Podcast
Questions and Answers
Why are NSAIDs like ibuprofen and aspirin avoided in the treatment of dengue fever?
Why are NSAIDs like ibuprofen and aspirin avoided in the treatment of dengue fever?
- They can exacerbate the risk of bleeding. (correct)
- They are known to cause liver damage in dengue patients.
- They interfere with the effectiveness of acetaminophen.
- They may promote viral replication.
How does the sylvatic cycle contribute to the spread of yellow fever?
How does the sylvatic cycle contribute to the spread of yellow fever?
- It occurs exclusively in regions where Aedes aegypti mosquitoes are not present.
- It involves direct transmission between humans in urban settings.
- It facilitates the spread of the virus among monkeys in the jungle, potentially leading to human infection. (correct)
- It is a man-made cycle.
What is the significance of hepatomegaly during the febrile phase of dengue fever?
What is the significance of hepatomegaly during the febrile phase of dengue fever?
- It is a sign of impending thrombocytopenia.
- It indicates the patient is entering the recovery phase.
- It suggests a co-infection with yellow fever.
- It serves as a warning sign of severe dengue. (correct)
Why does yellow fever sometimes cause coffee-ground vomitus?
Why does yellow fever sometimes cause coffee-ground vomitus?
How does the pathogenesis of yellow fever differ from that of dengue fever following a mosquito bite?
How does the pathogenesis of yellow fever differ from that of dengue fever following a mosquito bite?
What accounts for the increased risk of the critical phase in patients with a secondary dengue infection?
What accounts for the increased risk of the critical phase in patients with a secondary dengue infection?
How do the diagnostic approaches for dengue fever and yellow fever differ regarding the timing of RT-PCR use?
How do the diagnostic approaches for dengue fever and yellow fever differ regarding the timing of RT-PCR use?
In what scenario might a patient with yellow fever experience oliguria, and how is this condition related to the progression of the disease?
In what scenario might a patient with yellow fever experience oliguria, and how is this condition related to the progression of the disease?
Given that supportive care is the primary treatment for both dengue and yellow fever, what specific intervention is critical in managing dengue fever that is contraindicated in yellow fever and why?
Given that supportive care is the primary treatment for both dengue and yellow fever, what specific intervention is critical in managing dengue fever that is contraindicated in yellow fever and why?
Considering the transmission cycles of yellow fever, what measure would be most effective in preventing its spread following the identification of an infected human in a remote jungle area?
Considering the transmission cycles of yellow fever, what measure would be most effective in preventing its spread following the identification of an infected human in a remote jungle area?
Flashcards
Dengue Fever
Dengue Fever
Illness caused by a virus from the Flaviviridae family, common in tropical and subtropical climates, transmitted by Aedes mosquitoes.
Dengue Serology
Dengue Serology
Detects anti-Dengue IgM antibodies in the blood, aiding in Dengue fever diagnosis.
Dengue Treatment
Dengue Treatment
Supportive care, including fluids and acetaminophen, is the main focus. NSAIDs should be avoided due to bleeding risk.
Sylvatic Cycle
Sylvatic Cycle
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Urban Cycle
Urban Cycle
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Yellow Fever Vaccine
Yellow Fever Vaccine
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Febrile Phase
Febrile Phase
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Critical Phase
Critical Phase
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Study Notes
- Dengue fever is caused by a virus from the Flaviviridae family, characterized by enveloped, positive single-stranded RNA.
- Infection is prominent in tropical and subtropical climates, such as the Caribbean and Southeast Asia.
- Spread by Aedes aegypti mosquitoes, which also transmit Yellow fever, and Aedes albopictus.
- After a bite, the virus fuses with host cells, potentially Langerhans cells in the skin, and starts replicating.
Diagnosis
- Serology (anti-Dengue IgM)
- PCR testing.
Treatment
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Supportive care includes fluids and acetaminophen for pain relief.
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Avoid NSAIDs like ibuprofen and aspirin due to the risk of bleeding.
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Dengue vaccination can help prevent infection.
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Yellow fever virus is endemic to Africa and South America.
Transmission Cycles of Yellow Fever
- Sylvatic cycle (jungle cycle): Mosquitoes transmit the virus among monkeys; humans bitten in the jungle can spread it.
- Urban cycle: Aedes aegypti mosquitoes spread the virus among humans in cities.
- After a mosquito bite, the virus enters skin cells, particularly dendritic cells, spreads to lymph nodes, and then the bloodstream, reaching organs like the liver, kidneys, stomach, and heart.
Symptoms of Yellow Fever
- Most infections are asymptomatic.
- When symptoms occur, they appear 3 to 5 days after infection.
- Initial Symptoms (Viremia Phase): fever with chills, fatigue, severe headache, back pain, nausea and vomiting. Most people recover after 3 to 4 days.
- Remission and Toxic Phase: high fever, jaundice, upper abdominal pain, blood in stool and urine, bloody or coffee-ground vomit, oliguria (low urine output)
- Liver: hepatitis, leading to jaundice.
- Kidneys: renal tubular damage, leading to renal failure.
- Stomach: eroded gastric mucosa can lead to gastric hemorrhage. If blood remains in the stomach, gastric acid breaks down red blood cells, giving vomit a dark coffee-ground appearance.
- Heart: myocardial fiber damage, causing arrhythmias and myocardial infarction.
Diagnosis
- RT-PCR (detects viral RNA in blood)
- Serology (detects antibodies)
- Virus isolation in cell culture
Treatment
- Supportive care only; no antiviral treatment available.
Prevention
- The Yellow fever vaccine is a live attenuated vaccine.
- Administer as a single subcutaneous shot for individuals 9 months or older traveling to endemic areas.
Phases of Dengue Infection
- Febrile phase: lasts for 3 to 7 days, typically between days 4 and 7 after exposure.
- characterized by sudden high-grade fever (>38.5°C), headache.
- other symptoms include retro-orbital (behind-the-eye) pain, lymphadenopathy (swollen, tender lymph nodes), hepatomegaly.
- a maculopapular rash occurs in ~50% of cases, more common in first-time infections, appearing 2 to 5 days after fever onset.
- Critical phase: more likely in patients with a secondary Dengue infection or other medical comorbidities.
- occurs 3 to 7 days into infection, after fever resolves, and lasts 24 to 48 hours.
- thrombocytopenia (low platelet count) is key feature.
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