Hemorrhagic Viruses Flashcards
What Hemorrhagic disease might you suspect if your pt. had just traveled to Central or South America?
- Yellow Fever
* Arenavirus
What Hemorrhagic disease might you suspect if your pt. had just traveled to West Africa?
• Lassa Fever
What Hemorrhagic disease might you suspect if your pt. had just traveled to Central Africa?
- Ebola
- Marburg
- RVF
- CCHF
Flaviviridae
• Genomic structure and Packaging
• Important viruses caused by this pathogen
Genome: • Small • Non-Segmented • +ssRNA • Enveloped
Diseases Caused:
• Dengue Virus*
• Yellow Fever Virus*
• Hep C
Describe the Replication Cycle of Dengue and Yellow Fever Viruses.
Flavivirdae
Entry:
• pH Dependent
- +ssRNA translated by host ribosome to make RNA-dep.-RNA-pols.
- RNA-dep.-RNA-pols copies genome and Structural Prots. are made and capside is assembled
- Capside BUDS through the Goli or ER and then out of the Cell
How is the Flavivirus transmitted?
• diseases that it causes
• Prevalence
Diseases: Dengue Virus, Yellow Fever Virus
INSECT VECTORS:
• ARBOviruses (anthropod-borne virues)
Dengue is 2nd only to Malaria in importance of Tropical Diseases
What organs do Dengue and Yellow Fever infect?
• Primary and Secondary Viremia
Primary Viremia: Insect bite puts the virus into the epithelium and it becomes established then transmits to • Macrophages • Spleen • Lymph Node
Secondary Viremia:
Happens in Immunocompromised ONLY
• Hemorrhagic Fever and Shock Ensue
Where are you most likely to acquire a Dengue Fever Virus (DFV)?
- South America
- Southeast Asia
- Africa
***Note: most cases of dengue in America have been acquired abroad
Classic Dengue Virus • Incubation Period • Characteristic Symptoms (early?, late?) • Lab Values • Recovery
Incubation Period:
• 2-7 days
Early:
• Mottled Rash on day 1 or 2
• Metallic Taste in their mouth
Later:
• Myalgia
• Increased Muscle and Joint pain (Bonebreak Fever)
Lab Value:
• LOW PLATELETS less than 100x10^9/L
Recovery:
• Slow (~2 weeks post inf. recovery)
Dengue Hemorrhagic Fever (DHF) • WHO criteria for Dx. • Characteristic Symptoms (early?, late?) • Lab Values • Recovery
Dx: • Fever • Hemorrhagic symptoms (thrombocytopenia, etc) • Circulatory Failure (hypoproteinurea) • Hepatomegaly
Early:
• Abdominal Pain
• Restlessness and Change in Mental Status
• CAPILLARY LEAKAGE
Late (untreated):
• Progression to Dengue Shock Syndrome preceded by vomiting and restlessness
*shock is caused by capillary leakage causing hypovolemia and acidosis in lowly perfused tissues
What is suggested by the fact that in greater than 90% of Fatal DHF cases the person had previously been infected with a different Dengue Virus?
*Immune-mediated pathology initiates the events that cause the hemorrhagic syndrome
T or F: you need laboratory conformation to diagnose someone with DHF.
True, this is because the symptoms are so non-specific
How do you use lab tests to confirm a Dengue infection?
Serodiagnosis:
• 4 fold rise in antibody titer in paired IgG or IgM specimens
Other Methods:
• Culture
• RT-PCR
How should you avoid Dengue Infection?
Avoid Getting bit by mosquitoes
There is now a tetravalent dengue vaccine approved for use in Mexico, Brazil, and the Phillippines containing recombinant capsid proteins, it effective but not approved for use in children under 9
There is now a tetravalent dengue vaccine approved for use in Mexico, Brazil, and the Phillippines containing recombinant capsid proteins, it effective but not approved for use in children under 9
Where are you most likely to get infected with Yellow Fever?
*South and Central America as well as Africa
What is the difference between Jungle, Savannah, and Urban Yellow Fever Virus?
• Found where?
Jungle (S. America or Africa)
• Transmitted from monkey to man via mosquito - found in workers and ppl. who visit the jungle
Savannah (Africa only)
• Transmitted from monkey or man to monkey or man - found in workers and ppl. who live or work on the border of the jungle
Urban (Anywhere)
• Transmitted from human to human only
