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PubMed1993

Detection of Toxoplasma gondii in aqueous humour by the polymerase chain reaction.

Ocular toxoplasmosis is the most frequent infectious cause of chorioretinal inflammation in immunocompetent patients. Nowadays, the biological diagnosis of ocular toxoplasmosis requires serological tests and anterior chamber puncture to detect the local production of specific antibodies. A new technique is described to detect Toxoplasma in aqueous humour by a polymerase chain reaction in which the target is a specific ribosomal DNA segment. Sixty eight patients (71 eyes) were included; 59 (83%) eyes were suspected of having ocular toxoplasmosis. Of these 59 eyes, 15 (25.4%) had characteristic fundus lesions with obvious intraocular inflammation signs and 44 (75%) had retinal scar of ocular toxoplasmosis without clinically detectable inflammation. Twelve (17%) eyes had uveitis of non-Toxoplasma origin and constituted the control group. The parasite was present in aqueous humour in 20 (33.8%) cases. No false positives were detected. The sensitivity of the test is reduced by the low numbers of the sample. The combination of this technique with Witmer-Desmonts coefficient increases the probability of making a biological diagnosis of ocular toxoplasmosis. The physiopathological value of this technique is emphasised and the presence of tachyzoites in the anterior chamber is suggested. This should be a very promising technique for the diagnosis of ocular toxoplasmosis.

Adolescent↗
PubMed1999

Atovaquone for the treatment of toxoplasma retinochoroiditis in immunocompetent patients.

OBJECTIVE: To report the results of a phase I trial to evaluate the safety and efficacy of atovaquone for the treatment of ocular toxoplasmosis in immunocompetent patients. DESIGN: Open label, nonrandomized, prospective, clinical trial. PARTICIPANTS: Seventeen immunocompetent patients between the ages of 18 and 75 years with clinical and serologic evidence of ocular toxoplasmosis participated. INTERVENTION: Treatment of ocular toxoplasmosis with atovaquone tablets (750 mg four times a day) for 3 months. Prednisone (40 mg) tablets were added on day 3 of treatment and tapered as inflammation resolved. MAIN OUTCOME MEASURES: Clinical response and patient tolerance to atovaquone therapy for ocular toxoplasmosis. RESULTS: Average follow-up was 10 months. Most patients experienced no adverse treatment effects. When present, side effects were usually mild and included rash, pruritus, headache, and nausea. With the exception of one patient, who discontinued treatment at 6 weeks secondary to persistent epigastric discomfort, all patients completed the 12 weeks of therapy. All patients had a favorable response to treatment that began within 1 to 3 weeks. Visual acuity was stabilized or improved in all patients. Median initial visual acuity was 20/200 and median final visual acuity was 20/25. In general, atovaquone was well tolerated. CONCLUSIONS: Atovaquone is better tolerated than conventional antitoxoplasmosis therapy and appears to be at least as effective. Atovaquone is a promising alternative for the treatment of ocular toxoplasmosis in immunocompetent patients.

Adolescent↗
PubMed1995

HLA typing in congenital toxoplasmosis.

HLA-A, HLA-B, HLA-C, and HLA-D typing was performed in 47 mothers of patients suffering from ocular toxoplasmosis to investigate whether an immunogenetic predisposition exists for developing congenital toxoplasmosis in their offspring. No significant association between any HLA antigen was observed in the mothers of patients with ocular toxoplasmosis, although a total absence of the HLA-B51 antigen was found in this group. HLA-A, HLA-B, and HLA-C typing was also performed in their children (52 patients with ocular toxoplasmosis), to investigate a possible relation between the severity of ocular toxoplasmosis and an eventual immunogenetic factor. In the patients with ocular toxoplasmosis an increased frequency of the HLA-Bw62 antigen was observed in correlation with severe ocular involvement.

Disease Susceptibility↗
PubMed2005

Lacrimal secretory IgA in active posterior uveitis induced by Toxoplasma gondii.

