Department of Ophthalmology - Heidi Raies Eye Institute,Tunis (Tunisia)
The presence of retinitis, retinal vasculitis, optic neuropathy, or any intraocular inflammatory condition in a patient with fever or rash, living in or returning from from an endemic area, especially during spring or summer, strongly suggests a diagnosis of Rickettsiosis.
Systemic fundus examination, complemented with fluorescein angiography and ICG angiography in selected cases, may help establish the diagnosis of rickettsiosis while serologic testing is pending. Prevention is the mainstay of the disease control i.e. personal prevention against tick bites in endemic areas and improvement of sanitary conditions.
In patients with rickettsiosis retinal vascular involvement may present different clinical pictures: branch retinal artery occlusion, cystoid macular oedema, serous retinal detachment, and hypofluorescent choroidal spots.  Rickettsial retinitis presents as white retinal lesions that are typically juxtavascular in location and are associated with mild vitreitis. Differential diagnosis with Toxoplasmosis is often required. Large foci tend to involve all retinal layers extending to the retinal pigment epithelium and more deeply until the choroid. Small foci may also involve the entire retinal thickness, but in some cases only superficial retinal layers are involved and lesions resemble cotton-wool spots. White retinal lesions may number from 1 to more than 5, may be variable in size and located at the periphery or posteriorly. If the optic disk is involved, there may be disc oedema and staining. 
Systemic antibiotic treatment with doxycycline (100 mg/day for 10-14 days) represents the basic treatment. Systemic steroids, in association with docycycline is mandatory in the case of severe retinitis extending to the macular region, vitriitis, retinal vascular occlusion or optic nerve involvement. Furthermore, the ophthalmologist should also choose to add local therapy, depending on the main ocular symptom i.e. topical antibiotics for conjunctivits or keratitis, topical steroids and mydriatics if anterior uveitis is present.
1. Moncef Khairallah, Ahmed Ladjimi, Mohamed Chakroun, Riad Messaoud, Salim Ben Yahia, Sonia Zaouali, Foued Ben Romdhane, Noureddine Bouzouaia. Posterior segment manifestations of Rickettsia conorii infection. Ophthalmology. 2004;111:529-534
2. Moncef Khairallah, Sonia Zaouali, Salim Ben Yahia, Ahmed Ladjimi, Riadl Messaoud, Sonia Attia. Anterior Ischemic Optic Neuropathy Associated with Rickettsia Conorii Infection. J Neuro-Ophthalmol. 2005;25:3