Viral Hemorrhagic Fevers

Question 1

What are the major sources of exposure to VHF?

Answer 1

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

Question 2

What are the vectors?

Answer 2

Fruit bats, rodents and mosquitoes

Question 3

What virus causes Ebola and Marburg Virus infection?

Answer 3

Filovirus

Question 4

What virus causes Lassa Fever and LCMV?

Answer 4

Old World Arena Virus

Question 5

What virus causes Argentine, Bolivian and Venezuelan HF?

Answer 5

New World Arena Virus

Question 6

What virus causes Rift Valley, Congo Crimean and Hemorrhagic Fever with Renal Syndrome?

Answer 6

Bunya Virus

Question 7

What virus causes yellow fever, Dengue fever, Omsk Fever and Kyansur Forest Fever.

Answer 7

Flavivirus

Question 8

what is the average incubation period of the HF viruses?

Answer 8

3 to 21 days.

Question 9

What are the three phases of disease?

Answer 9

Abrupt onset of viral non specific sx
Bleeding diatheses
Multiorgan system failure

Question 10

What is the pathophysiology of the infection?

Answer 10

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.

Question 11

What are the finding in the blood of those affected?

Answer 11

Low WBC, low platelets and elevated AST and ALT. The inflammatory response is minimal.

Question 12

How is VHF diagnosed?

Answer 12

Serology: AgELISA, RT-PCR, Ab ELISA-IgM

Question 13

What diseases are considered in the differential diagnosis?

Answer 13

Falciparum Malaria, Meningococcemia, Leptospirosis, Typhus, Gram negative Sepsis. and Plague.

Question 14

what treatment are available?

Answer 14

Isolation
Supportive Care- IV Fluids
Medications: Steroids, Colloids, Immunoglobulins
Antiviral especially for Lassa Fever and Rift Valley Fever

Question 15

Which VHF have a high rate of transmission from human to human?

Answer 15

Ebola, Marburg and Congo-Crimean Fever

Question 16

Which VHF have a low Human to Human transmission?

Answer 16

Lassa Fever, South American Arenaviruses

Question 17

Which VHF have no human to human transmission?

Answer 17

Hantavirus, Yellow Fever, Dengue, Rift Valley, Kyansanur Forest Fever, Omsk Fever

Question 18

What is meant by containment?

Answer 18

2 incubation periods or 21 days without contacts developing sx.

Question 19

Where does one find Omsk HF?

Answer 19

Border of Kazakhstan

Question 20

When should you think about Kyasansur Forest fever?

Answer 20

A tick transmitted disease that looks like Dengue Fever.

Question 21

When should you consider Rift Valley Fever?

Answer 21

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.

Question 22

When should you consider Congo Crimean Fever?

Answer 22

A patient with extensive purpura. The disease is tick borne. Redness of eyes, throat and skin. It is treated with Ribavirin.

Question 23

What sx should alert you to the possibility of Hanta virus infection?

Answer 23

Abrupt onset of severe HA, Back Pain and Abdominal pain associated with Hypotension and DIC. Dx is with serology. Supportive treatment ? Ribavirin

Question 24

Sx that should help you consider an Arena virus infection?

Answer 24

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.

Question 25

When does the hemorrhage occur with Ebola?

Answer 25

At the peak of the disease, 5 to 7 days.