please compare Dengue Haemorrhagic Fever with Dengue

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Dengue fever (DF) and Dengue Hemorrhagic Fever (DHF) are both caused by the dengue virus, which is transmitted to humans by the bite of an infected Aedes species mosquito. The primary difference between the two conditions lies in their severity and clinical manifestations.

Dengue Fever (DF)

  • Symptoms: DF is characterized by the sudden onset of high fever, severe headache, pain behind the eyes, joint and muscle pain, fatigue, nausea, vomiting, skin rash, and mild bleeding (nose or gums bleed, easy bruising).
  • Complications: Usually less severe than DHF, with the main complications being febrile seizures and dehydration.
  • Treatment: Emphasizes symptom relief, such as pain relief and fever control. Patients are advised to avoid aspirin and nonsteroidal anti-inflammatory drugs due to the risk of hemorrhage and to stay well-hydrated.

Dengue Hemorrhagic Fever (DHF)

  • Symptoms: DHF includes all the symptoms of classic dengue fever but also leads to bleeding, blood plasma leakage, and low platelet count. Symptoms may progress to severe bleeding, plasma leakage, and blood vessel damage, which can lead to shock (dengue shock syndrome) and organ failure.
  • Severity: Classified into four grades of severity, with Grade I being the least severe, characterized by fever and non-specific constitutional symptoms, and Grade IV being the most severe, often leading to profound shock.
  • Treatment: More complex than DF, requiring close monitoring for signs of shock and organ failure. Fluid management is critical, and in severe cases, blood transfusion and intensive supportive care may be necessary.
  • Mortality Rate: Without proper treatment, DHF can have a mortality rate as high as 20%, but with good medical management, it can be reduced to less than 1%.
Both DF and DHF are more common in tropical and subtropical climates. While a person can be infected with dengue up to four times, once with each serotype, secondary infections increase the risk of developing DHF. This is due to the immune system's response to a previous infection with a different serotype, which can enhance the severity of a subsequent infection, a phenomenon known as antibody-dependent enhancement (ADE). In summary, while both DF and DHF are caused by the same virus, DHF is a more severe form of the disease with a higher risk of serious complications and death. It is essential for individuals with symptoms of DHF to seek medical attention promptly to reduce the risk of severe outcomes.
what are the relative intances of Dengue Haemorrhagic Fever and Dengue

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Dengue fever (DF) and Dengue Hemorrhagic Fever (DHF) are both caused by the dengue virus, transmitted through the bite of infected Aedes mosquitoes. The distinction between DF and DHF primarily lies in the severity and clinical manifestations of the disease. Dengue fever is generally milder, while DHF is a more severe form that can lead to serious complications, including Dengue Shock Syndrome (DSS).

Global Incidence and Prevalence

  • Dengue Fever: The World Health Organization (WHO) estimates that there are 390 million dengue virus infections per year globally, of which approximately 96 million manifest clinically. The CDC notes that each year, up to 400 million people get infected with dengue, with about 100 million people getting sick from the infection.
  • Dengue Hemorrhagic Fever: It is estimated that there are 500,000 cases of DHF annually, leading to approximately 25,000 deaths. This severe form of dengue fever has seen a resurgence and increased epidemic activity over the past 20 years, with an expanded geographic distribution of both the viruses and the emergence of DHF in new geographic regions.

Risk Factors for Severe Dengue

Individuals infected for the second time with a different serotype of the dengue virus are at greater risk of developing severe dengue, including DHF and DSS. This increased risk is due to the immune system's response to the previous infection, which can enhance the severity of a subsequent infection through a phenomenon known as antibody-dependent enhancement (ADE).

Geographic Distribution and Trends

Dengue is endemic in more than 100 countries across the WHO Regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia, and the Western Pacific. The disease's incidence has markedly increased over the past two decades, posing a substantial public health challenge. The Americas, for example, reported 3.1 million cases in a recent year, with more than 25,000 classified as severe.

Mortality and Morbidity

  • Dengue Fever: Typically, DF has a mortality rate of less than 1% when detected early and with access to proper medical care. Most cases are asymptomatic or mild and self-managed.
  • Dengue Hemorrhagic Fever: The fatality rates among patients with DSS can be 10% or higher, but with early recognition and treatment, it can be reduced to less than 1%. The total number of dengue deaths from 2001 to 2007 was 1,299, with a DHF case fatality rate of 1.2%.


While both DF and DHF result from infection with the dengue virus, DHF represents a more severe manifestation with a higher risk of serious complications and death. The global incidence of both conditions has increased, with millions of people at risk, especially in tropical and subtropical regions. The risk of severe dengue, including DHF, is particularly heightened in individuals experiencing a secondary infection with a different serotype of the virus.
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