Background: Japanese Encephalitis (JE) virus is a leading cause of encephalitis in children with high mortality and complication. JE is a dangerous infectious disease via Culex mosquitoes. Objective: To identify the density of some mosquitoes and vectors that transmit JE virus in Ha Nam province. Subject and Method:There were 30.333 mosquitoes including 05 genera and 15 species which were collected at night from April 2006 to March 2007 in the following communes: Tanson (midland area) Hungcong (plain area) and Liemchinh (suburban area). Results: A total of 06 Culex species, the highest rate is Culex tritaeniohychus (41.20%); Culex annulus (15.56%); other Culex species occupied around 0.15% -2.49%. In these communes, the density of Culex tritaeniohychus was higher than Culex annulus. They were found to be active all year round, but the highest density of Culex tritaeniohychus and Culex annulus is 5.86 and 2.15, respectively in April and fall to 4.35% and 1.71% in July. The collected mosquitoes during April, May, June and July includes 133 and 28 Culex tritaeniohychus and Culex annulus pools, respectively; all were to be processed for the isolation of Japanese Encephalitis (JE) virus. There were 12 Culex tritaeniohychus and 2 Culex annulus pools which were collected in Tanson commune yielding positive. Conclusion: The results were confirmed that Culex tritaenioohychus and Culex annulus are the major vectors that transmit JE virus in Ha Nam, 2006 - 2007. All 14 JE virus strains were isolated from collected mosquito pools during April, May and June; whereas JE virus strain was not yet isolated from collected mosquito pool in July. Thus, in order to control JE disease, it is necessary to control JE vectors in April, May and June.
Vector ; Culex tritaenioohychus ; Japanese encephalitis ; Ha Nam

Background: In recent years, some arbo viruses which causes acute encephalitis syndrome (AES) have been identified in serveral countries in the world such as Chandipura virus belonging to Rhabdoviridae family in India, Banna virus belonging to Reoviridae family in China. In Vietnam, apart from Japanese Encephalitis Virus which is considered as main cause of AES, there are a few intestinal viruses like Herpes symplex virus type 1 and 4 and Nam Dinh virus considering other causes of AES. Objective: To identify the hyppothesis that one virus strain parasitizing in mosquito in Gia Lai province causes AES in order to provide more information about virus strains which cause AES in Vietnam. Subjects and method: Aedes albopictus cell line clone C6/36 was used for the isolation of virus in 43 cerebrospinal fluid samples of patients who were treated in Gia Lai hospital, from January/2005 to July/2005. Result and Conclusion: One virus strain from a 3-year old girl in Gia Lai province was isolated in 2005. The virus coded 05VN225 has the morphology similar to other viruses belonging to Reoviridea family.The nucleic acid sequence of the virus was checked with specific primers of alphavirus and flavirus groups, Nam Dinh virus and Conti virus group B (reovirus) of the Reoviridae. The positive result was confirmed with reovirus primers. This member of the Reoviridae family was isolated from acute encephalitis syndrome in Vietnam in 2005. Further study on pathology of the virus is very necessary.
Encephalitis ; Arbovirus/ epidemiology ; pathology ; Reoviridae/ growth & ; development ; pathogenicity ;

Background: Recently Japanese Encephalitis (JE) virus type 1 has surfaced and is co-circulated with JE virus type 3 in the northern areas of Viet Nam, so a sensitivity of JE viral antigen genotype 3 to detect IgM is required. Objectives: To compare the sensitivity of JE viral antigen genotype 1 and 3 to detect IgM against the JE virus. Materials and method: 783 cerebrospinal fluid and serum samples from viral encephalitis cases from 1999-2005 were collected and examined by MAC-ELISA for JE viral antigen genotype 1 and 3. Results: The agreement on the diagnosis of these kinds of antigen was 99.7% and the sensitivity of JE viral antigen genotype 3 was higher than that of genotype 1. Thus, JE viral antigen genotype 3 could be considered as the selected antigen for JE diagnosis in Viet Nam. IgM titer determined by JE viral antigen genotype 1 was higher than that of genotype 3 in 2003 and 2005 and lower in 1999, 2000, 2001, 2002 and 2004. Conclusion: The dominant phenomenon of JE viral genotypes differing over the years might be due to the interaction of the virus and its vectors. Further study is required to clarify this observation.
Japanese Encephalitis ; antigen

