Dengue Dynamics in Binh Thuan Province,Southern Vietnam: Periodicity,Synchronicity and Climate Variability

Background

Dengue is a major global public health problem with increasing incidence and geographic spread. The epidemiology is complex with long inter-epidemic intervals and endemic with seasonal fluctuations. This study was initiated to investigate dengue transmission dynamics in Binh Thuan province, southern Vietnam.

Methodology

Wavelet analyses were performed on time series of monthly notified dengue cases from January 1994 to June 2009 (i) to detect and quantify dengue periodicity, (ii) to describe synchrony patterns in both time and space, (iii) to investigate the spatio-temporal waves and (iv) to associate the relationship between dengue incidence and El Niño-Southern Oscillation (ENSO) indices in Binh Thuan province, southern Vietnam.

Principal Findings

We demonstrate a continuous annual mode of oscillation and a multi-annual cycle of around 2–3-years was solely observed from 1996–2001. Synchrony in time and between districts was detected for both the annual and 2–3-year cycle. Phase differences used to describe the spatio-temporal patterns suggested that the seasonal wave of infection was either synchronous among all districts or moving away from Phan Thiet district. The 2–3-year periodic wave was moving towards, rather than away from Phan Thiet district. A strong non-stationary association between ENSO indices and climate variables with dengue incidence in the 2–3-year periodic band was found.

Conclusions

A multi-annual mode of oscillation was observed and these 2–3-year waves of infection probably started outside Binh Thuan province. Associations with climatic variables were observed with dengue incidence. Here, we have provided insight in dengue population transmission dynamics over the past 14.5 years. Further studies on an extensive time series dataset are needed to test the hypothesis that epidemics emanate from larger cities in southern Vietnam.     

Dragonets (Callionymidae) of soft bottoms from the coastal zone of southern Central Vietnam

A review of dragonets (Gallionymidae) from the coastal waters of Khanh Hoa (Nha Trang and Van Phong bays) and Binh Thuan (Phu Quy Island) provinces, Vietnam, was conducted based on the samples of the author. In total, nine species were recorded, including three species indicated in the fauna of the country for the first time. In addition, geographic and bathymetric distribution of C. altipinnis, as well as morphological variation of several other species, was specified.     

Assessing the impact of ecological security and forest fire susceptibility on carbon stocks in Bo Trach district,Quang Binh province,Vietnam

An assessment index of landscape ecological security (LES), different from other ecological models namely Pressure-State-Response (PSR), will be more accurate to capture temporal and geographic changes in landscape as well as ecosystem resilience and resistance to interference. In the present study, the impact of ecological security and forest fires on the carbon stock of forests in Bo Trach district, Quang Binh province, central Vietnam was evaluated and analyzed based on remote sensing data and a hybrid model of ant colony optimization (ACO) and neuro-fuzzy system (NFS). The present study indicated that forest fires are generally high throughout the study area, concentrating on areas exposed to and affected by human reclamation and production activities. The artificial neural network (ANN) model based on principal component analysis (PCA) combined Sentinel-1A data performed a higher prediction accuracy (R² = 0.74), being much greater than biomass estimation using optical data. It reveals that there is a reliability in estimating the aboveground carbon stocks (AGCs) from the aboveground biomass (AGB). The calculated data suggest the AGCs in the study area is high, but these parameters will loss severely in the coming years due to the nature and humans impacts. These results show that utilizing remote sensing combined with PCA-ANN model would have increased the accuracy of forest fire susceptibility, and detected assessment of the LES and forest fires on the AGCs. The above obtainings supply helpful information for managers and forest rangers to guard the forests in the study area better, and to limit human encroachment, thereby offering actions that contribute to sustainable development.     

