arboviruses along with dengue

1. ARBOVIRAL DISEASE PREVALENCE IN INDIAARBOVIRAL DISEASE PREVALENCE IN INDIA
WITH SPECIAL EMPHASIS ON DENGUEWITH SPECIAL EMPHASIS ON DENGUE
DR. KUMAR VIKRAMDR. KUMAR VIKRAM
MD (MICROBIOLOGY)MD (MICROBIOLOGY)
IGIMS, PATNAIGIMS, PATNA

2. Arthropod-borne viruses (arboviruses) are viruses that can be
transmitted to man by arthropod vectors.
WHO definition
Arboviruses are viruses that are maintained in nature principally, or to an
important extent, through biological transmission between susceptible
vertebrate host by hematophagous arthropods; they multiply in the tissues
of arthropods, and are passed on to new vertebrates by the bites arthropod
after a period of extrinsic incubation.

3.  Arboviruses are worldwide in distribution .
 More numerous in the tropical than in temperate zones.
 Over 500 viruses have been listed
Most cause silent infections in rodents and other wild mammals
100 of them can infect humans
 In India , over 40 arboviruses have been detected, of which more
than 10 are known to produce human disease
GEOGRAPHICAL DISTRIBUTIONGEOGRAPHICAL DISTRIBUTION

4. Many different factors can contribute to the emergence of arboviral disease.
These include:
(1)virological determinants such as mutation, recombination, reassort- ment, natural
selection, fitness adaptation, and evolutionary progression
(2)Individual host determinants such as specific risk behaviors, innate resistance,
acquired immunity, and physiological factors such as age, nutritional status, and pregnancy
(3)Host population determinants such as community, behavioral, societal, transport,
commercial, and iatrogenic factors;
(4)Environmental determinants such as ecological and zoonotic influences;
(5)viruses intentionally used for harm – the threat of bioterrorism
EMERGING/ RE-EMERGING ARBOVIRAL DISEASE

6. General propertiesGeneral properties
The arboviruses share some common biological properties:
1. All members produce fatal encephalitis in suckling mice after intracerebral inoculation
2. They possess haemagglutinin and agglutinate erythrocytes of goose
or day-old chicks
3. They can be grown in yolk sac or chorioallantoic membrane of chick embryo,in tissue cultures of
primary cells like chick embryo fibroblasts or continuous cell lines like vero, and in cultures of
appropriate insect tissues.
4. In general, arboviruses are readily inactivated at room temperature
and by bile salts, ether and other lipid solvents.

7. Arthropod Vectors
Mosquitoes
Japanese encephalitis, dengue, yellow fever, Rift valley fever
St. Louis encephalitis, EEE, WEE, VEE etc
Ticks
Crimean-Congo haemorrhagic fever, Kyasanur forest disease
and various tick-borne encephalitis etc.
Sandflies
Sicilian sandfly fever

8. Examples of Arthropod VectorsExamples of Arthropod Vectors
Aedes aegyptiAedes aegypti
Ixodid Ticks
Phlebotomine SandflyCulex Mosquito

9. Animal ReservoirsAnimal Reservoirs
In many cases, the actual reservoir is not known. The following animals areIn many cases, the actual reservoir is not known. The following animals are
implicated as reservoirsimplicated as reservoirs
BirdsBirds Japanese B encephalitis, St Louis encephalitis,
EEE, WEE
PigsPigs Japanese B encephalitis
MonkeysMonkeys Yellow FeverYellow Fever
RodentsRodents VEE, Russian Spring-Summer encephalitisVEE, Russian Spring-Summer encephalitis

10. Diseases CausedDiseases Caused
Fever with or without rash -- this is usually a non-specific illness resembling a number of
other viral illnesses such as influenza, rubella, and enterovirus infections. The patients
may go on to develop encephalitis or haemorrhagic fever
Encephalitis - e.g. EEE, WEE, St Louis encephalitis, Japanese B encephalitis- e.g. EEE, WEE, St Louis encephalitis, Japanese B encephalitis
Haemorrhagic fever - e.g. yellow fever, dengue, Crimean-Congo haemorrhagic fever- e.g. yellow fever, dengue, Crimean-Congo haemorrhagic fever
All arbovirus infections occur with varying degree of severity, subclinical infections being
common

