This presentation is prepared as part of the Course assignment of “Epidemiology of Diseases and Health Problems” for the Master's Degree of Public Health (MPH), Pokhara University and can be used as reference materials. The content and facts included in the presentation are as of information available till December 2022 and no conflict of interest is associated with the presentation. The presentation is prepared by Sagar Parajuli.

1. Sagar Parajuli
MPH Second Semester 2022
School of Health & Allied Sciences
Pokhara University
Epidemiological Perspective of Dengue & Review
of National programs and activities

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Introduction to Dengue (ICD 11, 1D20-1D2Z)
• An acute mosquito-borne arboviral disease caused by dengue virus
(DENV), dominantly found in tropical and sub-tropical regions
• Transmitted through bite of an infected Aedes mosquito, mainly by
Ae. aegypti and to lesser extent by Ae. albopictus
• Dengue virus (DENV) are of 4 serotypes; DEN-1, DEN-2, DEN-3, DEN-4
• Infection with one serotype gives lifelong immunity to that serotype but only
short-term immunity to other serotypes (cross-immunity is partial and
temporary)
• Subsequent infection increases risk of severe dengue fever. Severe Dengue
first time reported in 1950 during epidemic in Philippines and Thailand

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Epidemiological Determinants
• Agent: Dengue Virus; DEN-1, DEN-2, DEN-3, DEN-4, RNA virus of
Flaviviridae
• Vector: Female Aedes aegypti Mosquito ‘invertebrate primary vector’
anthropophilic nervous feeder and Aedes albopictus as ‘secondary vector’
aggressive feeder
• Host Factors: Human as ‘intermediate host’ and ‘reservoir’ as well, can occur
at any age irrespective of sex, in endemic areas
• Environmental Factors: Climatic factors (rainy, summer and spring), rainfall,
temperature and humidity. 16 ͦ C - 30 ͦ C temperature and the relative humidity of 60-
80%.
Risk population: living in endemic areas, pregnant women, traveler, children

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Transmission Dynamics
• Mode of transmission: ‘Bite, Blood, Birth’
1. Through bite of an infected female Aedes mosquito (daytime feeder; early
in the morning 2hrs after sunrise, evening before sunset),
2. Blood Transfusion & share of needles,
3. Vertical transmission to lesser extent (perinatal transmission and
peripartum maternal infection)
4. Transovarial transmission reported among vectors as well
• Incubation Period: ranges from 3-14 days, typically 5-7 days
• Period of communicability: No person to person transmission, 3-5 days
before end of febrile period and 8-12 days mosquito after viremic blood
meal

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Incubation period Dengue

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Infection Cycle

7. • Dengue cases ranges from asymptomatic to mild
to severe. An estimated 1 in 4 dengue virus
infections are symptomatic.(CDC)
• Undifferentiated dengue fever
• Classic dengue fever ‘breakbone fever’ (Fever,
headache, muscle and join pain, nausea,
vomiting, rash after 4-5 days of fever,
hemorrhagic manifestations)
• Dengue Hemorrhagic Fever (DHF); bruises,
epistaxis, gum and GI bleeding
• Dengue Shock Syndrome; Hypotension
Approximately 1 in 20 patients with dengue virus
disease progress to develop severe dengue. (CDC)
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Clinical presentations

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Dengue Categorization
Dengue Virus Infection
Symptomatic
Undifferentiated
Dengue
(Without Hemorrhage)
Dengue Fever
(With Hemorrhage)
Dengue Hemorrhagic
Fever (with plasma
leakage)
DHF with Shock DHF without Shock
Expanded Dengue
Syndrome
Asymptomatic

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Dengue Categorization
National Guideline on
Prevention,
Management and
Control of Dengue in
Nepal

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Clinical presentations; phases
Febrile phase (2-7 days, can be biphagic): Sudden onset of fever accompanied
by headache, retro-orbital pain, generalized myalgia and arthralgia, flushing of the
face, anorexia, abdominal pain and nausea, Rash on the trunk, on the medial aspect
of the arms and thighs, and on plantar and palmar surfaces
Critical phase (24-48 hrs): Begins with defervescence, Persistent vomiting and
severe abdominal pain , Increasingly lethargic, weakness, dizziness or postural
hypotension occur during the shock state, spontaneous mucosal bleeding
Increasing liver size and a tender liver is frequently observed, rapid and
progressive decrease in platelet count, plasma leakage
Convalescent phase: Plasma leakage subsides and begins to reabsorb extravasated
intravenous fluids, hemodynamic status stabilizes

