Objectives: To assess the effectiveness of ABATE 1SG larvicide in dengue prevention, in two wards of Rachgia city, Kiengiang province. Method: Intervention study in community, with an intervention group and a control group to assess the ffectiveness of ABATE 1SG larvicide application to water storage containers (excluding drinking water) in Rachgia city, Kiengiang province.
Journal of military pharmaco-medicine no2-2018 EFFECTIVENESS OF ABATE 1SG LARVICIDE IN DENGUE PREVENTION IN RACHGIA CITY, KIENGIANG PROVINCE Bui Khanh Toan*; Nguyen Huy Nga* Nguyen Xuan Truong*; Nguyen Van Chuyen** SUMMARY Objectives: To assess the effectiveness of ABATE 1SG larvicide in dengue prevention, in two wards of Rachgia city, Kiengiang province Method: Intervention study in community, with an intervention group and a control group to assess the effectiveness of ABATE 1SG larvicide application to water storage containers (excluding drinking water) in Rachgia city, Kiengiang province Result: The effectiveness of ABATE SG larvicide was 100% after 24 hours; 100% after a month and maintains a high efficiency after months (98.68%) The effectiveness of larvicide ABATE 1SG has been proven more than months even in the outdoor condition of the water storage containers whose levels are often changed due to the weather Conclusion: ABATE 1SG kills completely Aedes larvae in water storage containers after 24 hours and could eliminate Aedes larvae during the next months in the outdoor conditions of the water storage containers * Keywords: Aedes; Larvae; Mosquitoes; ABATE 1SG; Rachgia city, Kiengiang province INTRODUCTION Every year, about 100 million cases of dengue haemorrhagic fever are reported around the world Children under 15-yearold represent more than 90% of the cases; and dengue fever causes 5% of their deaths The disease mainly circulates in tropical and subtropical regions, especially in Southeast Asia and the Pacific, including Vietnam [1] Although scientific researchs focus on the disease over the past many years, to date, no vaccines have been developed and there is no specific treatment for dengue Therefore, the vector is nowaday the most effective measure to control dengue fever [2] Abate 1SG (a trading name is ABATE 1SG) is based on the active ingredient temephos and most trusted temephos larvicide It is a non-systemic organophosphorus insecticide, mainly used as a larvicide to control vector-born diseases by mosquitoes, such as dengue and malaria According to the World Health Organization, ABATE 1SG is recommended to use as a kind of larvicide in public health programs, which can be also used for drinking water storage containers [3] In Vietnam, ABATE 1SG has been approved by Ministry of Health (MOH) for insecticide use in non-drinking water storage containers [4] In 2003, National Institute of Hygiene and Epidemiology conducted the study on the effectiveness of ABATE 1SG application to larvae in laboratory The results showed that ABATE 1SG killed 100% of larvae in laboratory [5] ** Ministry of Health *** Military Medical University Corresponding author: Bui Khanh Toan (khanhtoandr@gmail.com) Date received: 31/07/2017 Date accepted: 22/01/2018 99 Journal of military pharmaco-medicine no2-2018 Aedes mosquitoes is the main vector of dengue in Vietnam Mosquitoes lay eggs in man-made water storage containers Its eggs grow into larvae and hatch into mosquitoes The removal of larvae can actually eliminate mosquitoes In recent years, there have been many measures to remove larvae such as organizing environmental sanitation campaigns, collecting waste, using biological agents, insecticides but the use of ABATE 1SG larvicide has not yet been realized widely in Vietnam for dengue prevention, especially in the South where rainy season lasts months and people have the habit to use water storage containers - The selected water storage containers requires these criteria: not for drinking water; not for useful aquatic or marine products; no natural biological agents which are resistant to larvae, such as mesocyclops; water storage containers should be fairly stable in terms of location and storage volume, ensuring traceability throughout the study Dengue haemorrhagic fever occurs mainly in the South of Vietnam where Kiengiang is one of the provinces with the highest dengue cases Assessing the effectiveness of ABATE 1SG larvicide in dengue vector control in the field in Rachgia city, Kiengiang province needs to have the effective measure in dengue prevention and therefore, to encourage community to use ABATE 1SG widely in the South of Vietnam as well as in the whole country This study aimed: To assess the effectiveness of ABATE 1SG larvicide in the field in Rachgia city, Kiengiang province, as well as its long-term effect The selected location are two