Original Article
Entomological situation analysis for Aedes-borne diseases threat
in rural Thiruvananthapuram, Kerala
R. Rajendran,1 S.B. Anusree,1 M.S. Sasi 2
1National Centre for Disease Control, Ministry of Health and Family Welfare, Government of
India, Thiruvananthapuram, 2Directororate of Health Services, Government of Kerala,
Thiruvananthapuram, Kerala, India
Corresponding author: R. Rajendran, Email: rajendran061@gmail.com
Journal of Experimental Biology and Zoological Studies. 2(1): p 53-65, Jan-Jun 2026.
Received: 20/10/2025; Revised: 31/10/2025; Accepted: 12/11/2025; Published: 01/01/2026
__________________________________________________________________________________
Abstract
Kerala’s diverse geo-climatic, environmental, and spatio-temporal conditions create a very
congenial haven for a wide variety of pathogenic microorganisms and their vectors. This fosters
the epidemiological convergence of disease-causing agents and vectors, enabling them to
breed, proliferate, establish perpetual habitats, and cause various vector-borne diseases
(VBDs). Of these VBDs, dengue accounts for the highest number of cases and fatalities,
followed by chikungunya. Notably, the Thiruvananthapuram District has reported the highest
incidence of dengue fever for over a decade. Since most studies on Aedes-borne diseases
(ABDs) have focused on urban areas, specifically the Thiruvananthapuram Municipal
Corporation area, an entomological situation analysis was conducted in rural areas to determine
entomological indices that could provide critical and sufficient indications of the potential of
VBDs outbreaks. This report presents the results and key inferences derived from the study,
which may be helpful in implementing timely and effective preventive interventions by public
health authorities.
Keywords: Adult premise index, Aedes-borne diseases, breeding preference ratio, Breteau
index, container index, house index, vector-borne diseases, vector control.
___________________________________________________________________________
Introduction
Newly emerging as well as re-emerging vector-borne diseases (VBDs) pose a formidable
public health threat in Kerala especially during the last few decades. This contributes to the
loss of many lives as well as socio-economic liabilities to individuals as well as families and
the state exchequer. The public health system is in continuous strain especially due to sustained
prevalence and frequent outbreaks ozikaf Aedes VBDs like dengue, chikungunya, and Zika.
Kerala with its warm and humid tropical climate naturally provides an ideal environment for
breeding and proliferation of mosquitoes. Moreover, rapid urbanization, accompanied by
widespread consumeristic ‘throw-away’ habits among the general public, has created diverse
and abundant breeding habitats for vector mosquitoes across the state. Consequently Aedes-
borne disease (ABD) incidences are rapidly increasing in Kerala irrespective of rural-urban or
geodemographic divides.[1]
In recent years, the onset of monsoon brings more fear than relief due to the apprehension of
deadly epidemic outbreaks. Among these, dengue and chikungunya, the most dreaded fevers,
have caused scores of deaths and incapacitated many victims with prolonged illness that
prevents them from carrying out their livelihood. Over the past two decades (2006 to 2024),
the state of Kerala has experienced a high prevalence of dengue fever (DF), with a total of
1,12,144 confirmed cases and 661 deaths. There are also a significant number of unconfirmed
cases of DF. Chikungunya has been a major health concern between 2006 and 2024, with 4,610
confirmed cases and 1,35,690 suspected cases. Kerala reported its first confirmed Zika case in
July 2021, and a total of 118 laboratory- confirmed cases have since been recorded. The
majority of Zika cases were from the Thiruvananthapuram district. This is notable because,
although dengue and other ABDs are now widespread and almost endemic throughout Kerala,
Thiruvananthapuram continues to be the most severely affected district.[2]
The adage ‘prevention is better than cure’ holds true, both individually and socially. For
instance, checking the outbreak of devastating fevers in advance would be formidably
advantageous for both safeguarding community health and saving the public exchequer. The
prevalence and proliferation of dengue, chikungunya and Zika can only be checked or
controlled through strategies focused on source reduction and vector management.
