The document discusses Dengue fever (DF), a mosquito-borne viral disease. It provides details on the history, transmission, clinical presentation, diagnosis and treatment of DF. DF is common in tropical and sub-tropical regions and is caused by the dengue virus, which has four serotypes. While most cases are mild, infection with a second serotype increases the risk of severe dengue which can be fatal if not properly treated through fluid resuscitation. Prevention relies on controlling the mosquito vectors and avoiding mosquito bites. There is no vaccine available for all four serotypes.

2. পৃথিবীর সবচাইতে সুন্দর গাছ. জাপাতেI ওতেতেথরো:বযাপক আকাতরর । সারা পৃথিবী থিতক
অসংখ্য মােুষ এই গাছ থেখ্তে আতস। ১৯৯০ বগগ ফু ট

5. DENGUE
FEVER
Dr mohammad nurul huq

6. History of DF
• 1780: epidemics in in Asia, Africa, N America
• First in Bangladesh in 1964 (Dacca Fever)
• 1968: a small outbreak occurred in border with Myanmar
• In India DF was first recorded in 1812. A double peak
hemorrhagic F epidemic occurred in Calcutta 1963-64
• In N Delhi, outbreaks reported in 1967, 1970, 1982, 1996

7. Overview of Dengue Fever
The commonest mosquito-borne viral disease
• Aka ‘break bone fever’, Dandy fever
• A multisystem inf. with wide clinical spectrum: ILI to fatal
• Found in tropical & sub-tropical, mostly in urban &
semi-urban areas
• Risks: rainfall, temp., unplanned rapid urbanization
• Severe DF is a leading c/of serious illness & death among
children in some Asian & LatAm countries
Aka: also known as. ILI: influenza like illness
7
Probably from Spanish, probably of African origin; compare Swahili kidinga

9. • Despite its complex features, Rx is relatively simple, cheap
& very effective if timely done.
Maintenance of body fluid is critical in severe DF
• The success key is early Dx & knowing its different phases
• Rx at the primary & secondary levels are critical. A well-
managed front-line response reduces admissions
• No specific Rx.
• Fatality <1%
• Prevention & control depends on effective vector
control measures

10. • Vectors: mainly female A aegypti, less: A albopictus
• 4 closely related serotypes: DENV-1, -2, -3, -4
• Every serotype can cause severe & fatal disease
• Recovery from 1 gives lifelong immunity against that.
Cross-immunity to another serotypes is partial &
temporary: subsequent inf. by that increases
the risk of severe DF
• 500,000 DHF are admitted/y: a large portion are children
• Death: 10,000/y
10

11. The commonest is female A aegypti (tiger mosquito). Unlike
others it is primarily a daytime feeder: early in morning
& before dusk. It lives near urban habitats &
breeds mostly in man-made containers
A albopictus, less common in Asia; has spread to N America &
Europe. It is highly adaptive & can survive cold. It
hibernates. Most active 5-6pm & 8-9am (2hours)
A aegypti (5mm) A albopictus

12. Global burden of DF
Underreported & misclassified
• 390 million/y (25% clinical)
• Incidence has grown x30 in recent decades
• 50% global population is now at risk
• <1970, only 9 countries had DF. Now >100. The Americas, SEA
& W. Pacific are worst affected
• DF spreads to new areas with explosive outbreaks
• For a given country:
DF knows only the entry but not the exit
• In Europe first cases were reported in France & Croatia in
2010 & imported cases in 3 other countries
12

13. • 2012: outbreak occurred on Madeira islands (Portugal)
& imported cases were detected in mainland Portugal
& 10 other countries in Europe
• 2013 saw outbreak in Florida & Yunnan; Costa Rica,
Honduras & Mexico, Laos. Singapore has more cases
after a lapse of several years
• 2014: more cases in China, Cook Islands, Fiji, Malaysia &
Vanuatu, Tonga & French Polynesia. DF was also
reported in Japan after >70y
• 2015: more cases occurred in Brazil & neighbors; worst
outbreak in Delhi 13

14. 14
Regions affected
DF 2001

17. Global dengue burden, 2014

18. Dengue Virus
• Arbovirus, flavivirus: 4 serotypes
• Induces cytokines in cells with effects on endothelia in:
– Heart, Liver, Kidneys, Lungs
– Gut, Spleen, LN, Brain, Skin
Causes increased permeability
But no inflammation!

