EFFECT OF TEMPERATURE, WATER ACTIVITY AND CINNAMON ESSENTIAL OIL ON THE GROWTH OF ASPERGILLUS FLAVUS LA01 AND ASPERGILLUS NIGER LA04

The aim of the study was to evaluate the influence of temperature, water activity and cinnamon essential oil on the growth of Aspergillus flavus LA01 and Aspergillus niger LA04 and these factors were further optimized to inhibit their growth. Both strains were isolated by Potato Dextrose Agar medium (PDA) and identified by sequencing method from rice collected in Long An province. Evaluating these factors’ inhibition on the fungi growth was based on growth rate at the various points of water activity (aw) (v/v) such as 0.85, 0.90, 0.95, 0.99 and at 25 oC, 30 oC, 37 oC, 42 oC; at various concentrations of the oils 0 %, 1 %, 3 %, 5 %, 7.5 %, 10 % and 15 % at  30 oC incubated for 5 days - the disc diffusion method. The results showed that             30 oC and aw = 0.95 - 0.99 were optimum conditions for Aspergillus flavus LA01 and Aspergillus niger LA04 growth. However, at 42 oC, 37 oC and aw = 0.85 - 0.9 could control Aspergillus flavus LA01 and Aspergillus niger LA04 growth. At concentration of 10 - 15% cinnamon essential oils (EOs), 30 oC and aw = 0.9 - 0.95 could also inhibit them

Incidence of dengue and chikungunya viruses in mosquitoes and human patients in border provinces of Vietnam

Background: Dengue virus remains a major threat in Vietnam, while chikungunya virus is expected to become one. Surveillance was conducted from 2012 to 2014 in Vietnam to assess the presence of dengue and chikungunya viruses in patients hospitalized with acute fever in five Vietnam provinces neighboring Lao PDR and Cambodia. Surveillance was extended to mosquitoes present in the vicinity of the patients' households. Results: A total 558 human serum samples were collected along with 1104 adult mosquitoes and 12,041 larvae from 2250 households. Dengue virus was found in 17 (3%) human serum samples and in 9 (0.8%) adult mosquitoes. Chikungunya virus was detected in 2 adult mosquitoes (0.18%) while no chikungunya virus was detected in humans. Differing densities of mosquito populations were found, with the highest in the Long An Province border with Cambodia. Long An Province also displayed the lowest rate of infection, despite a very high Breteau Index, high human population density and presence of the main cross border road system. The highest incidence was found in Dac Nong Province, where the Breteau and Container indices were the second lowest. Dengue virus was detected in five Aedes albopictus, three Aedes aegypti and one Culex vishnui. Chikungunya virus was detected in two Ae. aegypti. All infected mosquitoes belonged to haplotypes described in other parts of the world and a number of novel haplotypes were found among uninfected mosquitoes. Conclusions: Dengue is considered to be regularly introduced to Vietnam from Cambodia, mostly through human movement. The data reported here provides a complementary picture. Due to intensive international trade, long-distance transportation of mosquito populations may play a role in the regular importation of dengue in Vietnam through Ho Chi Minh City. It is important to decipher the movement of mosquitoes in Vietnam, not only at the Lao PDR and Cambodia borders but also through international trade routes. Mosquito surveillance programs should address and follow mosquito populations instead of mosquito species

ẢNH HƯỞNG CỦA DỊCH CHIẾT VI KHUẨN LAM ĐẾN NHÂN GIỐNG IN VITRO CÂY LAN HOÀNG THẢO GIẢ HẠC (Dendrobium anosmum Lindl.)