Accordingly, motivated by the pressing need of the present situation, a comprehensive
entomological situation analysis was undertaken in selected target areas of
Thiruvananthapuram District, Kerala, to investigate the potential environmental factors
contributing to the proliferation of vector mosquitoes and the increasing incidence of VBDs.
Materials and Methods
Target Area
A total of six rural panchayats in Thiruvananthapuram District were randomly selected for the
study (Table 1 and Figure 1).
Table 1: Details of selected study areas in Thiruvananthapuram District
Surveys conducted / Panchayaths
No. of households searched
Household Survey-1:
Malayinkeezhu (Ward Nos. I & II)
107
Kattakkada (Ward Nos. X &XI)
120
Kadinamkulam (Ward No. XI)
105
Household Survey-2:
Andoorkonam (Ward Nos. V &VII)
120
Mangalapuram (Ward Nos. XII & XV)
100
Pothencode (Ward No. XII)
110
Figure 1: Study areas in Thiruvananthapuram District
Study design
The aim of the study was to assess the dimensions and dynamics of vector mosquito activity in
the target areas and to ascertain the possibility of any impending vector-borne disease (VBD)
epidemic in the study areas. The study was carried out in over two phases. The first phase
during April to May 2023 across three randomly selected panchayath areas: Malayinkeezhu,
Kattakada and Kadinamkulam and the second phase during December 2023 in another three
rural locations: Andoorkonam, Mangalapuram, and Pothencode. The number of randomly
selected households chosen for the survey from each Panchayath is given in Table 1.
Entomological investigation
The entire household premises, both interior and exterior, was examined for two primary
purposes: (1) to identify goods, materials, and circumstances that could serve as vector
mosquito habitats, and (2) to collect direct evidence through the enumeration of immature
stages (larvae and pupae) and adult mosquitoes. Standard scientific methods were employed to
calculate various entomological indices.[3]
Potential containers searched included any natural, organic, or synthetic materials capable of
holding water and accessible to gravid female Aedes mosquitoes. A larval survey was
performed to identify and classify Aedes mosquito breeding habitats.[4] Active breeding habitats
were defined as those containers that had immature stages (larvae, pupae, or both). The
immature forms of mosquitoes were collected using devices appropriate to the container type,
such as dippers, pipettes, and strainers.[4] Data on all containers were documented using a pre-
designed proforma.
Field-collected immatures (larvae and pupae) were initially kept in separate, labelled vials and
examined at the National Centre for Disease Control (NCDC) laboratory in
Thiruvananthapuram. For immediate identification, approximately 10% of the fourth instar
larvae were dissected, and their comb scales and pecten teeth were examined under a dissection
microscope. The remaining larvae and all pupae were kept in separate rearing cages; and the
adults that subsequently emerged were identified. The specimens were identified following
standard keys.[5]
Field Protocol: Calculation of traditional Aedes larval indices
The data collected from the study were subsequently analysed to calculate standard
entomological indices. Aedes larval indices thus calculated include the House Premises Index
(HPI), Container Index (CI), and Breteau Index (BI). These indices were used to estimate
infestation levels. In addition, the Pupal Index (PI), Adult Aedes Index (AAI), and Breeding
Preference Ratio (BPR) were calculated for a complete assessment of the extent of vector
mosquito prevalence and the resultant potential public health threat.
The various entomological indices were calculated using the following equations.
1. HPI = Number of houses infested with Aedes immatures X 100
Number of total houses inspected
2. CI = Number of containers positive for Aedes immatures X 100
Total number of containers checked
3. BI = Number of containers positive for Aedes immatures X 100
Total number of houses inspected
The study also sought to estimate PI, AAI, and BPR. The PI is a key entomological measure
used to evaluate the adult mosquito population, especially species that transmit diseases such
as dengue. This index is a more accurate predictor of adult mosquito density than traditional
larval indices. The AAI measures the Aedes mosquito population in a specific area. This crucial
metric helps assess the level of infestation and guides the implementation of targeted vector
control interventions. The following equations were used to calculate the PI and AAI.
1. PI = Number of pupae collected X 100
Total No. of houses inspected
2. AAI = Number of house premises found positive for adult female Aedes X 10
Number of total houses inspected
The BPR measures a mosquito’s preference for laying eggs in a specific container or habitat.
