Details of epidemiology, prevention and control od dengue, DHF and Dengue shock syndrome.

1. Epidemiology, Prevention and
Control of Dengue Fever
Dr. Gopalrao Jogdand, Ph.D. (U.S.A.)
Professor & Head,
Car Medical College, Karim Nagar

2. Historical Background
• Dengue epidemics are known to have
occurred over the last three centuries in
tropical, sub tropical and temperate zones
• The first epidemic of dengue was recorded in
1635 in the French West Indies.
• Rush described about Break bone fever
occurred in Philadelphia in 1780.

3. Continued….
• The first recorded outbreak of DHF occurred in
Australia in 1897.
• Similar disease was found in Greece in 1928
and in Taiwan in 1931.
• First confirmed epidemic of DHF was recorded
in Philippines in 1953-54
• Now prevalent in India, Indonesia, Myanmar,
Sri lanka, New Caledonia, countries of western
Pacific region.

4. Magnitude of the Problem
• There are 2.5 to 3 billion people are at the risk
and living in epidemic prone areas globally
• South East Asia 100 million cases annually and
500,000 cases of DHF of which almost 90% are
children
• The mortality rate is 5% causing 25,000 deaths
annually
• Epidemics are cyclical

5. Continued….
• Africa----- 20 Endemic countries
• Epidemics have been caused by all four
serotypes in the past 18 years
• Recent major epidemics have been reported
in Comores and Eritrea
• DHF not reported

6. Continued….
• Eastern Mediterranean– 4 endemic countries
• Recent major epidemics in Diboti, Saudi
Arabia and Pakistan
• Multiple serotypes are circulating
• Sporadic cases of DHF documented

7. Continued….
• Western Pacific– 29 countries endemic
• Recent major epidemics are reported I
Singapore, Cambodia, Vietnam, Philippines,
Tahiti, Fiji and Palau
• All four serotypes circulating
• DHF is a major public health problem and
disease is endemic in many countries

8. Continued….
• Americas– 42 Endemic Countries
• Recent major epidemics in Central America,
Colombia, Peru, Venezuela, Brazil, Mexico,
Cuba, Puerto Rico, Barbados and Trinidad
• All 4 serotypes are circulating
• DHF is a newly emerging disease and now
occurs in 24 Countries

9. Continued….
• South East Asia– 7 Endemic countries
• Recent major epidemics are reported from
India, Sri Lanka, Myanmar and Indonesia
• All 4 serotypes are circulating
• DHF is a major cause for hospitalization and
deaths of children

10. The Agent
• Dengue is caused by a virus member of the
genus Flavivirus and family Flaviviridae.
• Virus is 50nm. in size and contains a single
strand RNA.
• There are 4 serotypes of this virus DEN1,
DEN2, DEN3 and DEN4
• There is a short lived cross immunity between
these species

11. The Vector
• Globally Aedis aegypti is a important vector
but has geographical limitation
• Other species are Aedis albopictus, A.
Stegomyia, A. ploynesiensis, A. scutellaris and
A. finalaya and in India A. tigris
• The most potent vector having epidemic
potential is A. aegypti

12. Habits and habitat of the vector
• Vector: Aedis tigris mosquito in India, Aedis
aegypti, stegomyia and albopictus in other
countries.
• Habits of the vector: Clear water breeder, day
time biter and domestic breeder
• Responsible for the transmission of Dengue
fever, Dengue hemorrhagic fever and Dengue
shock syndrome.

13. The Host
• Dengue virus infects humans and other lower
primates
• Humans are main urban reservoirs of the
disease
• Studies conducted in Africa and Malaysia
show that monkeys are infected and can be
reservoirs of the disease

14. Transmission Cycle
• Extrinsic incubation period: 8 to 10 days.
• Intrinsic incubation period: 3 to 14 days an
average of 4 to 7 days.
• Cyclic nature of the disease: In endemic
countries the cycle can be repeated at yearly
interval.
• India is a endemic country for dengue fever.

15. Characteristics of the disease
• It is caused by a virus called flavi virus.
• Virus gets access to human body by the bite of
a infected mosquito.
• Causes three types of clinical manifestations:
• Dengue Fever: High grade fever and joint
pains.
• DHF: dengue hemorrhagic fever causes
cutaneous hemorrhages and platelet
depletion.

16. Continued….
• Dengue shock syndrome: Fever, cutaneous
rash, GIT bleeding, severe bleeding, shock and
multiple organ failure.
• Risk factors for dengue fever:
• Immune status of the patient.
• Infecting virus strain and its virulence.
• Age of the patient.

17. Factors responsible for resurgence of
Dengue
• Unprecedented population growth
• Unplanned and uncontrolled urbanization
• Increased distribution and vector density
• Inadequate waste management and water
supply
• Development of hyperendemicity
• Inadequate health infrastructure

18. DHF as a serious Public Health
Problem
• Seven out of ten countries have serious DHF
problem
• DHF is a major cause for hospitalization and
death of children in these countries
• Incidence of DHF has increased five times in
the last 30 years beginning from 1980
• The geographic distribution has increased
within countries and in other countries of the
region.

19. Prevention & Control
• Elimination of breeding places of mosquito.
• Avoidance of man------- mosquito----- virus
contact.
• Drinking water storage containers are to be
drained at the interval of 3-4 days.
• Proper cleaning of overhead water storage
tanks, never leave the tanks uncovered.

20. Continued….
• Coolers and desert coolers should be dried
and then kept aside.
• Used tyres, bottles and containers should be
disposed of properly.
• Personal protection:
• Use of mosquito nets, repellant creams,
mosquito coils, mats and aerosols.

21. Continued….
• Medical measures:
• Passive surveillance
• Active surveillance
• Early diagnosis and treatment of cases.
• Integrated vector control and inter-sectoral
cooperation

22. Thank You