Dengue is an acute viral infection with potential fatal complications. Dengue fever was first referred as “water poison” associated with flying insects in a Chinese medical encyclopedia in 992 from the Jin Dynasty (265-420 AD). The word “dengue” is derived from the Swahili phrase Ka-dinga pepo, meaning “cramp-like seizure”. The first clinically recognized dengue epidemics occurred almost simultaneously in Asia, Africa, and North America in the 1780s. The first clinical case report dates from 1789 of 1780 epidemic in Philadelphia is by Benjamin Rush, who coined the term “break bone fever” because of the symptoms of myalgia and arthralgia
Dengue viruses (DV) belong to family Flaviviridae and there are four serotypes of the virus referred to as DV-1, DV-2, DV-3 and DV-4. DV is a positive-stranded encapsulated RNA virus and is composed of three structural protein genes, which encode the nucleocapsid or core (C) protein, a membrane-associated (M) protein, an enveloped (E) glycoprotein and seven non-structural (NS) proteins. It is transmitted mainly by Aedes aegypti mosquito and also by Ae. albopictus. All four serotypes can cause the full spectrum of disease from a subclinical infection to a mild self limiting disease, the dengue fever (DF) and a severe disease that may be fatal, the dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS).
Key clinical terms
Acute phase– Characterized by high fever that is driven by high viral loads (viraemia)
Critical phase– Characterized by plasma leakage into the abdominal and pleural cavities, which becomes evident at the end of the febrile (acute) stage of illness (days 3–Warning signs that announce shock are usually present
Convalescent phase– Involves both cessation of plasma leakage and reabsorption of leaked fluids
Dengue or dengue fever– A nonspecific febrile illness that is characterized by fever and the presence of two or more other symptoms, such as headache, rash, retro-orbital or ocular pain and myalgia. Most patients have a satisfactory resolution without signs of severity or warning signs (referred to as dengue without warning signs according to the 2009 WHO classification)
Dengue haemorrhagic fever – Characterized by increased vascular permeability, plasma leakage, bleeding, thrombocytopaenia and fever (according to the 1997 WHO classification).The term and concept are not included in the revised 2009 WHO classification nor are they recommended for triage of patients because it is not necessarily associated with severity, among other reasons
Dengue with warning signs– At the end of the febrile period, some patients have signs or symptoms that are suggestive of important fluid loss associated with capillary leakage (for example, severe abdominal pain), announcing the imminence of shock and indicating that fluid replacement is urgently required (according to the 2009 WHO classification)
Severe dengue – Circulatory shock or respiratory distress associated with severe plasma leakage, severe bleeding or severe organ involvement (frequently myocarditis, encephalitis and severe hepatitis) with or without shock or bleeding (according to the 2009 WHO classification)
Part of the Flavivirus family, the dengue virus is a 50 nm virion with three structural and seven nonstructural proteins, a lipid envelope, and a 10.7 kb capped positive sense single strand of ribonucleic acid. Infections are asymptomatic in up to 75% of infected humans. A spectrum of disease, from self-limiting dengue fever to hemorrhage and shock, may be seen. A fraction of infections (0.5% – 5%) progress to severe dengue. Without proper treatment, fatality rates may exceed 20%. These occur primarily in children. The typical incubation period for the disease is 4 to 7 days, but it can last from 3 to 10 days. Symptoms more than two weeks after exposure are unlikely to be due to dengue fever.
The exact course of events following the dermal injection of dengue virus by a mosquito bite is unclear. Skin macrophages and dendritic cells appear to be the first targets. It is thought that the infected cells then move to the lymph nodes and spread through the lymphatic system to other organs. Viremia may be present for 24 to 48 hours before the onset of symptoms. A complex interaction of host and viral factors then occurs and determines whether the infection will be asymptomatic, typical, or severe. Severe dengue fever with increased microvascular permeability and shock syndrome is thought to be associated with infection due to a second dengue virus serotype and the patient’s immune response. However, cases of severe dengue do occur in the setting of infection by only a single serotype. Worsening microvascular permeability often transpires even as viral titers fall.
State Wise Statics
Plagued by the viral fever and dengue outbreaks, state governments have started probes and taken other steps to get a grip on the grim situation.
More than 1,500 cases of dengue and viral fever have been reported from various districts of Uttar Pradesh, the worst affected state in the country. Areas of central UP, Bundelkhand and western UP have been hit hard. On Wednesday, 60 new dengue cases were reported and eight deaths were registered.
Farrukhabad, Kanpur and Unnao have been reporting a spike in cases. In Unnao, 678 people complained of viral fever and dengue at hospitals.
172 children have been admitted at two hospitals in North Bengal due to fever and other ailments. Of these, 67 children have been admitted to the pediatric ward of the North Bengal Medical College and Hospital so far, while several others have been discharged.
Dr Sanjay Mullick, Superintendent North Bengal Medical College and Hospital, confirmed that six children tested positive for dengue. 50 children were released from the Jalpaiguri district hospital on Thursday with 105 still admitted for treatment. A medical team was formed by the Jalpaiguri district health department to review the situation.
22 fresh cases of dengue have been reported from Madhya Pradesh’s Indore, taking the total number of infected people this year to 225. In state capital Bhopal, six fresh cases of dengue have been reported to take the total to 107 since January.
Among other affected districts, Rajgarh has so far reported 22 cases, while Gwalior and Jabalpur have witnessed sudden spikes as well. Gwalior has reported 95 cases and 15 other cases have been registered in Chambal.
Cases of viral fever too have spiked with Indore, Rajgarh, Jabalpur and Gwalior being the worst affected districts.
Of the total count of dengue cases recorded in Delhi this season, 665 have been recorded this month till October 23. Over 1,000 cases of dengue have been reported in the national capital this year, with more than 280 fresh cases logged in the last one week, according to a civic report released on October 25
Treatment / Management
Supportive management includes giving the patient fluids, acetaminophen for fever, and a blood transfusion for hemorrhage. Confirmed diagnosis is established by culture, antigen detection, polymerase chain reaction, or serologic testing. Avoid giving aspirin and nonsteroidal anti-inflammatory drugs and other anticoagulants. No antiviral medications are recommended.
Patients with thrombocytopenia or bleeding may require platelets and fresh frozen plasma.
No laboratory tests can predict the progression to severe disease.
Untreated severe dengue fever may have a mortality rate of 10% to 20%. Appropriate supportive care reduces the mortality rate to roughly 1%.
- Liver injury