Stand structure and natural regeneration of degraded forestland in the northern mountainous region of Vietnam

Vietnam experienced significant alterations of forest environments during the last half of the twentieth century, and reforestation efforts have increased since the 1990s. This study developed comparisons of naturally regenerated and plantation forestlands in northern Vietnam in order to gain a better understanding of reforestation options for the dual objectives of biodiversity and commercial tree production. Stand structure of secondary natural forest after logging and shifting cultivation were investigated at two study sites (Hoa Binh Province and Phu Tho Province). Natural regeneration of seedlings between the secondary natural forests and nearby mixed species plantations were measured and compared. The dominant tree species consisted of Aporosa villosa, Ficus racemosa, Machilus bonii and Vernicia montan at the Hoa Binh site and Cinnamomum parthenoxylum, Ormosia balabsae and Lithocarpus gigantophyllus at the Phu Tho site, which are mostly pioneer species. The secondary natural forests had higher abundance and diversity indices of seedlings than the mixed species plantations. Soil fertility of the secondary natural forests was better than that of the mixed species plantations (P < 0.05). An important finding is that, for the study sites examined, secondary natural forest resulted in more diverse and better-stocked forests than plantation forestry, implying that in areas where reforestation is undertaken the silvicultural potential of natural regeneration should not be underestimated.     

Adaptation,Ecological Impacts,and Risk Assessment: Insights from Research at Foundry Cove,Bayou Trepagnier,and Pass Fourchon

This paper takes a detailed look at the occurrence of genetic adaptations and ecological impacts at three contaminated sites (Foundry Cove, Bayou Trepagnier, Pass Fourchon) to assess the co-occurrence of adaptation and ecological impacts and the implications for risk assessment. Community-level ecological impacts were reported for all three sites. However, there was little evidence of population-level impacts (on the six populations that were also assessed for adaptation). Similarly, adaptation was found in only one of the populations. While this review provides an incomplete picture (adaptation was assessed on only a small subset of the species present and the reasons behind the lack of adaptation in the five populations remained unknown), it indicates that adaptation is uncommon even where ecological impacts are obvious. Theoretical considerations also predict that contaminants can have large impacts without resulting in an adaptation. While adaptation to a contaminant reflects an impact by that contaminant, the three case studies indicate that determining whether or not resistance has evolved does not appear to be a very efficient tool for detecting ecological impacts. Nevertheless, assessing the occurrence of adaptation does have a place in risk assessment, especially when assessing the likelihood of local extinction of a particular population     

安徽黄缘闭壳龟（ Cuora flavomarginata） 野生种群的现状及其保护建议

安徽是濒危物种黄缘闭壳龟的重要分布区之一,由于人类活动使得该龟栖息地日益减少,生存空间被挤占。加之近年来日益频繁的黄缘闭壳龟贸易所带来的肆意滥捕以及缺乏有效的保护措施,导致其野生种群衰减严重,数量已经十分稀少,同时买卖和饲养也进一步加剧了黄缘闭壳龟的非自然扩散和引入。目前黄缘闭壳龟在安徽的具体产地一直缺乏一个较为科学的研究,而了解黄缘闭壳龟在安徽的具体分布状况,对于该龟的保护至关重要。2011年—2012年5月至10月间,采用市场和访问调查以及野外实地调查相结合的方法,对安徽黄缘闭壳龟野生种群现状进行了研究,并对调查结果进行了报道,同时针对保护管理中存在的问题,提出相应的保护建议。     

Allowing for human socioeconomic impacts in the conservation of plants under climate change

Abstract

The impact of climate change on conservation planning is affected by the availability of data (especially in data-sparse countries) and socioeconomic impacts. We build models using MaxEnt for Egyptian medicinal plants as a model system, projecting them to different future times under two IPCC 4th assessment emission scenarios (A2a and B2a) assuming unlimited and no dispersal. We compare the effect of two indices of socioeconomic activity [Human Influence Index (HII) and human population density/km²] as cost layers in spatial prioritization for conservation using zonation. We assess the efficacy of Egypt's network of Protected Areas (PAs) by comparing the predicted conservation value inside and outside each PA under the various scenarios. The results show that there are many locations in Egypt (the main cities, agricultural land, coastal areas) that are highly ranked for conservation before human socioeconomic impacts are included. The HII had a stronger impact than using human population density. The PA value excess (inside–outside) varied significantly with the type of cost and dispersal, but not with climate-change scenario or Zonation settings. We conclude that human socioeconomic impacts add new scope and insights for future conservation; and conservation planning without consideration of such impacts cannot be complete.     