11. Virus Reservoir Vector Disease
Chikungunya Monkeys Mosquito Chikungunya fever
Dengue Monkeys, Man Mosquito Dengue haemorrhagic fever
Japanese B
encephalitis
Wild birds, pigs Mosquito Encephalitis
Kyasanur forest
disease
Forest birds,
animals
Tick Haemorrhagic fever
Sindbis - Mosquito Sindbis fever
Arboviruses prevalent in India

12.  virus first isolated from patients and mosquitoes during an epidemic in Tanzania in
1952-53
Outbreak in kolkata in 1963-64
In 1965 outbreak in chennai gave rise to 3,00,000 cases .
Virus was not active since 1965.
REAPPEARENCE after 41 years
During 2006, there was a large outbreak of chikungunya in India with 1.39 million
officially reported cases spread over 16 states.
First noticed in Andhra pradesh and subsquently spread to Tamil nadu, kerala ,
karnataka and then northwards as far as Delhi
Other states involved were: Maharashtra, Madhya pradesh, Gujarat, Rajasthan,
Pondicherry, Goa, Orissa, west bengal, U.P, Andaman and Nicobar islands.

13. Clinically SupectedChikungunya Fever Cases Since 2008
Sl.
No.
Affected States/UTs 2008 2009 2010 2011 2012 2013* 2014**
1 Andhra Pradesh 5 591 116 99 2827 4827 377
2 Assam 0 0 0 0 0 742 0
3 Bihar 0 0 0 91 34 0 0
4 Goa 52 1839 1429 664 571 1049 455
5 Gujarat 303 1740 1709 1042 1317 2890 200
6 Haryana 35 2 26 215 9 1 2
7 Jharkhand 0 0 0 816 86 61 0
8 Karnataka 46510 41230 8740 1941 2382 5295 5248
9 Kerala 24685 13349 1708 183 66 273 143
10 Madhya Pd. 0 30 113 280 20 139 142
11 Meghalaya 0 0 16 168 0 0 0
12 Maharashtra 853 1594 7431 5113 1544 1578 1093
13 Orissa 4676 2306 544 236 129 35 10
14 Punjab 0 0 1 0 1 0 1
15 Rajasthan 3 256 1326 608 172 76 22
16 Tamil Nadu 46 5063 4319 4194 5018 859 392
17 Telangana 0 0 0 0 0 0 518
18 Tripura 0 0 0 0 0 0 21
19 Uttar Pradesh 11 0 5 3 13 0 3
20 Uttarakhand 0 0 0 18 0 0 0
21 West Bengal 17898 5270 20503 4482 1381 646 827
22 A& N Island 0 0 59 96 256 202 156
23 Chandigarh 0 0 0 1 0 1 0
24 D&N Haveli 0 0 0 0 100 2 0
25 Delhi 14 18 120 110 6 18 4
26 Lakshadweep 0 0 0 0 0 0 0
Puduchery 0 0 11 42 45 146 290
Total 95091 73288 48176 20402 15977 18840 9904

14. Chikungunya virus
Chickungunya is the native word for the disease in which the
patient lies ‘doubled up’ due to severe joint pain.
 The virus is transmitted by Aedes aegypti
 There is no animal reservoir for the virus
 Incubation period – 4-7 days
 The disease is chracterised by fever, crippling joint pains,
lymphadenopathy, conjunctivitis and rash
 Migratory polyarthritis mainly affects the small joints of the hands
and wrists
 The fever is typically biphasic with a period of remission after
1-6 days

15.  A maculopapular rash is common and most intense on the trunk
and limbs that may desquamate
 Haemorrhagic manifestations are seen in some patients
DIAGNOSIS
Virus isolation – intracerebral inoculation in suckling mice or VERO cell
 serological diagnosis – haemagglutination inhibition, serum neutralisation, CFT, ELISA
 RT-PCR
CONTROL
• VECTOR CONTROL
•VACCINE – no vaccine has been developed

