Dengue Fever | Pathophysiology, Symptoms, Diagnosis & Treatment

Summary

This lesson provides an in-depth overview of dengue fever, including its transmission, symptoms, diagnosis, and treatment. It covers the four dengue virus serotypes, the role of mosquitoes in spreading the disease, and the viral pathogenesis. The video explains the three phases of infection: febrile, critical, and recovery, highlighting key symptoms such as high fever, muscle pain, and bleeding risks in severe cases. It also discusses diagnosis through serology and PCR, and treatment focused on supportive care. Lastly, prevention strategies, including mosquito control and vaccination, are explored.

Takeaways

• 😀 Dengue fever is caused by the dengue virus, which belongs to the Flaviviridae family, and there are four distinct types of the virus (DEN-1 to DEN-4).
• 😀 The primary mode of transmission is through mosquito bites, specifically from *Aedes aegypti* and *Aedes albopictus* mosquitoes.
• 😀 The virus enters host cells, replicates, and spreads, often causing a wide range of symptoms from mild to severe.
• 😀 Dengue fever symptoms typically include sudden high fever, headache, retro-orbital pain, muscle/joint pain, nausea, abdominal pain, and a rash.
• 😀 The fever phase usually lasts for 3 to 7 days, with a high fever above 38.5°C and common symptoms like muscle pain and a maculopapular rash.
• 😀 The critical phase can occur in some patients, particularly those with a prior dengue infection or other medical conditions, and can involve severe bleeding and shock.
• 😀 Critical phase symptoms include severe thrombocytopenia (low platelets), bleeding (e.g., nosebleeds, vomiting blood), and vascular leakage leading to shock.
• 😀 The recovery phase follows the critical phase and is marked by resolution of symptoms, but some patients may experience chronic fatigue for weeks to months.
• 😀 Diagnosis is primarily through serology, detecting anti-dengue IgM antibodies, typically present by day 4 of infection, or PCR in earlier stages.
• 😀 Treatment for dengue fever is supportive, with acetaminophen for symptom relief, and avoiding NSAIDs like ibuprofen due to bleeding risks.
• 😀 Preventive measures include mosquito control, avoiding mosquito bites, and the dengue vaccine, which helps reduce symptom severity but does not provide complete protection.

Q & A

What is dengue fever and what causes it?

Dengue fever is an illness caused by infection with the dengue virus, which is part of the Flavivirus family. There are four types of dengue viruses, named DENV1 to DENV4, all of which are transmitted by mosquitoes.

How is dengue fever transmitted to humans?

Dengue fever is primarily transmitted to humans through bites from mosquitoes, particularly *Aedes aegypti* and *Aedes albopictus* mosquitoes. These mosquitoes carry the dengue virus.

What are the main symptoms of dengue fever during the febrile phase?

In the febrile phase, symptoms include a sudden high fever (above 38.5°C), headache, retro-orbital pain (pain behind the eyes), muscle pain (myalgia), joint pain (arthralgia), and sometimes gastrointestinal issues like nausea, vomiting, and abdominal pain.

What is retro-orbital pain and why is it significant in dengue fever diagnosis?

Retro-orbital pain is pain behind the eyes, a common symptom of dengue fever. It is significant because when combined with fever and headache, it can help doctors identify dengue fever, especially in a traveler who has recently returned from endemic areas.

What is the difference between the febrile phase and the critical phase of dengue fever?

The febrile phase involves fever, pain, and discomfort, and typically lasts 3 to 7 days. The critical phase, which occurs after the fever resolves, is marked by severe complications such as low platelet count, bleeding risks, and potential organ damage due to vascular leakage. This phase occurs in a small percentage of patients.

What are the warning signs that a patient with dengue fever may progress to the critical phase?

Warning signs include severe thrombocytopenia (low platelet count), which can lead to bleeding, and the presence of other comorbidities or a secondary infection with a different serotype of the dengue virus.

What is the role of thrombocytopenia in the critical phase of dengue fever?

Thrombocytopenia, or a low platelet count, increases the risk of bleeding, leading to symptoms like nosebleeds, blood in stools, and heavy menstrual bleeding. It is a key feature of severe dengue and can lead to bleeding complications.

What is dengue hemorrhagic fever and how is it related to the critical phase?

Dengue hemorrhagic fever refers to severe dengue that involves thrombocytopenia, increased bleeding risks, and vascular leakage. This term is often used interchangeably with severe dengue, which can occur during the critical phase.

How is dengue fever diagnosed?

Dengue fever is diagnosed through serology, specifically by detecting IgM antibodies against the dengue virus. PCR testing can also be used in the early stages to detect viral genetic material before antibodies are produced.

What is the recommended treatment for dengue fever?

There is no specific antiviral treatment for dengue fever. Treatment is supportive, including symptom relief with acetaminophen for pain and fever, while avoiding ibuprofen due to its bleeding risks. Hydration and rest are also important.

Can dengue fever be prevented, and is the vaccine effective?

Dengue fever can be prevented by reducing mosquito exposure through measures like using insect repellent and wearing protective clothing. A vaccine is available, but it does not provide complete protection. It does, however, reduce the severity and duration of the infection in vaccinated individuals.