Background: In recent year, Japanese Encephalitis Virus (JEV) genotype 1 has been detected among isolates from mosquitoes and pig\u2019s blood samples in northern Viet Nam, but there has been no information on the presence of this genotype in the Central, Southern and Highland regions. Objectives: This study aims to detect the Japanese encephalitis genotype 1 in various different geographic regions of Viet Nam. Material and method: Sequence analysis\u2019s of whole E gene of 18 strains isolated from human, mosquitoes and pig\u2019s blood during 2001-2007. Results: 7 strains isolated from pig\u2019s blood and mosquito samples in the Northern, Central, Southern and Highland fell into genotype 1, but 11 others isolated from humans in the Northern and Central regions belonged to genotype 3. Conclusion: This is the first time that JEV genotype 1 was detected in the central, northern, highland Viet Nam and further studies on genotype 1 causing human diseases needs to be carried out.\r\n', u'\r\n', u'
Virus ; Japanese Encephalitis ; genotype 1 ; E gene.

Background: Currently, tracking, monitoring insecticide resistance of mosquitoes transmitting disease is an urgent need.\r\n', u'Objectives: To evaluate resistance to insecticide of three mosquito species: Aedes Aegypti, Culex quinquefasciatus and culex tritaenyorhynchus in Ha Noi\r\n', u'Subject and method: Aedes Aegypti, Culex quinquefasciatus culex tritaenyorhynchus mosquito species was collected from some districts of Ha Noi city. These mosquito species was tested sensitivity with 4 insecticides: permethrin 0.75%, lambda-cyhalothrin 0.05%, alpha-cypermethrin 30mg/m2 and DDT 4.0%.\r\n', u'Results: Three main vectors of Dengue fever, Japanese Encephalic and Filariasis mosquitoes were found in a very high density in some areas of Ha Noi City. Aedes aegypti mosquitoes in the districts of Thanh Xuan (TX), Dong Da (DD) and Hoang Mai (HM) was found highly resistant to permethrin, alpha - cypermethrin, lambda - cyhalothrin and DDT with the mortalities rates of 51 % (TX) and 59%(DD); 70%(HM); 90%, 82% and 96%; 74%, 54% and 59%; 1 %, 8% and 32%, respectively. \r\n', u'Culex tritaenyorhynchus was found also highly resistant to permethrin with the mortality rate of 29%, alphacypermethrin - 18%, lambdacyhalothrin - only 3% and DDT x36%. Culex quinquefasciatus was found also highly resistant to those insecticides. \r\n', u'Conclusion: Other insecticides should choose to replace the chemicals used in this experiment to control, kill mosquitoes when epidemics occur.\r\n', u'
Insecticides ; resistance ; Aedes Aegypti ; Culex quinquefasciatus ; culex tritaenyorhynchus

Vaccines are the most effective and cost-efficient method for preventing diseases caused by infectious pathogens. Despite the great success of vaccines, development of safe and strong vaccines is still required for emerging new pathogens, re-emerging old pathogens, and in order to improve the inadequate protection conferred by existing vaccines. One of the most important strategies for the development of effective new vaccines is the selection and usage of a suitable adjuvant. Immunologic adjuvants are essential for enhancing vaccine potency by improvement of the humoral and/or cell-mediated immune response to vaccine antigens. Thus, formulation of vaccines with appropriate adjuvants is an attractive approach towards eliciting protective and long-lasting immunity in humans. However, only a limited number of adjuvants is licensed for human vaccines due to concerns about safety and toxicity. We summarize current knowledge about the potential benefits of adjuvants, the characteristics of adjuvants and the mechanisms of adjuvants in human vaccines. Adjuvants have diverse modes of action and should be selected for use on the basis of the type of immune response that is desired for a particular vaccine. Better understanding of current adjuvants will help exploring new adjuvant formulations and facilitate rational design of vaccines against infectious diseases.
Adaptive Immunity ; Adjuvants, Immunologic ; Communicable Diseases* ; Humans ; Immunity, Innate ; Vaccine Potency ; Vaccines

Background: Mosquitoes and pigs play important roles in maintaining and increasing the Japanese Encephalitis (JE) virus in nature and which is then transmitted to humans. Thus, surveillance of the JE infection frequency in the pig population may predict the human JE cases. \r\n', u'Objectives: The study aimed to determine IgG antibody against the JE virus in the pig population in Hanam province \r\n', u'Subjects and methods: The study included 1791 pig serum samples collected from 3 districts of Hanam province from Apr 2006 to Mar 2007. GAC-ELISA technique was used to determine the JE virus infection in the swine population.\r\n', u'Results: The average positive rate in pig population was 34.9 % (626/1791); with the highest frequency occurring in the summer (37.7%- 84.0 %), co-incident with the JE season in Northern Vietnam. On the contrary, in winter JE case are rare, frequency of IgG antibody against JE virus in the swine population was low, ranging from 9.2% to 22.0.%. \r\n', u'Conclusions: These results have shown the ecologically close relationship between the amplification of the JE virus in the swine population, vector and JE cases in northern Vietnam. \r\n', u'
Japanese encephalitis ; pig population ; GAC-ELISA.