wards in Rachgia city, Kiengiang province: Anhoa ward (intervention group) and Anbinh ward (control group) The communities in two wards have similar habitat conditions Study design Intervention study in community, under an intervention group and a control group, pre-post comparison of the effectiveness of the intervention * Study location: * Study time: The study was conducted from April 2014 to November 2014 - Select study location and intervention arrangment: from April to August 2014 - Investigation before application; application of ABATE 1SG; investigation 24 hours, month and months after application: from August to November 2014 * Sample size and sampling method: METHODS Study target - Water storage containers and larvae of Aedes in household water storage containers 100 - Sample units are water storage containers regardless of types and volumes Sample size is calculated by the formula for the sample size of the intervention study: Journal of military pharmaco-medicine no2-2018 Z1 - α/2 p.q.f n = -D2 p1 - p2 EI = x 100 p1 p1 + p2 among them: p = q = 1-p p1 = CI before application p2 = CI after application f = (Zα/2 + Zβ)2 D = [p1 - p2] n: Number of water storage containers applied in the study before * Materials and application techniques: - Chemicals and dosage: p: Container index (CI) p1: The rate (approx 80%) - Indicator formulas and investigation methods were followed by Ministry of Health Procedures [6, 7] intervention p2: The rate after intervention, is expected to be 10% With a confidence interval is 95% and a sample effect is 95%, the minimum sample size of each group is 200 * Indicators: - Indicators of larvae: House index (HI), container index (CI), Breteau index (BI) - The efficiency index (EI): + ABATE 1SG: contains temephos 1%, product of BASF AG company (Federal Republic of Germany) The license by Ministry of Health VNDP-HC-194-08-09, WHO/SIF/40.R1/1999 quality standards + Dosage: g ABATE 1SG/10 liters of water + ABATE 1SG is packed in a plastic jar with a weight of 100 g - Application techniques: followed the manufacturer’s catalogue RESULTS AND DISCUSSION Assessment after application Table 1: CI before and after application CI Before application Intervention group (n = 348) Control group (n = 345) Comparison Number % Number % 290 83.3 293 84.9 p > 0.05 After 24 hours 0.0 293 84.9 p < 0.01 After month 0.0 274 79.4 p < 0.01 After months 1.1 250 72.5 p < 0.01 The results of the investigation before intervention in Anhoa showed that in the intervention group, the percentage of water storage containers with Ae aegypti larvae was 83.3%, in the control group, it was 84.9% There was no difference in the percentage of water storage containers with Ae aegypti larvae between groups (p > 0.05) 101 Journal of military pharmaco-medicine no2-2018 After 24 hours, investigation of larvae showed that the percentage of water storage containers with larvae in the intervention group decreased from 83.3% to 0.0% In the control group, the percentage of water storage containers with larvae did not decrease in comparison with before application Also, during the application day in the intervention group, in the control area of Anbinh ward, health authority implemented an environmental sanitation campaign, that is killing larvae on a large scale with a participation of many health workers and collaborators Although health workers and collaborators have been informed about the intervention study, and the water storage containers in the control group have been marked, some of the water storage containers were still removed larvae by the collaborators and health workers if possible However, there was a big difference in the percentage between the water storage containers with larvae in the control group and in the intervention group one, which was statistically significant (p < 0.01) The results of the larval investigation one month after application in Anhoa ward indicated that in the intervention group, all of the water storage containers did have no larvae, whereas in the control group, the percentage of water storage containers with larvae was 79.4% The difference between the intervention and control groups was statistically significant (p < 0.01) months after application, in Anhoa ward - the intervention group, larvae return to only 1.1% of its water storage containers, while in the control group, the percentage of water storage containers with larvae was 72.5% The difference between the intervention and the control groups was statistically significant (p < 0.01) Assessment of EI Table 2: Comparison of EI between control and intervention groups Time of assessment Control group (n = 345) Intervention group (n = 348) CI EI (%) CI EI (%) Before application 84.9 - 83.3 - 24 hours after application 84.9 0 100 month after application 