To assess this, three indices for every breeding habitat were calculated, one for each container
grouping category. The available containers index (ACI) is the ratio of the total count of a
specific container type in each category to the overall number of containers found on the
premises. The contribution index to breeding sites (CIB) represents the proportion of positive
containers in each category compared to all positive containers present on the premises. [6] The
BPR for each container type was determined by dividing CIB by ACI. A BPR value exceeding
one indicates a stronger preference for that container type as a breeding site, while a value
below one suggests that it is less preferred.
Information, Education, and Communication (IEC) intervention
The household survey has been complemented with an intervention activity involving
awareness education programs and distribution of IEC materials among the target community.
Observations and Results
Household Survey - 1
During the first Aedes survey, only nine of the 332-house premises searched in three randomly
selected rural areas of Thiruvananthapuram District (Malayinkeezhu, Kattakkada,
Kadinamkulam) were found positive for Aedes immatures, resulting in an overall HPI of 2.7%.
A house premises is a specific type of premises used for residential purposes, encompassing a
house along with its associated land, grounds, outbuildings, and other fixed structures.
The locality-wise Aedes survey revealed the highest HPI in Kadinamkulam (4.8%), followed
by Malayinkeezhu (2.8%), and Kattakkada (0.8%) (Table 2). Of the total 669 water-holding
containers checked in the same Panchayath areas, only 10 were found to be positive for Aedes
larvae/pupae, yielding an average CI of 1.49%.
The locality-wise evaluation indicated that the CI was highest in Kadinamkulam Panchayath
area (2.2%), followed by Malayinkeezhu (2.0%), and Kattakkada (0.4%).
Panchayath-wise comparison revealed that Kadinamkulam Panchayath area recorded the
highest Breteau index (5.7), significantly higher than Malayinkeezhu (2.8) and Kattakkada
(0.8) (Table 2 and Figure 2).
Table 2: Household Survey - 1: Panchayath-wise entomological indices
Entomological indices
Name of the Panchayaths with Ward numbers
Malayinkeezhu
(Ward Nos. I & II)
Kattakkada
(Ward Nos. X & XI)
Kadinamkulam
(Ward No. XI)
Number of house premises
examined
107
120
105
House premises positive for
Aedes immatures
3
1
5
Number of containers
checked
152
247
270
Containers positive for
Aedes immatures
3
1
6
House premises index in %
2.8
0.8
4.8
Container index in %
2.0
0.4
2.2
Breteau index in %
2.8
0.8
5.7
Pupal index in %
0.0
0.0
1.9
Adult premises index in %
0.0
0.0
1.0
During the first household Aedes survey, pupae were found only in the Kadinamkulam Panchayath area,
where the PI was 1.9%. No Aedes pupae were collected from the positive containers examined in the
Malayinkeezhu and Kattakkada areas (Table 2).
The different types of water-holding containers or sources found on household premises,
including those positive for Aedes, are detailed in Table 3 for the selected localities. An
examination of 669 water-holding containers /sources found scattered around the household
premises of the surveyed areas revealed that plastic materials were the most common (28.4%),
followed by earthen containers (23.3%), metal objects (16.7%) and glass items (9.1%), with
other materials making up the remainder (Figure 3).
HPI- House premises index, CI- Container index, BI- Breteau index
Figure 2: Household Survey-1: Panchayat wise entomological indices
Table 3: Household Survey - 1: Total containers examined vs. containers found positive
Name of the Panchayaths and Ward numbers
Malayinkeezhu
(Ward Nos. I & II)
Kattakkada
(Ward Nos. X &XI)
Kadinamkulam
(Ward No. XI)
E
P
E
P
E
P
40
1
65
1
51
0
25
1
43
0
44
0
48
1
70
0
72
1
2
0
5
0
3
1
6
0
14
0
41
0
4
0
5
0
11
2
2
0
7
0
17
01
13
0
17
0
19
1
12
0
21
0
12
0
152
3
247
1
270
6
E=Examined, P=Positive for Aedes immatures
Figure 3: Proportionate distribution of various water-holding containers/sources identified
during Household Survey-1
2.8
0.8
4.8
2
0.4
2.2
2.8
0.8
5.7
Malayinkeezhu Kattakada Kadinamkulam
HPI(%) CI(%) BI
Earthen
23%
Metal
17%
Plastic/Leather
28%
Grinding stone
2%
Glass items
9%
Tyres
3%
Cement tanks
4% Fridge
7%
Wells
7%
It was found that the laboratory-reared adult mosquitoes and wild-caught specimens from the
specified localities revealed the presence of only Aedes albopictus. This finding is further
supported by the fact that no Aedes aegypti larvae or pupae were found in any containers across
the surveyed area.