Biological flora of Central Europe: Ailanthus altissima (Mill.) Swingle

Ailanthus altissima (tree of heaven), Simaroubaceae, is an early successional tree, native to China and North Vietnam, which has become invasive in Europe and on all other continents except Antarctica. It is most abundant in urban habitats and along transportation corridors, but can also invade natural habitats. This paper reviews the literature on the morphology, distribution, ecology, habitat requirements, population biology, genetics, physiology, impacts, management and uses of this species.     

L’orang-outan fossile de Hoà Binh (Viêt-nam) : poids corporel et hypothèse locomotrice

The orang-utan of Hoà Binh (Vietnam): body weight and locomotor hypothesis. The discovery of the first complete skeleton of an adult orang-utan (Pongo pygmaeus), probably a female, in the Hoà Binh province, Vietnam, brings original data about the evolution of these primates. We have predicted the body weight of this orang-utan by using two parameters : dental (crown area of cheek teeth) and skeletal (lengths of femur, radius and tibia). The dental dimensions give plausible predicted estimates of body weights that range between 70.9–112.4 kg for M¹ (with a mean of 89.3 kg) and 67.9–98.1 kg for M₁ (with a mean of 81.6 kg). From the observations of Sugardjito and van Hoof [21] on modern orang-utans, heavy body weights have some influence both on the employment of certain types of locomotion and on travelling heights. To cite this article : A.-M. Bacon, V.T. Long, C. R. Palevol 2 (2003).     

越南防己科植物新记录

报道了越南防己科1新记录种肾子藤(Pachygone valida Diels),原记载分布于中国。该种产自越南北部和平(Hoa Binh)省的Mai Chau地区,凭证标本保存在HN。     

Dynamics of Horizontal Gene Transfer and the Ecological Risk Assessment of Genetically Engineered Organisms

The extensive published discussion of potential ecological impacts of introduced genetic sequences and genetically engineered organisms has lacked a quantified delineation of the critical questions for the estimation of risk. Ultimately, the ecological risk assessment of introduced gene sequences is the application of evolution, population genetics, and ecology to risk estimation and decision making. This paper provides a framework for the estimation of risk due to introduced sequences in bacteria, and the principles should also hold for many diploid species. Horizontal genetic exchange poses new challenges for ecological risk assessment. Plasmid transfer can occur without any impacts, although the sequence can become ubiquitous in the population. Conversely, the introduction of a plasmid can change the dynamics of the host population, potentially altering the population minimum and maximum characteristics of its dynamics. Because of genetic exchange, new genetic information is unlikely to be constrained among one type of prokaryote. An example of the use of the model is given using genetic exchange data from a series of published soil microcosm experiments. The model demonstrates the increase in plasmid frequency when using experimentally derived conjugation frequencies. Application of these results to ongoing discussion of the risks of genetically engineered organisms is presented. Particular attention is paid to the transfer of genetic material and the resultant changes in host population dynamics.     

Prevalence of Opisthorchis viverrini-Like Fluke Infection in Ducks in Binh Dinh Province,Central Vietnam

Following the first report of Opisthorchis viverrini infection in a domestic duck in Phu My District of Binh Dinh Province, Central Vietnam, many other cases were observed in the province. We determined the infection rate and intensity of O. viverrini infection in ducks in 4 districts of the province. A total of 178 ducks were randomly selected from 34 farms for examination of flukes in the liver and gall bladder. An infection rate of 34.3% (range 20.7-40.4% among districts) was found; the intensity of infection was 13.8 worms per infected duck (range 1-100). These findings show the role of ducks as a host for O. viverrini, duck genotype, which is sympatric with the human O. viverrini genotype in this province. It also stresses the need for investigations on the zoonotic potential and the life cycle of this parasite.     

紫茎泽兰在我国的分布、危害与防除途径的探讨

紫茎泽兰于解放前后由缅、越方向传入我国云南南部,目前向北已蔓延到25°33′N地区,向东扩展到广西、贵州境内。其中在早期侵入的滇南地区,早已发展成连片的单优群落,侵占农地,危害牲畜,影响林木生长,广大群众反映十分强烈。 文章提出要消除紫茎泽兰的这种危害,首先应采取严禁毁林开荒,固定耕地,森林采伐迹地要及时更新等预防措施。同时尽快引进泽兰天敌,开展以恢复种群生态平衡为基础的生物防除。应用2、4-D、2、4、5-T百草枯等行之有效的化学防除方法也是十分必要的。至于诸如人工拔除等机械措施,据国内外试验证明一般是无效的。 文章最后着重分析了紫茎泽兰在我国这样的新发展医域,其潜在危害十分广泛,应引起注意。     

Age-specificity of clinical dengue during primary and secondary infections

Background

This study aims to estimate the age-specific risks of clinical dengue attack (i.e., the risk of symptomatic dengue among the total number of dengue virus (DENV) infections) during primary and secondary infections.