11. Diagnosis
• Virological test
• Serological test
RDT, RT-PCR
Complications
• DHF
• DSS
• Liver, Kidney damage
• Multi-organ damage
• Bleeding & respiratory distress
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Diagnosis & Complications

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Global Status- Dengue
• Globally estimated 100-400
million infections occurs per
year
• 80% mild and asymptomatic
• Dengue cases increased by 8
fold in last two decades
• Dengue Epidemic in more
than 100 countries (before
1970 only in 9)
• Highest cases in 2019
Source: WHO Factsheet 2022

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Global Status- Dengue
• In 2020/21, Dengue
reported from Asia,
Africa, America,
Caribbean, and
Pacific region.
• Five countries with
highest cases
1. Brazil
2. Paraguay
3. Mexico
4. Vietnam
5. Malaysia
Source: WHO Factsheet 2022

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South East Asia Status- Dengue
Categories A
Bangladesh, India, Indonesia,
Maldives, Myanmar, Sri Lanka,
Thailand, Timor-Laste
1. Major Public Health
Problem
2. Leading cause of
hospitalization and death
among children
3. Hyperendemicity with all 4
Serotypes circulating in
urban areas
4. Spreading to rural areas
Categories B
Bhutan, Nepal
1. Endemicity Uncertain
2. First reported case in
Bhutan and Nepal
Categories C
DPR Korea
1. No evidence of
endemicity
• South East Asia accounts for more than
half burden of dengue in the world.
• From 2015 to 2019, dengue cases in
SEA region increased by 46% whereas
deaths decreased by 2% (WHO)

15. Trend of Dengue cases in
Nepal (2004-2022)
• Dengue first reported in
2004 in Nepal
• DENV1 and DENV2
contributing to
Dengue Outbreak in
Nepal (EDCD 2019)
• Outbreak reported
mostly during
September
• January-September
2022, CFR 0.13%
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National Status- Dengue Trend
Source: Dengue situation Report 2022, EDCD

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National Status- Dengue 2022
#Situation Report Dengue, EDCD
2022
• Total National cases: 54232
• Highest no of cases reported from
Bagmati, Lumbini and Province 1
• Bagmati cases -78.2% and 68.4 % deaths
(WHO 2022)
Source: Dengue situation Report 2022, EDCD

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National Status- Dengue 2022
17
Source: Dengue situation Report 2022, EDCD

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National Status- Dengue 2022
Number of Dengue
cases reported from
districts of Nepal from
1 January- 28
September 2022.

19. Goal: To reduce the morbidity and mortality due to dengue fever, dengue
hemorrhagic fever (DHF) and dengue shock syndrome (DSS)
Objectives
• To develop an integrated vector management (IVM) approach for prevention
and control
• To develop capacity on diagnosis and case management of dengue fever,
DHF and DSS
• To intensify health education and IEC activities
• To strengthen the surveillance system for prediction, early detection,
preparedness and early response to dengue outbreaks
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National Dengue Control Program

20. • Case Notification, Surveillance and Information System: Reporting
through DHIS 2, EWARS (Immediate reporting of single case of clinical
dengue), within 24 hrs
1. Case-based surveillance
2. Entomological Surveillance (A. aegypti identified in 5 peri-urban areas of
terai; Kalilali, Chitwan, Parsa, Dang and Jhapa)
• Case Identification and Detection: Dengue testing at Health Facilities &
Community-based testing as per necessity, Mobilization of RRT
• Risk mapping and identification of population at risk
• Prevention & Promotion activities: Development of IEC and SBCC
materials, Distribution of LLIN and IBN
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National programs and activities

21. • Capacity building of HSPs and
stakeholders: Palika level, district
level, women group focused,
FCHVs focused
• Research: Operational research on
dengue, vectors and parasites
• Interventions: Vector control
interventions (search and destroy)
• System strengthening: Supportive
supervision
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National programs and activities

22. • Case Definition; Dengue without warning signs, with warning signs, severe
dengue (WHO classification)
• Case Definition; suspected, probable, confirmed
• Surveillance categories
1. Passive Disease surveillance
2. Enhanced Disease surveillance
3. Syndromic surveillance
4. Sentinel surveillance and active case finding
5. Vector surveillance
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Surveillance for Dengue

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Govt. Response to Dengue Control in 2022

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WHO Response towards Dengue
• supports countries in the confirmation of outbreaks
• provides technical support and guidance to countries for the effective
management of dengue outbreaks
• provides training on clinical management, diagnosis and vector control
• formulates evidence-based strategies and policies
• support countries in the development of dengue prevention and control
strategies and adopting the Global Vector Control Response (2017-2030)
• publishes guidelines and handbooks for surveillance, case management,
diagnosis, dengue prevention and control for Member States.