It is quite difficult to diagnose active toxoplasmosis in patients with ocular toxoplasmosis. Active posterior uveitis presumably due to Toxoplasma gondii infection (APUPT) is seldom produced during a prime-infection; hence most patients do not show high IgM antibodies. High levels of IgA have been described in active toxoplasmosis. The purpose of this study was to investigate possible association between APUPT and the specific anti-parasite sIgA in tears. The study was carried out as case-control. Tears of 25 clinically confirmed APUPT patients and 50 healthy control subjects were analyzed. All were IgG seropositive. Specific sIgA was determined by ELISA assay using T. gondii RH strain crude extract. Anti-T. gondii sIgA was found in 84% of the cases and in 22% of the control subjects. The intensity of the reaction was higher in APUPT cases (P = 0.007). There was strong association between APUPT patients and lacrimal sIgA (odds-ratio 18.61, P = 0.0001). ELISA test sensitivity was 84% and specificity 78%. Our data suggest that anti-T.gondii secretory IgA found in tears may become an important marker for active ocular toxoplasmosis.

Adolescent↗
PubMed1996

[Acquired toxoplasmosis of ocular or neurologic site: 49 cases].

OBJECTIVES: Over a period of 13 years (1982-1995), 49 cases of acquired toxoplasmosis complicated with ocular and/or neurologic or meningeal involvement were observed in our toxoplasmosis laboratory. This series includes 43 cases of isolated ocular lesions, 3 cases of meningoencephalitis (associated with retinochoroiditis in 1 case), 1 case of meningitis with uveitis, 1 case of polyradiculoneuritis and 1 case of facial nerve palsy. METHODS: The patients were aged 1 to 62 years. None had either spontaneous or iatrogenic immunodeficiency. There were two steps in the diagnosis. First congenital infection was eliminated on one or several of the following criteria: any possibility of maternal infection during pregnancy ruled out in 26 cases, evidence of recent acquired infection (i.e. clinical and/or serological evidence of recent acquired toxoplasmosis in 17 cases, retinochoroiditis in non-twin siblings in 3 cases). The second step was to confirm the diagnosis of toxoplasma infection. Apart from serological evidence of recent infection, confirmation included specific local antibody synthesis in the aqueous humor of the eye and/or in cerebro-spinal fluid or ocular lesions characteristic of toxoplasmosis and absence of other etiology. RESULTS: Ocular lesions were unilateral in 43 cases among 45. A mean follow-up of 37.9 months revealed relapses in 14 among 36 patients (39%). As routine serological examination for toxoplasmosis is compulsory in France since 1978, it was possible to document retrospectively the immune status of the mothers of many of the patients of the present series during pregnancy and to rule out congenital toxoplasmosis in a number of cases. This might explain the discrepancy between the relatively large number of cases in the present series and the fact that complicated acquired toxoplasmosis has been considered hitherto as relatively rare in immunocompetent patients. CONCLUSION: Based on the epidemiology of ocular toxoplasmosis and the data obtained here, it is suggested that the acquired pattern of ocular toxoplasmosis might be more frequent than estimated up to now.

Adolescent↗
PubMed1991

[Direct detection of toxoplasma in the aqueous humor by gene amplification].

For immunocompetent patients, ocular toxoplasmosis is the most frequent infectious cause of chorioretinal inflammation. Nowadays, the laboratory diagnosis of ocular toxoplasmosis requires serological tests and anterior chamber puncture to detect the local production of specific antibodies. The authors describe a new technique to detect toxoplasma in aqueous humor by a polymerase chain reaction in which the target is a 88 bp specific rDNA fragment. 31 patients were concerned (23 highly suspect of ocular toxoplasmosis and 8 controls). The presence of the parasite in aqueous humor was found in 7 cases. No false positive was detected. The sensitivity of the test is reduced by the poor volume of the sample. The combination of this technique with Desmont's coefficient gives a better positive predictive value. We emphasize the pathophysiological value of this technique by suggesting the presence of tachizoites in the anterior chamber. According to our knowledge, this finding has never been demonstrated. In the future, this should be a very promising technique for the diagnosis of ocular toxoplasmosis.

