Ocular toxoplasmosis.

Abstract

A large amount of research has been done on toxoplasmosis in the last 30 years, and the world-wide incidence of the infection, and its clinical manifestations, are recognized and documented in an extensive literature. New discoveries concerning the life-cycle of the organism (Frenkel, I970; Hutchison, Dunachie, Siim, and Work, I970) promise to solve many of the problems of the transmission of infection and will give added stimulus to epidemiological studies. In the field of ophthalmology the importance of toxoplasmosis is now established, but some problems still remain.The ocular lesions in infants with congenital toxoplasmosis are well recognized as pathogenic, but whether similar chorioretinal lesions in adults, although now acknowledged to be due to toxoplasmosis, result from recurrences of congenital infection or follow a postnatally acquired infection is still controversial. Other types of uveitis have been attributed to toxoplasmosis, and if this is correct it is important to recognize such cases. The present study attempts to clarify these problems by a review of the relevant literature supported by clinical studies in patients with uveitis. A further problem which will be discussed is whether congenital toxoplasmosis results from a chronic maternal infection or from one acquired during pregnancy: although this is not strictly an ophthalmological problem, ophthalmologists are often asked to advise on the prognosis for future pregnancies. Review of the literatureNo attempt is made here to provide a comprehensive general review of the literature on toxoplasmosis, but a list of recent reviews is given in the Bibliography. Attention here will be concentrated on the incidence of ocular complications in acquired systemic infections with clinical manifestations, the evidence for acquired infection in cases of uveitis, and the type ofmaternal infection causing toxoplasmosis. INCIDENCE OF OCULAR COMPLICATIONS IN RECENTLY ACQUIRED TOXOPLASMOSISIn reviewing the literature on this subject, an immediate problem is that of deciding on the criteria which should be accepted as evidence ofinfection. Most authors have relied on one or a combination of three methods: the detection of high levels of antibody, particularly the demonstration of rising titres; the observation of organisms in biopsy specimens or tissue fluids; and the demonstration of infection in animals after the inoculation oftissue extracts.The demonstration in biopsy or post mortem specimens of organisms morphologically resembling Toxoplasma is not entirely reliable, as nuclear fragments (Duke-Elder, Ashton, and Brihaye-van Geertruyden, I953) and even pine pollen (Langer, I966) can cause confusion. Even if the organism

Transforming growth factor-β expression in human retinal pigment epithelial cells is enhanced by Toxoplasma gondii: a possible role in the immunopathogenesis of retinochoroiditis

“…Retinochoroiditis caused by T. gondii infection is a frequent cause of uveitis, an intraocular inflammatory disease of the eye in humans [1][2][3][4][5]. The hallmark of toxoplasma-induced retinochoroiditis is the recurrent episodes of reactivation and localized inflammatory responses to these episodes.…”

“…Ocular toxoplasmosis results in inflammation and disorganization of the retina and is one of the common causes of uveitis, an intraocular inflammatory disease [1][2][3][4][5]. The intensity of the damage to the retina and choroid depends on the severity of infection and the associated inflammatory reaction [3][4][5].…”

Use of CD25 as an immunohistochemical marker for acquired ocular toxoplasmosis

“…Seventy percent of infants with congenital infection show chorioretinal scars (7) . Although most of the cases in adults were thought to be a consequence of the reactivation of congenital lesions (9) , several studies indicate that ocular disease may be caused by T. gondii infection after birth (1,6,(10)(11)(12) . In fact, most cases in Brazil are a consequence of post-natal infection (6) .…”

Toxoplasmosis

“…In a British Columbia outbreak, of 100 people who were diagnosed with acute infection, 51 had lymphadenopathy (swollen, enlarged lymph nodes) and 20 had retinitis (inflamed retina) (Aramini and others, 1998;1999). Most ocular toxoplasmosis is now believed to result from postnatally acquired disease (Holland, 1999;2003), contrary to what was generally accepted prior to the 1990s, when almost all cases of this disease were believed to be a result of congenital infection (Perkins, 1973).…”