Ocular Toxoplasmosis

Ocular Toxoplasmosis is an illness produced by the parasite Toxoplasma gondii and constitutes the most frequent cause of posterior uveitis that then evolves into inflammation of the uvea or half crown of the eyeball, charged with sending blood to the retina or internal membrane of the eye, along with other functions.

Normally in terms of the eye, it produces a severe swelling of the retina and the posterior uvea or choroid membrane, known as retino coroiditis. The interviewee on this occasion is Doctor Eddy Mesa Hernández, specialist in ophthalmology and director of Uveitis Service and Eye Inflammations at the Cuban “Ramon Pando Ferrer” Institute of Ophthalmology.

What is the natural habitat of the toxoplasmosis parasite?

Felines, including the domestic cat, are the mains ones. Also humans and other hot bloodied animals, like birds and mammals, are their intermediary hosts. It is a very frequent parasitosis and giving its large global spreading it is being studied by researchers in internal medicine, pediatrics, obstetrics, infectologos and others.

And the main means of transmission?

They are numerous. Transmission from the mother to the foetus (through the placenta) has been the most accepted and it’s become known that the majority of patients with ocular toxoplasmosis contract it in this way. However, it is also contracted orally by the digestion of parasites cysts continued in products such as vegetables, fruits, drinking water and raw or undercooked meat from an infected animal is today accepted as the main means of transmissibility.

Does it affect people of different ages in the same way?

Yes, and it doesn’t discriminate between sex, race or social stratum. To clarify: approximately 80% of the episodes of ocular toxoplasmosis occur in patients between the ages of 15 and 45.

What signs or symptoms in general can make us think we have been infected by this parasite?

I would initially say that infection by the parasite Toxoplasma gondii  isn’t synonymous with illness, which is normally sent asymptomatic or with symptoms that are light, benign, of a short duration and in rare occasions threatens other organs in the patients with normal defense systems.

An acute phase of this suffering could manifest itself by swelling of the nodes in the cervical region, fever and decay (asthemia).

Now well, in the immunodeficiency and sickness of AIDS the manner of this ailment is different. It could be more serious, and until fatal owing to the rise in affectations in various organs, among them brain.

Could I ask you to define ocular toxoplasmosis for us, as it is the theme of our column?

It can be congenital and appear from birth, or appear later, with a stronger frequency between the ages of 10 and 20; or if acquired then presents itself at any point of life.

As it manifests, in small children it dominates the strabismus, leukococoria or white pupil and nystagmus (spontaneous eye movements). In older children, adolescents and adults the most common symptoms are turbity of visual intensity or loss of central vision. In some occasions the affectation doesn’t give any symptoms are usually diagnosed during routine check ups.

What tests are required to establish a correct diagnosis?

It is eminently clinical

What treatments are used? How long do they last on average?

In therapeutics they use a combination of medication. In patients with an adequate immune state, it lasts one or two months. In patients with immunesuppression or with AIDS medical therapy can be prolonged for a number of months to obtain the best results.

What’s the most feared complication?

The loss of central vision caused by affectation of the macula, regrettably frequent due to the predilection of the parasite in this part of the retina. Also the appearance of cataracts, opacity in the vitreous and detachment of the retina.

Is it possible to prevent?

The appropriate removal of pet cat faeces is one of ways to control the spread of protozoan. Other means are cooking meat adequately and making sure foods that we eat raw are washed properly.

(Translated by Nykhil Emanuel-Stanford)