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1. Mohd. Azri bin Mohd. Suan (GS 48384)
Noor Syazwani Bt Sahar (GS 49799)
Khairul Anuar Bin Abdullah (GS 49433)
Mardiana Bt Omar (GS 49609)
Raja Nurul Najwa Bt Raja Ismail (GS 50169)

2. Outline
• Epidemiology of dengue
• Trend of disease in
• Burden of disease
• Disease progress, mode of transmission
• Risk factors
• Strategies for prevention & control
• Challenges/ issues
• Program & services
• Recommendation

3. 1
Epidemiology of Dengue

4. Dengue as an emerging disease
• DEN was a minor, geographically restricted disease until mid-20th century
• World War II/global cargo transport of Aedes mosquitoes likely responsible
for dissemination.
• DEN/DHF present in the WHO regions of the Americas, South-East Asia,
Eastern Mediterranean and Western Pacific; Africa reports DEN but only
sporadic DHF 1.
• DHF first documented in 1950s in the Philippines and Thailand.

7. • Several combining factors produce
epidemiological conditions in
tropical and subtropical developing
countries that favouring viral
transmission by Aedes aegypti:
• rapid population growth
• rural–urban migration
• inadequate basic urban infrastructure
• increase in volume of solid waste
which provide larval habitats in urban
areas.

8. Dengue in the Western Pacific Region
• Dengue is a major public health problem in the Western Pacific
Region
• All four serotypes (DENV-1, -2, -3, -4) are present in the Region
• Occurs throughout the year but rates increase 1-2 months after the
start of the rainy season in June

10. • In Malaysia, dengue is predominantly an urban disease due to the
abundance of the principle vector Aedes aegypti which is at a close
proximity to high densities of susceptible hosts.
• The states of Selangor, Wilayah Persekutuan Kuala Lumpur and Johor
are the areas that have been largely affected by the disease and are
reporting high numbers of cases.
• Factors like population growth in urban areas, the indiscriminate
disposal of waste coupled with the lack of efficient solid waste
management and the increased and efficient movement of dengue
viruses in infected humans through modern transportation have all
contributed to the marked increase in the occurrence of dengue.

12. 2
Trend of Disease in Developed &
Developing Countries

13. Dengue situation update number 530
21 November 2017
Northern Hemisphere
Cambodia
• As of 14 November 2017, a total of 2,979 suspected dengue cases
were reported in 2017. The total number of reported dengue cases
including dengue haemorrhagic fever and dengue shock syndrome
was lower than the 3 year-threshold of the same period from 2014-
2016 (Figure 1).

14. Figure 1: Number of cases of Dengue fever, Dengue haemorrhagic fever, and Dengue shock syndrome
Reported by week in 2017 and threshold, Ministry of Health, Cambodia

15. China
• From 1 to 31 August, there were 1,645 cases of dengue reported in China in
2017. The number of reported cases was lower than the previous month
and follows historical trends (Figure 2).
Figure 2: Number of Dengue cases per
month, China 2012-2017
National Health and Family Planning
Commission, China

16. Laos
• As of 27 October, there were 10,302 cases of dengue with 14 deaths reported
in Lao PDR in 2017, with 199 cases with no death reported in epi week 43.
• Compared to the same time period during the previous five years, dengue
continues to be at epidemic level in the country (Figure 3). However, there has
been a declining trend since week 35.

17. Malaysia
• In week 45, 2017 (from 5 to 11 November 2017), 1,015 dengue cases were
reported, decreased 12.4% compared to week 44 (Figure 4).
• As of week 45, the cumulative number of dengue cases in 2017 was 77,069
with 163 deaths compared to 91,879 cases with 212 deaths during the same
period in 2016.
Figure 4: Weekly Dengue
trends in Malaysia, 2016-17
Department of Health,
Malaysia

18. Philippines
• A total of 97,287 dengue cases including 526 deaths were reported
nationwide from 1 January to 30 September, 2017.
• This number is 41.8% lower (167,102) than that for the same period
in 2016.
Figure 5: Number of Dengue
cases per morbidity week in
2017,
Philippine Integrated Diseases
Surveillance and Response, Public
Health Surveillance Division,
MOH, Philippines

