Malaria in central Vietnam: analysis of risk factors by multivariate analysis and classification tree models

BACKGROUND: In Central Vietnam, forest malaria remains difficult to control due to the complex interactions between human, vector and environmental factors. METHODS: Prior to a community-based intervention to assess the efficacy of long-lasting insecticidal hammocks, a complete census (18,646 individuals) and a baseline cross-sectional survey for determining malaria prevalence and related risk factors were carried out. Multivariate analysis using survey logistic regression was combined to a classification tree model (CART) to better define the relative importance and inter-relations between the different risk factors. RESULTS: The study population was mostly from the Ra-glai ethnic group (88%), with both low education and socio-economic status and engaged mainly in forest activities (58%). The multivariate analysis confirmed forest activity, bed net use, ethnicity, age and education as risk factors for malaria infections, but could not handle multiple interactions. The CART analysis showed that the most important risk factor for malaria was the wealth category, the wealthiest group being much less infected (8.9%) than the lower and medium wealth category (16.6%). In the former, forest activity and bed net use were the most determinant risk factors for malaria, while in the lower and medium wealth category, insecticide treated nets were most important, although the latter were less protective among Ra-glai people. CONCLUSION: The combination of CART and multivariate analysis constitute a novel analytical approach, providing an accurate and dynamic picture of the main risk factors for malaria infection. Results show that the control of forest malaria remains an extremely complex task that has to address poverty-related risk factors such as education, ethnicity and housing conditions

FIRST RECORD OF CANTHARELLUS MINOR IN VIETNAM

This species of mushroom with orange fruiting bodies and yellow flesh grows in clumps on the forest land in the coordinates 11o56'34.45" N, 108o28'33.56" E in the pine (Pinus kesiya) forest, Da Lat City, Lam Dong Province, Vietnam. The results of analysis on the morphology, both macro- and micro-morphological characteristics of this mushroom showed that, pileus: 5-15 mm wide, infundibuliform; yellowish to orange; margin incurred, wavy-liked margin, non-striate; Pileus surface: smooth, scaleless, yellowish; Lamellae: distant, decurrent, not intervenose, concolorous to pileus; Context: concolourous to the pileus, slight sweetness, aromatic flavor; Stipe: cylindrical shape, surface smooth, concolourous to pileus, 1-2 mm diameter, 20-50 mm length; Basidiospores: 6-11.5 x 4-6.5 μm, ovoid-ellipsoid with smooth surface; Basidia: 65 x 10 μm, cornuted 4-6 spores per basidium. Phylogenetic analysis of nrLSU sequence yielded consistent topology in different taxa of Cantharellus. The phylogenetic position of XC02 was obtained and accepted at sub-generic level: subgenus Parvocantharellus. This clade was suggested to be monophyletic, and separated from other sub-generic levels. Morphologically phylogenetically distinct from the other species of clade 4, such as C. appalachiensis, C. tabernensis, C. aff. Congolensis. The highly supported monophyletic group with referent Cantharellus minor was obtained with the bootstrap value of 99, indicated that XC02 was significant closely to Cantharellus minor. Phylogenetic of nrLSU analysis revealed clades with statistical support corresponding to morphological observation, thus, XC2 was concluded as Cantharellus minor

Performance of DASH over Multipath TCP

Recently, dynamic adaptive streaming over HTTP (DASH) is a dominated traffic in Internet. The client requests a suitable representation depending on the current network condition. On the other hand, multipath transmission control protocols emerges as potential data transmission utilizing multiple network paths concurrently. In this paper, we conduct extensively experiments to evaluate the performance of DASH over MPTCP. Four different performance metrics are investigated, i.e., time on high quality, impactful switches, switch frequency, and average bitrate. The results show that the performance of DASH decreases when the paths of MPTCP have different bandwidths

Epidemiology of forest malaria in central Vietnam: a large scale cross-sectional survey

