impaginato piccolo - Società Italiana di Parassitologia (SoIPa)

Parassitologia 50: 35-36, 2008
Ocular impaiment of toxoplasmosis
E. Antoniazzi, R. Guagliano, V. Meroni, S. Pezzotta, P.E. Bianchi
Clinica Oculistica-Università di Pavia-Fondazione I.R.C.C.S. Policlinico S. Matteo; Clinica di Malattie Infettive- Università di
Pavia- Fondazione I.R.C.C.S. Policlinico S. Matteo.
Introduction
Toxoplasmosis in humans may be conveniently considered
under four general headings:
(i) acquired
(ii) congenital
(iii) toxoplasmosis in immunocompromised host
(iv) ocular (Ryan)
Ocular toxoplasmosis in one of the most common types
of infectious uveitis affecting the posterior pole worldwide.
The infection is prevalent throughut the world,
affecting a large proportion of young adults, who usually
have no symptoms.
For many years ocular toxoplasmosis was thought to be
a local reactivation in the eye of a systemic congenital
infection.
Contents
Abstract. The purpose of this review is to update the latest information about ocular toxoplasmosis. The
infection can be congenital or acquired, but also depends about the immune condition of the patient and
can affect the eye. Ocular symptoms are variable according to the age of the subject. Retinochoroiditis is
the most common manifestation of toxoplasmic infection. Toxoplasmic retinochoroiditis typically affects the
posterior pole, and the lesions can be solitary or multiple. Active lesions present as grey-white focus of retinal
necrosis with adjacent choroiditis, vasculitis, hemorrhage and vitreitis. Anterior uveitis is a common finding.
Atypical presentations include punctate outer retinitis, neuroretinitis and papillitis. Depending on the
patient’s age and the localization of the lesion, ocular symptoms vary usually presenting with reduced visual
acuity or without symptoms.
The laboratory diagnosis of toxoplasmosis is based on detection of antibodies and T. gondii DNA using
polymerase chain reaction (PCR) which fulfillis clinical findings.
Toxoplasmosis therapy includes antimicrobial drugs and corticosteroids. There are several regimens with
different drug combinations including, among others, pyrimethamine, sulfadiazine, clindamycin, and trimethoprim-sulfamethoxazol.
Acquired toxoplasmosis
Acquired toxoplasmosis is generally a subclinical and
asintomatic infection; only in 10-20% the acute infection
is syntomatic. Clinically these patients have fever,
lynphoadenopathy, myalgias, maculopapular skin rush
and less often epatosplenomegaly and linfocitosis. In
the immunocompetent host the desease is self-limited
and benign. However in immunocompromised host
(e.g. AIDS) a life-treatening encephalitis, pneumonitis
or myocarditis may develop.
Actually is not clear if the acquired infection is only a
reactivation of congenital disease or a new first infection.
Correspondence: Dr. Elena Antoniazzi
Clinica Oculistica-Università di Pavia-Fondazione I.R.C.C.S.
Policlinico S. Matteo,
Tel +39 0382 503732,
e-mail: e.antoniazzi@smatteo.pv.it
Literature explain that toxoplasmic chorioretinitis is a
postnatally acquired disease but clinical presentation is
quite different from a congenital infection.
Usually the acquired form has the first manifestation
in the 2 nd -4 th decade with or without symptoms and
signs. Acquired ocular toxoplasmosis may present with
primary ocular lesions in the absence of an old scar.
Atypical clinical presentation has to be expected in
elder individuals or in the context of immunosuppression
and immune defects.
Anyway laboratory means is necessary to do a differential
diagnosis.
Congenital toxoplasmosis
Congenital toxoplasmosis results from transplacental
transmission of Toxoplasma gondii infection. The
prevalence is very different between countries.
Cronic maternal infection is not associated with congenital
disease; only maternal infection acquired before
or during gestation endangers the foetus.
The incidence and the severity of congenital infection
vary with the time of infection (incidence in 1 st
trimester: 15-20%; incidence in 3 rd trimester: 40%).
Most patients (80%) who has contracted the infection
develop evidence of ocular disease in adolescence, with
bilateral manifestation. When the manifestation is
bilateral visual acuity is heavily compromised.
Clinical manifestation of ocular toxoplasmosis are:
retinocoroiditis, hydrocephalus, mycrocephaly, cerebral
calcifications, seizures and psychomotor retardation,
organomegaly, rush, fever.
Bilateral retinochoroiditis is the most frequent manifestation,
presenting in 80% of cases.
The most common finding are chorioretinal scars in the
peripheral retina instead of the acute lesions which are
predominantly in the posterior pole of the eye. The congenital
form tends to be a bilateral disease with multiple
satellite lesions located particularly in the macula.