25. Level of actions recommended as per National Guideline on Prevention,
Management and Control of Dengue in Nepal
• Household level; Use of personal protection measures, mosquito repellants and
tight fitting mesh/screens on windows and doors, elimination of mosquito
breeding in and around the house
• Community level; Community awareness program, basic sanitation measures,
eliminating outdoor breeding sites, promoting use of insecticide treated nets to
• Institutional level; Early case detection and treatment, source elimination
activities, notification of fever case (suspected/confirmed), entomological
surveillance
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Prevention, Control and Management

26. • Chemical Control
• Biological control
• Environmental
management;
modification,
manipulation, change in
human habitation or
behavior
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Prevention, Control and Management
A vaccine to prevent dengue (CYD-TDV, Dengvaxia®) is licensed and available in 20 countries
for people ages 9–45 years old. The World Health Organization recommends that the vaccine only
be given to persons with confirmed prior dengue virus infection. (CDC)

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Prevention, Control and Management

28. • National Guideline on Prevention, Management and Control of Dengue
in Nepal, 2019
• Global strategy for Dengue prevention and control 2021- 2030
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Guiding Documents

29. 1. Castro, M. C. (2017). Malaria Transmission and Prospects for Malaria Eradication: The Role of the Environment. Cold Spring
Harbor Perspectives in Medicine, 7(10), a025601. https://doi.org/10.1101/cshperspect.a025601
2. CDC. (2021, September 13). Dengue Clinical Presentation | CDC. Centers for Disease Control and Prevention.
https://www.cdc.gov/dengue/healthcare-providers/clinical-presentation.html
3. Huang, H.-W., Tseng, H.-C., Lee, C.-H., Chuang, H.-Y., & Lin, S.-H. (2016). Clinical significance of skin rash in dengue fever:
A focus on discomfort, complications, and disease outcome. Asian Pacific Journal of Tropical Medicine, 9(7), 713–718.
https://doi.org/10.1016/j.apjtm.2016.05.013
4. Midekisa, A., Beyene, B., Mihretie, A., Bayabil, E., & Wimberly, M. C. (2015). Seasonal associations of climatic drivers and
malaria in the highlands of Ethiopia. Parasites & Vectors, 8, 339. https://doi.org/10.1186/s13071-015-0954-7
5. Nguyen, N. M., Kien, D. T. H., Tuan, T. V., Quyen, N. T. H., Tran, C. N. B., Thi, L. V., Thi, D. L., Nguyen, H. L., Farrar, J. J.,
Holmes, E. C., Rabaa, M. A., Bryant, J. E., Nguyen, T. T., Nguyen, H. T. C., Nguyen, L. T. H., Pham, M. P., Nguyen, H. T.,
Luong, T. T. H., Wills, B., … Simmons, C. P. (2013). Host and viral features of human dengue cases shape the population of
infected and infectious Aedes aegypti mosquitoes. Proceedings of the National Academy of Sciences of the United States of
America, 110(22), 9072. https://doi.org/10.1073/pnas.1303395110
•
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References

30. 6. Nishiura, H., & Halstead, S. B. (2007). Natural History of Dengue Virus (DENV)—1 and DENV—4 Infections: Reanalysis of
Classic Studies. The Journal of Infectious Diseases, 195(7), 1007–1013. https://doi.org/10.1086/511825
7. Prevention, C.-C. for D. C. and. (2020, July 16). CDC - Malaria—About Malaria—Biology.
https://www.cdc.gov/malaria/about/biology/index.html
8. Rijal, K. R., Adhikari, B., Adhikari, N., Dumre, S. P., Banjara, M. S., Shrestha, U. T., Banjara, M. R., Singh, N., Ortegea, L., Lal,
B. K., Thakur, G. D., & Ghimire, P. (2019). Micro-stratification of malaria risk in Nepal: Implications for malaria control and
elimination. Tropical Medicine and Health, 47(1), 21. https://doi.org/10.1186/s41182-019-0148-7
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References

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Thank you!