In Vietnam, a large proportion of all malaria cases and deaths occurs in the central mountainous and forested part of the country. Indeed, forest malaria, despite intensive control activities, is still a major problem which raises several questions about its dynamics. A large-scale malaria morbidity survey to measure malaria endemicity and identify important risk factors was carried out in 43 villages situated in a forested area of Ninh Thuan province, south central Vietnam. Four thousand three hundred and six randomly selected individuals, aged 10–60 years, participated in the survey. Rag Lays (86%), traditionally living in the forest and practising "slash and burn" cultivation represented the most common ethnic group. The overall parasite rate was 13.3% (range [0–42.3] while Plasmodium falciparum seroprevalence was 25.5% (range [2.1–75.6]). Mapping of these two variables showed a patchy distribution, suggesting that risk factors other than remoteness and forest proximity modulated the human-vector interactions. This was confirmed by the results of the multivariate-adjusted analysis, showing that forest work was a significant risk factor for malaria infection, further increased by staying in the forest overnight (OR= 2.86; 95%CI [1.62; 5.07]). Rag Lays had a higher risk of malaria infection, which inversely related to education level and socio-economic status. Women were less at risk than men (OR = 0.71; 95%CI [0.59; 0.86]), a possible consequence of different behaviour. This study confirms that malaria endemicity is still relatively high in this area and that the dynamics of transmission is constantly modulated by the behaviour of both humans and vectors. A well-targeted intervention reducing the "vector/forest worker" interaction, based on long-lasting insecticidal material, could be appropriate in this environment

Long-Lasting Insecticidal Hammocks for controlling forest malaria: a community-based trial in a rural area of central Vietnam.

BACKGROUND: In Vietnam, malaria remains a problem in some remote areas located along its international borders and in the central highlands, partly due to the bionomics of the local vector, mainly found in forested areas and less vulnerable to standard control measures. Long Lasting Insecticidal Hammocks (LLIH), a tailored and user-friendly tool for forest workers, may further contribute in reducing the malaria burden. Their effectiveness was tested in a large community-based intervention trial carried out in Ninh Thuan province in Central Vietnam. METHODS AND FINDINGS: Thirty villages (population 18,646) were assembled in 20 clusters (1,000 individuals per cluster) that were randomly allocated to either the intervention or control group (no LLIH) after stratification according to the pre-intervention P. falciparum antibody prevalence ( or =30%). LLIH were distributed to the intervention group in December 2004. For the following 2 years, the incidence of clinical malaria and the prevalence of infection were determined by passive case detection at community level and by bi-annual malariometric surveys. A 2-fold larger effect on malaria incidence in the intervention as compared to the control group was observed. Similarly, malaria prevalence decreased more substantially in the intervention (1.6-fold greater reduction) than in the control group. Both for incidence and prevalence, a stronger and earlier effect of the intervention was observed in the high endemicity stratum. The number of malaria cases and infections averted by the intervention overall was estimated at 10.5 per 1,000 persons and 5.6/100 individuals, respectively, for the last half of 2006. In the high endemicity stratum, the impact was much higher, i.e. 29/1000 malaria cases and 15.7 infections/100 individuals averted. CONCLUSIONS: LLIH reduced malaria incidence and prevalence in this remote and forested area of Central Vietnam. As the targets of the newly-launched Global Malaria Action Plan include the 75% reduction of the global malaria cases by 2015 and eventually the elimination/eradication of malaria in the long term, LLIH may represent an additional tool for reaching such objectives, particularly in high endemicity areas where standard control tools have a modest impact, such as in remote and forested areas of Southeast Asia and possibly South America. TRIAL REGISTRATION: ClinicalTrials.gov NCT00853281

TextANIMAR: Text-based 3D Animal Fine-Grained Retrieval

3D object retrieval is an important yet challenging task, which has drawn more and more attention in recent years. While existing approaches have made strides in addressing this issue, they are often limited to restricted settings such as image and sketch queries, which are often unfriendly interactions for common users. In order to overcome these limitations, this paper presents a novel SHREC challenge track focusing on text-based fine-grained retrieval of 3D animal models. Unlike previous SHREC challenge tracks, the proposed task is considerably more challenging, requiring participants to develop innovative approaches to tackle the problem of text-based retrieval. Despite the increased difficulty, we believe that this task has the potential to drive useful applications in practice and facilitate more intuitive interactions with 3D objects. Five groups participated in our competition, submitting a total of 114 runs. While the results obtained in our competition are satisfactory, we note that the challenges presented by this task are far from being fully solved. As such, we provide insights into potential areas for future research and improvements. We believe that we can help push the boundaries of 3D object retrieval and facilitate more user-friendly interactions via vision-language technologies.Comment: arXiv admin note: text overlap with arXiv:2304.0573