20. LC of flavivirus

21. Transmission
• Within mosquito replication (extrinsic IP: 8-10d). It can
transmit for the rest of vector’s life (2-3w)
• Within humans (reservoir). Transmit for 4–5d (12d) after
onset of disease. SS appear 4-7d (3-14d) (intrinsic IP)
• Viremia starts slightly before SS; may last 3-10d (5d). The
illness persists several days after the viremia has ended
21

22. 22
Transmission
Infected
person
Healthy person
Infected
mosquito
IP: 3-14d
Most commonly 4-7d

23. • Depends on the host immune response
• Primary inf. is usually benign; but, 2y inf. with different
serotype(s) within 3mo may cause DHF/DSS
Antibody-dependent enhancement: by non-
neutralizing, cross-reactive Ab from a primary inf.,
cause a heavy viral load: multisystem spread
• Memory T cells & cytokines (INF-gamma, TNF-alpha, IL-
10) cause vascular leakage. No inflam.! Complements
are reduced by NS1
Pathogenesis

25. • Hallmark of DHF: transient dysfunction of endoth.: leakage:
(raised hct., low albumin, pl. effusions, ascites, hge.,
(thrombocytopenia & coagulation d.)
• Loss of intravascular fluid causes hypoperfusion (lactic
acidosis), hypoglycemia, hypoCa; finally, multi-organ
failure
• Infants can have DHF during a primary inf. due to
transplacental antibodies
Pathogenesis …

26. • Inf. with 1 serotype gives life-long immunity only for that
with a very brief period of partial cross immunity (3mo)
• Subsequent inf. by other serotypes increase the risk DHF
• Everyone can be inf. by all 4. Several serotypes can be in
circulation during an epidemic
• Differential targeting of specific vascular beds triggers local
vascular hyperpermeability
No generalized edema!
Pathogenesis …

27. 3 Cl. Syndromes of DF:
1. Undifferentiated fever;
2. Classic DF
3. Severe DF: DHF, DSS
Case Definition for DF
an ac. viral biphasic F, frequently presenting with HA,
bone/joint & muscular pains, rash, & leucopenia

28. DF VIRUS INFECTION
Asymptomatic Symptomatic
Undiffrentiated fever
(viral syndrome)
DF
DF Haemorrhagic
fever
No Shock
DF Shock
Syndrome (DSS)
(Plasma
leakage)DF
DF Haemorrhagic
fever

29. 29
SS Classical DF
a severe, ILI that affects infants, young children & adults
• Suspect DF if a HGF (40°C) is accompanied by any 2 of:
severe HA, pain behind eyes, backache, muscle & joint
pains, NV, swollen glands or rash on 3rd/4th d
• Age: commonly 2-7y
• Duration of illness: 2–7d
• F: 3-5d
• Slight gum & nasal bleeding
• Pts. may also have itching, altered taste, particularly a
metallic taste, extreme fatigue & severe depression

31. Skin rash
Symptoms

32. 4 Dx Criteria for DHF
• Fever/recent F
• Bleeds: skin, gum, nose, GIT, urine, menstruation
• Low platelet (<100,000/mm3)
• Leaky capillaries: raised hct. (≥20% over baseline)
• low albumin
• pleural or other effusions
4 Grades of DHF
Grade 1: +ve tourniquet test
Grade 2: above + spontaneous
bleeding
Grade 3: above + circulatory failure
Grade 4: above + profound shock

34. Warning Signs of DHF
3–7d after onset with a fall in temp.: severe AP, HA, F., rash,
persistent vomiting, tachypnea, bleeding gums/nose,
fatigue, restlessness & internal hge
All these show impending shock & should alert clinicians:
close observation & fluids
• The next 48h is critical for organ failure
34

35. Definition for DSS:
DHF +
• Evidence of shock: pinched face, sunken eyes, rapid thready
pulse, cold clammy skin, beads of sweats on face,
narrow pulse pressure (<20mmHg), hge., hypotension,
low urine, late cap.refill, & altered mentation
SS of Encephalitis/Encephalopathy in DF
• Decreased consciousness: lethargy, confusion, coma
• Seizures
• Nuchal rigidity
• Paresis

