Evaluation of the efficacy of Bistar 80SC by residual application in dengue vectors control in the North of Vietnam

Background: Two species, Aedes aegypti and Aedes albopictus are the main intermediate vectors of transmission of the dengue viruses in Vietnam. Insecticide applications by different methods that may help interrupt the spread of dengue outbreaks. Many different groups of insecticides have been used for dengue vector control. Some recent studies revealed that Aedes vectors obscuring their resistance to insecticides at different levels. Therefore, a new insecticide formula is required for effective dengue vectors control. Objective: To evaluate the efficacy of Bistar 80SC by residual application in suppression of Aedes species in a northern province of Vietnam. Subject and methods: Bistar 80 SC with a component of Bifenthrin 80g/L was evaluated by residual application in suppression of 2 Aedes species in vitro and in an intervention commune of Hien Giang, Thuong Tin district and a control commune of Van Mo, Ha Dong town, Ha Tay province from March, 2004 to June, 2004. Results: WHO Bifenthrin paper test kit was effective at the concentration of 37.5mg/m2 and over with Aedes aegypti vectors ranged from 80% to 100% mortality in the North, In other words, Aedes vector remains susceptible to Bifenthrin in the region. The mortality on wood surface after 60 minutes of exposure to Bistar 80SC at concentrations of 25mg/m2 by using residual application was higher than those on brick walls. Up to 100% Aedes aegypti was killed after 60 minutes in exposure and remains in effect until the end of the third months and one month with Aedes albopictus. No side effects, to the sprayer and humans, livestock and environment caused by Bistar 80SC were reported in the intervention area. Conclusion: Bistar 80SC is suggested as a nominated alternative to effectively control the dengue outbreak by residual application.

Evaluation of the effectiveness of Interceptor bed net on controlling disease vectors Aedes aegypti in Vietnam, 2007

Background: Using insecticides is considered as a temporary and rapid method for interrupting the disease transmission through disease vectors such as dengue. The insecticide Fendona, when absorbed into bed nets, is slowly released and rapidly knocks out, kills or repels mosquitoes as they come into contact with the bed net. Objectives: To evaluate the effectiveness of the Interceptor bed net (a unique textile-finishing product developed by BASF, Singapore PTE. LTD, that were coated with the Fendona insecticide) on controlling disease vector Aedes aegypti. Subjects and method: An experimental trial was carried out at the National Institute of Hygiene and Epidemiology and in the field of Hien Giang commune, Thuong Tin district, Ha Tay province. The changes of efficacy of Interceptor bed net were compared by not washing with washing at the different levels. Results: The unwashed bed nets can knock out and kill Aedes aegypti mosquitoes by 50% after 20 minutes of exposure on every trial. About 90-100% of total mosquitoes were killed after the first 30 minutes of exposure. Bed net\u2019s efficacy remains until 24 hours of the trial. The recovery rate of the mosquito is 0%. The same results were also observed after 90 days, 36 days and 18 days of bed nets being laundered. However, after 9 day of washing, the bed nets can only kill the mosquitoes up to about 90-95% of the total after the first 30 minutes of exposure. It also reached 100% of killing after 24 hours. However, its efficacy was conversely reduced with regard to the increase of laundry times. Conclusion: The density of adult mosquitoes and larvae for Aedes aegypti was significantly reduced in the intervention areas, even at zero level in comparison to the control sites. The insecticide had no side-effect or any stimulation to users, community, poultry, cattle and environment in the intervention sites.

Study fluctuation and confirmation of Japanese encephalitis vector in Ha Nam province, 2006-2007 \r\n', u'\r\n', u'

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.

Evaluation of the efficacy of cynoff 25 ULV to eradicate aedes species, dengue vectors in Vietnam, 2004

Background: Dengue fever remains a major public health problem in Vietnam. It was transmitted through two main Aedes species, namely Aedes aegypti and Aedes albopictus in which Aedes aegypti played the predominant role in transmitting the dengue viruses (accounted for 94% of the Aedes genus).Different groups of insecticides have been widely used in the community. As a consequence, it increased the resistance level of Aedes vectors to the insecticides. Therefore, a new synthesized insecticide was required for future control and prevention of dengue epidemics. \r\n', u'Objectives: To evaluate the efficacy of Cynoff 25 ULV in suppressing Aedes species in Vietnam. \r\n', u'Subjects and methods: The study was conducted in the entomology laboratory and in the fields of Ha Tay province. ULV spraying was implemented in Hiengiang commune, Thuongtin district, in comparison with a control area, Van Mo commune in Ha Dong town.\r\n', u'Results and conclusions: : Cynoff 25 ULV had a high efficacy that kills over 90% of 2 dengue vector species, namely Aedes aegypti and Aedes albopicctus after 24 hours exposure at the distance of 30 meters from the brass nozzle of a STIHL SR 400 sprayer. In the field trials, Cynoff 25 ULV also had high efficacy in killing Aedes species, e.g. 100% of Aedes species were killed after spraying and the effects lasted for 3 months for Aedes aegypti and one month for Aedes albopictus species. The insecticide had no side-effects or any other adverse effects to humans, livestock and the environment in the intervention areas. \r\n', u'

