How toxoplasmosis affects the eyes

10/05/2021

Prevention is essential to healthcare; food hygiene and hand cleanliness are fundamental pillars to controlling infectious diseases

Us human beings are just like everyone else in our habitat. The hygiene improvements brought about by civilisation prevent diseases but they do not prevent the disease completely. One example is toxoplasmosis. It rings a bell with us because we protect pregnant women from it, however, we don't know much more about it. 

It is a disease caused by a protozoan (Toxoplasma gondii) that is found in the global atmosphere: more than 6 billion people are infected. The protozoan's life cycle occurs in the digestive tract of cats, which infect us by contaminating water and food with faeces. We catch it through undercooked meat and poorly washed fruit and vegetables. 

If the infection is acute, the majority of patients will remain asymptomatic, however, a small percentage present with symptoms similar to glandular fever: swollen lymph nodes, muscle pains, painful swallowing, fever, hiccups, etc., which are mild symptoms that go away themselves, but the germ remains stationed in the body (latent infection). And it will go on like this for most of our lives. 

Described below, the most serious forms of the disease are the congenital form and reactivations.

►Congenital toxoplasmosis: Happens to the new-borns of infected mothers, who present with the ocular and/or neurological form of the disease. Potential consequences are blindness, hydrocephalus, psychomotor retardation and epilepsy. 

►Toxoplasmic encephalitis: Happens in the congenital disease and reactivations in immunosuppressed patients (AIDS and others). 

►Toxoplasmic retinochoroiditis: They are small, white, localised retina lesions.  When the disease reactivates, it is accompanied by intense vitritis. The active lesions are usually associated with old scarring. Retinochoroiditis is treated with antibiotics and anti-inflammatory medicine (corticosteroids) by oral route and long-term (2 to 4 months). The lesions may cause serious visual effects if the retinochoroiditis affects the area of maximum vision (macular area): this happens more commonly in congenital toxoplasmosis, but it may develop into the acquired disease in adults. The risk that inflammation reappears (recurrence) is higher after the age of 40, and 5 years after the inflammation. 

• Prevention is essential to healthcare; food hygiene and hand cleanliness are fundamental pillars to controlling infectious diseases, and we should never tire of explaining them.

Dr. Ramón Rey, internal medecine