**Clinical Issues**

126 Toxoplasmosis – Recent Advances

Veterinary Parasitology 158: 121–128.

Remote Arctic Svalbard Archipelago Reveals Widespread Clonal Type II Lineage.

[9] Wendte JM, Gibson AK, Grigg ME (2011) Population Genetics of *Toxoplasma gondii*: New Perspectives from Parasite Genotypes in Wildlife. Veterinary Parasitology 182: 96-111.

**Chapter 7** 

© 2012 Dupouy-Camet et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

**Risk Factors, Pathogenesis** 

**and Diagnosis of Ocular Toxoplasmosis** 

Ocular toxoplasmosis (OT) is a major cause of posterior uveitis worldwide but its incidence and prevalence are difficult to establish precisely. In 1993, a survey in a French Hospital Service of Ophthalmology showed that OT was seen in less than 1 per thousand outpatients [1]. In a study performed in Germany, toxoplasmosis accounted for 4.2 % of all cases of uveitis at a referral centre [2]. Around 5000 people develop symptomatic OT each year in the United States [3]. OT is a complication of both acute acquired and reactivated congenital in immunocompetent but particularly in immunocompromissed individuals and its severity can be influenced by variation in parasite isolates, parasitic load, route of infection and hostrelated factors such as immune function, age and pregnancy. Diagnosis is usually based on ophthalmological examination and is confirmed by the response to specific treatment, but also by biological assays including local antibody production, PCR and western blot. All

Classically, retinochoroiditis secondary to acquired toxoplasmosis was considered an exceptional event in immunocompetent individuals, and was usually defined as a periodic reactivation of latent cysts associated with undiagnosed congenital infections. But recent data, based on ophthalmological examination, seem to establish that acquired infection might be responsible for most cases. This fact was particularly demonstrated by outbreaks reported in Canada, Brazil and India. In Canada, amongst 100 individuals infected during a water-borne outbreak, 19 had OT [4]. In southern Brazil 17.7% of 1,042 individuals examined had OT with lesions in 0.9% of 1- to 8-year-olds and in 21.3% of all individuals older than 13, suggesting that in this population, the disease was a sequel of postnatal rather

and reproduction in any medium, provided the original work is properly cited.

Jean Dupouy-Camet, Hana Talabani, Emmanuelle Delair,

**2. A complication of acquired and congenital infections** 

Florence Leslé, HélèneYera and Antoine P. Brézin

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/50267

these points will be detailed below.

**1. Introduction** 

**Chapter 7** 