From Household survey-1, it was observed that Aedes albopictus mosquitoes preferred to breed
in tyres and grinding stones (BPR 6.7 each). Cement tanks (2.6) and fridges (1.4) were found
to be less preferred breeding sites (Table 4 and Figure 4).
Table 4: Household Survey - 1: Breeding preference of Aedes mosquitoes in the target area.
Type of Breeding
sources
Examined
Positive for Aedes
immatures
Breeding preference
ratio
No.
ACI (%)
No.
CIB (%)
CIB %/ACI %
Earthen
156
23.3
2
20.0
0.9
Metal
112
16.7
1
10.0
0.6
Plastic/Leather
190
28.4
2
20.0
0.7
Grinding stone
10
1.50
1
10.0
6.7
Glass items
61
9.1
0
0.0
0.0
Tyres
20
3.0
2
20.0
6.7
Cement tanks
26
3.9
1
10.0
2.6
Fridge
49
7.3
1
10.0
1.4
Wells
45
6.7
0
0.0
0.0
ACI= Available container index, CIB= Contribution index to breeding sites
BPR= Breeding preference ratio
Figure 4: Household Survey-1: Breeding preference ratio of Aedes mosquitoes
in the target area
Household survey - 2
In the three sample wards, 18.5% of the surveyed households were at high risk of mosquito-
borne diseases, being Aedes-positive as indicated by containers holding mosquito immatures.
Andoorkonam Panchayath showed the highest positivity rate (HPI-20%), while Pothencode
and Mangalapuram Panchayaths reported successively lower, but still significant rates (Table
5). The CI was high across the entire area. The highest CI was recorded in Andoorkonam
(56.8%), followed by Pothencode (37.1%), and Mangalapuram (24.8%). A moderately high BI
was observed in both the Andoorkonam and Pothencode Panchayath areas, while the BI in
Mangalapuram (Ward Nos. XII andXV) was the lowest of the three (Table 5 and Figure 5).
The different types of containers/sources found on house premises, by locality, are presented
in Table 6. Of the total 302 water-holding containers examined for Aedes breeding,
Mangalapuram Panchayath accounted for the largest share at 36.1%, followed closely by
Earthern Metal Plastic/Le
ather
Grinding
stone
Glass
items Tyres Cement
tank Fridge Wells
BPR 0.9 0.6 0.7 6.7 0 6.7 2.6 1.4 0
0
1
2
3
4
5
6
7
8
BPR
Pothencode (34.8%), and then Andoorkonam (29.1%). The different types of water-holding
containers examined, and the proportion of each found positive for Aedes larvae and pupae, are
presented in Figure 6.
