Viral Hemorrhagic Fevers Flashcards
What are the major sources of exposure to VHF?
Hospitals and Burials. They tend to occur in high conflict zones.
Ebola, Marburg and Congo-Crimean Fever- highly transmitted human to human
Lassa Fever and South American Arena Virus- low transmission
Yellow Fever, Hanta virus, Dengue, Rift Valley , Omsk and Kyansur Forest
What are the vectors?
Fruit bats, rodents and mosquitoes
What virus causes Ebola and Marburg Virus infection?
Filovirus
What virus causes Lassa Fever and LCMV?
Old World Arena Virus
What virus causes Argentine, Bolivian and Venezuelan HF?
New World Arena Virus
What virus causes Rift Valley, Congo Crimean and Hemorrhagic Fever with Renal Syndrome?
Bunya Virus
What virus causes yellow fever, Dengue fever, Omsk Fever and Kyansur Forest Fever.
Flavivirus
what is the average incubation period of the HF viruses?
3 to 21 days.
What are the three phases of disease?
Abrupt onset of viral non specific sx
Bleeding diatheses
Multiorgan system failure
What is the pathophysiology of the infection?
Virus move to small vessels where complement is activated and vessels develop increased permeability. Intravascular hypovolemia ensues followed by acidosis and hyperkalemia. There is very little of an inflammatory response.
What are the finding in the blood of those affected?
Low WBC, low platelets and elevated AST and ALT. The inflammatory response is minimal.
How is VHF diagnosed?
Serology: AgELISA, RT-PCR, Ab ELISA-IgM
What diseases are considered in the differential diagnosis?
Falciparum Malaria, Meningococcemia, Leptospirosis, Typhus, Gram negative Sepsis. and Plague.
what treatment are available?
Isolation
Supportive Care- IV Fluids
Medications: Steroids, Colloids, Immunoglobulins
Antiviral especially for Lassa Fever and Rift Valley Fever
Which VHF have a high rate of transmission from human to human?
Ebola, Marburg and Congo-Crimean Fever
Which VHF have a low Human to Human transmission?
Lassa Fever, South American Arenaviruses
Which VHF have no human to human transmission?
Hantavirus, Yellow Fever, Dengue, Rift Valley, Kyansanur Forest Fever, Omsk Fever
What is meant by containment?
2 incubation periods or 21 days without contacts developing sx.
Where does one find Omsk HF?
Border of Kazakhstan
When should you think about Kyasansur Forest fever?
A tick transmitted disease that looks like Dengue Fever.
When should you consider Rift Valley Fever?
A patient from the MIddle East or Africa who presents with a Flu like illness with stiff neck and reduced appetite associated with Encephalitis. Visual complications with Retinitis may result. It is arthropod borne with an incubation 0f 2 to 6 days. It occurs cyclically every 5 to 20 years. It is transmitted by Aedes mosquito but can be transmitted by Anopheles and Culex as well as flies. Care is supportive ? Ribavirin.
When should you consider Congo Crimean Fever?
A patient with extensive purpura. The disease is tick borne. Redness of eyes, throat and skin. It is treated with Ribavirin.
What sx should alert you to the possibility of Hanta virus infection?
Abrupt onset of severe HA, Back Pain and Abdominal pain associated with Hypotension and DIC. Dx is with serology. Supportive treatment ? Ribavirin
Sx that should help you consider an Arena virus infection?
Flu like sx followed by retrosternal pain, pharyngitis and proteinuria. The classic sx are: Mucosal Bleeding, Neck and Facial Edema and Shock. Swollen Baby Syndrome is a manifestation of this disease.