79.4 6.48 100 months after application 72.5 14.61 1.1 98.68 Assessing EI in the intervention group, it reached 100% after 24 hours It maintained 100% after a month and after months, the EI was staying around 98.68% In the control group, despite an addition of the campaign of environmental sanitation against larvae, the EI was only 6.48% after a month and 14.61% after months This result is also consistent with a study by National Institute of Hygiene and Epidemiology (2003): ABATE 1SG with a dose of g/10 liters, which removes 100% of larvae of Aedes 1, 2, 3, days of age [5] 102 Journal of military pharmaco-medicine no2-2018 Assessment of HI and BI Table 3: Comparison of HI HI Intervention group Control group Comparison 83.49 86.89 p > 0.05 24 hours after application 86.89 p < 0.01 month after application 71.84 p < 0.01 months after application 1.89 60.68 p < 0.01 Before application Before application, comparing HI between two groups, there was no difference between the intervention group and the control group (p > 0.05) But after the application, HI showed a marked difference between the two groups In the intervention group, after 24 hours, HI decreased to zero and remained zero after a month Meanwhile, in the control group, HI values were 86.89 and 71.84, respectively The differences in HI between the two groups at two different timemarks were both statistically significant (p < 0.01) After months, the HI in the intervention group was still very low (1.89) On the other hand, in the control group, the HI was 60.68 There was a big difference in HI between these two groups and the difference was statistically significant (p < 0.01) Table 4: Comparison of BI BI Intervention group Control group Comparison 136.79 142.23 p > 0.05 24 hours after application 142.23 p < 0.01 month after application 133.01 p < 0.01 months after application 1.89 121.36 p < 0.01 Before application Comparison of the BI in the table above shows that between the two groups, before application, the BI between the intervention and control groups was not significantly different (p > 0.05) After application, in the intervention group, the BI was reduced to zero at the time of the investigation after 24 hours and after a month After months, the BI was low Meanwhile, in the control group, the BIs were consistently high in all three investigations, 142.23, 133.01, and 121.36, respectively The differences in BI between the intervention and control groups in all three investigations were statistically significant (p < 0.01) 103 Journal of military pharmaco-medicine no2-2018 In the world, studies on the effectiveness of ABATE 1SG larvicide have also been conducted and shown to be effective Usavadee Thavara et al conducted a study in three villages in Kanchanaburi province of Thailand for drinking water storage containers The results showed that: in the group of ABATE 1SG application, all water storage containers did not have larvae after 48 hours and after months; there was only one water storage container discovered with a few larvae After months, the percentage of water storage containers without larvae reached 77.5% From the results of the study, the authors conclude that a single-use of ABATE 1SG can prevent Aedes larvae in water storage containers efficiently for at least months in the field under normal water conditions [8] CONCLUSION The effectiveness of ABATE 1SG larvicide is 100% after 24 hours; maintains 100% after a month, and keeps a high percentage after months (98.68%) The effectiveness of ABATE 1SG larvicide keeps an high level after months even in the outdoor conditions of water storage containers whose levels are changed due to the weather RECOMMENDATIONS Abate 1SG can be used as a larvicide in dengue prevention and control for residential areas with full attention Households are advised to use ABATE 1SG widely for non-drinking water storage containers, including outdoor water storage containers The effectiveness of ABATE 1SG larvicide lasts up to months 104 REFERENCES WHO Asia-Pacific dengue program managers meeting World Health Organization 2008 WHO Global strategy for dengue prevention and control 2012 - 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Kiengiang is one of the provinces with the highest dengue cases Assessing the effectiveness of ABATE 1SG larvicide in dengue vector control in the field in Rachgia city, Kiengiang province needs to... ABATE 1SG larvicide in the field in Rachgia city, Kiengiang province, as well as its long-term effect The selected location are two wards in Rachgia city, Kiengiang province: Anhoa ward (intervention... the minimum sample size of each group is 200 * Indicators: - Indicators of larvae: House index (HI), container index (CI), Breteau index (BI) - The efficiency index (EI): + ABATE 1SG: contains