dengue fever & dengue hemorrhagic fever

DENGUE FEVER & DENGUE DENGUE FEVER & DENGUE HEMORRHAGIC FEVERHEMORRHAGIC FEVER

Kamilah FernandezKamilah FernandezTSMUTSMU

YEAR 5 GROUP#1YEAR 5 GROUP#1

DENGUE FEVER & DENGUE HEMORRHAGIC FEVER

• Dengue is caused by dengue virus, a single-stranded RNA virus with an icosahedral nucleocapsid and covered by a lipid envelope. The virus is in the family Flaviviridae, genus Flavivirus and has 4 serotypes ; DENV-1, DENV-2, DENV-3, and DENV-4.

• Dengue is transmitted between people by the mosquitoes Aedes aegypti and Aedes albopictus, which are found throughout the world.

• Humans serve as the primary reservoir for dengue. Especially in children younger than 15 years.

• Dengue is endemic in at least 100 countries in Asia, the Pacific, the Americas, Africa, and the Caribbean.

• Dengue fever is typically a self-limiting disease with a mortality rate of less than 1%. When treated, dengue hemorrhagic fever has a mortality rate of 2-5%, but when left untreated, the mortality rate is as high as 50%.

Distribution of Dengue in the Western Hemisphere

Distribution of Dengue in the Eastern Hemisphere

Transmission and Pathogenesis of Dengue

Aedes egypti

Aedes Albopticus

Transmission and Pathogenesis of

Dengue

Pathogenesis of Dengue

• Once inoculated into a human host, dengue viral replication takes place in target dendritic cells. Infection of target cells, primarily those of the reticuloendothelial system, such as dendritic cells, hepatocytes, and endothelial cells, result in the production of immune mediators that serve to shape the quantity, type, and duration of cellular and humoral immune response to both the initial and subsequent virus infections.

Pathogenesis of Dengue

Clinical Presentation of Dengue Fever


• The incubation period is 3-14 days (average, 4-7 days);• Prodrome ; chills, erythematous mottling of the skin, and facial flushing (2-3 days). • Accompanying symptoms in patients with dengue may include any of the following: Headache Retro-orbital pain Severe myalgias: (lower back, arms, and legs) and arthralgias: Usually of the knees and

shoulders, Nausea and vomiting Rash Weakness Altered taste sensation and Anorexia Sore throat Mild hemorrhagic signs (petechiae, bleeding gums, epistaxis, menorrhagia, hematuria) Lymphadenopathy


1. Febrile phase : high grade fever suddenly, which can last for 2 to 7 days. Facial flushing, skin erythema, generalised body ache, myalgia, arthralgia and headache. Some patients may also complain of sore throat and conjunctival redness. Anorexia, nausea and vomiting are fairly common at this stage.

2. Critical phase: between the 3 and 5 day of illness when there is a rapid fall in temperature . The patient will may become better if there is no or minimal plasma leakage, or worse if a critical volume of plasma is lost which can lead to shock. The critical phase lasts for about 24 to 48 hours.


• In more severe plasma leakage, the patients may develop symptoms such as sweating and restlessness. cool extremities and prolonged capillary refill time. Tachycardia, increase in diastolic blood pressure and narrowing of pulse pressure as well as abdominal pain, persistent vomiting, altered conscious level, clinical fluid accumulation, mucosal bleed or tender enlarged liver are important clinical warning signs of severe dengue and should alert clinicians to the high possibility of rapid progression to shock .The patient can deteriorate very quickly to profound shock and death if fluid resuscitation is not instituted promptly.

3. Recovery phase: around 24 to 48 hours after fever, plasma leakage stops, followed by reabsorption of extravascular fluid. Patients’ general condition improves, with return of appetite, improvement in gastrointestinal symptoms, hemodynamic status stabilizes and diuresis ensues. Some patients may have a classical rash of “isles of white in the sea of red”. Some may experience generalized pruritus. Hematocrit level stabilizes or drops further due to hemodilution following reabsorption of extravascular fluid. Platelet count typically recovers earlier than recovery of white cell count.

Physical Examination of Dengue Fever

• Rash : 50% patients with dengue fever develop a characteristic rash. The rash is variable and may be maculopapular or macular.

• Hemorrhagic Manifestation : Petechiae and purpura on the skin, nasal or gingival bleeding, melena, hematemesis, and menorrhagia.

• A tourniquet test is often positive. This test is performed by inflating a blood pressure cuff on the upper arm to midway between diastolic and systolic blood pressures for 5 minutes. The results are considered to be positive if more than 20 petechiae per square inch are observed on the skin in the area that was under pressure.

• Neurologic manifestations such as seizures and encephalitis/encephalopathy have been reported in rare cases of dengue infection. Some of these cases did not display other typical features of dengue infection. Other neurologic complications associated with dengue infection include neuropathies, Guillain-Barré syndrome, and transverse myelitis.


Additional findings may include the following:• Injected conjunctivae• Facial flushing, a sensitive and specific predictor of dengue infection• Inflamed pharynx• Lymphadenopathy• Nausea and vomiting• Nonproductive cough• Tachycardia, bradycardia, and conduction defects

Severe Dengue : Dengue Hemorrhagic Fever and

Dengue Shock Syndrome DHF/DSS is caused by an acute increase in vascular permeability which leads to

leakage of plasma into the extravascular compartment. This results in hemoconcentration and hypovolemia or shock. Clinicians managing dengue patients therefore need to be aware that the clinical manifestations are, in fact, a continuum of various pathophysiological changes in a patient who progresses from normal circulatory state to hypovolemic shock.

