Parasitic Eye Infection

Parasitic eye infection is something that has affected nearly half of the U.S. population. Its effects are not always severe, but with the right conditions it can have serious ramifications, like causing blindness. A full understanding of where the infection originates from, how it spreads and how to treat it can avoid any unnecessary complications.

Basics

• Parasitic eye infection, or ocular toxoplasmosis, is classified as a mild to severe infection of the eye and the adnexa surrounding it. The parasite itself is a larva or adult, protozoan or metaozoan, intracellular, obligate parasite that causes zoonotic infection in humans and most mammals. Having affected a quarter to half of the population of the U.S., and more around the world, ocular toxoplasmosis is most prevalent in hot, humid climates.

Causes

• The most frequent host and cause of the infection in humans is the cat. If a cat eats raw meat, birds or mice, it can be infected with the trachyzoites, bradyzoites and sporozoites that make up the disease. The infection spreads to humans through a cat's feces, which contain oocysts that undergo sporulation and, if ingested by humans, results in acute infection. Other causes of infection include a human eating raw, uncooked meat themselves or having a problem with the immune system, like AIDs. Finally, infection can occur congenitally if the mother acquires the infection prior to or during the gestation period.

Infection

• Once the tachyzoites enter the body, they enter the cell, become vacuolated and reproduce. Then they enter the blood stream until they reach the eye, where the tachyzoites convert themselves to bradyzoites. The infection manifests itself as a cyst, which is resistant to the immune system. If the cyst ruptures, the substance it produced restarts the inflammatory process all over.

Symptoms

• In immunocompetent hosts, the infection is mild, resulting in slight pain and blurred vision, perhaps with a greater frequency of spots in the eye. However, in an immunocompromised host the infection can produce severe necrotizing retinities. If the parasite continues to multiply and expands into the retina, destroying the tissue within, blindness can result.

Cures

• A number of drugs are available to combat ocular toxoplasmosis. Pyrimethamine mixed with sulfadiazine inhibits the survival of the toxoplasmosis, as does the use of clindamycin with sulfadiozine. After the antibiotic therapy, oral steroids can be used to combat the infection. Always consult a doctor about what treatment path to take.