16. GEOGRAPHICAL DISTRIBUTION
Leading cause of viral encephalitis in Asia and occurs in almost all
Asian countries.
The disease has been recognised in Japan since 1871 and was
named Japanese B encephalitis to distinguish from encephalitis A.
Virus was first isolated in Japan during epidemic in 1935.
As a result of immunisation, its incidence has been declining in japan ,
the Korean peninsula and in some of regions of china.
The disease is increasingly reported from Bangladesh, India, Nepal,
Pakistan, northern Thailand, and Vietnam.

17. PROBLEM IN INDIA
•Recognition of JE was first made in 1955 in Tamil nadu when the virus was isolated
from culex vishnui.
•Remained confined to southeastern parts of India till 1973 when it caused large
outbreak in West Bengal
•From 1976, there have been periodic outbreaks in various parts of India –
Dibrugarh(Assam) in the east, Gorakhpur (UP) and Haryana in the north and Goa
and Maharashtra in the west.
•Endemic in 14 states.
•Assam, Bihar, Haryana, UP, Karnataka, and Tamil nadu report outbreaks every year
and contribute to 80% of cases and deaths .
•About 300 million people are at risk.

20. Epidemiology
Vector –culicine mosquitoes like culex tritaeniorhynchus, c. vishnui, c. gelidus
and some anophelines
breeding place – rice fields, shallow ditches, pools
Reservoir host – herons, egrets
Amplifier host – pigs
Human infection is a incidental “dead end’ event.

21. Clinical features
 Most human infections are subclinical: the inapparent to clinical
cases is 500-1000:1
 Incubation period: 5-15 days
 The course of the disease in man may be divided into three stages
1.Prodromal stage
2.Acute encephalitic stage
3.Late stage and sequelae

22. Prodromal stage
The onset of illness is usually acute and symptoms include fever,
headache and vomiting
Acute encephalitic stage
 After 1-6 days, signs of encephalitis characterised by neck rigidity,
convulsions, altered sensorium and coma appear
Late stage and sequelae
 Convalescence may be prolonged and residual neurological deficits
may not be uncommon
 Case fatality rate varies between 20-40%, but it may reach 58% and
over in some epidemics
 Residual neurological damage may persist in about 50% of survivors

23.  The disease is usually diagnosed by serology
No specific therapy is available
Prevention
Preventive measures include mosquito control and establishment
of piggeries away from residential areas
VACCINES:
1.Formaline inactivated mouse brain vaccine
• Based on Nakayama or Beijing strains
• Dose-0.5 ml for children< 3yrs and 1 ml for children more than
1 yr
• Route- subcutaneously
• Administration – 2 primary doses 4 weeks apart and booster doses
after 1 year and subsquently at 3 year interval until the age of
10-15 yrs.

24. 2. Live attenuated vaccine
Based on SA 14-14-2 strain
 dose – 0.5 ml
Route - subcutaneously
Single dose followed by a single booster given at an interval of 1 year

25. Yellow fever

26. Yellow FeverYellow Fever
 Yellow fever is a mosquito-borne acute febrile illness accompanied by hepatic necrosisYellow fever is a mosquito-borne acute febrile illness accompanied by hepatic necrosis
 It occurs mainly in tropical Africa and Latin AmericaIt occurs mainly in tropical Africa and Latin America
 It does not exist in IndiaIt does not exist in India
 The name has been derived from ‘yellow quarantine flag’ usedThe name has been derived from ‘yellow quarantine flag’ used
by the ships during 17by the ships during 17thth
century to warn the presence, on boardcentury to warn the presence, on board
of this infectionof this infection
 Yellow fever occurs in 2 major forms: urban and jungle (sylvatic) cycleYellow fever occurs in 2 major forms: urban and jungle (sylvatic) cycle

27.  In the urban cycle, man serves both as reservoir and as definitive
host, the virus being transmitted by Aedes aegypti mosquito
 In the forest or sylvatic cycle, wild monkeys act as reservoirs and several species
of forest mosquitos (Haemagogus spegazzinnii in south America and Aedes
africanus and A. simpsoni in Africa) are vectors. Human cases occur only when
humans trespass into the forest or when monkeys raid villages.