19. Singapore
• As of 11 November 2017, there were 2,469 dengue cases reported in
Singapore since January 2017.
• This is lower than the number of reported cases during the same period since
2013.
• During week 45, there were 44 cases reported and the number of reported
cases in 2017 remains lower than those reported for the same time period in
the previous 5 years (Figure 6).
Figure 6 Number of Dengue cases per week,
2012-2017
Communicable Diseases Division, Ministry of
Health, Singapore

20. Viet Nam
• As of 12 November 2017, there were 166,994 cases of dengue reported in
Viet Nam including 30 deaths.
• During week 45, there were 2,447 cases reported and without deaths. This
was a 17.9% reduction compared to week 44 when 3,260 cases and no
death were reported.
• The Central-coastal region recorded the highest number of cases per
100,000 population (179 cases per 100,000 population); followed by
Southern region (148 cases per 100,000 population).
• In Ha Noi, as of 12 November 2017, there were approximately 36,345
dengue cases recorded including seven deaths.
• Although the cummulative number of cases is much higher than in
previous years, there is now a consistentdownward trend .

21. Figure 7: Number of dengue admitted cases and deaths reported by month in 2017 compared to 2016
General Department of Preventative Medicine, Ministry of Health, Viet Nam Southern

22. Southern Hemisphere
Australia
• As of 21 November, there were 859 laboratory-confirmed dengue
cases reported in Australia in 2017.
• The number of cases reported is lower than that reported during the
same period in the previous years (2012-2016) (Figure 8).
Figure 8: Number of reported
laboratory-confirmed Dengue cases per
month, 2012-2017
Department of Health, Australia

23. 3
Burden of DENGUE in Malaysia

24. KEDAH
Cases : 913
Death : 2
PERLIS
Cases : 176
Death : 1
P. PINANG
Cases : 2,409
Death : 12
PERAK
Cases : 3,403
Death : 10
SELANGOR (51%)
Cases : 48,327
Death : 73
N. SEMBILAN
Cases : 2,577
Death : 24
MELAKA
Cases : 1,787
Death : 7
JOHOR
Cases : 10,171
Death : 21
PAHANG
Cases : 2,769
Death : 9
TERENGGANU
Cases : 1,957
Death : 19
KELANTAN
Cases : 5,654
Death : 9
SARAWAK
Cases : 2,560
Death : 6
LABUAN
Cases : 13
Death : 0
SABAH
Cases : 3,385
Death : 2
DENGGUE CASES IN MALAYSIA, 2016 (UNTIL 27
NOVEMBER)
Source : iDengue
KL/PUTRAJAYA
Cases : 8065
Death : 18
Total number of dengue cases in Malaysia : 94,166
Total number of death : 214

25. SABAK BERNAM
Cases : 229
Death : 0
HULU SELANGOR
Cases : 1,010
Death : 3
KUALA SELANGOR
Cases : 566
Death : 2
GOMBAK
Cases : 5,427
Death : 8
HULU LANGAT
Cases : 11,032
Death : 24
SEPANG
Cases : 1,817
Death : 1
KLANG
Cases : 7,095
Death : 10
KUALA LANGAT
Cases : 1,324
Death : 1
PETALING
Cases : 19,808
Death : 25
DENGUE CASES IN SELANGOR 2016 (UNTIL 27 NOVEMBER)
Petaling, Hulu Langat and Klang contributed 40% of all dengue cases
Source : iDengue

26. Incidence of Denggi in Malaysia
• The global increase of dengue incidence is also experienced by
Malaysia.
• Since the year 2000, the dengue incidence in Malaysia continues to
increase from 32 cases per 100,000 populations to 361 cases per
100,000 populations in 2014
• Most of the dengue cases reported were from urban areas (70 – 80%)
where factors such as high density population and rapid development
favour dengue transmission.