Background: IgM antibody capture ELISA (MAC-ELISA) technique has been widely applied for Japanese Encephalitis Virus (JEV) diagnosis. So far rare internationally commercial kits are available. Thus, the international evaluation of the kit is required as per the recommendation of the WHO. Objectives: To evaluate the quality of the IgM antibody capture ELISA diagnostic kit for JEV produced by the Vietnam National Institute of Hygiene and Epidemiology (NIHE). Subjects and method: In this study, NIID kit was used as control to check the kit from NIHE. Both NIHE and NIID kits were used to detect JEV IgM among 38 serum and 6 CFS samples, which belongs to 5 sample groups (JE patients group, dengue patients group, other viral encephalitis patients group, Tick Born Encephalitis (TBE) patient group and healthy JE vaccinated donors group). Results: The detection of JEV IgM by NIHE kit was concurrent with the NIID kit. There is no positive with the JE in the groups of Dengue patients, TBE, other virus encephalitis patients and JE vaccinated donors. Conclusion: MAC-ELISA kit of NIHE can be used for different diagnosis of JEV and Dengue virus (both viruses are in Flavivirus genus), as well as other viruses caused by encephalitis.
IgM antibody ; ELISA diagnostic kit ; Japanese encephalitis virus

Background: Coronavirus disease 2019 (COVID-19) vaccine acceptance is influenced by the trusted recommenders. This survey examined the public references, concerns, and trust in seven groups of recommenders regarding COVID-19 vaccine in Vietnam. Materials and Methods: A cross-sectional survey was conducted on 1,579 participants between April 16 and July 16, 2021. Participants’ references, concerns, and responses to vaccination recommendations made by government officials, employers, physicians, nurses, pharmacists, senior family members, and religious leaders were captured using a selfadministered questionnaire. Results: Rates of trust ranged from 18.5% to 89.1%. The highest rates were attributable to government (89.1%) and physicians (85.9%). Less than half of participants would accept the vaccines if pharmacists (45.5%), nurses (44.7%), employers (42.4%), senior family members (28.1%), and religious leaders (18.4%) recommended it. Only 37.6% of participants thought that vaccines were safe for them, while 57% were unsure. Most participants would wait and see how people respond to the vaccines before getting vaccinated (91.5%), preferred to receive the vaccines at public hospitals (88.6%), and were concerned about vaccine effectiveness (86.9%) and side effects (76.4%), while 61.8% were concerned about vaccine cost. Conclusion Focusing on the personal benefit and relying on the government, physicians, and social role models would make the vaccine advertising campaigns more effective. If annual vaccinations were needed, providing the community with affordable vaccines would be an appropriate, long-term solution to ensure vaccination coverage in low-resource countries like Vietnam. Further studies are needed to examine reasons for the public reference of vaccination centers which may help in improving their confidence in getting the vaccine, regardless of the settings.

Background: Vietnam is among the few countries that were successful in the fight against the first wave of coronavirus disease 2019 (COVID-19). However, subsequent domestic outbreaks of COVID-19 continue to occur. To sharp the community education program to guarantee the final success in the fight against COVID-19 in Vietnam and comparable countries, we examined the levels of COVID-19 knowledge and associated predictors among university students in Vietnam. Materials and Methods: A cross-sectional study was conducted on all students enrolling at Phenikaa University using a self-developed questionnaire consisted of 20 questions regarding COVID-19's risk factors, transmission routes, symptoms, and prevention. Results: Among 728 participants, 40.9% were male, 63.2% studied health-related majors, and 18.1% lived alone. Correct response rates ranged from 25.3% to 98.9% across 20 questions. Only 51.9% (378/728) of participants had good knowledge levels. Studying health majors (adjusted odds ratio [AOR] 0.547, 95% confidence interval [CI] 0.398 - 0.751, P <0.001), and living with the seniors (AOR 0.612, 95% CI 0.389 - 0.963, P= 0.034) or with friends (AOR 0.405, 95% CI 0.252 – 0.650, P <0.001) were negatively associated with a poor level of COVID-19 knowledge. Conclusion The proportion of university students having good knowledge levels is suboptimal. It is essential to improve the quality of COVID-19 education with a more focus on not only the preventive measures, but also the disease itself. More studies are needed to improve the level of COVID-19 knowledge among those living alone or do not study healthrelated majors.