Adolescent↗
PubMed1980

Vitreous cylinders.

Vitreous cylinders, a rarely discussed ophthalmologic entity, were studied in two clinical cases and in five enucleated eyes. The cylinders were found in four cases of ocular toxoplasmosis, one case of vitreous hemorrhage complicating a malignant melanoma, and one case of pars planitis and one of uveitis, both of unknown causes. Results of scanning electron microscopy in one specimen suggested that cylinders are formed by condensation of vitreous collagen fibers. We emphasize the nonspecific nature of this interesting vitreous finding.

Aged↗
PubMed1984

Presumed toxoplasmic papillitis.

Six patients with ocular toxoplasmosis are described whose only active site of inflammation was at the optic nervehead. These patients presented with severe papillitis, vitreous inflammation, and sector or nerve fiber bundle field defects. Because of the papillitis and the absence of other typical foci of retinitis to suggest toxoplasmosis in these patients, the initial diagnoses were usually incorrect. These cases are presented to familiarize ophthalmologists with this unusual cause of papillitis.

Adolescent↗
PubMed2005

[Recurrent toxoplasmic retinochoroiditis after clindamycin treatment].

PURPOSE: To evaluate the efficacy and safety of subconjunctival injections of clindamycin associated with oral corticotherapy in the treatment of toxoplasmic retinochoroiditis (TRC) and its effect on recurrence. PATIENTS AND METHODS: This study investigated 21 patients (10 males and 11 females) who presented to an ophthalmological department from 1995 to 2000, aged 14-55 years (mean, 28 years), with unilateral TRC. They were treated with subconjunctival injections of clindamycin and systemic corticotherapy at a dose of 1 mg/kg/day. Clinical follow-up consisted of assessment of visual acuity and biomicroscopic fundus examination, completed by retinal angiography if necessary. RESULTS: We observed clinical improvement in 68.75% of patients within 4 days and in all patients healing of the chorioretinal area within 1.6 months. During the follow-up period ranging from 6 to 52 months (mean, 22 months), there have been two recurrences (9%) over the first 18 months. Tolerance of the injections was good. Serious side effects were noted in two patients: one case of conjunctival necrosis and one case of corneal and conjunctival erosion. CONCLUSION: In treating ocular toxoplasmosis, clindamycin appears to be a safe and effective substitute for the classic protocol (pyrimethamine-sulfadiazine, pyrimethamine-azithromycin), for which a 50% recurrence rate has been reported. It provides relatively good protection against recurrence and warrants testing in further controlled studies.

Adolescent↗
PubMed2001

Detection of Toxoplasma gondii DNA in primary intraocular B-cell lymphoma.

Primary intraocular lymphoma, a variant of primary central nervous system lymphoma with ocular involvement, is a large B-cell non-Hodgkin's lymphoma. Some cases of primary intraocular lymphoma have been reported to be associated with microorganisms including Epstein-Barr virus (EBV) and human herpes virus-8 (HHV-8), but not parasites. We analyzed 10 cases of primary intraocular lymphoma using microdissection and PCR. Tumor and normal cells were microdissected from ocular tissue on slides and subjected to PCR for genes from Toxoplasma gondii, EBV, and HHV-8. We detected Toxoplasma gondii, not HHV-8 or EBV, DNA in the lymphoma but not in normal cells of two cases that resembled ocular toxoplasmosis clinically. We speculate that Toxoplasma gondii may play a role in some forms of primary intraocular B-cell lymphoma.

Adult↗
PubMed2002

Hypersensitivity reaction to intravitreal clindamycin therapy.

