Toxoplasmosis: A Zoonotic Disease

Toxoplasmosis

                While many illnesses are species specific, there are multiple diseases that can be shared between animals and people.  These are known as zoonotic diseases.  One such zoonotic disease is toxoplasmosis.

                Toxoplasmosis is a disease caused by a parasite known as Toxoplasma gondii.  Cats are the main hosts of toxoplasma, but most infected cats do not show any sign of illness.  The parasite is spread in cat feces.   People can be infected by accidental ingestion of toxoplasma cysts when cleaning litter pans, when gardening or working in soil contaminated with cat feces (i.e. not washing hands after gardening or eating unwashed foods from a garden) by drinking contaminated water or by eating contaminated meats such as pork, lamb, venison or shellfish.  It can also spread from a mother to her unborn baby in the uterus. 

As many as 40 million Americans are thought to be infected, though most are not ill.  Who is at risk and why do most people not get sick?  In a person with a healthy immune system, the body can prevent the parasite from becoming infected. However, anyone with immune compromise may be at risk for becoming ill and pregnant women, who become infected during or just before becoming pregnant, are at risk of passing toxoplasmosis to their unborn child if pregnant. 

Most infected persons do not develop any symptoms, but some people have flu-like symptoms that can last up to a month.  Immunocompromised individuals and unborn babies can develop more serious symptoms such as seizures, vision changes and damage to the brain, eyes and other organs.

Transmission can be prevented by thoroughly cooking meats and shellfish, washing produce and by avoiding cleaning the litter box when pregnant or if immune compromised.  If you are at risk but must clean a litter pan, wear gloves and wash hands thoroughly.  Cleaning the litter pan every day may also reduce infectivity as toxoplasma cysts become infective within 1-5 days of being shed.   You do NOT need to get rid of your pet cat if you are pregnant, just use precautions and avoid contact with cat feces.  Keep cats indoors (to reduce hunting) and avoid feeding raw diets to cats to reduce infection.

What about the cats?  How do they get this parasite and what does it do to them?  Toxoplasma eggs or oocysts are shed in cat feces.  Animals such as rodents and birds ingest the eggs which then form cysts in the muscle tissue.  If a cat eats an infected bird or mouse, the cysts go through several changes within the cat reproducing and continuing the life cycle.  Cysts are shed in feces for one to three weeks.  Cats typically show no sign of illness, though occasionally neurologic symptoms can occur. Active or symptomatic toxoplasmosis can be treated in cats and humans with a variety of drugs, though some patients have long term effects of the disease.

If you think your cat may be infected and showing symptoms, contact your vet. If you are pregnant and own cats, your doctor can perform blood tests to check for toxoplasmosis.

This blog brought to you by the Patton Veterinary Hospital serving Red Lion, York and the surrounding communities.

Sources:

https://www.cdc.gov/parasites/toxoplasmosis/gen_info/index.html

https://www.healthline.com/health/toxoplasmosis#prevention