28. India is a yellow fever “receptive area” that is “ an area in which yellow fever
does not exist, but where conditions would permit its development if
introduced”
The population of india is unvaccinated and susceptible to yellow fever.
The vector, Aedes aegypti is found in abundance
The climatic conditions are favourable in most parts of india for its
transmission
The only missing link is the virus of yellow fever which does not seem
to occur in india

29. Clinical features
 After an incubation period of 3-6 days, patient develops fever with
chills, headache, myalgia and vomiting
 Most cases are mild in nature, especially in the endemic areas, in
whom the disease may present as undifferentiated fever without
jaundice
 The pulse is usually slow despite a high temperature
 In 15-20% of cases, the disease progresses to a more serious form
with jaundice, albuminuria, renal failure and haemorrhagic
manifestations and the patient may die of hepatic and renal failure

30. Prophylaxis
 There is no antiviral drug against yellow fever
The control of urban yellow fever can be achieved by eradicating
the vector mosquito
 vaccine
 17D vaccine was developed by Theiler in 1937 by passaging the
Asibi strain.
 Given subcutaneously
 Mandatory for travel to or from endemic areas.
 Valid for 10 years beginning 10 days after vaccination.

31. Kyasanur Forest Disease (KFD)
oKyanasur forest disease is a febrile disease associated with haemaorrhages transmitted to man
by bite of infective ticks.
HISTORY
 first recognised in 1957 in Shimoga district of karnataka state .
Local inhabitants called it “monkey disease”
Later named after the locality – kyanasur forest
PROBLEM STATEMENT
Remained confined to the areas contiguous to its original focus in the Sagar, Sorab and
Shikarpur taluks of Shimoga district for many years.
Between 1972 and 1975 , another foci developed in adjacent areas in north Kanara.
In 1982, appearance of epizoonotic and epidemic in Belthangadi taluk in south kanara.
The ecological disturbance caused by clear felling of virgin forest is believed to have
activated a silent enzoonotic focus of the virus.

33. Epidemiology
NATURAL HOST AND RESERVOIR
Reservoir- small mammals particularly rats and squirrels, birds and bats
Monkeys- amplifying host
VECTORS
Haemaphysalis spinigera
H. turtura
INCUBATION PERIOD – between 3 and 8 days
CLINICAL FEATURES
Sudden onset of fever, headache and sever myalgia
Gastrointestinal disturbances and haemorrhages from nose, gums , stomach
and instestine in severe cases
Case fatality rate – 5-10 %

34. Control
 Control of ticks
 The population at risk should be vaccinated with killed KFD vaccine
 Personnel protection – protection of individuals by adequate clothing
and insect repellents

36. HISTORY
Dengue virus was isolated in Japan in 1943 by inoculation of serum of patients in
suckling mice and at Calcutta (now Kolkata) in 1944 from serum samples of US
soldiers.
The first epidemic of clinical dengue-like illness was recorded in Madras (now
Chennai) in 1780 and the first virologically proved epidemic of DF in India occurred
in Calcutta and Eastern Coast of India in 1963-1964.
The first major epidemic of the DHF occurred in 1953-1954 in Philippines
followed by a quick global spread of epidemics of DF/DHF.
The DHF started simmering in various parts of India since 1988.
The first major wide spread epidemics of DHF/DSS occurred in India in 1996
involving areas around Delhi and Lucknow13 and then it spread to all over the
country

37. PROBLEM STATEMENT
oDengue is the most rapidly spreading mosquito-borne viral disease in the world.
o In the last 50 years, incidence has increased 30-fold with increasing geographic expansion
to new countries and, in the present decade, from urban to rural settings.
o An estimated 50 million dengue infections occur annually and approximately 2.5 billion
people live in dengue endemic countries.
o5,00,000 people with DHF require hospitalisation each year.
o 90% of them are childern less than 5 years and about 2.5 % of those affected die.
o Dengue is endemic in more than 100 countries.
o The south – east asia and western pacific regions are the most seriously affected.

