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It is possible that the main title of the report Toxoplasmosis is not the name you expected.

Disorder Subdivisions

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General Discussion

Toxoplasmosis is an infectious disease that can be caused by contact with a microscopic parasitic organism called Toxoplasma gondii. This parasitic infection, found worldwide, can either be acquired or be present at birth (congenital). The congenital type is a result of a maternal infection during pregnancy that is transmitted to the fetus and involves lesions of the central nervous system. These lesions may lead to blindness, brain defects and more serious conditions. The disorder may be most severe when it is transmitted to the fetus during the second through sixth month of pregnancy.

Millions of people are infected with the Toxoplasma parasite, but very few exhibit symptoms because a healthy person's immune system usually keeps the parasite from causing illness. For people with a compromised immune system, such as those with HIV-AIDs, toxoplasmosis can be a serious disorder.

The most common ways in which the acquired form is spread include cleaning a cat's litter box, eating contaminated meat that is raw or under-cooked, and drinking contaminated water.


Symptoms of toxoplasmosis may be severe, rapidly appearing, or there may be no symptoms at all.

The more common mild form, which may resemble infectious mononucleosis, is characterized by a disease of the lymph nodes in the neck and armpit area (cervical and axillary lymphadenopathy), a vague feeling of discomfort (malaise), muscle pain and irregular low fever. Mild anemia, hypotension, reduction of total white blood cells (leukopenia), elevation of lymphoid white blood cell count (lymphocytosis), and slightly altered liver function may also occur. More commonly, it is a neck area lymph node disorder involving no other obvious symptoms (asymptomatic cervical lymphadenopathy).

In some cases, the disorder may be an acute, suddenly occurring, disseminated infection that affects primarily those people who seem to have a reduced ability to fight infection. This is usually characterized with a rash, high fever, chills, and prostration. Some patients may develop inflammation of the lungs (pneumonitis), liver (hepatitis), muscular walls of the heart (myocarditis), and possibly inflammation of the brain and possibly meninges (meningoencephalitis).

Chronic toxoplasmosis, which causes severe inner eye inflammation (retinochoroiditis or posterior uveitis), may be marked by muscular weakness, weight loss, headache, and diarrhea. Symptoms are usually vague and indefinite making proper diagnosis difficult.

In some cases of toxoplasmosis, confusion and headaches may be the primary symptoms.

In the neonatal congenital type of toxoplasmosis, features can be variable. Spontaneous abortion (miscarriage) may ensue if the infection occurs early in pregnancy. Infection later in pregnancy may result in miscarriage or stillbirth, or in the birth of a living child with the disease.

Symptoms of subacute toxoplasmosis infection may begin shortly after birth, but more often appear months or several years later. Central nervous system (CNS) disorders such as hydrocephalus, microcephaly, intracranial calcifications, and mental retardation may occur. Skin rashes, enlargement of the liver and spleen (hepatosplenomegaly), jaundice and inflammation of the choroid and retina of the eye (chorioretinitis) may also be present.

Inflammation of the choroid and retina (chorioretinitis) usually accompanies the congenital form and may occur in the acquired forms. Chronic disease with relapses can continue to occur in patients who survive the subacute phase. Abdominal organ (visceral) lesions, aside from those in the liver, are unusual and tend to heal more readily than the central nervous systems lesions.


Toxoplasmosis is an infectious disease which may be either congenital or acquired. Several modes of transmission may occur and must be guarded against. These include a parasite carried by birds and certain mammals, notably cats, cattle, swine, sheep, rabbits, and dogs. The disorder may also be transmitted by consumption of under-cooked meat containing the parasitic organisms (cysts), or by contact with cat feces containing the encapsulated organisms (oocysts). Care must be taken when cleaning the litter boxes of infected cats as inadvertent hand-to-mouth contact with the parasite may occur. There is also evidence that the infection can be acquired through inhalation of the dust arising when cleaning the litter. However, with proper hygienic precautions, infection is very unlikely. Flies and/or cockroaches may possibly transport the oocysts to human food. In a human host, the infection may possibly represent a reactivation of the latent disease.

The congenital type of toxoplasmosis is due to the infection being contracted during pregnancy and passed on to the fetus. In particular, contact with cats and cat feces during pregnancy must be avoided in particular to control this occurrence.

Affected Populations

Toxoplasmosis affects men and women in equal numbers world wide. The occurrence rate in infants is 0.25 - 5.0 per 100,000 live births. This disorder also may cause many abortions and stillbirths in areas of the world where the disorder may be more prevalent.

Approximately 40% of children with toxoplasmosis become infected in the womb because of maternal infection during pregnancy. Of these children, 15% have severe symptoms and 19% have mild symptoms. Fetal damage is most likely when the infection occurs during the second to the sixth month of gestation. The majority of children born with toxoplasmosis have no symptoms at birth, but show evidence of damage several months to years later. The most common abnormalities are eye disease and low I.Q. The estimated frequency of toxoplasmosis during pregnancy is 1.1 cases per 1,000 pregnant women. However, maternal toxoplasmosis acquired a month or longer before the pregnancy is rarely transmitted to the fetus.

Standard Therapies


The blood of persons suspected of being infected with the toxoplasmosis parasite is tested for the presence of toxoplasmosis antigen. In some cases, the blood test may need to be repeated.


When toxoplasmosis is diagnosed in a healthy person who is not pregnant, treatment may not be needed. For pregnant women and people whose immune systems are compromised, medications are available

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:



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