Key containers of Aedes species, vectors to transmit dengue viruses in Nam Dinh province, 2007

Background: Dengue Fever/Dengue Hemorrhagic Fever (DF/DHF) has emerged as one of the most important public health concerns in Viet Nam in recent years. Key breeding containers plays an important role in driving dengue vector control in the public. Objectives: The research was conducted to discover the dengue situation, its vectors and key containers to make relevant recommendations in reducing effectively the vector population. Subjects and methods: Two hundred households in two communes of Nam Dinh province (100 in each studied commune) were selected randomly. Vectors collected from the field were identified using mosquito key. The number of dengue larvae and mosquitoes were directly counted or adjustment methods were used to estimate the true number in each type of water storage facility. Results: In Minh Thuan commune, Ae. albopictus larvae were mainly concentrated in jars (49%) and discards (59%), most of Ae. aegypti was found in cement tanks with a volume more than 500L (72%). In Trung Dong commune, larvae of Ae. albopictus concentrated in jars (40%) and discards (25%) and aquariums (15%), while most of the Ae. aegypti larvae was discovered in cement tanks with volumes more than 500L (86%). Mosquito density index of Ae. albopictus in Trung Dong and Minh Thuan communes was 0.56 and 0.38, respectively. The Aedes larvae, houses for larvae and Breteau index were nearly at the threshold of dengue epidemic occurrence for Ae. aegypti and over a certain threshold for Ae. albopictus. Some recommendations were provided to help reduce the dengue vectors. Conclusion: Investigation of key mosquito larvae in water containers was useful in driving the effective dengue vector control. Further studies are required to evaluate the impact and methods to manage water containers in the local area.

Respiratory airway resistance of asthmatic children from 6 to 10 years old at Respiratory department of Saint-Paul hospital

Background:Asthma is a chronic disease. Its characteristic is a chronic process of infection on respiratory leading to obstructed respiratory airway. In order to evaluate the obstructed respiratory disorder on asthma children, there are many various methods in which two methods are been applied widely: measure respiratory function and measure the resistance of respiratory airway. Objectives:This study aims to learn aboutthe respiratory airway resistance of asthmatic children from 6 to 10 years old at Respiratory Department of Saint-Paul hospital. Subjects and method: A retrospective, cross sectional and descriptive study was conducted on 135 children with asthma hospitalized at the Pulmonary Division at the Hospital Saint - Paul from January to October 2006. Results:- Value through thoracic pulmonary resistance in children asthmatics:The average resistance of the respiratory tract had inspiration: 7.31 \xb1 2.14 hPa.s L -1 . The average resistance of the respiratory tract had expiration: 8.30 \xb1 2.42 hPa.s L -1. There was no significant difference in the resistance of the respiratory tract between boy and girl children. Conclusion: Thoracic pulmonary resistance decreased with age from 6 to 10 years. After the inspiration of Ventolin, resistance of the respiratory tract decreased of 22.2% in the inspiration and 17.5 in expiration. The difference was significant.

Clinical observation on treating optic burns due to lime in children

During 2 years (1993-1994), 46 children with 66 burnt eyes due to lime (46.8%) were treated. Internal therapy and surgical procedure were described. Results were evaluated and recommendations were given

Preparation of in-house reference for diphtheria vaccine

The IVAC in-house reference for diphtheria vaccine has an average dry weight of 51.18 mg/ampoule, 2.85% moisture content (standard 3%). The reference vaccine kept at -20oC for 60 months still remains stable with 333.84 IU/ampoule. Kept at 37oC for 1, 2, 4, 6 and 8 weeks still remains stable. Potency of diphtheria component of DPT vaccine controlled by in-house reference vaccine and international standard vaccine gave the same results.

Preparation of in-house reference for tetanus vaccine

The IVAC in-house reference for tetanus vaccine has an average dry weight of 51.18 mg/ampoule, 2.85% moisture content (standard 3%). The reference vaccine kept at -20oC for 60 months still remains stable with 333.84 IU/ampoule. Kept at 37oC for 1, 2, 4, 6 and 8 weeks still remains stable. Potency of tetanus vaccine produced at IVAC controlled by in-house reference vaccine and international standard vaccine gave the same results.