Methods

We analyzed two pieces of epidemiological information in Binh Thuan province, southern Vietnam, i.e., age-specific seroprevalence and a community-wide longitudinal study of clinical dengue attack. The latter data set stratified febrile patients with DENV infection by age as well as infection parity. A simple modeling approach was employed to estimate the age-specific risks of clinical dengue attack during primary and secondary infections.

Results

Using the seroprevalence data, the force of infection was estimated to be 11.7% (95% confidence intervals (CI): 10.8–12.7) per year. Median age (and the 25–75 percentiles) of dengue fever patients during primary and secondary infections were 12 (9–20) and 20 (14–31) years, respectively. The estimated age-specific risk of clinical dengue increases as a function of age for both primary and secondary infections; the estimated proportion of symptomatic patients among the total number of infected individuals was estimated to be <7% for those aged <10 years for both primary and secondary infections, but increased as patients become older, reaching to 8–11% by the age of 20 years.

Conclusions/Significance

For both primary and secondary infections, higher age at DENV infection was shown to result in higher risk of clinical attack. Age as an important modulator of clinical dengue explains recent increase in dengue notifications in ageing countries in Southeast Asia, and moreover, poses a paradoxical problem of an increase in adult patients resulting from a decline in the force of infection, which may be caused by various factors including time-dependent variations in epidemiological, ecological and demographic dynamics.     

Impact assessment for LCAs involving agricultural production

LCA has been developed primarily for industrial production systems. Application to agricultural systems requires systematic application of existing methodology and new methodological developments. Conventional approaches can obscure potential options for improving the environmental performance of systems involving agricultural production due to use of restricted system boundaries, incomplete assessment of impacts, and exclusion of ancillaries from the analysis. For use of nutrients such as phosphorus, it is proposed that Impact Assessment should be based on the quantity dispersed after use rather than on the input to the productive system. Eventually, the impacts associated with depletion should be based on technological or thermodynamic assessment of concentration for reuse, but this approach requires further theoretical development.     

The Cassava Mealybug (Phenacoccus manihoti) in Asia: First Records,Potential Distribution,and an Identification Key

Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), one of the most serious pests of cassava worldwide, has recently reached Asia, raising significant concern over its potential spread throughout the region. To support management decisions, this article reports recent distribution records, and estimates the climatic suitability for its regional spread using a CLIMEX distribution model. The article also presents a taxonomic key that separates P. manihoti from all other mealybug species associated with the genus Manihot. Model predictions suggest P. manihoti imposes an important, yet differential, threat to cassava production in Asia. Predicted risk is most acute in the southern end of Karnataka in India, the eastern end of the Ninh Thuan province in Vietnam, and in most of West Timor in Indonesia. The model also suggests P. manihoti is likely to be limited by cold stress across Vietnam''s northern regions and in the entire Guangxi province in China, and by high rainfall across the wet tropics in Indonesia and the Philippines. Predictions should be particularly important to guide management decisions for high risk areas where P. manihoti is absent (e.g., India), or where it has established but populations remain small and localized (e.g., South Vietnam). Results from this article should help decision-makers assess site-specific risk of invasion, and develop proportional prevention and surveillance programs for early detection and rapid response.     

A remarkable new cave scorpion of the family Pseudochactidae Gromov (Chelicerata, Scorpiones) from Vietnam

A new genus and species of scorpion belonging to the family Pseudochactidaeare described based on four specimens collected in the Tien Son cave at the Phong Nha - Ke Bang National Park, Quang Binh Province, Vietnam. The new species represents a true troglobitic element, the first one known for the family Pseudochactidae. This represents the third known record of a pseudochactid, and the first from Vietnam.     

