Dengue fever is a global problem affecting 500,000 people annually. During epidemics, infection rates can reach 80-90% among non-immune individuals. Without proper treatment, fatality rates from dengue hemorrhagic fever can exceed 20%, but are reduced to less than 1% with access to medical care. The disease is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Controlling the mosquito vectors through insecticides and reducing breeding sites is important for prevention, as vaccines do not yet exist. National strategies include integrated vector control, active disease surveillance, emergency preparedness, capacity building, and research on vector biology and control methods.

1. Dengue Fever Prevention and
Control
Saleem M. Rana, PhD

2. The Dengue Fever a Global Problem
• During epidemics of dengue, infection rates among those
who have not been previously exposed to the virus are
often 40% to 50%, but can reach 80% to 90%.
• An estimated 500 000 people with DHF require
hospitalization each year, a very large proportion of
whom are children. About 2.5% of those affected die.
• Without proper treatment, DHF fatality rates can exceed
20%.
• Wider access to medical care from health providers with
knowledge about DHF - physicians and nurses who
recognize its symptoms and know how to treat its effects
can reduce death rates to less than 1%.

3. Aedes aegypti Aedes albopictus

4. Aedes aegypti

6. Aedes albopictus

12. Behavior
 Day-time biter
 Lives outside
 But comes indoors
 May lay eggs indoors
 Lays eggs in artificial containers
 Anything that can hold water
 Rests in low, shaded areas.
 Under tables, chairs
 In machinery- if damp

13. More behavior
 Day-time biter – also in lighted rooms at night.
 Silent flier – no buzz in your ear.
 Very gentle on skin and not easily felt biting.
 Adults not active under 15-16 degrees.
 Adults not killed by cold, just go inactive.
 Eggs laid containers of water
 Egg to Larva to Adult in one week or less.

14. Movies

15. Comparison of Aedes (Larvae)
Characters Ae. aegypti Ae.albopictus
ANTENNAE single hair near middle single hair near saddle
HEAD upper & lower hairs upper & lower hairs
single single
THORAX heavy hooks on sides weak or no hooks on side
COMB SCALES pitchfork-shaped; 7-12 in thorn-like; in 1 row
1 row
SIPHON index 2.0; pectin evenly pectin evenly spaced
spaced
GILLS all the same length, all the same length,
rounded; longer than anal rounded; longer than anal
segment segment

16. Comparison of Aedes (Adult)
Characters Ae. aegypti Ae.albopictus
PALPS dark with white tip; dark with white tip;
clypeus white clypeus black
PROBOSCIS dark dark
SCUTUM dark with white lyre- dark with white median
shaped pattern stripe
THORAX dark with patches of dark with patches of
white scales white scales
WINGS dark dark
ABDOMEN dark with narrow white dark with narrow white
basal bands basal bands
HIND LEGS dark with white basal dark with white basal
bands bands

17. Possible Weapons to Fight Dengue
Fever
• Drugs that kill the virus in humans
• Insecticides that kill the mosquito vector
• Vaccines

18. 1. Drugs
• No specific anti viral
• Symptomatic treatment

19. 2. Insecticides:
Mosquitoes Quickly Acquire Resistance
Before During After
Biologic niche intact Mosquitoes return

20. 3. Vaccine
Does not exist (yet)

22. Mosquito Breeding

26. No comments

27. Before sunrise
Near sunset

29. Symptoms
 Dengue fever is a flu-like illness with varying characteristics:
 Infants and youths often experience an undifferentiated febrile disease
with rash.
 Older children and adults may have a mild febrile syndrome but more
typically experience:
 high fever,
 severe headache,
 pain behind the eyes,
 muscle and joint pains and
 rash.
 Typically, a person will develop dengue fever as a result of initial
exposure to one serotype. Upon recovery, a patient develops immunity to
this single serotype.

30. SYMPTOMS
 Upon second infection with a different serotype:
 the patient stands a greater risk of developing dengue haemorrhagic
 fever (DHF), a more serious and potentially fatal disease.
 DHF is characterized by:
o High fever, haemorrhagic phenomena, enlarged liver and
circulatory failure.
o A sudden onset of fever is the first indication of DHF,
accompanied by facial flush and other symptoms of
dengue fever.
o The fever persists for 2-7 days and can reach 41° C,
followed by febrile convulsions and haemorrhagic phenomena.

31. SYMPTOMS
The patient may recover and symptoms abate. But
if left untreated, the patient may go into shock
(DSS) with a rapid, weak pulse, followed by signs
of circulatory failure such as cool, blotchy skin.
Without proper treatment, the patient may die
within 12-24 hours.

32. Strategies for Dengue Control

33. National Strategy.
VECTOR
CONTROL
SOLID WASTE
MANAGEMENT
SURVEILLANCE
DENGUE
CELL
CASE
ACSM
MANAGEMENT
CAPACITY
BUILDING

34. Control Strategy
Selective integrated vector control, with community and
intersectoral participation
 Active disease surveillance based on a strong health information
system-involves clinical and laboratory-based
vector surveillance for monitoring and evaluation of control
programmes.

35. Control Strategy
Emergency preparedness for development of emergency and
contingency plans, including education of the medical
community, hospitalization plans, case management and
emergency vector control.
Capacity building and training for surveillance, laboratory
diagnosis, case management and vector control at professional,
supervisory, technical and field levels.
Vector control research including studies on vector biology and
control, disease relationships, design and management of control
programmes (including social and economic approaches) and
cost benefit analyses. The relative impact of the components of
integrated vector control require further elucidation.

36. Problems And Challenges
• demographic changes
▫ uncontrolled population growth
▫ Mobility
▫ unplanned urbanization.
▫ man-made larval habitats e.g. household water storage
containers, discarded solid waste items, such as plastics, glass
containers and used automobile tyres.

37. NEW APPROACH:
GENETIC MODIFICATION OF MOSQUITOES
1 ) G E N E T I C A L LY E N G I N E E R M O S Q U I TO E S
TO M A K E T H E M R E S I S TA N T TO V I R U S
2) I N T R O D U C E T H E R E F R A C TO RY G E N E ( S )
I N TO M O S Q U I TO P O P U L AT I O N S
LESS TRANSMISSION LESS DENGUE FEVER

38. DF +ve cases Aedes egypti Aedes albopictus
larvae Fogging larvicide
IRS
100 96
88 93
86
8080
71 67
57 60 60
40 40 36
33 33 31
20 19 24 2727 27 24 20
7 12
1st week 2nd week 3rd week 4th week
Monthly Temperature, Rainfall and DF Correlation between dengue fever prevalence,
2008 in Lahore vector density and control activities 2008 in
Lahore
Annual correlation between dengue fever, temperature
and rainfall 2008 in Lahore

39. Message
Start
 Active disease surveillance based on :
 a strong health information system to involves the
clinical and laboratory-based dengue surveillance
for early detection of epidemics, and
 Develop a quick reporting system from:
FLCF ----EDOH---DGHS
 vector surveillance for monitoring and evaluation of
control programmes.
 Aware the Community

40. Thanks