Monthly Report on Dengue Entomological Surveillance Vol. 02 :Issue 05
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Transcript of Monthly Report on Dengue Entomological Surveillance Vol. 02 :Issue 05
MONTHLY REPORT ON DENGUE ENTOMOLOGICAL SURVEILLANCE A publication of the National Dengue Control Unit
Ministry of Health, Sri Lanka
National Dengue Control Unit-Ministry of Health, Sri Lanka Public Health Complex, 555/5, Elvitigala Mawatha, Narahenpita, Colombo 05.
Tel : +94(0)112368416 / 7 Fax: +94(0)11 2369893 Email: [email protected]
Web : http://www.dengue.health.gov.lk
Vol.02 Issue No 05 May 2015
Role of Entomological surveillance in
Dengue Control
Dengue fever (DF)/ Dengue Haemorrhagic fever
(DHF) is a mosquito borne viral disease which is
endemic in Sri Lanka. Entomology is defined as the
scientific study of insects, a branch of Zoology. Entomological surveillance is a scientific process to
understand the dynamics of the disease transmitting
vector.
Dengue is transmitted by female mosquitoes of
Aedes aegypti (Linnaeus) and Aedes albopictus
(Skuse). A.aegypti is the primary and the epidemic
causing vector of DF/DHF and it is a highly
domesticated and anthropophilic very efficient
vector mosquito while Aedes albopictus is the
secondary vector that is important in maintaining an
epidemic. The life cycle of the Aedes mosquito is as
follows (Fig 1.):
Fig 1- Life cycle of dengue mosquito
Life cycle consists of water stages i.e. eggs, pupa
and larvae and non-water stages i.e. adult mosquito.
Based on existing evidence, control of water stages
of the life cycle is cost effective. Therefore under
entomology surveillance more emphasis is given
for studying of water stages of life cycle of the
mosquito.
The objectives of vector surveillance are to
determine breeding sites, temporal and spatial
distribution, interventions that are used for dengue
vector control seasonal population fluctuations,
feeding and resting habits (vector bionomics/
behaviour), and effectiveness of vector control to
collect data for early warning and forecasting
dengue outbreaks / epidemics.
Dengue vector surveillance is carried out both at
sentinel sites, routine surveillance areas and spots
(spot checks).
Commonly used vector surveillance methods are
larval surveys (both larvae and pupae). Here, the
basic sampling unit is the house or premise. During
the survey, all potential dengue vector breeding
sites that are prevalent in and around the selected
houses/ premises should be examined for Aedes
larvae.
Once identification is completed, larval density
indices are calculated for A.aegypti and A.
albopictus separately, and combine for Aedes
aegypti and A.albopictus, in order to give the vector
density in the area. The indices, namely, Container
index (CI), House/premise index (HI) and Breteau
index (BI) are used to give the vector density.
High container index of a particular type of
containers indicates the importance of that
container type as a dengue vector breeding site and
the vector control interventions need to be directed
to eliminate such types of containers immediately.
Cut-off points of larval density indices, container
types and the most productive container types also
need to be considered in dengue prevention and
control. In Sri Lanka, HI and BI (A.aegypti) >3 is
an indication for dengue transmission and
application of appropriate dengue vector
prevention/ control interventions.
Appropriate utilization of entomology surveillance
data would be helpful in successful control of
dengue by implementing targeted interventions.
Compiled by :Dr.Sinha De Silva
Contents Page
1. Role of Entomological surveillance in Dengue Control
2. Island wide Entomological Surveillance Summary -2014 April
3. Entomological Forecast
1
2
2
Comments and contributions for publication in the MRDES Sri Lanka are welcome. Prior approval should be obtained from the NDCU before publishing data in this publication.