38. An Epidemic, Endemic& Hyper Endemic
South- East Asia is divided into 3 Categories:
Cat A: India, Bangladesh, Myanmar, Sri Lanka, Indonesia, Thailand,
Maldives
Cat B: Bhutan, Nepal
Cat C: DPR Korea

39. INDIAN SCENARIO
Increased risk in recent years due to
 Rapid urbanisation
 Lifestyle changes
 Deficent water management
Seasonal pattern – cases peak after monsoon
Perennial transmission in southern states and Gujarat
Endemic in 31 states/UTs.
All the serotypes have been isolated in India.
At present DENV-1 and DENV-2 serotypes are widespread.

40. Epidemiological studies where dengue virus was identified
Year Region where study was conducted Type of dengue virus
detected
1964 Vellore, Tamil Nadu DV-2
NA South India DV-3
1966 Vellore, Tamil Nadu DV-3
1968 Vellore, Tamil Nadu DV- 1,2,3 & 4
1968 Kanpur, Uttar Pradesh DV-4
1969 Kanpur, Uttar Pradesh DV-4 and DV-2
1970 Hardoi, Uttar Pradesh DV-2
NA NA DV- 1,2,3 & 4
1983 Kolkata, West Bengal DV-3
1985 Jalore town, South-West
Rajasthan
DV-3
NA Chikalthana, Pimpalgaon and
Waloor villages in Parbhani
district of Maharashtra.
DV-1 & 2
1988 Delhi DV-2
1990 Calcutta, West Bengal DV-3
1988 Rural and urban areas of Gujarat DV-2
1993 Mangalore, Karnataka DV-2
NA Assam and Nagaland DV-2
1996 Ludhiana, Punjab DV- 1,2,3 & 4
1996 Lucknow DV-2
1996 Delhi DV-2
1996 Delhi DV-2
1997 Delhi DV-1
1996 Delhi DV-2 (Genotype IV)
NA Ahmedabad, Gujarat DV-2
1997 Delhi DV-1
NA Delhi DV-2 (Genotype IV)
1996 Rural areas of Haryana DV-2
2001 Dharmapuri district, Tamil Nadu DV-2
NA Andaman and Nicobar Islands DV-2
2001 Gwalior, Madhya Pradesh DV-2
NA Northern India DV-2 (Genotype IV)
2001 Chennai, Tamil Nadu DV-3
2003 Northern India (Delhi & Gwalior) DV-3
2005 Kolkata, West Bengal DV-3
2003 Kanyakumari district, Tamil Nadu DV-3
2003-04 Delhi DV-3 (subtype III)
2003-05 Delhi 2003 - DV - 1,2,3 & 4
2005 - D - 3
2006 Delhi DV-3
2006 Delhi DV-1 & 3
2001-07 North India (Delhi and Gwalior
region)
DV-1 (Genotype III)
2006 Delhi DV-1,3 & 4
2008 Delhi region DV-1,2 & 3