CHẾ TẠO VÀ TÍNH CHẤT CỦA VẬT LIỆU TỔ HỢP GRAPHENE – ỐNG NANO CÁCBON – HẠT NANO VÀNG

In this work, a composite nanomaterial consisting of graphene (Gr), double-wall carbon nanotube (DWCNTs) and gold nanoparticles (AuNPs), designated as DWCNTs-AuNPs-Gr was synthesized via the thermal chemical vapour deposition technique. The morphology and electrical and electrochemical properties of the material were characteried by using field emission scanning electron microscopy, Raman spectroscopy, four-probe sheet resistance measurement, and cyclic voltammetry (CV). The average sheet resistance value of DWCNTs-AuNPs-Gr is 549 W/sq, 2.3 times lower than that of graphene. The current response of a DWCNTs-AuNPs-Gr-modified electrode in a 2 mM K3[Fe(CN)6]/K4[Fe(CN)6] solution with 0.1 M PBS is 15.79 µA, 1.48 times higher than that of a graphene-modified electrode and 2.57 times higher than that of a bare electrode. The DWCNTs-AuNPs-Gr material can be used for electrochemical biosensors to detect various bioelements.Trong công trình này, màng tổ hợp của vật liệu graphene (Gr) – ống nano cácbon hai tường (DWCNT) và hạt nano kim loại vàng (AuNPs) (DWCNT-AuNPs-Gr) đã được chế tạo bằng phương pháp lắng đọng pha hơi nhiệt hóa học (CVD). Hình thái học bề mặt và các tính chất điện, điện hóa của vật liệu tổ hợp đã được khảo sát thông qua kính hiển vi điện tử quét phát xạ trường, phổ Raman, điện trở bốn mũi dò và kỹ thuật quét thế vòng (CV). Với nồng độ DWCNTs 0,3 g/L và tốc độ quay phủ 4000 vòng/phút, vật liệu DWCNTs-AuNPs-Gr có điện trở bề mặt giảm 2,3 lần so với màng Gr và đạt khoảng 549 W/sq; dòng đỉnh đáp ứng trong dung dịch 2 mM K3[Fe(CN)6]/K4[Fe(CN)6] trong 0,1 M PBS đạt 15,79 µA tại 50 mV/s, cao gấp 1,48 lần so với điện cực biến tính màng Gr và gấp 2,57 lần so với điện cực trần. Vật liệu DWCNTs-AuNPs-Gr có tiềm năng ứng dụng trong cảm biến điện hóa để phát hiện các phần tử sinh học khác nhau

Rapid decrease of malaria morbidity following the introduction of community-based monitoring in a rural area of central Vietnam

<p>Abstract</p> <p>Background</p> <p>Despite a successful control programme, malaria has not completely disappeared in Vietnam; it remains endemic in remote areas of central Vietnam, where standard control activities seem to be less effective. The evolution of malaria prevalence and incidence over two and half years in a rural area of central Vietnam, after the introduction of community-based monitoring of malaria cases, is presented.</p> <p>Methods</p> <p>After a complete census, six cross-sectional surveys and passive detection of malaria cases (by village and commune health workers using rapid diagnostic tests) were carried out between March 2004 and December 2006 in Ninh-Thuan province, in a population of about 10,000 individuals. The prevalence of malaria infection and the incidence of clinical cases were estimated.</p> <p>Results</p> <p>Malaria prevalence significantly decreased from 13.6% (281/2,068) in December 2004 to 4.0% (80/2,019) in December 2006. <it>Plasmodium falciparum </it>and <it>Plasmodium vivax </it>were the most common infections with few <it>Plasmodium malariae </it>mono-infections and some mixed infections. During the study period, malaria incidence decreased by more than 50%, from 25.7/1,000 population at risk in the second half of 2004 to 12.3/1,000 in the second half of 2006. The incidence showed seasonal variations, with a yearly peak between June and December, except in 2006 when the peak observed in the previous years did not occur.</p> <p>Conclusion</p> <p>Over a 2.5-year follow-up period, malaria prevalence and incidence decreased by more than 70% and 50%, respectively. Possibly, this could be attributed to the setting up of a passive case detection system based on village health workers, indicating that a major impact on the malaria burden can be obtained whenever prompt diagnosis and adequate treatment are available.</p

