It is short compact topic for pedagogy for community medicine PG students

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2. Agent Factors of Dengue
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3. Agent Factor of Dengue
POINTS TO BE Learnt ;
• Introduction
• Agent
• Vector
• Transmission
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4. Agent Factors of Dengue
Introduction :
• Dengue fever is self limiting viral fever if not severe form it dengue
hemorrhagic fever / dengue shock syndrome.
• most rapidly spreading mosquito-borne viral disease in the world
• incidence: 30-fold increase
• increasing geographic expansion to new countries, and from urban to rural settings
• 50 million dengue infections annually
• India : presently 31 states endemic , first epidemic 1812 ,1963-64 kolkatta
• peak cases in post monsoon
• Still 11th september 2016 total 36110 cases, deaths 70
• Highest west Bengal 6650 cases and 24 deaths
• Maharashtra 2572 cases 2 deaths
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5. Agent Factors of Dengue
• Agent
• Arbovirus, flavirus
• Single stranded RNA
• 50 nm diameter with
multiple copies of
3 structural proteins
• ( membrane bilayer and
single-stranded RNA)
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6. Agent Factors of Dengue
• Agent
• 4 Serotypes
• DENV1 , DENV2 ,
DENV3 & DEN 4
All four associated for
Dengue epidemics .
India : DENV 1 ,DEN2
Predominant
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7. Agent Factors of Dengue
• Agent
IMMUNITY :
One serotype infection provides lifelong Immunity for that serotype
But
Few months cross immunity for other Serotypes
SECONDARY INFECTION IMMUNOLOGICAL CATASTROPHY :
Secondary infection with different serotype leads to severe dengue
i.e. DHF dengue hemorrhagic fever
DSS dengue shock syndrome
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8. Agent Factors of Dengue
Pathogenesis of Secondary infection :
First virus produced non neutralizing antibodies acts with second virus and
this complex increases/ makes easy entry into monocytes
This infected monocytes releases cytokines TF IL which triggers the vasoactive
mechanism and coagulation resulting disseminated intravascular coagulation .
Activated platelets utilized in DIC and also act on capillary endothelium .
This leads to increased vascular permeability
Bone marrow suppression by virus complexes
Thrombocytopenia
hemorrhage
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9. Agent Factor of Dengue
Reservoir :
Man and mosquito
It replicates in both and
infect each other by mosquito bite .
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10. Agent Factor of Dengue
VECTOR
• Aedes mosquitoes
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•
• A. aegypti A. albopictus A. polynesiensis
• Tropical and subtropical species
• Urban places and now in rural too
• Various life stages are found in BREEDING PLACES
In India mostly aegypti but at some places albopictus (south india , south asia) ,polnesiensis
australia pacific region
Grey to dark body and wings , white stripes/spots on body and legs … tiger mosquito .
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11. Agent Factor of Dengue
VECTOR
common breeding places of aedes mosquitos
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12. Agent Factor of Dengue
VECTOR
common breeding places of aedes mosquitos
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13. Agent Factor of Dengue
VECTOR
Life Cycle : 7-10 days EGG
LARVA
PUPA
MATURING
PUPA
ADULT
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14. Agent Factor of Dengue
VECTOR
Life Cycle : 7-10 days
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15. Agent Factor of Dengue
VECTOR
FEMALE aedes mosquito is restless feeder it bites multiple
human to complete its feed .
Its day biter. Indoor dweller . Can fly 0.5-1km , lives for 1 to 2
weeks
Sex Differentiaton :
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16. Agent Factor of Dengue
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Difference between Anopheles , Aedes and Culex

17. Agent Factor of Dengue
Mosquito bites infected human , virus gets in midgut from there ovary , nervous tissue ,fat
cells and salivary glands ..replicates ..bites second human virus . In circulation , target organs
replicates ..viraemia .
Transovarian / vertical transmission : virus is transmitted from ovary to eggs and larvae ,next
generation mosquito
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Transmission

18. Agent Factor of Dengue
RECAP …
• Introduction
• Agent
• Vector
• Transmission
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19. Agent Factor of Dengue
QUICK TEST
1. Which serotype of dengue virus is predominant in india ?
DEN1 & DEN 2
2. One time infection of dengue virus provides life long immunity for that particular serotype . True or False
True
3. Cross infection by different serotypes of dengue virus may cause …… ..
Dengue Hemorrhagic fever / Dengue Shock SYNDROME
4. Name the stages of life cycle of aedes mosquito
EGG .. LARVA … PUPA .. ADULT
5. Aedes mosquitoes breeds in dirty stagnant water mostly . True or false
False
6. Can aedes mosquito transmit dengue virus to its next generation ?
yes
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20. Agent Factor of Dengue
References
1. K..Park. Park`s Textbook Of Preventive and Social Medicine. 23rd edition , Bhanot
jabalpur 2015, Antropod-borne infections, page no.246.
2. NVBCP , Dengue cases and deaths in country since 2010 , Ministry of public health and
family welfare , govt of india. Date 11/9/2016 report
http://nvbdcp.gov.in/den-cd.html accessed on 18/9/2016.
3. WHO , National Institute Of communicable disease . Guidelines for control and prevention
of dengue. Govt .of India ; 2006.
4. The University of Florida / Institute of Food and Agricultural Sciences. Asian tiger mosquito
Featured Creatures website
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