Toxoplasma gondii is a microscopic parasite that can infect humans and animals. It causes a disease called toxoplasmosis, which can range from mild to severe depending on the host’s immune system and the stage of infection. In this article, we will explain what toxoplasma and toxoplasmosis are, how they are transmitted, what are the symptoms and complications, how they are diagnosed and treated, and how they can be prevented.
What is Toxoplasma?
Toxoplasma gondii is a single-celled organism that belongs to the phylum Apicomplexa, which includes other parasites such as malaria and cryptosporidium. Toxoplasma has a complex life cycle that involves two types of hosts: definitive hosts and intermediate hosts. Definitive hosts are cats and other members of the cat family (felids), which can shed the parasite in their feces. Intermediate hosts are any warm-blooded animals, including humans, which can become infected by ingesting the parasite from contaminated sources or by transplacental transmission from mother to fetus. Toxoplasma can exist in three forms: tachyzoites, bradyzoites, and oocysts. Tachyzoites are the rapidly dividing form that can invade any cell in the body and cause acute infection. Bradyzoites are the dormant form that can form cysts in the tissues, especially in the brain, muscles, and eyes, and cause chronic infection. Oocysts are the environmentally resistant form that can survive for months in soil or water and infect new hosts.
What is Toxoplasmosis?
Toxoplasmosis is the disease caused by Toxoplasma gondii infection. It can affect humans and animals worldwide, but the prevalence varies depending on the geographic region, climate, culture, and animal husbandry practices. According to the Centers for Disease Control and Prevention (CDC), more than 40 million people in the United States may have been infected with Toxoplasma. However, most people do not develop any symptoms or have mild flu-like symptoms that go away on their own. This is because the immune system usually keeps the parasite under control and prevents it from causing serious damage. However, some people may have more severe or life-threatening complications from toxoplasmosis, such as:
- Congenital toxoplasmosis: This occurs when a pregnant woman gets infected with Toxoplasma for the first time during pregnancy and passes it to her unborn baby. This can result in miscarriage, stillbirth, or birth defects such as hydrocephalus (excess fluid in the brain), eye infections, brain abnormalities, or developmental delays. The risk of congenital toxoplasmosis depends on the timing of infection during pregnancy, with the first trimester being the most dangerous.
- Ocular toxoplasmosis: This occurs when Toxoplasma infects the tissues of the eye, causing inflammation, pain, blurred vision, floaters (specks that seem to swim in your vision), or even blindness. This can happen in people with healthy or weakened immune systems, but it is more common in people who were infected as children or who have chronic infections.
- Cerebral toxoplasmosis: This occurs when Toxoplasma infects the brain, causing encephalitis (brain inflammation), which can lead to confusion, poor coordination, muscle weakness, seizures, coma, or death. This is more likely to happen in people with weakened immune systems, such as those with HIV/AIDS, cancer, organ transplantation, or immunosuppressive drugs.
- Other organ involvement: Toxoplasmosis can also affect other organs such as the lungs (pneumonia), heart (myocarditis), liver (hepatitis), or spleen (splenomegaly). These manifestations are rare and usually occur in people with severe immunodeficiency.
How is Toxoplasma Transmitted?
There are four main ways that humans can get infected with Toxoplasma:
- Eating undercooked or raw meat that contains Toxoplasma cysts. This is especially common with pork, lamb, venison, or wild game meat.
- Accidentally swallowing Toxoplasma oocysts from cat feces. This can happen by touching your mouth after handling cat litter or soil contaminated with cat feces, or by drinking water or eating food that has been contaminated with cat feces.
- Getting a blood transfusion or organ transplant from an infected donor. This is very rare because blood donors and organ donors are screened for Toxoplasma infection.
- Getting infected by your mother during pregnancy. This can happen if your mother gets infected with Toxoplasma for the first time during pregnancy or if she has a reactivation of a chronic infection.
How is Toxoplasmosis Diagnosed and Treated?
Toxoplasmosis is diagnosed by testing your blood for antibodies (proteins that your immune system makes to fight the parasite) or by testing your body fluids or tissues for the parasite itself. Depending on your symptoms and risk factors, your doctor may also order other tests such as an eye exam, a brain scan, or an amniocentesis (a procedure that collects fluid from the sac around the baby) to check for signs of infection or damage.
Toxoplasmosis is treated with a combination of antibiotics and antiparasitic drugs that kill the parasite and prevent it from multiplying. The duration and type of treatment depend on your age, health status, and severity of infection. For example:
- Most healthy adults and children who have mild or no symptoms do not need treatment, as their immune systems can clear the infection on their own.
- Pregnant women who have been infected with Toxoplasma for the first time during pregnancy need treatment to prevent or reduce the risk of passing the infection to their baby. They may also need regular ultrasounds and blood tests to monitor the health of their baby.
- Newborn babies who have congenital toxoplasmosis need treatment for at least one year to prevent or treat the complications of the infection. They may also need long-term follow-up to check for any developmental problems or vision loss.
- People who have ocular toxoplasmosis need treatment to reduce the inflammation and prevent further damage to their eyes. They may also need eye drops or surgery to repair their vision.
- People who have cerebral toxoplasmosis or other organ involvement need treatment to control the infection and prevent further complications. They may also need other medications to support their immune system or treat their underlying condition.
How Can Toxoplasmosis Be Prevented?
There are several steps you can take to prevent toxoplasmosis or reduce its impact on your health²:
- Cook meat thoroughly to an internal temperature of at least 160°F (71°C) and use a meat thermometer to check. Avoid eating raw or undercooked meat, especially pork, lamb, venison, or wild game meat.
- Wash your hands with soap and water before and after handling raw meat, cat litter, soil, or gardening tools. Wear gloves when gardening or cleaning cat litter boxes. Do not touch your mouth, eyes, or nose until you wash your hands.
- Wash fruits and vegetables thoroughly before eating them. Peel or cook them if possible. Avoid drinking untreated water from wells, streams, or lakes that may be contaminated with cat feces.
- Keep cats indoors and feed them only dry or canned cat food. Do not feed them raw meat or let them hunt rodents or birds. Change cat litter boxes daily and dispose of the litter in a sealed bag. If you are pregnant or have a weakened immune system, ask someone else to change the litter box for you.
- If you are pregnant, get tested for Toxoplasma infection before or during pregnancy. If you are infected, follow your doctor’s advice on treatment and monitoring. Avoid getting a new cat or handling stray cats during pregnancy.
- If you have a weakened immune system, get tested for Toxoplasma infection regularly. If you are infected, follow your doctor’s advice on treatment and prevention. Avoid activities that may expose you to Toxoplasma, such as gardening, cleaning cat litter boxes, or eating raw meat.
Toxoplasma gondii is a common parasite that can infect humans and animals. It causes toxoplasmosis, which can range from mild to severe depending on the host’s immune system and the stage of infection. Toxoplasmosis can be transmitted by eating undercooked meat, swallowing cat feces, getting a blood transfusion or organ transplant, or getting infected from your mother during pregnancy. Toxoplasmosis can be diagnosed by testing your blood, body fluids, or tissues for antibodies or parasites. It can be treated with antibiotics and antiparasitic drugs that kill the parasite and prevent it from multiplying. Toxoplasmosis can be prevented by cooking meat thoroughly, washing hands and food properly, keeping cats indoors and feeding them only cat food, getting tested for Toxoplasma infection if you are pregnant or have a weakened immune system, and avoiding activities that may expose you to Toxoplasma.
We hope this article has helped you understand what toxoplasma and toxoplasmosis are, how they are transmitted, what are the symptoms and complications, how they are diagnosed and treated, and how they can be prevented.