Table 5: Household Survey- 2: Panchayath-wise entomological indices
Field activities
Name of the Panchayaths (Ward numbers)
Andoorkonam
(Ward Nos. V,
VII)
Mangalapuram
(Ward Nos. XII & XV)
Pothencode
(Ward No. XII)
Number of house premises
examined
120
100
110
House premises positive for
Aedes immatures
24
16
21
Number of containers
checked
88
109
105
Containers positive for
Aedes immatures
50
27
39
House premises index in %
20.0
16.0
19.1
Container index in %
56.8
24.8
37.1
Breteau index in %
41.7
27.0
35.5
Pupal index in %
21.7
14.0
12.7
Adult Aedes Index in %
11.7
14.0
14.5
HPI- House premise index, CI- Container index, BI- Breteau index
Figure 5: Household Survey -2: Panchayath-wise entomological indices
Table 6: Household Survey - 2: Total containers examined vs. containers found positive
Name of the Panchayaths and Ward Numbers
Andoorkonam
(Ward Nos. V, VII)
Mangalapuram
(Ward Nos. XII &XV
Pothencode
(Ward No. XII)
E
P
E
P
E
P
19
12
8
4
29
11
9
7
5
3
14
3
43
20
44
19
37
15
0
0
1
0
4
3
11
5
50
0
8
2
2
2
1
1
4
3
2
2
0
0
3
1
2
2
0
0
6
1
88
50
109
27
105
39
E=Examined, P=Positive
20
16
19.1
56.8
24.8
37.1
41.7
27
35.5
Andoorkonam Mangalapuram Pothencode
HPI(%) CI(%) BI
Figure 6: Household Survey -2: Types of water-holding containers examined, showing the
proportion of each that tested positive for Aedes immatures.
Table 7: Household Survey -2: Breeding preference of Aedes mosquitoes in the target area.
Type of Breeding
sources
Examined
Positive for Aedes
immatures
Breeding preference
ratio
No.
ACI (%)
No.
CIB (%)
CIB %/ACI %
Earthen
56
18.5
27
23.3
1.3
Metal
28
9.3
13
11.2
1.2
Plastic/Leather
124
41.1
54
46.6
1.1
Grinding stone
05
1.7
03
2.6
1.5
Glass items
69
22.9
07
6.0
0.3
Tyres
07
2.3
06
5.2
2.3
Cement tanks
05
1.7
03
2.6
1.5
Fridge
08
2.7
03
2.6
1.0
ACI= Available container index, CIB= Contribution index to breeding sites
BPR=Breeding preference ratio
Figure 7: Household Survey - 2: Breeding preference of Aedes mosquitoes in the target area
Earthen Metal Plastic/Le
ather Grinding
stone Glass
items Tires Cement
tanks Fridge
positive 27 13 54 3 7 6 3 3
examined 56 28 124 5 69 7 5 8
0
20
40
60
80
100
120
140
160
180
200
Earthen Metal Plastic/L
eather
Grinding
stone
Glass
items Tyres Cement
tank Fridge
BPR 1.3 1.2 1.1 1.5 0.3 2.3 1.5 1
0
0.5
1
1.5
2
2.5
BPR
Out of the 116 Aedes-positive containers found during the post-monsoon survey in selected
Thiruvananthapuram Panchayath areas, 92.3% (114 containers) contained Aedes albopictus
immatures. The remaining 1.7% (2 containers) were positive for Aedes vittatus larvae. Species
identification was confirmed by microscopic examination of fourth instar larvae and validated
by observing the emerged adult mosquitoes from rearing cages. Neither the immatures nor the
adults of Aedes aegypti were detected in this study.
In the Household survey-2, Aedes albopictus in the selected localities showed a clear breeding
preference for tyres (2.3%), followed by cement tanks and grinding stones (1.5% each) (Table
7 and Figure 7).
Discussion
Aedes-borne diseases, primarily dengue, chikungunya and Zika, pose a significant and growing
public health threat in Kerala, across urban, peri-urban, and rural areas. The emergence and re-
emergence of ABDs in Kerala are driven by a combination of environmental, demographic,
and socio-economic factors that collectively foster ideal conditions for mosquito breeding and
disease transmission. [7] The year-round warm, humid climate, coupled with extensive
agricultural practices and increasing urbanization, contribute to a highly favourable
environment for the breeding and proliferation of Aedes mosquitoes in Thiruvananthapuram
District.