27. Incidence rate and mortality rate for communicable diseases, 2013
(per 100,000 population)

28. Top 10 communicable diseases causing YLL
burdens, Malaysia, 2008

29. Top 10 communicable diseases causing YLD
burdens, Malaysia, 2008

30. WHO equation, DALY = YLL + YLD

31. Top 12 communicable diseases causing a
DALY burden, Malaysia, 2008

32. Economy burden
• Because Malaysia has a passive surveillance system, the total number of dengue cases is
underreported.
• An estimate of economic burden of dengue illness of US$102.25 (95%CI: 77.94 –
310.66)(MYR 359.79 mil) million per year-- approximately US$3.72 (95%CI: 2.83-11.30)
(MYR 13.08) per capita.
(Shepard. et al 2013).
• In Puerto Rico, US estimate of economic burden of dengue illness of US$46.46 million
per year
(Gubler, 2012)
• The overall economic burden of dengue would be even higher if we included costs
associated with dengue prevention and control, dengue surveillance, and long-term
sequelae of dengue.

33. Predicted values of direct and indirect unit
costs per dengue case (2010 US dollars)
Source: Shepard, Undurraga, & Halasa, 2013

34. DENGUE VIRUS AND SEROTYPE TRENDS IN
MALAYSIA
• Dengue virus : a mosquito-borne flavivirus.
• Transmitted by: Aedes aegypti and Aedes albopictus.
• 4 distinct serotypes: DENV-1,2,3 and 4.
• Each episode of infection induces a life-long protective immunity to the
homologous serotype but confers only partial and transient protection
against other serotypes.
• Secondary infection is a major risk factor for severe dengue due to
antibody-dependent enhancement.
• Other important contributing factors are viral virulence, host genetic
background, T-cell activation, viral load and auto-antibodies.
• In Malaysia, all four serotypes can be isolated at any one time.

35. A particular dengue virus serotype can predominate for at least
two years before it is replaced by another serotype
Source: CPG Dengue Malaysia

36. In year 2013-2014, the predominant serotype had switched
twice from DENV-2 to DENV-1 in February and June 2014

37. SPECTRUM OF DENGUE INFECTION
• Incubation period: 4-7 days (range 3-14 days)
• It may be asymptomatic or may result in a spectrum of illness ranging
from undifferentiated mild febrile illness to severe disease, with or
without plasma leakage and organ impairment.
• Symptomatic dengue infection is a systemic and dynamic disease with
clinical, haematological and serological profiles changing from day to
day.
• These changes accelerate within hours or even minutes during the
critical phase, particularly in those with plasma leakage

38. Signs and
Symptoms
High grade fever,
rash, headache,
body ache, facial
flushing
Abd pain,
vomiting,
diarrhea,
mucosal bleed
general well being improves,
appetite returns, GI symptoms
improves
High grade fever Rapid drop in temp
rash
Facial flushing
Body ache
Headache

39. LABORATORY INTERPRETATION
• The median HCT level among Malaysian population is taken as:ͦ
male < 60 years : 46% ͦ
male > 60 years : 42% ͦ
female (all age groups): 40%
• In the absence of baseline HCT, a HCT value higher than the above
should raise the suspicion of plasma leakage.
• Usually, leucopaenia preceeds thrombocytopaenia.

40. DENGUE SEROLOGY TESTS
• Rapid combo test (dengue NS1 antigen/dengue IgM/IgG antibodies)
should be done as a screening tool in suspected dengue infection and
results can be obtained within 15-20 minutes.
• Dengue non-structural protein-1 (NS1 Antigen) is helpful in early
phase (< day 5) of dengue infection and usually becomes undetectable
in the convalescence phase.
• Real time reverse transcriptase polymerase chain reaction (RT-PCR)
should be done in clinically suspected seronegative patients and also in
seropositive severe dengue infection (serotyping).

41. DENGUE CLASSIFICATION & LEVEL OF SEVERITY

42. 5
Risk Factors

43. Risk factor of dengue fever
Host
Environment
Agent
Vector

44. Toan, 2015
• Case control study
• 73 dengue fever patients, 73 control group
• People living in rented houses (aOR 2·2, 95% CI 1·1-4·6)
• People living in an unhygienic house (aOR 3·4, 95% CI 1-11·7)
• People living in a house discharging sewage directly to the ponds
(aOR 4·3, 95% CI 1·1-16·9).

