoochotei Taai & Harbach from Vietnam, and re-emphasizes the significance of using molecular data in an integrated systematic approach to identify cryptic species and better understand their role in disease transmission.

Gekko phuyenensis sp. nov. (Squamata: Gekkonidae), a new species from southern Vietnam.

A new species of the genus Gekko Laurenti, 1768 is described from Phu Yen Province, southern Vietnam based on morphological and molecular evidence. Gekko phuyenensis sp. nov. differs from other congeners by its moderate size, with a snout-vent length of 90.292.8 mm; nares in contact with rostral; internasal 1; interorbitals 35 or 36; ventrals 3032; dorsal tubercle rows 9 or 10; precloacal pores 12 or 13 in males and precloacal pits 13 in female; subdigital lamellae under first finger 1821, fourth finger 19 or 20, first toe 1820, and fourth toe 2123; subcaudals median enlarged; no webbing between toes; and the absence of tubercles on hind limbs. Molecular phylogenetic analyses of mitochondrial gene COI (681 bp) using the geckos from Phu Yen and its congeners in southern Vietnam resolve the new species as the sister lineage to G. cf. grossmanni from Khanh Hoa Province. Genetic distances between G. phuyenensis sp. nov. and its congeners in southern Vietnam range from 16.924.2%. The discovery of this new species raises the number of known species of Gekko in Vietnam to 14.

The first discovery of the “Pheidole quadricuspis group” in the Indo-Chinese Peninsula (Insecta: Hymenoptera: Formicidae: Myrmicinae)

Pheidole leloi is described as a new species based on a colony series collected in an evergreen forest on the Da Lat Plateau's eastern edge (Hon Ba Nature Reserve, Khanh Hoa Province, Vietnam). It is the first discovery of the Pheidole quadricuspis group in the Indo-Chinese Peninsula. The p-distance between COI sequences of P. leloi and its putative named allies of the species group is 13.4-15.8%. This may indicate that P. leloi has been genetically isolated for several million years. An ancestor of P. leloi probably expanded its distribution into the Indo-Chinese peninsula during the Miocene expansions of rainforests, and survived into rainforest patches (refugia) during the Quaternary glacial age.