Rift Valley Fever

Question 1

Family

Answer 1

phenuiviridae

Question 2

Structure

Answer 2

enveloped, capsid, negative-sense ssRNA

Question 3

Reservoir hosts

Answer 3

domestic cattle, wild ruminants

Question 4

Transmitted (vector-borne)

Answer 4

mosquito Aedes spp.
Also can be transmitted animal-to-animal

Question 5

When it is more common

Answer 5

during flooding or heavy rainfall

Question 6

Is it zoonotic

Answer 6

YES

Question 7

Transmission cycle

Answer 7

female mosquito-> eggs-> naive species-> naive species (blood and tissue)

Question 8

Pathogenesis

Answer 8

Liver->monocytes->CNS

Question 9

Severe acute

Answer 9

high viremia that appears fast-> causes sudden death

Question 10

Mild to asymptomatic

Answer 10

viremia reduces quickly

Question 11

Delayed onset

Answer 11

starts with viremia and fever, then another fever episode

Question 12

Incubation

Answer 12

12-72 hrs

Question 13

Clinical Signs

Answer 13

biphasic fever, lethargy, vomiting bloody, bloody diarrhea, nasal discharge, anorexia, salivation, abortion of fetus (5-100%)

Question 14

Pathologic Lesions

Answer 14

-aborted fetuses have worst lesions
-moderately to greatly enlarged soft, friable livers with irregular congested patches -> numerous grayish-white necrotic foci
-hemorrhage and edema of wall of gallbladder and mucosa of abomasum
-intestinal contents are dark chocolate-brown
-splenomegaly and peripheral lymphomegaly with edema and may show petechiae

Question 15

Diagnostics

Answer 15

Histological findings of liver, IFA, PCR, ELISA, Virus neutralization tests

Question 16

Management

Answer 16

-there’s no way to stop an outbreak once it starts
-vaccination programs of domestic animals most efficient way
-avoid contact with bodily fluids of suspect infectious cases
-personal mosquito prevention
-limit exposure of domestic animals to wildlife