45. Kholedi, 2007
• Case control study
• 129 cases, 240 controls
• presence of stagnant water in the indoor drainage holes (OR = 4.934)
• presence of indoor larvae (OR = 2.208)
• presence of nearby buildings under construction (OR = 2.2)
• older age groups (OR = 1.226)

46. Heukelbach, 2001
• Case control study
• 34 cases, 34 controls
• plants with temporary water pools on the property, gutter to collect
rainwater, uncovered water storage container (p= 0.02)
• no waste collection (p= 0.03)

47. Syed, 2014
• Cross sectional study
• 350 households
• middle age group 37 to 54 years
• density of vegetation (p<0.01)
• self-mosquito bite protection (p<0.01)
• Self prevention in breeding mosquitoes (p<0.01)
• lack of self-efficacy in controlling vector (p<0.01)
• lack of preventive measure in community (p<0.01)

48. Fong, 2015
• AI, BI, CI and HI, based on the operating point selected, yielded a
sensitivity of 82, 87, 86 and 85%, respectively; and a specificity of 76,
80, 80 and 80%, respectively
• The accuracy of Model-AI, BI, CI and HI in predicting the occurrence
of dengue cases were 83.8, 87.8, 88.3 and 88.4%, respectively

50. Cheong, 2013
• The increase of minimum temperature from 25.4 °C to 26.5 °C
increased dengue cases by the highest amount, that is, 5.04% (95%
CI: 3.58, 6.51) at a lag of 51 days
• The increase of cumulated rainfall from 215 mm (90th percentile) to
302 mm (99th percentile) increased dengue cases by the highest,
4.75% (95% CI: 3.50, 6.01) at a lag of 26 to 28 days

51. Agent Host Vector Environment
• secondary infection
– DHF/ severe
manifestation
• DENV-1 & DENV-3 –
severe symptoms in
primary infection
(Gauzman MG,
2000)
• DENV-2 – severe
symptoms in
secondary infection
(Vaughn DW, 2000)
• Younger age (2-15
y.o)
• Older age
• Diabetes mellitus –
DHF
• Poor socioeconomic
status
• Low risk perception
• Lack of self- efficacy
• Lack of preventive
measures in
community
• Human- population
growth
• Population
movement –
migration/ tourism
• Aedes aegypti –
urban & more
severe symptoms
• Aedes albopictus –
rural areas & milder
symptoms
• Adult index (AI)-
female aedes
mosquitoes density
• Pupal index
• AI, HI, BI
• Tropical/ subtropical
countries
• Heavy rainfall
• Humidity
• High temperature
• Unplanned
urbanization
• Poor sanitation
• Poor water supply
• Poor waste
management system

52. 6
Strategies for Prevention &
Control of DENGUE

53. GOAL & OBJECTIVE
To reduce
the
burden of
Denggue
To reduce dengue
morbidity by at
least 25% by 2020
To reduce dengue
mortality by at
least 50% by 2020
To estimate the
true burden of
disease by 2015

54. TECHNICAL ELEMENTS FOR IMPLEMENTATION.
Diagnosis & case
management
Integrated
surveillance and
outbreak
preparedness
Sustainable vector
control
Future vaccine
implementation
Basic operational
and
implementation
research

55. 1) Diagnosis & case management
• By implementing timely and appropriate clinical
management;
• Early clinical & laboratory diagnosis
• Intravenous rehydration
• Staff training
• Hospital reorganization

56. 2) Integrated surveillance
• To detect epidemic rapidly for
early intervention
• To measure disease burden &
provide data for assessment
• To monitor trends in distribution
& spread
• To monitor environmental risk
factors
• To evaluate effectiveness of
program
• To facilitate planning & resource
allocation

57. Outbreak preparedness
• Establish a multisectorial dengue
action committee
• Formalize an emergency action
plan
• Enhance disease surveillance
• Perform diagnostic laboratory
testing
• Enhance vector surveillance &
control
• Protect special populations
• Ensure appropriate patients care
• Engage community
• Investigate epidemic
• Manage mass media

58. 3) Sustainable vector control
• Control of dengue vectors has mainly been approached by source
reduction:
• Elimination of containers that are favorable sites for oviposition and
development of the aquatic stages.
• by covering containers or by killing the aquatic stages using insecticides.
• Carrying out pupal surveys in human habitations
• Innovative vector control tools:
• Insecticide-treated materials; lethal ovitraps; spatial repellents; genetically
modified mosquitoes; and Wolbachia-infected Aedes.

