Brief note on Dengue fever
Dr. C. Gopinath Reddy, Consultant Internal Medicine, KIMS Hospitals, Kurnool.
Most common and important arthropod born viral febrile illness in humans caused by one of four dengue viruses.
It is transmitted by mosquitoes of the genus Aedes, (aedes aegypti, aedes albopictus), which are widely distributed in sub-tropical and tropical areas of the world.
Incidence of dengue has increased dramatically in recent decades, with estimates of 40- 50 % of the world population at risk for the disease in tropical, subtropical and more recently more temperate areas.
- Retrobulbar pain ( behind the eyes)
- Severe myalgia
- Nausea and vomiting
- Rash ( maculo papular )
- Weakness, malaise and lethargy
- Sore throat
- Hemorrhagic manifestations (petechiae, bleeding gums, epistaxis, menorrhagia, hematuria, rarely intracranial bleed in severe dengue).
Dengue becomes symptomatic after a 4 to 10 day incubation period, dengue symptoms usually lasts 2 – 7 days.
WHO CLASSIFICATION OF SYMPTOMATIC DENGUE INFECTION
- Dengue without warning signs
- Dengue with warning signs
- Severe dengue ( previously dengue hemorrhagic fever and dengue shock syndrome)
There are 3 phases of infection:
- Febrile phase
- Critical phase
- Recovery or convalescence phase
Severe dengue only have critical phase where hemorrhagic manifestation and shock develops
Established by direct and indirect methods, directly by detection of viral components, indirectly by serology.
Detection of of viral nucleic acid or viral antigen has high specificity but more costly and labour intensive.
Serology has lower specificity but is more accessible and less costly
First week of illness the diagnosis by detection of viral nucleic acid by means of RT-PCR or detection of viral antigen non-structural protein 1( NS1).
Serology by detecting IgM or IgG antibodies by immunoassay or ELISA
PREVENTION AND TREATMENT
- Mosquito control ( reducing breeding areas, larva control, use of insecticide)
- Personal protective measures
Dengue fever is typically a self-limited disease with a mortality rate of less than 1% when detected early and with access to proper medical care.
There is no direct anti-viral therapy available against dengue, management is supportive consists of maintaining adequate intravascular volume, antipyretic and bed rest.
Now in this COVID 19 pandemic, it is very important to differentiate both illnesses, as both presentations are overlapping.
Early presentation of respiratory symptoms are more common in COVID especially shortness of breath
Dengue with COVID 19 or COVID 19 with Dengue coinfection also reported hence high suspicion and early evaluation and management will reduce mortality and morbidity.