West Nile virus: Difference between revisions

Revision as of 06:44, 18 August 2020

Background

Single-stranded positive-sense enveloped virus in the family Flaviviridae and genus Flavivirus
Essentially worldwide distribution
Vector is mosquitoes
Main reservoir is birds
As well as being vector-borne, can also be transmitted by blood transfusion, solid organ transplantation, and vertically

Clinical Manifestations

Incubation period of 3 to 14 days
Up to 80% of infections are asymptomatic; of those with symptoms, fever is most common
Some form of CNS disease develops in 1:150 people
- Meningoencephalitis
- Acute flaccid paralysis
- 10% mortality, with about half of survivors having neuropsychiatric sequelae

Differential Diagnosis

Other causes of meningitis, encephalitis, and acute flaccid paralysis

Diagnosis

Serology
- Serum or CSF for IgM antibodies is the standard test; usually positive by 3 to 8 days, and persist for 2 to 3 months
  - If submitted CSF, must also submit serum
- May cross-react with other flaviviruses
- Can be seronegative if immunosuppressed (e.g. rituximab), therefore may need to do PCR
PCR
- RNA virus, therefore needs reverse transcriptase step (RT-PCR)
- Can be done on serum, CSF, and tissue
On MRI, may have a slight preference for thalamus

Management

Supportive care

@@ Line 1: / Line 1: @@
-== Diagnosis ==
+== Background ==
+* Single-stranded positive-sense enveloped virus in the family [[Flaviviridae]] and genus [[Flavivirus]]
-* Serology
+* Essentially worldwide distribution
-** Serum or CSF for IgM antibodies is the standard test; usually positive by 3 to 8 days, and persist for 2 to 3 months
+* Vector is [[Vector::mosquitoes]]
-*** If submitted CSF, must also submit serum
+* Main reservoir is birds
-** May cross-react with other flaviviruses
+* As well as being vector-borne, can also be transmitted by blood transfusion, solid organ transplantation, and vertically
-** Can be seronegative if immunosuppressed (e.g. rituximab), therefore may need to do PCR
-* PCR
+== Clinical Manifestations ==
-** RNA virus, therefore needs reverse transcriptase step (RT-PCR)
-** Can be done on serum, CSF, and tissue
+* Incubation period of [[Usual incubation period::3 to 14 days]]
-* On MRI, may have a slight preference for thalamus
+* Up to 80% of infections are asymptomatic; of those with symptoms, [[fever]] is most common
+* Some form of CNS disease develops in 1:150 people
+** [[Meningoencephalitis]]
+** [[Acute flaccid paralysis]]
+** 10% mortality, with about half of survivors having neuropsychiatric sequelae
+== Differential Diagnosis ==
+* Other causes of [[meningitis]], [[encephalitis]], and [[acute flaccid paralysis]]
+==Diagnosis==
+*Serology
+**Serum or CSF for IgM antibodies is the standard test; usually positive by 3 to 8 days, and persist for 2 to 3 months
+***If submitted CSF, must also submit serum
+**May cross-react with other flaviviruses
+**Can be seronegative if immunosuppressed (e.g. rituximab), therefore may need to do PCR
+*PCR
+**RNA virus, therefore needs reverse transcriptase step (RT-PCR)
+**Can be done on serum, CSF, and tissue
+*On MRI, may have a slight preference for thalamus
+== Management ==
+* Supportive care
 [[Category:Flaviviridae]]