The insecticide resistance status of malaria vectors in the Mekong region

<p>Abstract</p> <p>Background</p> <p>Knowledge on insecticide resistance in target species is a basic requirement to guide insecticide use in malaria control programmes. Malaria transmission in the Mekong region is mainly concentrated in forested areas along the country borders, so that decisions on insecticide use should ideally be made at regional level. Consequently, cross-country monitoring of insecticide resistance is indispensable to acquire comparable baseline data on insecticide resistance.</p> <p>Methods</p> <p>A network for the monitoring of insecticide resistance, MALVECASIA, was set up in the Mekong region in order to assess the insecticide resistance status of the major malaria vectors in Cambodia, Laos, Thailand, and Vietnam. From 2003 till 2005, bioassays were performed on adult mosquitoes using the standard WHO susceptibility test with diagnostic concentrations of permethrin 0.75% and DDT 4%. Additional tests were done with pyrethroid insecticides applied by the different national malaria control programmes.</p> <p>Results</p> <p><it>Anopheles dirus s.s</it>., the main vector in forested malaria foci, was susceptible to permethrin. However, in central Vietnam, it showed possible resistance to type II pyrethroids. In the Mekong delta, <it>Anopheles epiroticus </it>was highly resistant to all pyrethroid insecticides tested. It was susceptible to DDT, except near Ho Chi Minh City where it showed possible DDT resistance. In Vietnam, pyrethroid susceptible and tolerant <it>Anopheles minimus s.l</it>. populations were found, whereas <it>An. minimus s.l</it>. from Cambodia, Laos and Thailand were susceptible. Only two <it>An. minimus s.l</it>. populations showed DDT tolerance. <it>Anopheles vagus </it>was found resistant to DDT and to several pyrethroids in Vietnam and Cambodia.</p> <p>Conclusion</p> <p>This is the first large scale, cross-country survey of insecticide resistance in <it>Anopheles </it>species in the Mekong Region. A unique baseline data on insecticide resistance for the Mekong region is now available, which enables the follow-up of trends in susceptibility status in the region and which will serve as the basis for further resistance management. Large differences in insecticide resistance status were observed among species and countries. In Vietnam, insecticide resistance was mainly observed in low or transmission-free areas, hence an immediate change of malaria vector control strategy is not required. Though, resistance management is important because the risk of migration of mosquitoes carrying resistance genes from non-endemic to endemic areas. Moreover, trends in resistance status should be carefully monitored and the impact of existing vector control tools on resistant populations should be assessed.</p

Parasite egg contamination of water and air in a suburban area of Hanoi, Vietnam

Contamination of water and air by soil-transmitted helminth eggs was investigated in a small village located in the suburbs of Hanoi, Vietnam. Water samples were collected from 29 households, two schools, two kindergartens, one restaurant, three ponds and 23 ditch sites during the rainy season. Water samples were also collected at the same places, except for one household and one restaurant, during the dry season. The water samples collected from households, schools, kindergartens and restaurant were comprised of well-water and rain-water. These samples included both water filtrated with sand and gravel and non-filtrated water. Two-liter water samples were examined for helminth eggs by either a centrifugation or flotation method. The contamination of air by helminth eggs was assessed by the method of Kroeger et al. (1992). Eggs in air were trapped on adhesive tapes hanging in rooms and in the area around 29 houses, two schools, two kindergartens, one restaurant and 18 utility poles. Out of 63 water samples collected from households in the rainy season, helminth eggs were found in four water samples; one from non-filtrated well-water and three from filtrated well-water samples. The one non-filtrated water sample contained six eggs of Toxocara sp., while the three filtrated water samples contained one egg each of Trichuris sp., Trichiuris sp. and Taenia sp. No eggs were found in the water samples collected from schools, kindergartens or the restaurant in the rainy season. All water samples collected from ponds and ditches in the rainy season contained many helminth eggs. The eggs found were Ascaris sp., Trichuris sp., Toxocara sp., Ascaridia galli, hookworm, Taenia sp. and Fasciola sp. Examination of the adhesive tapes hanging in the air showed that four sites were contaminated by helminth eggs, i. e. one site near the house, two sites near the school and one site at a utility pole. The species of eggs found were Trichuris sp., Ascaridia galli and Taenia sp. The number of eggs found on tapes was only one or two. In the dry season, a few samples of well-water and rain-water collected from the residential area were contaminated with helminth eggs, and all samples collected from ponds and ditches contained many eggs of various species similar to those collected in the rainy season. The present study clearly indicates that, in our study area, the villagers were subject to infection from soil-transmitted helminthes directly and indirectly through water