41. DISTRIBUTION OF DENGUE/DHF IN INDIA

42. Sl.
No.
Affected States/UTs
2008 2009 2010 2011 2012 2013* 2014**
C D C D C D C D C D C D C D
1 Andhra Pradesh 313 2 1190 11 776 3 1209 6 2299 2 910 1 264 2
2 Arunachal Pradesh 0 0 0 0 0 0 0 0 346 0 0 0 0 0
3 Assam 0 0 0 0 237 2 0 0 1058 5 4526 2 48 0
4 Bihar 1 0 1 0 510 0 21 0 872 3 1246 5 1 0
5 Chattisgarh 0 0 26 7 4 0 313 11 45 0 83 2 56 5
6 Goa 43 0 277 5 242 0 26 0 39 0 198 2 97 0
7 Gujarat 1065 2 2461 2 2568 1 1693 9 3067 6 6272 15 1161 0
8 Haryana 1137 9 125 1 866 20 267 3 768 2 1784 5 136 1
9 Himachal Pd. 0 0 0 0 3 0 0 0 73 0 89 2 0 0
10 J & K 0 0 2 0 0 0 3 0 17 1 1837 3 0 0
11 Jharkhand 0 0 0 0 27 0 36 0 42 0 161 0 0 0
12 Karnataka 339 3 1764 8 2285 7 405 5 3924 21 6408 12 2277 0
13 Kerala 733 3 1425 6 2597 17 1304 10 4172 15 7938 29 1804 9
14 Madhya Pd. 3 0 1467 5 175 1 50 0 239 6 1255 9 1319 9
15 Meghalaya 0 0 0 0 1 0 0 0 27 2 43 0 0 0
16 Maharashtra 743 22 2255 20 1489 5 1138 25 2931 59 5610 48 3551 7
17 Manipur 0 0 0 0 7 0 220 0 6 0 9 0 0 0
18 Mizoram 0 0 0 0 0 0 0 0 6 0 7 0 15 0
19 Nagaland 0 0 25 0 0 0 3 0 0 0 0 0 0
20 Orissa 0 0 0 0 29 5 1816 33 2255 6 7132 6 5079 9
21 Punjab 4349 21 245 1 4012 15 3921 33 770 9 4117 25 218 0
22 Rajasthan 682 4 1389 18 1823 9 1072 4 1295 10 4413 10 380 2
23 Sikkim 0 0 0 0 0 0 2 0 2 0 38 0 5 0
24 Tamil Nadu 530 3 1072 7 2051 8 2501 9 12826 66 6122 0 1574 0
25 Tripura 0 0 0 0 0 0 0 0 9 0 8 0 5 0
26 Telangana 0 0 0 0 0 0 0 0 0 0 0 0 351 0
27 Uttar Pradesh 51 2 168 2 960 8 155 5 342 4 1414 5 28 0
28 Uttrakhand 20 0 0 0 178 0 454 5 110 2 54 0 1 0
29 West Bengal 1038 7 399 0 805 1 510 0 6456 11 5920 6 2212 1
30 A& N Island 0 0 0 0 25 0 6 0 24 0 67 0 112 0
31 Chandigarh 167 0 25 0 221 0 73 0 351 2 107 0 6 0
32 Delhi 1312 2 1153 3 6259 8 1131 8 2093 4 5574 6 340 2
33 D&N Haveli 0 0 0 0 46 0 68 0 156 1 190 0 266 1
34 Daman & Diu 0 0 0 0 0 0 0 0 96 0 61 0 0 0
35 Puduchery 35 0 66 0 96 0 463 3 3506 5 2215 0 466 0
Total 12561 80 15535 96 28292 110 18860 169 50222 242 75808 193 21772 48

43. The Epidemiological TriadThe Epidemiological Triad

44. The AgentThe Agent
Arbovirus (ss RNA Virus)
Genus Flavivirus
Family Flaviviraede
4 serotypes- DENV 1, DENV 2, DENV 3 & DENV4
Antigenic similarity but infection with one serotype does not
provide lifelong immunity for other serotypes (Cross Immunity
lasts only a few months),
…Instead prior immune sensitization worsens the disease
scenario

45. Denv Has…Denv Has…
A lipoprotein envelope
3 structural protein genes encoding: {CME}
– Nucleocapsid or core protein (C),
– Membrane- associated protein (M),
– Envelope protein (E), and
7 non-structural protein (NS) genes including, envelope glycoprotein,
NS 1
NS 1 is of diagnostic and pathological importance.
It is associated with viral haemagglutination and neutralization activity.

