A mosquito-borne viral disease occurring in tropical and subtropical areas. Those who become infected with the virus a second time are at a significantly greater risk of developing severe disease. Symptoms include high fever, headache, rash and muscle and joint pain. In severe cases there is serious bleeding and shock, which can be life threatening. Treatment includes fluids and pain relievers. Severe cases require hospital care.

1. DENGUE

2. Introduction
• Dengue is a febrile illness caused by a flavivirus transmitted by
mosquitoes.
• It is endemic in Asia, the Pacific, Africa and the Americas
• Approximately 400 million infections and 100 million clinically
apparent infections occur annually, and
• dengue is the most rapidly spreading mosquito-borne viral illness.

3. Aetiology
Causative organism : Genus Flavivirus
• There are four serotypes of dengue virus, all producing a similar clinical
syndrome
• type-specific immunity is life-long but immunity against the other serotypes lasts
only a few months.
• Dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) occur in
individuals who are immune to one dengue virus serotype and are then infected
with another.
1. The principal vector is the mosquito Aedes aegypti, which breeds in standing
water; collections of water in containers, water-based air coolers and tire dumps
are a good environment for the vector in large cities.
(Nervous feeder, discordant species)
2. Aedes albopictus is a vector in some South-east Asian countries.
(aggressive feeder, concordant species)

4. Epidemiology
• Prior Immunity results in
• increased uptake of virus by cells expressing the antibody fc receptor
• increased t-cell activation with resultant cytokine release,
• Causing capillary leak and disseminated intravascular coagulation
• Previously, dengue was seen in small children and DHF/DSS in children 2–
15 years old
• But these conditions are now being seen in children less than 2 years old,
and most frequently in those 16–45 years of age or older, in whom severe
organ dysfunction is more common.
• Other epidemiological changes include the spread of dengue into rural
communities and greater case fatality in women.

5. Clinical features and diagnosis
• Many cases of dengue infection are asymptomatic in children.
• Clinical disease presents with undifferentiated fever termed dengue-
like illness.
• When dengue infection occurs with characteristic symptoms or signs
it is termed ‘dengue’
• The clinical features of dengue manifest as
1. Febrile phase
2. Critical phase
3. Recovery phase
4. Severe dengue(atypical manifestations)

6. Febrile phase : similar to(or aka) classical dengue fever
• In mild forms, petechiae occur in the arm when a blood pressure cuff is inflated to
a point between systolic and diastolic blood pressure and left for 5 minutes (the
positive ‘tourniquet test’) – a non-specific test of capillary fragility and
thrombocytopenia.
• A maculopapular rash frequently follows the initial febrile phase as the fever
settles.
• Laboratory features include leucopenia, neutropenia, thrombocytopenia and
elevated alanine aminotransferase (ALT) or aspartate aminotransferase (AST).
• Many symptomatic infections run an uncomplicated course
• In some, complications or a protracted convalescence may ensue.
1. Classical Dengue fever/ Febrile phase

7. Critical phase : The period 3–7 days after onset of fever is termed the ‘critical’ phase, during which
signs of DHF or DSS may develop.
• As the extent of capillary leak increases, DSS develops, with a raised hematocrit, tachycardia
and hypotension, pleural effusions and ascites.
• This may progress to metabolic acidosis and multi-organ failure, including acute respiratory
distress syndrome.
• Minor (petechiae, ecchymoses, epistaxis) or major (gastrointestinal or vaginal) hemorrhage, a
feature of DHF, may occur. Cerebrovascular bleeding may be a complication of severe dengue.
• Warning signs justify intense medical management and monitoring for progression to severe
dengue.
• Atypical clinical features of dengue are increasingly common, especially in infants or older
patients .These, along with DHF or DSS, are recognized as features of severe dengue in the 2015
case definition.
3. Recovery phase
Gradual resorption of extravascular component in next 48 hours of critical phase
2. Dengue Hemorrhagic Fever/Critical Phase

8. 4. Severe Dengue
• As the extent of capillary leak increases, DSS
develops, with a raised hematocrit, tachycardia
and hypotension, pleural effusions and ascites.
• This may progress to metabolic acidosis and
multi-organ failure, including acute respiratory
distress syndrome.