A high population density, irrespective of urban-rural divide, results in people living in close
proximity to mosquito breeding areas. This problem is compounded by the improper disposal
of solid wastes, especially non-degradable plastics, which creates innumerable new habitats for
Aedes mosquitoes. For more than two decades, recurring outbreaks of ABDs, such as dengue
and chikungunya, have posed significant public health challenges for Kerala state, particularly
in the Thiruvananthapuram District. In Kerala, the Zika virus infection was first reported in
Thiruvananthapuram in 2021. Since then, the state has reported over a hundred cases, with the
majority concentrated in the state capital, adding to an already precarious ADB situation.[8]
Thiruvananthapuram District, with the rest of Kerala, experiences four distinct seasons: a pre-
monsoon period of hot and humid weather (March to May); the Southwest Monsoon (June to
September), which brings heavy rains; the Northeast Monsoon (October to November) and a
post-monsoon season (December to February) with cold and pleasant weather. During the first
household Aedes survey, conducted in selected localities in Thiruvananthapuram District, 669
water-holding containers were identified on house premises. Scattered summer showers during
the survey period (April-May 2023) resulted in the accumulation of standing water in many of
the containers. This, coupled with poor adherence to household source reduction or container
emptying practices, likely led to the increased number of water-holding sites. While the average
number of water-holding containers per household premises was 2.02, the rate of Aedes
positive containers per house remained low at 0.03. This marked discrepancy suggests that
scattered rains, household water storage, and plant-watering on non-rainy days probably
contributed to the observed increase in the number of water-filled containers on the premises.
However, the combination of infrequent rainfall, hot weather, and high evaporation during dry
periods probably deterred the Aedes mosquitoes from ovipositing and further proliferation.
Traditional Aedes larval indices, or Stegomyia indices, are significant tools for public health,
as they provide a quantitative metric for assessing potential disease vector habitats and are
crucial for predicting the risk of dengue and other ABDs. The PI and AAI are key entomological
tools used to estimate the risk of disease transmission for Aedes-borne diseases such as dengue,
chikungunya, and Zika. The PI, which measures the number of pupae in an area, provides a
more accurate prediction of possible adult mosquito populations and disease transmission risk,
compared to other larval indices. The AAI measures the percentage of premises containing
adult female Aedes mosquitoes and serves as a direct indicator of current, immediate risk of
disease transmission, since only female mosquitoes bite and transmit pathogens. In the present
study, all the entomological indices-including house premises, container, Breteau, pupal, and
adult Aedes indices, were significantly high, i.e., above the critical threshold [9] in all the
surveyed localities during the month of December. This finding is directly attributed to the
preceding Northeast monsoon (mid-October to November), as this period is considered the
most favourable for the breeding and proliferation of Aedes mosquitoes, particularly Aedes
albopictus, leading to a substantial increase in mosquito population. A recent study indicated
the significant role of rainfall in dengue incidence in Thiruvananthapuram District, suggesting
the need for intensified vector surveillance and control activities during the monsoon season.
[10] Entomological surveillance in Alappuzha District demonstrated a noteworthy seasonal
difference in Aedes larval indices, with higher HPI, CI and BI recorded during the post-
monsoon period, compared to the pre-monsoon period across both urban and rural areas.[11]
The present study on Aedes mosquito biology, ecology, and population dynamics in the
Thiruvananthapuram Corporation area revealed a high prevalence of Aedes albopictus, with
comparatively low collection numbers for both Aedes aegypti and Aedes vittatus. Furthermore,
the overall Aedes mosquito population peaked during the monsoon season, which may be
attributed to the increased availability of breeding sites during rainy days. [12] A recent
retrospective spatio-temporal analysis of dengue cases, utilizing public domain data from the
Directorate of Health Services, Kerala, identified ten high-priority dengue epidemic risk
districts. Among these, Thiruvananthapuram exhibited the highest relative risk.[13] For
assessing dengue risk in Thiruvananthapuram District, the AHP and F-AHP models identified
a total of 20 localities as risk zones.[14] The Panchayaths of Kadinamkulam, Kattakkada,
Malayinkeezhu, and Mangalapuram, in particular, were designated as very high-risk areas for
dengue. It is worth noting that four of these high-risk localities were randomly included in the
present study.