Protocorms of 4-week-old Dendrobium anosmum Lindl. were used as initial material for in vitro propagation. The stock extract of Arthrospira sp. was prepared by grinding 1 g of fresh biomass in 100 mL of distilled water. The in vitro propagation results show that the cyanobacterial extract has the effect of enhancing shoot multiplication and rooting of Dendrobium anosmum. An MS basal medium supplemented with 6 g·L–1 agar, 30 g·L–1 saccharose, and 1.5 mg·L–1 BAP in combination with 20 mL·L–1 cyanobacteria extract was suitable for protocorm multiplication with a protocorm cluster diameters of 2.43 cm. An MS medium supplemented with 6 g·L–1 agar, 30 g·L–1 sucrose, and 1.0 mg·L–1 BAP combined with 20 mL·L–1 cyanobacterial extract was optimal for shoot multiplication. The number of shoots/explant reached 4.7 and a shoot height of 1.37 cm. An MS medium supplemented with 6 g·L–1 agar, 30 g·L–1 sucrose, and 1.5 mg·L–1 NAA in combination with 30 mL·L–1 cyanobacteria extract was the most suitable for rooting with 4.87 roots/bud; the root length was 0.74 cm, and the shoot height was 2.76 cm. These results would open up the application of cyanobacterial extract to reduce costs in plant tissue culture technology.Protocorm của cây lan Hoàng thảo Giả hạc (Dendrobium anosmum Lindl.) bốn tuần tuổi được sử dụng để làm vật liệu khởi đầu cho nhân giống in vitro. Dịch chiết gốc vi khuẩn lam Arthrospira sp. được tạo thành bằng cách nghiền 1 g sinh khối tươi trong 100 mL nước cất. Kết quả cho thấy dịch chiết vi khuẩn lam có tác dụng tăng cường sự nhân chồi và ra rễ của cây lan Hoàng thảo Giả hạc nuôi cấy in vitro. Môi trường MS cơ bản bổ sung 6 g·L–1 agar, 30 g·L–1 saccharose và 1,5 mg·L–1 BAP kết hợp với 20 mL·L–1 dịch chiết vi khuẩn lam thích hợp cho sự nhân protocorm và môi trường tối ưu cho nhân chồi. Đường kính cụm protocorm thu được là 2,43 cm. Môi trường MS cơ bản bổ sung 6 g·L–1 agar, 30 g·L–1 saccharose và 1,0 mg·L–1 BAP kết hợp với 20 mL·L–1 dịch chiết vi khuẩn lam là môi trường tối ưu cho nhân chồi, số chồi/mẫu đạt 4,7; chồi cao 1,37 cm. Môi trường MS cơ bản bổ sung 6 g·L–1 agar, 30 g·L–1 saccharose và 1,5 mg·L–1 NAA kết hợp với 30 mL·L–1 dịch chiết vi khuẩn lam thích hợp nhất cho tạo rễ từ chồi in vitro với 4,87 rễ/chồi; chiều dài rễ là 0,74 cm và chiều cao chồi là 2,76 cm. Kết quả này sẽ mở ra triển vọng ứng dụng dịch chiết vi khuẩn lam giúp giảm chi phí trong công nghệ nuôi cấy mô tế bào thực vật

Transmission of Japanese Encephalitis (JE) Virus in Gia Luong District, Ha Bac Province, Vietnam, After Je Vaccination, 1993-1994

A total of 15,183 children under 10 years old (37% of target population) was immunized with JE vaccine in Gia Luong District, Ha Bac Province, Vietnam, in 1993 to 1994. JE virus transmission was investigated by swine antibody survey and virus isolation from field mosquitoes. By the hemagglutination inhibition (HI) test, 73-90% of swine were antibody positive all year round, with high geometric mean titer (GMT) of 92.67-95.14 in May and June. By suckling mouse brain inoculation, 6 JE virus strains were isolated from Culex tritaeniorhynchus and Cx. vishuni, as well as laboratory reared F1 from field-caught Cx. tritaeniorhynchus. Serodiganosis by IgM-capture ELISA (MAC-ELISA) carried out on 60 of 85 clinical encephalitis cases detected 43 positives (71.66%). All these serologically confirmed JE cases had not been vaccinated. The results supported the vaccine efficacy to prevent overt JE

Overseas Treatment of Latent Tuberculosis Infection in US-Bound Immigrants.

Seventy percent of tuberculosis (TB) cases in the United States occur among non-US-born persons; cases usually result from reactivation of latent TB infection (LTBI) likely acquired before the person's US arrival. We conducted a prospective study among US immigrant visa applicants undergoing the required overseas medical examination in Vietnam. Consenting applicants >15 years of age were offered an interferon-γ release assay (IGRA); those 12-14 years of age received an IGRA as part of the required examination. Eligible participants were offered LTBI treatment with 12 doses of weekly isoniazid and rifapentine. Of 5,311 immigrant visa applicants recruited, 2,438 (46%) consented to participate; 2,276 had an IGRA processed, and 484 (21%) tested positive. Among 452 participants eligible for treatment, 304 (67%) initiated treatment, and 268 (88%) completed treatment. We demonstrated that using the overseas medical examination to provide voluntary LTBI testing and treatment should be considered to advance US TB elimination efforts

Tourist motivation and activities : a case study of Nha Trang, Vietnam

The study investigates tourist’s motivation with a segmentation approach in order to give an understanding of the theory of motivation in general and the motivation factors influencing consumer decision making in a tourism context in particular. The segmentation based on motivation, which was supported by a factor-cluster analysis, was carried out on a primary survey of 446 international tourists visiting the city of Nha Trang, Vietnam in order to identify tourists segments. The research findings identified two tourist segments based on motivation, referred to as “Traditional Tourists” and “Nightlife and Positive Recommenders”, with social and intellectual motives found as the strongest motivations. There are significant differences found between the two segments in perceptions of activities, satisfaction, and intentions of revisitation and recommendation of the destination to others. The findings of the study indicate that the Nightlife and Positive Recommenders segment has trends higher than those of the Traditional Tourists segment in terms of all factors found, perceptions of activities, satisfaction, recommendation the destination to others and revisit intention. Based on the findings of the study, some policy recommendations are given to the local tourism marketers and managers in order to develop the local tourism industry appropriately