10. Diagnosis
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11. Diagnosis
• In endemic areas, mild dengue must be distinguished from other viral
infections.
1. The diagnosis can be confirmed by seroconversion of IgM or a fourfold
rise in IgG antibody titers.
2. Serological tests may detect cross-reacting antibodies from infection or
vaccination against other flaviviruses, including yellow fever virus,
Japanese encephalitis virus and West Nile virus.
3. Isolation of dengue virus or detection of dengue virus RNA by PCR in
blood or CSF is available in specialist laboratories.
4. Commercial enzyme linked immunosorbent assay (ELISA) kits to detect
the NS1 viral antigen, although less sensitive than PCR, are available
inmany endemic areas.

12. Treatment
1. Treatment is supportive
• emphasizing fluid replacement
• appropriate management of shock and organ dysfunction
2. which is a major determinant of morbidity and mortality.
3. With intensive care support, mortality rates are 1% or less.
4. Aspirin should be avoided due to bleeding risk.
5. Glucocorticoids have not been shown to help.
6. No existing antivirals are effective.
7. Breeding places of Aedes mosquitoes should be abolished and the adults
destroyed by insecticides.
8. A recently licensed vaccine is available.

17. Dengue in Pads

18. • Etiology
• Epidemiology
• Clinical Features
Same as that of adults
Refer as the slides above or tot the textbook

19. Differential of Diagnosis
• Other hemorrhagic fever,
• chikungunya infection : The features of chikungunya infection are similar to that of dengue. However, fever is
of shorter duration,. And thrombocytopenia and bleeding are less frequent. Patties with chikungunya often
have skin eruptions, mucosa lesions, polyarthralgia and encephalopathy.
• influenza,
• malaria,
• Enteric Fever, leptospirosis and less commonly meningococcemia and rickettsiosis.
• Malaria, leptospirosis, flu, enteric fever an chikungunya infections may be coinfected with dengue·

20. Diagnosis
• Following clinical and laboratory features suggests presence of severe dengue infection:
• Clinical criteria: Acute onset high-grade fever, haemorrhagic manifestations (positive tourniquet test), tender
hepatomegaly, effusion in body cavities and/ shock.
• Laboratory criteria: Thrombocytopenia (100,000 cells per mm3 ; <1-2 platelets per oil immersion field),
rising haematocrit
• Tourniquet test: This test is part of the WHO case definition for dengue, and a marker of capillary fragility.
The test is one by inflating the blood pressure cuff to a point midway between the systolic and diastolic blood
pressure for 5 minutes. The cuff is deflated and removed. After waiting for 2 minutes, the number of
petechiae is counted in the antecubital fossa. The presence of 10 or more petechiae per 1 square inch
indicates a positive finding. This finding is present in more than 50% of cases.

21. Lab findings
1. Children with severe dengue infection show
• increasing PCV and
• low platelet and leukocyte counts with lymphocyte predominance.
• A low leukocyte count in a child with febrile illness during the endemic season suggests possible dengue infection.
• While malaria and enteric fever may have low white cell counts, leukopenia is more severe in dengue.
2. Blood levels of total protein and albumin are reduced, more marked in patients with shock.
3. Levels of transaminases are raised; higher increase in SGOT than SGPT suggests dengue rather than other
virus infection.
4. Patients with severe dengue may show hyponatremia and acidosis, with increase in urea and creatinine.
5. X-ray chest or ultrasound examination may show varying degrees of pleural effusion that is more common
on the right, but occasionally bilateral.
6. Ultrasound examination of abdomen may show ascites and enlarged gallbladder

22. Confirmation of diagnosis
1. Direct methods: Virus isolation by culture; genome detection by PCR; NSl antigen detection.
2. Indirect methods:
1. IgM detection;
2. IgG detection.
3. Virus isolation or PCR requires the sample to be obtained within the first 5 days of fever, is technically demanding, not universally
available and hence of limited practical use.
4. NSl antigen is a highly conserved glycoprotein of dengue virus and secreted during the initial phase of illness. It disappears as
antibodies appear and hence declines as illness advances and in secondary dengue infections. The specificity is -100% and sensitivity
in the first 4 days of illness is 90% in primary dengue and 70% in secondary dengue infection.