A Caucasian woman presenting with recurrence of intra-ocular toxoplasmosis was given intravitreal clindamycin. She subsequently developed a hypersensitivity reaction in the form of a generalized erythematous rash. To the authors' knowledge, hypersensitivity reactions to an antibiotic given by the intra-vitreal route have not previously been reported.

Anti-Bacterial Agents↗
PubMed1984

Congenital toxoplasmic retinochoroiditis in a mouse model.

A study of the eyes of adult mice infected in utero with Toxoplasma gondii is reported. The histopathological features of the ocular inflammatory response in the infected mice ranged from minimal damage to complete destruction of the retinal tissue. Notable features such as retinal vasculitis and an almost uniform and highly selective destruction of the photoreceptor layer of the retina suggest a similarity between experimental autoimmune retinitis and the disease process in the retinas of our Toxoplasma-infected mice. We suggest that our mouse model could provide a simple and inexpensive tool for the investigation of immuno-pathological processes in the retina resulting from congenital Toxoplasma infection. The model has the advantage of low post-natal mortality coupled with high ocular morbidity. Furthermore, its aetiology is probably analogous to that of human ocular toxoplasmosis, in that the foetus becomes infected in utero via a mother whose primary infection is acquired during gestation.

Animals↗
PubMed1977

Toxoplasmic chorioretinitis affecting the macula.

To study macular changes in toxoplasmic chorioretinitis 41 patients with ocular toxoplasmosis were reviewed. Of the 41 patients, seven had central, large, deep, pigment ringed scars of congenital toxoplasmosis with poor central vision; squint was seen in two and nystagmus in two; 32, including 11 cases with a macular lesion, had recurrent active toxoplasmic chorioretinitis with a focal, yellowish-white, elevated lesion with indistinct borders mostly at the margin of an old scar and associated with vitreous opacities in all, secondary anterior uveitis in 28, macular oedema in 22, papilloedema in 14, and retinal perivasculitis in 16 cases; two had rare acquired toxoplasmic chorioretinitis affecting the macula. The results show that active toxoplasmic chorioretinitis often causes a widespread intraocular inflammation with vitritis, macular oedema, papilloedema, retinal perivasculitis and secondary anterior uveitis, and suggest a combined treatment of active lesions with antimicrobial agents and corticosteroids.

Adolescent↗
PubMed1981

Antibodies against Toxoplasma gondii in the aqueous humour of patients with active retinochoroiditis.

In active cases of ocular toxoplasmosis, antibodies against the parasite are produced locally in the eye. This antibody production may be revealed by examination of the aqueous humour, and comparing the antibody titer with that of serum. We examined the dye test titer as well as the total IgG concentration of the aqueous humour and serum in 10 patients with active retinochoroiditis. Six of the 10 patients had a significantly higher antibody titer in the aqueous humour than in serum, in relation to their contents of total IgG, proving that the retinochoroiditis was caused by infection with Toxoplasma gondii. Negative results do not exclude the possibility that the inflammation is caused by this parasite. False negative results may occur when the total IgG concentration is either very low, or very high. The time at which the test is performed, in relation to the onset of the inflammation, is also of importance. Our results also suggest that the larger the size of the active lesions is, the higher is the chance of obtaining a definite diagnosis. It is concluded that aqueous humour analysis for antibodies against Toxoplasma gondii should be considered in cases of active retinochoroiditis of unclear or suspected toxoplasmic etiology.

Adult↗
PubMed1996

Aetiology of uveitis in Sierra Leone, west Africa.

