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.
Trang 1EFFECTIVENESS 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 3 months (98.68%) The effectiveness of larvicide ABATE 1SG has been proven more than 3 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 3 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-year-old 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
Trang 2Aedes 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
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
METHODS
1 Study target
- Water storage containers and larvae
of Aedes in household 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
2 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:
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 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, 1 month and 3 months after application: from August to November 2014
* Sample size and sampling method:
- 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:
Trang 3Z1 - α/2 p.q.f
n = -
D2 p1 + p2
among them: p = -
2
q = 1-p
f = (Zα/2 + Zβ)2
D = [p1 - p2]
n: Number of water storage containers
applied in the study
p: Container index (CI)
p1: The rate before intervention
(approx 80%)
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):
p1 - p2
EI = - x 100
p1
p1 = CI before application
p2 = CI after application
- Indicator formulas and investigation methods were followed by Ministry of Health Procedures [6, 7]
* Materials and application techniques:
- Chemicals and dosage:
+ 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: 1 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
1 Assessment after application
Table 1: CI before and after application
Intervention group (n = 348)
Control group (n = 345)
CI
Comparison
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 2 groups (p > 0.05)
Trang 4After 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)
3 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)
2 Assessment of EI
Table 2: Comparison of EI between control and intervention groups
Time of assessment
Assessing EI in the intervention group, it reached 100% after 24 hours It maintained 100% after a month and after 3 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 3 months
This result is also consistent with a study by National Institute of Hygiene and Epidemiology (2003): ABATE 1SG with a dose of 1 g/10 liters, which removes 100% of
larvae of Aedes 1, 2, 3, 4 days of age [5]
Trang 53 Assessment of HI and BI
Table 3: Comparison of HI
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 3 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
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 3 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)
Trang 6In 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 2 months;
there was only one water storage
container discovered with a few larvae
After 3 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 3 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 3 months (98.68%)
The effectiveness of ABATE 1SG larvicide
keeps an high level after 3 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 3 months
REFERENCES
1 WHO Asia-Pacific dengue program
managers meeting World Health Organization
2008
2 WHO Global strategy for dengue
prevention and control 2012 - 2020 Dengue Bulletin (WHO) 2012, Vol 36, pp.240-241
3 WHO Temephos in drinking-water: Use
for vector control in drinking-water Sources and Containers, http://www.who.int/water_ sanitation_health/dwq/chemicals/temephos/en /index.html, 15/6/2010 2 2009
4 Ministry of Health List of insecticides
and disinfectants permitted to register for the use, restricted use and prohibited use in Vietnam Circular No 25/2011/TT-BYT dated 23/6/2011 2011
5 National Institute of Hygiene and Epidemiology Study on the effectiveness of
larvicide Temephos (Abate 1%) for dengue mousquito larvae 2003
6 Ministry of Health Guideline of dengue
1499/QD-BYT dated 17/5/2011 2011
7 Ministry of Health Guideline of dengue
surveillance and control Decision No 3711/QD-BYT dated 19/9/2014 2014
8 Usavedee Thavara, A.T, Jakkrawam Chompoosri, Morteza Zaim et al Laboratory
and field evaluation of novaluron, a new acylurea insect growth regulator, against Aedes aegypti (Diptera: Culicidae), http://lib.bioinfo.pl/ pmid:14714674, 12/12/2009 2003
9 George L, Lenhart A, Toledo J, Lazaro
A, Han W.W, Velayudhan R, et al Community-
effectiveness of temephos for dengue vector control: A systematic literature review PLOS Neglected Tropical Diseases 9 (9): e0004006, https://doi.org/10.1371/journal.pntd.0004006
2015