47. The HostThe Host
Infective Stage: 1 day before onset of fever to day 5
Intrinsic Incubation Period: 4- 6 days
High Risk Patients:
– Extremes of Age
– Pregnancy
– Any condition prone to heavy blood loss: Peptic ulcer disease;
menstruation; haemolytic anaemia; G- 6PD deficiencies;
thalassemia; patients on steroids, NSAIDS
– Any chronic condition: DM, HTn, Asthma, Cirrhosis, IHD, CRF

48. Remember… “Prior immune sensitization
worsens the disease scenario”
1st
Infectio
n with
DENV-
1
Asymptomatic/
Non specific
manifestations/
DF
2nd
Infection
with
DENV- 2, 3
or 4
DHF/
DSS/
Severe
Disease
Secondary Infection with DENV 2 or multiple infections with different
serotypes causes Severe Disease (DHF/ DSS)
DENV 1/ DENV 2 Sequence is the worst

49. Non neutralizing
Ab(s)
Mononuclear cells Cytokines,
vasoactive
mediators
procoagulants
DIC
2nd
Infection

50. The EnvironmentThe Environment
Tropical& Sub- tropicalTropical& Sub- tropical
Urban, Peri urban;Urban, Peri urban; RuralRural
Rapid Unplanned uncontrolledRapid Unplanned uncontrolled urbanizationurbanization,,
Transportation:Transportation: human movement and congregationhuman movement and congregation
Poor water storage and managementPoor water storage and management
Seasonal Pattern:Seasonal Pattern: Post Monsoon (But Perennial in Gujarat&Post Monsoon (But Perennial in Gujarat&
South India)South India)

51. Global WarmingGlobal Warming
2 degree rise in temp-2 degree rise in temp-
– Shortens extrinsic IP- more infected mosquitos to furtherShortens extrinsic IP- more infected mosquitos to further
spread DENVspread DENV
– Enhances the life cycle of AedesEnhances the life cycle of Aedes
– Shortens the size of the mosquitoShortens the size of the mosquito
– Rise in temp- mosquito bites more frequently due toRise in temp- mosquito bites more frequently due to
“dehydration”- further spreads DENV“dehydration”- further spreads DENV

52. The VectorThe Vector
Ae albopictusAe albopictus Eggs Survive Sub Freezing TempEggs Survive Sub Freezing Temp
Ae aegyptiAe aegypti-- Cosmo tropical species between latitudes 45°N and 35°SCosmo tropical species between latitudes 45°N and 35°S
Vector CompetencyVector Competency
Vector CapacityVector Capacity
Transovarial SpreadTransovarial Spread
Endophagic, EndophilicEndophagic, Endophilic
16- 35 °C, 60- 80% Relative Humidity16- 35 °C, 60- 80% Relative Humidity

53. Vector CompetencyVector Competency
– High susceptibility to infecting virus
– Ability to replicate the virus
Ability to transmit the virus to another host
Both Ae. aegypti and Ae. albopictus carry high vectorial
competency for dengue viruses.

54. VectorialVectorial CapacityCapacity: Depends on the: Depends on the
Environmental and BiologicalEnvironmental and Biological
characteristics of the Vectorcharacteristics of the Vector
Ae. aegyptiAe. aegypti
Highly domesticated
Strongly anthropophilic
Nervous feeder (i.e. it bites more
than one host to complete one blood
meal) and
Discordant species (i.e. it needs
more than one feed for the
completion of the gonotropic cycle)
These habits epidemiologically result
in the generation of multiple cases
and the clustering of dengue cases
in cities.
Ae. albopictusAe. albopictus
Feral
Feeds on both humans and animals
Aggressive feeder (i.e. it can complete
its blood meal in one go on one
person)
Concordant species (does not require
a second blood meal for the
completion of the gonotropic cycle)
So, Ae. albopictus has poor vectorial
capacity.