Larval identification and the examination of laboratory-reared and wild-caught adult
mosquitoes consistently showed that Aedes albopictus was the most prevalent species found in
all surveyed localities, during both the pre-monsoon and post-monsoon periods. Notably, no
Aedes aegypti immatures were found in any containers. An investigation of domestic and
environmental factors associated with chikungunya-affected families in rural
Thiruvananthapuram revealed that the majority of study areas presented highly favourable
breeding conditions for Aedes albopictus mosquitoes. [15]
The household survey showed a seasonal shift in the BPR, with the pre-monsoon observation
highlighting grinding stones and tyres with the highest BPR (6.7 each), followed by cement
tanks at 2.6. In the post-monsoon period, tyres were observed to be the most preferred site with
a BPR of 2.3, followed by cement tanks and grinding stones, which shared a BPR of 1.5 each.
Despite the change in order, it is noteworthy that the same three sites (tyres, cement tanks, and
grinding stones) remained the most preferred breeding sites of Aedes albopictus in both
seasons. The high BPR observed in the present study validates previous findings in
Thiruvananthapuram District that discarded tyres and grinding stones are the most preferred
container breeding sites for Aedes mosquitoes, especially Aedes albopictus.[16] Surveillance of
Aedes mosquitoes around Cochin International Airport area revealed that BPR was highest in
tyres, followed by grinding stones and cement tanks, as observed in the present study.[17]
Caution must be exercised when interpreting BPR from infrequently encountered container
types; however, the extensive field data in the present study validated this apparent preference
for the specific artificial sites.
Previous entomological surveys in Thiruvananthapuram District established a pattern in which
Aedes aegypti was confined to urban areas, while Aedes albopictus was found breeding
profusely in both rural and urban localities. However, more recent surveys indicate a significant
decline, or even absence of Aedes aegypti in the district’s urban areas.[8] The reason for this
shift in the Aedes vector breeding profile warrants detailed investigation. The throwaway habit,
characteristic of the consumeristic culture originally confined to urban centres, is rapidly
spreading across Kerala. This diffusion is facilitated by pervasive urbanization, which has
blurred the traditional urban–rural distinctions. Scattered heaps of litter, comprising non-
degradable plastic, metal items and various scraps, are a common sight in household premises,
marketplaces, public spaces, parks, and along roadsides. These materials retain water for long
periods, providing an ideal breeding environment for mosquito vectors, especially Aedes
species.
The best strategy for Aedes vector control and averting outbreaks of diseases such as dengue is
pre-monsoon source reduction with active community participation. However, it is observed
that public health warnings, though regularly issued by authorities, are often not followed by
the public. This persistent non-compliance necessitates a fundamental shift in approach both
from the community and the public health authorities. The community must transition from
negligence to proactive behaviour through regular measures to eliminate mosquito breeding
sites in and around households and public areas. Meanwhile, public health authorities must
evolve their role from issuing occasional media announcements to ensuring sustained,
participatory intervention programmes involving multiple stakeholders, including residents,
local organizations, and community health workers. Successful management of any public
health challenge, comprising prevention and control of vector-borne diseases, requires a
participatory intervention strategy. Active engagement of the community, involving residents’
associations, and other stakeholders at various levels is vital, as this multi-level involvement
ensures the sustained commitment necessary for long-term primary prevention.
Conclusion
The present entomological study revealed a high prevalence of Aedes mosquito immatures in
household premises, particularly during the post-monsoon season. This finding, coupled with
the confirmed presence of female Aedes mosquitoes in the area, significantly heightens the risk
of ABD outbreaks and calls for immediate action by the authorities as well as the inhabitants
to control mosquito proliferation by eliminating natural and man-made breeding habitats,
particularly the sources of standing water and to forestall VDB outbreaks. Routine health
education, driven by community participation, is essential for promoting positive behavioural
changes that improve personal hygiene, sanitation, and environmental management. Active
collaboration involving Non-Governmental Organizations, Community-Based Organizations
like Residents’ Associations, and social work agencies is crucial for the successful
implementation of vector and disease control programmes.
Acknowledgement
We extend our sincere gratitude to the Director of the National Centre for Disease Control,
Ministry of Health and Family Welfare, Government of India, for his valuable support. We
would also like to express our thanks to the Director of Health Services, Government of Kerala,
for the support in execution of this work.
Financial support and sponsorship
Nil
Conflicts of interest
There are no conflicts of interest
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