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Dengue fever: An Emerging Exanthematous Fever

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Dr Lakhan Poswal, Udaipur    16 January 2018

  1. Dengue is the most rapidly spreading mosquito borne viral disease with a major public health concern in the Global annual incidence: about 390 million cases, with 50-100 million symptomatic cases in recent years; 30-fold increase in last 30 years.
  2. India has also shown doubling up of cases of dengue from 2014 to 2015 and the worst hit city was Delhi with over 1,800 cases.
  3. There are 4 antigenically related but distinct serotypes of the dengue virus: DENV-1, DENV-2, DENV-3 and DENV-4. All 4 serotypes can cause disease.
  4. Seasonal variation in dengue transmission is due to the survival characteristics of vectors, best between 30°C at relative humidity of 60-80%.
  5. CLINICAL FEATURES: The clinical infection can have 3 phases: Febrile phase: Onset of dengue fever with sudden rise in temperature, lasts for around 4-5 days and is usually associated with severe frontal headache, myalgia, retro-orbital pain, flushing, rash and minor bleeds like epistaxis. Rash (in about 50% patients)may be maculopapular or scarlatiniform, usually appears after 3rd/4th day of fever, centrifugal distribution, described as “islands of white in a sea of red” and can become petechial; a positive tourniquet test (TT) may be seen in some patients. A second episode of fever and symptoms can arise, called “saddleback” pattern. Potential complications can include dehydration due to decreased fluid intake, emesis and increased metabolic state. Febrile convulsions can occur. Critical phase (Leakage phase): Occurs after 3-4 days after onset of fever. It is characterized by hypovolemia and hemorrhagic manifestations due to increased vascular permeability and plasma leakage, which persists for 36-48 hours. Potential complications include unrecognized plasma leakage/hemorrhage leading to shock. Pleural effusion, ascites are seen. Convalescent phase (Recovery phase): Usually occurs after 6-7 days of fever and lasts for 2-3 days. ECF lost during capillary leakage returns to circulatory system. Clinical improvement is seen. Potential complications can include intravascular fluid overload due to continuous aggressive volume resuscitation during convalescence.
  6. Currently no effective antiviral is available for dengue, so treatment is supportive and symptomatic in the form of paracetamol for fever and pain along with liberal fluid intake.
  7. No hemorrhagic manifestations/TT -ve and patient is well-hydrated: home treatment.
  8. Hemorrhagic manifestations or hydration borderline: outpatient observation or hospitalization.
  9. Warning signs (abdominal pain or tenderness, persistent vomiting, clinical fluid accumulations, mucosal bleed, lethargy or restlessness, liver enlargement >2 cm, lab findings like hemoconcentration with rapid decline in platelet count) or DSS: hospitalize in PICU. Manage shock mainly by crystalloids (NS/RL). Colloids/plasma/human albumin may be required in refractory cases.
  10. Blood transfusion should be given with the presumption that lack of improvement is due to occult blood loss.
  11. There is little evidence to support the practice of transfusing platelet concentrates and/or FFP for severe bleeding.
  12. WHO position on CYD-TDV dengue vaccine: In July 2016, WHO has recommended the introduction of CYD-TDV vaccine in endemic areas. All other comprehensive dengue control measures and surveillance are to be continued with vaccination.

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