59. 4) Vaccine
• The most advanced vaccine candidate, which is based on live-
attenuated chimeric yellow fever-dengue virus, has progressed to
phase III clinical trials (Guy B et al., 2011).
• A subunit and a DNA vaccine, are in earlier stages of clinical
development (Coller BA, 2011).
• Additional technological approaches, such as virus-vectored and
inactivated vaccines, are under evaluation in preclinical studies
(Schmitz J et al., 2011).
• Recently, in Nov 2017; Dengvaxia by Sanofi.

60. 5) Research
• Focus on the efficacy, cost-effectiveness, sustainability and scaling up
of existing and promising new control methods.
• New diagnostic tools and means of vector control.
• Effective approaches to fostering sustained community participation.

61. ENANBLING FACTORS FOR IMPLEMENTATION
Advocacy &
resource
mobilization
Partnership,
coordination &
collaboration
Communication
to achieve
behavioural
outcome
Capacity building
Monitoring &
evaluation

62. 7
Challenges / issues in
controlling DENGUE in Malaysia

63. 1- Unfortunately, there is no specific treatment for
dengue, and a safe tetravalent vaccine is still in
development and at least a decade away from
being available for widespread use
2-As Aedes is a day-biting mosquito, treated bed nets are also not
very effective against Aedes-borne diseases like
Dengue

64. **** The current strategy is to control the mosquito
vectors, Aedes aegypti (L.) (primary vector) and
Aedes albopictus Skuse (secondary vector).
Mosquito control in a dengue programme generally
comprises 3 major components: Vector control &
surveillance; community participation and
enforcement. In vector control, application of
insecticides is often used widely to reduce and kill the infected mosquito population whenever
cases are reported. The application of insecticides
especially the pyrethroids is effected through space
application in the form of cold or thermal fogging. The main purpose of space spraying is to kill
the
infected mosquitoes thereby interrupting the
transmission cycle & stop the disease cycle, hence stopping the spread and occurrence of
dengue.
Surveillance is generally done through house-to-house larval survey and the results are used to
formulate several indicators, most commonly the House Index and Breteau Index. These indices
are used to denote the risk areas. In most countries, larval survey is used as a form of
enforcement, rather than as indicators of Aedes breeding.

65. 3-Thus most of the time, larval indices are not reflective of the true & actual
situation of larval population in the field, rendering HI & BI inaccurate as indicators
of breeding
4-However, these methods cannot prevent dengue
outbreaks by themselves , A key reason for this is the low threshold for dengue
transmission; as low as 2-3 adult female mosquitoes emerging every day in a
locality of 100 people
5-This does not call for the discontinuation of
conventional vector control methods; in fact it would be
necessary to continue public education and
‘COMmunication for Behavioural Impact’ (COMBI) for sustained breeding site
reduction involving the
public.

66. 6-Legally-enforced larval control, whether by breeding site elimination or
larviciding, is neither practical for a large and diverse country like Malaysia, nor has
it stopped the resurgence of dengue in Singapore
7-Aedes aegypti breeds in a diverse set of small
containers, often rainwater-filled, therefore finding and
treating all or most of these containers are impractical
8-However, none of the aforesaid methods, by themselves or together, have been
able to stop the spread of dengue, mainly due to not being able to reduce the
mosquito population below the low transmission threshold

67. 8
Program & services in controlling
DENGUE in Malaysia

68. 8. Program & services in controlling DENGUE
in Malaysia
• Dengue Surveillance
• National Cleanliness Policy and Integrated Vector Management
(IVM)
• Management of Dengue Cases
• Social Mobilization and Communication for Dengue