36. DHF causes death through dysfunction of
endothelium (shock) & coagulopathy

37. Dx of DF
• Direct: DENV isolation, genome detection (PCR), Ag.
detection
• Indirect: IgM & IgG
– IgM to DENV or a ≥x4 rise in IgG in paired sample (ac. &
convalescence serum)
• Reverse transcription PCR (RT-PCR) & Ab (65.9%). PCR
during first 5d of SS and/or early conval. (>5d)
• NS1 & Ab (62.0%)
Sample: serum or autopsy tissues

38. • Pts. who have IgM but a negative RT–PCR have probably
a recent DF. IgM may remain elevated for 2-3mo
• Also, there is cross reactivity with W. Nile V, St. Louis
encephalitis V, Japanese Encephalitis V, Yellow FV. Dr
should review past illness, recent travel, vax. record
(especially YF) to Dx DF
• Often paired specimens are needed for Dx. as Ag & IgM
may be undetectable initially

39. Dx of DF ..,.

40. Flavivirus replication complex

42. 42
Treatment
No specific Rx.
• For severe DF, medical care can decrease MR to <1%
• Maintenance of fluid is critical
• Classical DF recovers in 11d
• DHF: intensive supportive Rx
No NSAIDs: worsen the hemorrhage

43. DHF: emergency!
• IVF is the essential & is the sole intervention: isotonic, for
effective circulation. Boluses of 10−20 ml/kg/h for a
limited period under close supervision; can avoid
pulmonary edema
• Blood transfusion
• Follow urine output
• In shock, colloid solution is preferred
• Hct. before & after IVF. Basal Hct: 35−40% in adult females,
40−45% in males

44. Goals of fluid resuscitation:
• improving circulation: less Hct., improving BP & pulse
pressure, warm & pink limbs, a cap-refill <2sec
• improving end-organ perfusion: stable mentation, urine
≥0.5ml/kg/h or decreasing metabolic acidosis
• Later, IVF is given 10ml/kg/h for 1−2h; then 7ml/kg/h
x2−4h & finally 3-5ml/kg/h for 24−48h

45. Prognosis
• DF is typically self-limiting. CFR: <1%
• Untreated, CFR: 50%
• Usually recover without sequelae with serotype immunity
• Factors for severity: age, preg., nutritional status,
ethnicity, inf. with different serotypes, virus genotype,
quality & extent of available medical care

46. 46
Prevention & control
Only by combating vector:
Prevention of Mosquito Bites:
• avoid going out when vector feeds
• wear light-colored, long-sleeved
clothing & trousers
• mosquito-repellents over exposed
parts of body & clothes
every 4-6h

47. 47
Prevention of Mosquito Bites
Your accommodation should
be air-conditioned or have
mosquito nets
Use insecticides or coil
incenses

48. 48
Elimination of Mosquitoes
The most effective way is to
keep environment clean &
to remove stagnant water
Cover water containers
tightly so that mosquitoes
can’t get in to lay eggs.

49. 49
Elimination of Mosquitoes
• Dispose of domestic wastes
properly to prevent stagnant water
• Dispose of empty bottles, cans &
lunchboxes properly

50. 50
Elimination of Mosquitoes
• Change water for vases &
aquatic plants/w, leaving no
water under the pots or in the
bottom saucers
• Scrub the container surfaces
thoroughly to prevent mosquito
eggs sticking on them

51. 51
Elimination of Mosquitoes
Remove or puncture any
dumped tyres to prevent
the accumulation of
stagnant water

52. 52
Elimination of Mosquitoes
Ditches should be free
from blockage.
Fill up uneven ground
to prevent stagnant
water

53. 53
Elimination of Mosquitoes
Remove stagnant water
immediately if mosquitoes are
found to be breeding. Use
environmentally friendly
insecticides such as lavicidal oil if
necessary
Biological controls such as keeping
fishes to eat mosquito larvae
would be a good option

54. Potential Breeding Sites

60. • Cover rarely used gully traps. Replace the gully trap
with non-perforated ones & install anti-mosquito
valves.