BACKGROUND: In 1992, non-onchocercal uveitis caused 9% of blindness, 8% of visual impairment, and 11% of uniocular blindness among patients visiting an eye hospital in Sierra Leone, west Africa. The aim of this study was to determine the aetiology of uveitis in this population. METHODS: General and ophthalmic examination complemented by serum and aqueous humour analyses for various infectious agents was performed for 93 uveitis patients and compared with serum (n = 100) and aqueous humour (n = 9) analysis of endemic controls. RESULTS: At the initial examination, 45 patients (48%) proved to be severely visually handicapped. After clinical and laboratory analyses, an aetiological diagnosis was established for 49 patients (52%). Toxoplasma gondii was the most important cause of uveitis (40/93; 43%). Anti-toxoplasma IgM antibodies were detected in serum samples of seven of 93 patients (8%) compared with one of 100 controls (1%, p < 0.05). At least six patients (15%) with ocular toxoplasmosis had acquired the disease postnatally. Antibodies against Treponema pallidum were detected in 18 of 92 patients (20%) and in 21 controls (21%). Other causes of uveitis were varicella zoster virus (one patient), herpes simplex virus (two patients), and HLA-B27 positive acute anterior uveitis with ankylosing spondylitis (one patient), while one patient had presumed HTLV-I uveitis. CONCLUSIONS: In a hospital population in Sierra Leone, west Africa, uveitis was associated with severe visual handicap and infectious diseases. Toxoplasmosis proved to be the most important cause of the uveitis. Although the distribution of congenital versus acquired toxoplasmosis in this population could not be determined, the results indicate an important role of postnatally acquired disease. The results further suggested minor roles for HIV, tuberculosis, toxocariasis, and sarcoidosis as causes of uveitis in this population.

Adolescent↗
PubMed2003

IFN-gamma-regulated Toxoplasma gondii distribution and load in the murine eye.

PURPOSE: To establish a mouse model of ocular toxoplasmosis in both wild type (WT) and immunocompromised hosts and to clarify the effects of interferon (IFN)-gamma on the infectivity of Toxoplasma gondii in various parts of the eye. METHODS: Susceptible WT C57BL/6, resistant WT BALB/c, and IFN-gamma knockout (GKO) mice were infected with cysts of T. gondii perorally. The tissues were harvested for molecular and histopathologic studies. Analysis included a quantitative competitive polymerase chain reaction (QC-PCR) assay and reverse transcription (RT)-PCR for IFN-gamma and stage conversion markers. All animals underwent ophthalmic examinations including fluorescein angiography (FA). RESULTS: In WT C57BL/6 mice, T. gondii was detected in tissue in the following order: brain, retina, choroid, sclera, and optic nerve (ON). The highest T. gondii load was observed in the posterior retina, and was much greater than that in WT BALB/c mice. In GKO mice, disseminated infection was evident, and the T. gondii load was highest in the choroid and ON. IFN-gamma mRNA expression in WT C57BL/6 mice was higher than that in WT BALB/c mice after infection. Tachyzoites existed in GKO mice, whereas bradyzoites existed in WT C57BL/6 mice. FA showed dye leakage from the retinal capillaries of GKO mice. CONCLUSIONS: The T. gondii load in the retina in the susceptible WT strain continued to increase, unlike in the resistant WT strain. IFN-gamma was shown to regulate the T. gondii load and interconversion in the eye. A toxoplasmic vasculitis model was established with GKO mice and assay systems with QC-PCR and FA.

Animals↗
PubMed2006

Recently acquired Toxoplasma gondii infection, Brazil.

The city of Erechim, Brazil, has a 17% prevalence of ocular toxoplasmosis, and type 1 Toxoplasma gondii predominates. To examine risk factors for acute T. gondii infection in this area, we administered a questionnaire to recently infected persons (n = 131) and seronegative controls (n = 110). Eating undercooked meat; having a garden; working in the garden or yard more than once per week; eating rare meat; eating cured, dried, or smoked meat; eating frozen lamb; and being male increased risk for T. gondii infection in univariate analysis. Risk factors independently associated with acute T. gondii infection in multivariate analysis were working in the garden (odds ratio [OR] 2.35, 95% confidence interval [CI] 1.27-4.33) and eating frozen lamb (OR 2.06, 95% CI 1.15-3.67). Among women (n = 86), having had children markedly increased the risk for T. gondii infection (OR 14.94, 95% CI 3.68-60.73).

Adolescent↗