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Blinded by Cat Feces

"Blinded by Cat Feces: The Hidden Dangers of Toxoplasmosis"

Cats, like all pets, are susceptible to various illnesses, including infections from Toxoplasma gondii, one of the most widespread parasites globally. Despite the long-standing awareness of this disease, many remain uninformed about its serious consequences.

Contrary to popular belief, anyone can contract toxoplasmosis. Most warm-blooded animals, including humans, can act as intermediate hosts, while cats and other members of the Felidae family are the definitive hosts.

An infected cat can shed millions of parasite eggs, or oocysts, through its feces. Humans can become infected in various ways: by consuming fruits or vegetables contaminated with oocysts, coming into direct contact with cat feces (e.g., during gardening), eating raw or undercooked meat, or using contaminated utensils or cutting boards that have touched raw meat. Additionally, the infection can be transmitted through organ or blood transfusions from individuals already infected with T. gondii (Figure 1).

Globally, between 25% and 30% of the population is infected with this parasite. However, most infected individuals may be unaware due to the mild, self-limiting symptoms, which include fever, fatigue, and lethargy. One severe complication of toxoplasmosis is ocular toxoplasmosis, which can affect key organs in the body, including the eyes.

Ocular toxoplasmosis, an infection of the retina and choroid (the eye's inner layer), is one of the leading causes of severe ocular inflammation. Depending on the affected area of the eye, symptoms can include painful, red, or watery eyes. In cases of active ocular toxoplasmosis, inflammation of the vitreous (the gel-like substance within the eye), known as vitritis, is the primary cause of visual disturbances such as floaters or blurred vision. If the infection affects the macular region (a highly sensitive area of the retina) or causes significant inflammation in the vitreous, the patient's vision can deteriorate (Figures 2 and 3).

In some cases, patients may not exhibit any symptoms and only discover the condition during a routine eye exam, at which point the infection may no longer be active.

Ocular toxoplasmosis is diagnosed based on clinical symptoms, so individuals experiencing any of these signs should consult an ophthalmologist immediately. The treating physician will perform a blood test to detect Toxoplasma antibodies (IgG and IgM) using the enzyme-linked immunosorbent assay (ELISA). Pregnant women in their first trimester are also advised to undergo the TORCHES test, which screens for infections like toxoplasma, rubella, cytomegalovirus (CMV) and herpes. These infections can lead to vision problems in the developing fetus if transmitted in utero.

Treatment typically involves a combination of antiparasitic medications, antibiotics, and steroids, prescribed for a period of three to twelve weeks. Immediate treatment is crucial to prevent irreversible damage, such as scarring of the macula or optic nerve damage, both of which can lead to blindness.

Preventive measures are vital to control the spread of the disease. These include thoroughly washing fruits and vegetables that are consumed raw, washing hands before handling food, and avoiding the consumption of raw or undercooked meat. For high-risk groups, especially cat owners, additional precautions include regular veterinary check-ups for pets, avoiding feeding raw meat to cats (particularly indoor cats), avoiding cat ownership during pregnancy, wearing gloves when handling cat litter, and washing hands with soap and water immediately after cleaning up after cats.