62. Prevention includes use of bug spray & other
mosquito preventatives

63. WHO
• provides technical support & guidance for effective
management of DF outbreaks
• supports to improve reporting systems & capture the true
burden of the disease
• provides training on Rx, Dx & vector control
• formulates evidence-based strategies & policies
• develops new tools, including insecticide products &
application technologies
• gathers official records of DF & severe DF from over 100
Member States
• publishes guidelines & handbooks for case Mx, prevention
& control for Member States

64. 64
Immunization
• Vaccine available

65. C H I K U N G U N Y A
Facts
a mosquito-borne RNA viral d. 1st reported in Tanzania 1952
• Means “to be contorted”, stooped due to severe arthralgia,
fever; myalgia, HA,, nausea, fatigue & rash
• Usually not fatal
• Arthralgia is often debilitating & varies in duration
• C. shares some SS with DF & zika
• C. mostly occurs in Africa, Asia & Indian sub-. But a major
outbreak; 2015 affected several countries in Americas
No cure!

67. Signs & Symptoms
Typical: abrupt F, frequent arthralgia, myalgia, HA, nausea,
fatigue & rash. Arthralgia is often debilitating, but
usually lasts for a few days. May be prolonged:
acute, subacute or chronic
• Often mild & unrecognized, or be misdiagnosed in areas
where DF occurs
• Most recover fully. Some have joint pain for several mo., or
even years
• Rarely eye, neurological & heart complications are reported
as well as GI complaints. Serious complications are not
common; but in elderly, death may occur

72. Transmission
• C. has been identified in >60 countries
• Most commonly by A aegypti & A albopictus (also DF)
• Vectors usually bite outdoors, but A aegypti will also readily
feed indoors
• IP: usually 4-8d (2-12d)
A aegypti (5mm) A albopictus

73. More about Disease Vectors
• Both vectors cause large outbreaks
• A aegypti is confined in tropics & sub-. But A albo. also
lives in temperate & even cold temperate. A aegypti is
more closely a/with human habitation & uses indoor
breeding sites: flower vase, water vessels &
water tanks, as well as same artificial outdoor
habitats as A albo.
• A albopictus thrives in a wider range of water-filled
breeding sites than A aegypti: coconut husks, cocoa
pods, bamboo stumps, tree holes, rock pools,
tires, etc. So, it is abundant in rural as well
as peri-urban areas

75. Diagnosis
• Confirmed by IgM & IgG anti-C. Ab. & RT-PCR during the
first week
• IgM is highest 3-5w after onset (~2 mo.)
• RT-PCR during the first week. RT–PCR samples may also
be used for genotyping, allowing comparisons with
virus samples from various areas
• C. virus may be isolated from blood in first few d. of inf.
• Treatment. No specific Rx. Supportive only

76. R a r e complications in C.
At risk: neonates exposed intrapartum, age >65y, & HTN,
DM, CV diseases or other illnesses:
• uveitis, retinitis
• myocarditis, hepatitis, nephritis
• bullous skin lesions, hge
• Meningoencephalitis, myelitis, GBS, & cr. nerve palsies
• Some may have relapse of polyarthralgia, polyarthritis,
tenosynovitis in the months following acute illness
• Mortality is rare & occurs mostly in elderlies

77. Prevention & Control
relies heavily on reducing natural & artificial habitats
• Outbreaks: insecticides may be sprayed to surfaces in &
around containers. Treat water in these to kill larvae
• Protection during outbreaks: full dress, repellents on skin
or clothing
• Insecticide-treated mosquito nets afford good protection.
Mosquito coils or vaporizers may also reduce biting
• Basic precautions should be taken by people travelling to
risk areas (repellents, long sleeves & pants & rooms
with screens)
No vaccine

78. Disease Outbreaks
• 1999–00: DR Congo & in 2007 Gabon had a large outbreak
• 2005: a major outbreak occurred in islands of I. Ocean,
causing a large number of imported cases in Europe
• 2006-7: India had a large outbreak. Several SEA countries
were also affected
• Since 2005: India, Indonesia, Maldives, Myanmar &
Thailand have reported >1.9 million
• 2007: 1st local C. was reported in Italy (197 cases). It
confirmed that outbreaks by A albopictus are plausible
in Europe

79. Countries where chikungunya has been reported (2016)

80. • 2013: France reported 2 confirmed autochthonous cases in
the French Caribbean island St Martin. Since then, local
transmission has been confirmed in over 43 countries
& territories in Americas
• 2014: France confirmed 4 local cases. Outbreaks were
reported in the Pacific islands, Senegal, India
• 2015: >1,379,788 cases of C. were recorded in Caribbean
islands, LatAm countries, & the USA with 191 deaths
Canada, Mexico & USA have also imported cases
Disease Outbreaks …

