1. West Nile Virus Infection
Rim Kahloun, MD
Salim Ben Yahia, MD
Moncef Khairallah, MD
Department of ophthalmology
Fattouma Bourguiba University Hospital
Faculty of Medicine, University of Monastir
Monastir, Tunisia

2. History
A 52-year-old woman
History: diabetes

3. Presentation Visual acuity: 20/25 OD, 20/32 OS
No cells in anterior chamber or vitreous OU
Intraocular pressure: 14 mm Hg OU
Mild cataract OU
Fundus OU: Inactive multifocal chorioretinitis

4. Fundus photography shows inactive multifocal chorioretinitis OU
Fundus photography shows inactive multifocal chorioretinitis OU. Note the presence of mild non proliferative diabetic retinopathy.

5. Fluorescein angiography
Mid-phase fluorescein angiogram shows central
hypofluorescence and peripheral hyperfluorescence of chorioretinal
lesions (“target-like” appearance) Note the linear clustering of chorioretinal lesions, especially OS.

6. Initial work-up For causes of multifocal chorioretinitis: - Syphilis
- Tuberculosis
- Sarcoidosis
- Histoplasmosis
- Idiopathic multifocal chorioretinitis
Negative

7. Work-up
History retaking: Episode of febrile illness with severe headache six months before presentation (during the summer season)
Serology: positive for West Nile virus (WNV)

8. Treatment No specific treatment Supportive
Symptomatic for ophthalmic complications

9. Conclusion
WNV infection is a worldwide zoonotic disease caused by a single-stranded RNA flavivirus, transmitted to human by a mosquito vector (type Culex ) with wild birds serving as its reservoir
Most human WNV infections are subclinical (80%) or manifest as febrile illness (20%) and occur in last summer and autumn. Severe neurologic disease (meningoencephalitis) occurs in less than 1% of patients and is associated with advanced age and diabetes

10. Conclusion
Typical bilateral or rarely unilateral multifocal chorioretinitis is the most common ocular manifestation of WNV infection
The unique pattern of multifocal chorioretinitis can help establish an early diagnosis of the disease while serologic testing is pending