MRDES Sri Lanka - Vol.02 Issue No 05 May 2015
Table 1: Dengue Entomological Surveillance - 2015 April Summary
Pro
vin
ce
Dis
tric
t
No. of Premises Percentage Positivity by type of containers
Insp
ecte
d
Fo
un
d
po
siti
ve
%
Po
siti
ve
Dis
card
ed
rece
pta
cles
Wat
er s
tora
ge
con
tain
ers
Cem
ent
tan
ks
Co
ncr
ete
slab
Nat
ura
l
A/C
& R
P
& O
Wel
ls
Oth
ers
WP
Colombo 1,377 165 11.98 35% 13% 1% 1% 3% 0% 14% 0% 33%
Colombo MC 225 15 6.67 9% 3% 0% 0% 0% 0% 0% 0% 88%
Gampaha 610 124 20.33 31% 18% 0% 0% 9% 0% 1% 0% 41%
Kalutara 1,817 181 9.96 61% 7% 0% 0% 11% 0% 2% 0% 19%
NWP Kurunegala 1,393 41 2.94 33% 33% 6% 0% 0% 0% 8% 0% 20%
Puttalam 150 23 15.33 54% 11% 0% 0% 13% 0% 3% 0% 19%
UP Monaragala 3,037 194 6.39 66% 15% 0% 0% 0% 0% 1% 0% 18%
Badulla 641 52 8.11 35% 14% 9% 11% 3% 3% 2% 0% 23%
CP
Matale 871 50 5.74 33% 0% 41% 0% 0% 7% 4% 0% 15%
NuwaraEliya * * * * * * * * * * * *
Kandy 1,354 67 4.95 27% 17% 17% 0% 2% 8% 0% 0% 29%
EP
Batticaloa 2,080 108 5.19 14% 35% 6% 0% 5% 4% 0% 8% 28%
Kalmunai 860 14 1.63 42% 16% 27% 0% 0% 0% 5% 5% 5%
Trincomalee 155 4 2.58 57% 14% 0% 0% 29% 0% 0% 0% 0%
Ampara 300 6 2.00 16% 67% 17% 0% 0% 0% 0% 0% 0%
NCP Anuradhapura 650 72 11.08 52% 1% 5% 0% 1% 0% 18% 0% 23%
Polonnaruwa 154 13 8.44 30% 15% 15% 0% 0% 5% 30% 0% 5%
SGP Kegalle 1,008 145 14.38 47% 17% 5% 0% 10% 4% 1% 0% 16%
Rathnapura 1,202 88 7.32 49% 11% 4% 0% 8% 4% 0% 0% 24%
SP
Galle 167 15 8.98 50% 9% 9% 0% 23% 0% 4% 0% 5%
Matara 300 33 11.00 53% 10% 3% 0% 3% 5% 8% 0% 18%
Hambantota 932 53 5.69 28% 10% 3% 0% 0% 5% 7% 0% 47%
NP
Jaffna 300 21 7.00 65% 12% 17% 0% 0% 0% 6% 0% 0%
Mannar 950 134 14.11 7% 88% 0% 0% 0% 0% 1% 0% 4%
Killinochchi 418 21 5.02 14% 0% 0% 0% 0% 0% 0% 0% 86%
Vavuniya 802 31 3.87 43% 27% 7% 0% 0% 0% 10% 0% 13%
Mullativu 439 58 13.21 21% 24% 17% 0% 0% 0% 0% 0% 38%
Sri Lanka 22,192 1,728 7.79 38% 18% 5% 0% 5% 2% 4% 0% 28%
Ad
dre
ss:
Director,
National Dengue Control Unit,
Public Health Complex,
555/5, Elvitigala Mawatha,
Colombo 05.
Address:
Key: This report is based on the weekly returns sent by Entomological Assistants (EAA) to N DCU. P & O- Ponds and Ornamentals; R –
Refrigerators ; * No data ; Others- Tyres, Roof gutters and other miscellaneous places (eg. Tube wells, Earth pipes, Water meters, etc)
Entomological Forecast of High-Risk Areas
RDHS MO(O)H
Colombo Kolonnawa,Moratuwa, Maharagama, Homagama
Kaluthara Horana, Aluthgama
Rathnapura Rathnapura Ps, Kuruwita
Gampaha Katana, Divulapitiya
Badulla Badulla MC
Matara Malimbada
Kandy Akurana
Kegalle Yatiyanthoya, Galigamuwa
Batticaloa Batticaloa
Kurunegala MC Kurunegala
NB:
Entomological
surveillance data for the
month of April 2015
done by MRI
entomology teams has
not received