81. • 2015: In Americas, >693k C. were reported, Colombia bore
the biggest burden. It was >1 million in 2014
• 2016: >349k C. cases reported; most in Brazil, Bolivia &
Colombia. First time autochthonous transmission was
reported in Argentina (>1,000 cases). In Africa: Kenya
reported an outbreak (>1,700 )
• 2017: Pakistan had a continued outbreak starting in 2016.
Bangladesh also had a large outbreak
Disease Outbreaks …

82. WHO Response for Chikungunya
• formulates evidence-based outbreak management plans
• provides technical support & guidance
• supports improve reporting systems
• provides training on Dx & Rx & vector control & publishes
guidelines & handbooks on these
• Encourages to develop social communication strategies to
reduce mosquito vectors

83. Mosquito-borne d.
1 of the deadliest animals; cause millions of deaths/y
• Malaria alone kills >1 million/y; a child/30 sec.
• DF has risen x30 in the past 30y, & more countries affected
• Aedes: Zika, DF, chikungunya, & YF, filariasis, Rift Valley F
• Culex: West Nile virus, Japanese encephalitis, filariasis
• Anopheles: malaria, filariasis
• >half of world’s popn. live in areas where it is present
• Sustained mosquito control is essential

84. Vector-borne diseases
Facts
• VBD cause >17% of all IDs
• >700k deaths/y
• >3.9 billion people in >128 countries are at risk of DF, with
96 million cases/y
• Chagas d., leishmaniasis & schistosomiasis affect hundreds
of millions
• Many of these are preventable

85. Vector-borne Diseases
• VBD are c/by parasites, viruses & bacteria
• Major VBD, together, account for 17% of IDs
• Burden is highest in tropics & sub- . VBD affect the
poorest. Since 2014, major outbreaks of DF, malaria,
C., YF & Zika have claimed lives & overwhelmed health
systems
• Distribution of VBD is determined by complex
demographic, environmental & social factors. Global
travel & trade, unplanned urbanization & climate
change can impact on transmission, making
period longer or more intense or causing d. to
emerge in de-novo countries

86. Main vectors & d. they transmit
• Vectors can transmit ID between humans or from animals
to humans
• Many are bloodsucking insects, which ingest pathogens
during a blood meal from a host (human or animal) &
later inject it into a new host
• Mosquitoes are the best known vector. Others include
ticks, flies, sandflies, fleas, triatomine bugs & some
freshwater aquatic snails

87. • Mosquitoes
– Aedes:
– Anopheles:
– Culex:
• Sandflies: Leishmaniasis, Sandfly F (phelebotomus F)
• Ticks:
– Crimean-Congo haemorrhagic F
– Lyme d
– Relapsing F (borreliosis)
– Rickettsial d. (spotted F &Q F)
– Tick-borne encephalitis
– Tularaemia

88. • Triatomine bugs
– Chagas d (American trypanosomiasis)
• Tsetse flies
– Sleeping sickness (African trypanosomiasis)
• Fleas
– Plague (fleas from rats to humans)
– Rickettsiosis
• Black flies
– Onchocerciasis (river blindness)
• Aquatic snails
– Schistosomiasis (bilharziasis)
• Lice
– Typhus & louse-borne relapsing F

89. • Changes in agricultural practices due to variation in temp.
& rainfall can affect the transmission of VBD
• The growth of urban slums, lacking reliable piped water or
adequate solid waste management, can render large
populations in towns & cities at risk of viral d. spread by
mosquitoes
• Together, such factors influence the reach of vector
populations & the transmission patterns of disease-
causing pathogens
Vector-borne Diseases …

90. থপাটগ ল্যাতের জাপাথে মযাতপল্, অতেক পুতরাতো একটি গাছ। েতব অেযােয মাতসর েু ল্োে বসন্ত
এবং গ্রীষ্মকাতল্ এ গাতছর থসৌন্দর্গ থবশী ফু তট উতে। এই গাতছর বাহাথর রঙ মােুষতক আকৃ ষ্ট কতর।