DENGUE HEMORRHAGIC FEVERFindings for dengue hemorrhagic fever are similar to those for dengue fever and include

the following: • Biphasic fever curve• Hemorrhagic findings more pronounced than in dengue fever• Signs of peritoneal effusion, pleural effusion, or both


Dengue Shock SyndromeMinimal criteria for the diagnosis of dengue hemorrhagic fever, according to the WHO, are

as follows• Fever• Hemorrhagic manifestations (eg, hemoconcentration, thrombocytopenia, positive

tourniquet test)• Circulatory failure, such as signs of vascular permeability ( hypoproteinemia, effusions)• Hepatomegaly• Conjunctival injection (~1/3). Optic neuropathy may cause permanent and significant

visual impairment. Pharyngeal injection develops in almost 97% of patients with dengue hemorrhagic fever. Generalized lymphadenopathy

• Hepatic transaminase levels may be mildly to moderately elevated. • Encephalopathy is a rare complication that may result from a combination of cerebral

edema, intracranial hemorrhage, anoxia, hyponatremia, and hepatic injury.


Dengue Shock Syndrome


Dengue Shock Syndrome

Dengue shock syndrome• Findings of dengue shock syndrome include the following: • Hypotension• Bradycardia (paradoxical) or tachycardia associated with hypovolemic shock• Hepatomegaly• Hypothermia• Narrow pulse pressure (< 20 mm Hg)• Signs of decreased peripheral perfusion

Severe Dengue

Diagnosis of Dengue

Because the signs and symptoms of dengue fever are nonspecific, attempting laboratory confirmation of dengue infection is important.

Laboratory criteria for diagnosis include one or more of the following: • Isolation of the dengue virus from serum, plasma, leukocytes, or autopsy samples.• Demonstration of a fourfold or greater change in reciprocal immunoglobulin G (IgG)

or immunoglobulin M (IgM) antibody titers to one or more dengue virus antigens in paired serum samples

• Demonstration of dengue virus antigen in autopsy tissue via immunohistochemistry or immunofluorescence or in serum samples via enzyme immunoassay (EIA)

• Detection of viral genomic sequences in autopsy tissue, serum, or cerebral spinal fluid (CSF) samples via polymerase chain reaction (PCR)

Diagnosis of Dengue

COMPLETE BLOOD CELL COUNT:• Leukopenia ( sometimes lymphopenia) at the end of the febrile phase.

Lymphocytosis, with atypical lymphocytes, commonly develops before defervescence or shock.

• A hematocrit level >20% is a sign of hemoconcentration and precedes shock. The hematocrit level should be monitored at every 24 hours to facilitate early recognition of dengue hemorrhagic fever and every 3-4 hours in severe cases of dengue hemorrhagic fever or dengue shock syndrome.

• Thrombocytopenia seen in up to 50% of dengue fever cases. Platelet counts less than 100,000 cells/μL are seen in dengue hemorrhagic fever or dengue shock syndrome and occur before defervescence and the onset of shock. The platelet count should be monitored at least every 24 hours to facilitate early recognition of dengue hemorrhagic fever.

Diagnosis of Dengue

METABOLIC PANEL• Hyponatremia is the most common electrolyte abnormality in patients with dengue

hemorrhagic fever or dengue shock syndrome. • Metabolic acidosis is observed in those with shock and must be corrected rapidly.

Elevated BUN levels are observed in those with shock.• Transaminase levels may be mildly elevated in patients with dengue hemorrhagic fever

who have acute hepatitis. Low albumin levels are a sign of hemoconcentration. COAGULATION TEST• Coagulation studies may help to guide therapy in patients with severe hemorrhagic

manifestations. Findings are as follows:• Prothrombin time is prolonged• Activated partial thromboplastin time is prolonged• Low fibrinogen and elevated fibrin degradation product levels are signs of disseminated

intravascular coagulation

Treatment of Dengue

Dengue Fever • It is usually a self-limited illness. There is no specific antiviral treatment currently

available for dengue fever. Supportive care Analgesics, fluid replacement, and bed rest is usually sufficient. Acetaminophen may be used to treat fever and relieve other symptoms.Dengue Hemorrhagic Fever and Dengue Shock Syndrome• Successful management of severe dengue requires careful attention to fluid

management and proactive treatment of hemorrhage. Admission to an intensive care unit is indicated for patients with dengue shock syndrome.

Volume Replacement- Isotonic fluids such as Ringer lactate solution Blood Transfusion- Blood, Platelet and Fresh Frozen Plasma

Prevention1. The best way to reduce mosquitoes is to eliminate the places where the mosquito

lays her eggs, like artificial containers that hold water in and around the home. Outdoors, clean water containers like pet and animal watering containers, flower planter dishes or cover water storage barrels. Look for standing water indoors such as in vases with fresh flowers and clean at least once a week.

2. The adult mosquitoes like to bite inside as well as around homes, during the day and at night when the lights are on. To protect yourself, use repellent on your skin while indoors or out. When possible, wear long sleeves and pants for additional protection. Also, make sure window and door screens are secure and without holes. If available, use air-conditioning.

3. If someone in your house is ill with dengue, take extra precautions to prevent mosquitoes from biting the patient and going on to bite others in the household. Sleep under a mosquito bed net, eliminate mosquitoes you find indoors and wear repellent!

Prevention

dengue fever & dengue hemorrhagic fever

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