69. 8.1 Dengue Surveillance
 eNotification
• - Dengue is a notified disease as defined in
Section 10 (c) Act 342, the Prevention and
Control of Infectious Diseases Act, 1988
 eDengue system
 Dengue Outbreak Management System
(SPWD)
 iDengue System - for the community
 Laboratory Surveillance – coordinated by The
National Public Health Laboratory (NPHL)
eDengue

70. 8.2 National Cleanliness Policy and Integrated
Vector Management (IVM)
I – National Cleanliness Policy
• The National Cleanliness Policy was drafted based on a holistic and
integrated approach through the concept of Blue Ocean Strategy
(BOS) between ministries, agencies, NGOs and the publics.
• Focusing on clean environment whereby Malaysia was targeted as
one of the cleanest country in the world by the year 2020 and free
from infectious diseases.

71. 8.2 National Cleanliness Policy and Integrated
Vector Management (IVM)
I – National Cleanliness Policy
• Emphasized on 5 main core areas:-
i. Establishment of National Cleanliness Policy.
ii. Establishment and adopt a National Cleanliness Index.
iii. Expanding the implementation of solid waste management and public
cleansing as provided under the Solid Waste Management and Public
Cleansing Act 2007 (Act 672) throughout the country.
iv. Banning or limiting the use of plastic bags and containers.
v. Declaration of the National Cleanliness Week and hold a celebration every
year.

72. 8.2 National Cleanliness Policy and Integrated
Vector Management (IVM)
II – Integrated Vector Management
Integration and cooperation with all relevant agencies. Example of
activities are :-
 Space spraying using Temephos EC or Bti in the hotspot areas.
 Residual spraying as a complementary measures.
 Effective waste collection system by local authorities.
 A reliable water supply system to reduce the need for additional water storage.
 Cleanliness activities (Gotong Royong).
 Advice on personal protection during the peak of mosquito bites.
 Enforcement activities in the construction sites with other agencies such as local
authorities, CIDB and DOSH.

73. 8.3 Management of Dengue Cases
• The Ministry of Health Malaysia has prepared and distributed Guidelines - Clinical
Practice Guideline on Management of Dengue Infection in Adults.
• The main feature of this CPG are:-
• Early detection of dengue cases
• Standard and effective dengue
• management
• Public awareness on symptoms and signs of dengue and seek
early treatment
• Medical practitioners awareness to detect dengue cases

74. 8.4 Social Mobilization and Communication
for Dengue
• Community involvement as a COMBI volunteers
•- Till December 2015, there are 3007 COMBI localities through out the
country
• Involvement of universities, NGO’S and private sectors
• Communication through the mass media, for example TV and radio channels,
electronic billboards and social media such as whatsapp, facebook, blog etc

75. Communication for Behavioral Impact
(COMBI)
• COMBI is a ‘by community-for community’
orientated approach.
• Objectives;
• To mobilize multi-sectorial community in handling dengue issues in the
community.
• To create joint responsibility in the community.
• To influence and strengthen the decision, behavior and social norms in the
community.
• How effective is the program in Malaysia?

80. 8.4 Social Mobilization and Communication
for Dengue
• Community involvement as a COMBI volunteers
•- Till December 2015, there are 3007 COMBI localities through out the
country
• Involvement of universities, NGO’S and private sectors
• Communication through the mass media, for example TV and radio channels,
electronic billboards and social media such as whatsapp, facebook, blog etc

81. 9
Recommendation to improve the
program & service in controlling
DENGUE in Malaysia.

82. 9. Recommendation to improve the program
& service in controlling DENGUE in Malaysia.
• Enhanced current prevention & control program
• Dengue Research
• New tools

83. 9.1 Enhanced Current Prevention & Control
Program
▪ Case notification within 24 hours of clinical diagnosis via phone, fax, e-
notice or e-mail.
▪ Enhancing laboratory diagnostic support through the use of rapid
screening tests and confirmation by standard laboratory technique.
▪ Improved clinical management through early case detection.
▪ Case control through rapid response aimed at case investigation and
destruction of vector by fogging.