Gastropods alien to South Africa cause severe environmental harm in their global alien ranges across habitats

Alien gastropods have caused extensive harm to biodiversity and socioeconomic systems like agriculture and horticulture worldwide. For conservation and management purposes, information on impacts needs to be easily interpretable and comparable, and the factors that determine impacts understood. This study aimed to assess gastropods alien to South Africa to compare impact severity between species and understand how they vary between habitats and mechanisms. Furthermore, we explore the relationship between environmental and socioeconomic impacts, and both impact measures with life‐history traits. We used the Environmental Impact Classification for Alien Taxa (EICAT) and Socio‐Economic Impact Classification for Alien Taxa (SEICAT) to assess impacts of 34 gastropods alien to South Africa including evidence of impact from their entire alien range. We tested for correlations between environmental and socioeconomic impacts per species, and with fecundity and native latitude range using Kendall's tau tests. Kruskal–Wallis tests were used to compare impact magnitude among mechanisms and habitats, respectively. This study presents the first application of EICAT and SEICAT for invertebrates. There was no correlation between environmental impacts and socioeconomic impacts. Habitats did not differ regarding the severity of impacts recorded, but impacts via disease transmission were lower than other mechanisms. Neither fecundity nor native range latitude was correlated with impact magnitude. Despite gastropods being agricultural and horticultural pests globally, resilience of socioeconomic systems makes high impacts uncommon. Environmental systems may be vulnerable to gastropod impacts across habitats, having experienced multiple local extinctions of wetland island snail fauna. South Africa stands out as the only continental country that follows this trend. The knowledge gained on severity and nature of gastropod impacts is useful in risk assessment, which can aid conservation management. To make impact assessments more realistic, we suggest alternative ways of reporting impacts classified under EICAT and SEICAT.     

Assessing household livelihood vulnerability to climate change: The case of Northwest Vietnam

This study applied livelihood vulnerability index (LVI) and livelihood effect index (LEI) to assess vulnerability from climate variability and change of three agricultural and natural resources dependent commune in northwest Vietnam, a country that is expected to bear some of the most severe impacts of climate change. Based on a survey of 335 farm household data, complemented with secondary data on climate factors, a composite index was calculated and differential vulnerabilities were compared. The results of the analysis suggest that one of the communities, “Pa Vay Su,” was more vulnerable than the others, particularly in relation to housing, knowledge and skills, socio-demographics, health and water security, social networks, and livelihood strategy. “Hien Luong” commune, on the other hand, was more vulnerable in relation to other LVI indicators with the exception of food security, climate variability, and natural disasters. “Moc Chau” community was more vulnerable in relation to water security, social demographic than Hien Luong commune. Overall, the article shows that three different vulnerability assessment indices can be broadly applied in comparable setting in other areas of country and they could usefully establish the basis for a nationally applicable index to identify and prioritize adaptation and mitigation needs.     

Vocal Diversity and Taxonomy of <Emphasis Type="Italic">Nomascus</Emphasis> in Central Vietnam and Southern Laos

Previous researchers suggested that gibbon song repertoire is genetically determined and song characteristics are useful for assessing systematic relationships. The southern white-cheeked crested gibbon is regarded as either a subspecies of Nomascus leucogenys or its own species (Nomascus siki). I studied vocal diversity among different wild populations of Nomascus in central Vietnam and southern Laos to assess their taxonomic relationships and to examine whether their vocal patterns correspond to forms previously described for Nomascus siki. I examined the songs of 7 Nomascus populations in Vietnam and Laos. I analyzed 192 song bouts from different gibbon groups including 173 phrases of 42 females and 192 phrases of 42 males. Linear discriminant analysis, classification trees, and multidimensional scaling revealed marked separation of groups in the northern and southern populations. Within the 2 geographic populations, there is little variability and the vocal characteristics exhibited no apparent cline. I conclude that the northern and southern geographic populations may represent 2 distinct taxa. I postulate that a taxonal boundary such as large rivers existing between southern Quang Binh province and northern Thua-Thien Hue province in Vietnam and northern Phou Xang He NBCA and southern Dong Phou Vieng NBCA in Laos has limited gene flow between the populations. Differing topographic features could also serve as a selective force for improved sound transmission in a highly territorial species, driving the divergence between the 2 populations.