56. Undifferentiated FeverUndifferentiated Fever
Primary dengue infection
May develop a simple fever indistinguishable from other viral
infections.
Maculopapular or rubelliform rashes on face, neck and chest may
accompany the fever or may appear during defervescence (Day 3-5)
URTI and GI symptoms are common

57. Dengue FeverDengue Fever
Older children, adolescents and adults
Acute (Sudden, sharp) rise in temperature (39°C- 40°C) for 5- 7 days
Biphasic fever with severe headache, myalgia, arthralgia and bone pains
(break-bone fever), particularly in adults
Rashes, flushed face, retro-orbital pain on eye movement or eye pressure,
photophobia
Altered taste sensation, Anorexia, Sore throat, Dragging pain in inguinal region
Leukopenia and thrombocytopenia- mild
Occasionally, Haemorrhage such as gastrointestinal bleeding, hyper
menorrhea, massive epistaxis (DF with Hmrgh)

58. Dengue Haemorrhagic Fever (DHF)Dengue Haemorrhagic Fever (DHF)
Children less than 15 years of age in hyper endemic areas, in association with repeated
dengue infections (secondary dengue infection). Incidence of DHF in adults is increasing
Rarely DHF may occur in Primary infections with DENV-1 and DENV-3 as well as in infants.
Signs and symptoms similar to DF in the early febrile phase.
Positive tourniquet test (TT), petechiae on extremities, easy bruising and/or GI haemorrhage
Abnormal haemostasis and plasma leakage are the main pathophysiological hallmarks of
DHF
Thrombocytopenia and rising haematocrit/haemo concentration before the subsidence of
fever/ onset of shock.

59. COURSE AND CLINICAL FEATURES
3 PHASES
 FEBRILE PHASE
 Sudden high grade fever
 accompanied by facial flushing, skin erythema, generalised
body ache, myalgia, arthralgia, retro-orbital eye pain,
photophobia
Sore throat, injected pharynx, conjunctival injection
Anorexia, nausea and vomiting – common
Mild haemorrhagic manifestations – petechiae, mucosal
bleeding
Last for 2-7 days
Progressive decrease in total white cell count

60. CRITICAL PHASECRITICAL PHASE
Warning signs
Condition worsen around the time of deferevescence
On 3-8 days of illness
Progressive leucopenia
Rapid decrease in platelet
Increase in heamatocrit severity of plasma leakage
Haemorrhagic manifestation – easy bruising and bleeding at venepuncture site
Profound shock
hypoperfusion metabolic acidosis, organ impairement,
DIC severe haemorrhage decrease heamatocrit

61. WARNING SIGNSWARNING SIGNS
Between 3-7 days of illness
Abdominal pain and tenderness
Persistent vomiting
Clinical fluid accumulation
Mucosal bleed
Lethargy, restlessness
Liver enlargement > 2cm
Increase in Hct with rapid decrease in platelet count

62. RECOVERY PHASERECOVERY PHASE
Gradual reabsorption of extravascular fluidGradual reabsorption of extravascular fluid
Improvement inImprovement in
– General well beingGeneral well being
– ApetiteApetite
– GI symptomsGI symptoms
– Hemodynamic statusHemodynamic status
Isles of white in the sea of redIsles of white in the sea of red
Haematocrit stabilisesHaematocrit stabilises
Rise of WBC countRise of WBC count
Recovery of platelet countRecovery of platelet count

63. Dengue Shock Syndrome (DSS)Dengue Shock Syndrome (DSS)
Hypovolemic shock due to plasma leakage
Pleural effusion, Ascites (plasma leakage to pleural& peritoneal cavities)
Hypothermia- Cold clammy skin
Fulminant hepatic failure
Optimal fluid management is important- Avoid over hydration

64. Dengue case classification by severityDengue case classification by severity

65. Dengue diagnosisDengue diagnosis

66. Laboratory confirmationLaboratory confirmation

67. ManageMent

70. CONTROL MEASURES
MOSQUITO CONTROL
– ANTI-LARVAL MEASURES
– ANTI- ADULT MEASURES
VACCINES
– NO SATISFACTORY VACCINE
OTHER MEASURES
– Bed-nets
– Wearing full sleeve shirts, full pants
– Mosquito repellent creams
– Environmental measures
Elimination of mosquito breeding places
Management of roof tops
Proper covering of stored water