84. 9.1 Enhanced Current Prevention & Control
Program
▪ Entomological surveillance through regular Aedes
larval surveys.
▪ Legislative control by enforcement of the Destruction
of Disease-Bearing Insect Act 1975 on Aedes breeding
through premises inspection and destruction of
breeding sources.
▪ Public education through health education activities
in the community and with community involvement.
▪ Inter-agency collaboration targeting at high-risk area
and population groups such as schools, construction
sites, solid-waste dumps, factories, and government
facilities.

85. 9.2 Dengue Research
• Research should be given attention in order to enhance the effectiveness, cost
effectiveness, sustainability and increasing the scale of existing interventions as
well as producing ideas and new methods.
• Collaboration with the National Public Health Laboratory (NPHL) and the Institute
for Medical Research (IMR).
• Collaboration with other agencies such as the universities, private companies and
other government agencies.

86. 9.3 New Tools
I. Wolbachia-infected mosquitoes
• One of the most promising strategies is the introduction of the intracellular
bacterium wolbachia into A.aegypti.
• Wolbachia pipientis is a bacterial endosymbiont that was originally identified
in ovaries of culex mosquitoes in the 1920s.
• This bacteria has been found to infect two-thirds of all living insect species.
• However, A. aegypti does not carry Wolbachia naturally but has been stably
transinfected with the bacterium.

87. WOLBACHIA
• Wolbachia targets adult mosquitoes instead of the larva and is found
residing in the mid-gut and ovaries.
• Other locations of Wolbachia within the insect host include salivary
glands and the brain, which may be correlated with reduced DENV
transmission and replication.

88. WHAT WOLBACHIA DO TO THE HOST?
• Wolbachia can induce reproductive abnormalities such as
feminisation and cytoplasmic incompatibility between sperm and
eggs.

90. WHAT WOLBACHIA DO TO THE HOST?
• Wolbachia also influence the ability of insects to transmit pathogens.
• This can be achieved indirectly by reducing insect lifespan or directly
by reducing the ability of viruses and other pathogens to proliferate
within the insect.

91. 1ST FIELD RELEASE OF WOLBACHIA
• In Australia - 2011

92. • Open releases of mosquitoes with the wMel Wolbachia strain into
wild Australian A. aegypti populations.
• Field locations chosen for the study were Yorkeys Knob (614 houses)
and Gordonvale (668 houses) near Cairns in north-eastern Australia.
1ST FIELD RELEASE OF WOLBACHIA

93. • Wolbachia successfully invaded two natural A. aegypti populations in
Australia, reaching near-fixation in 4 months period following releases
of wMel infected A. aegypti adults.
• These findings demonstrate that Wolbachia-based strategies can be
deployed as a practical approach to dengue suppression with
potential for area-wide implementation.
1ST FIELD RELEASE OF WOLBACHIA

94. IN OTHER COUNTRIES
• Vietnam: After 17 weeks of releasing Wolbachia mosquitoes on Tri
Nguyen Island in Vietnam, 62% of local Aedes aegypti mosquitoes
now carry Wolbachia.
• Colombia: After ten months of releases, 90% of the Aedes aegypti
mosquitoes captured in the Paris neighbourhood of Bello
carry Wolbachia.

96. WOLBACHIA IN MALAYSIA

97. 9.3 New Tools
II. Dengue Vaccine
• Several dengue vaccines are currently being evaluated in clinical studies.
• The candidate currently at the most advanced clinical development stage;
• A live-attenuated tetravalent vaccine based on chimeric yellow fever dengue
virus, has progressed to phase III &IV efficacy studies.
• Several other live-attenuated vaccines, as well as subunit, DNA and purified
inactivated vaccine candidates, are at earlier stages of clinical development.
• Additional technological approaches, such as virus-vectored and virus-like
particle-based vaccines, are under evaluation in preclinical studies.
• Thus, till now, there is no satisfactory vaccine and no immediate prospect of
preventing the disease by immunization.

98. References
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