Toxoplasmosis Leading Cause of Death

TOXOPLASMA GONDII

 
Toxoplasmosis is considered to be a leading cause of death attributed to foodborne illness in the United States. More than 60 million men, women, and children in the U.S. carry the Toxoplasma parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness.
However, women newly infected with Toxoplasma during pregnancy and anyone with a compromised immune system should be aware that toxoplasmosis can have severe consequences.
Toxoplasmosis is considered one of the Neglected Parasitic Infections, a group of five parasitic diseases that have been targeted by CDC for public health action.

Causal Agent: Toxoplasma gondii is a protozoan parasite that infects most species of warm blooded animals, including humans, and can cause the disease toxoplasmosis. Life Cycle: The only known definitive hosts for Toxoplasma gondii are members of family Felidae (domestic cats and their relatives).  Unsporulated oocysts are shed in the cat’s feces .  Although oocysts are usually only shed for 1-2 weeks, large numbers may be shed.  Oocysts take 1-5 days to sporulate in the environment and become infective.  Intermediate hosts in nature (including birds and rodents) become infected after ingesting soil, water or plant material contaminated with oocysts .  Oocysts transform into tachyzoites shortly after ingestion.  These tachyzoites localize in neural and muscle tissue and develop into tissue cyst bradyzoites .  Cats become infected after consuming intermediate hosts harboring tissue cysts .  Cats may also become infected directly by ingestion of sporulated oocysts.  Animals bred for human consumption and wild game may also become infected with tissue cysts after ingestion of sporulated oocysts in the environment .  Humans can become infected by any of several routes: eating undercooked meat of animals harboring tissue cysts . consuming food or water contaminated with cat feces or by contaminated environmental samples (such as fecal-contaminated soil or changing the litter box of a pet cat) . blood transfusion or organ transplantation . transplacentally from mother to fetus . In the human host, the parasites form tissue cysts, most commonly in skeletal muscle, myocardium, brain, and eyes; these cysts may remain throughout the life of the host.  Diagnosis is usually achieved by serology, although tissue cysts may be observed in stained biopsy specimens .  Diagnosis of congenital infections can be achieved by detecting T. gondii DNA in amniotic fluid using molecular methods such as PCR . Geographic Distribution: Serologic prevalence data indicate that toxoplasmosis is one of the most common of humans infections throughout the world.  A high prevalence of infection in France has been related to a preference for eating raw or undercooked meat, while a high prevalence in Central America has been related to the frequency of stray cats in a climate favoring survival of oocysts and soil exposure.  The overall seroprevalence in the United States among adolescents and adults, as determined with specimens collected by the third National Health and Nutrition Examination Survey (NHANES III) between 1988 and 1994, was found to be 22.5%, with a seroprevalence among women of childbearing age (15 to 44 years) of 15%. Diagnosis A Toxoplasma-positive reaction, stained by immunofluroescence (IFA). (CDC Photo) The diagnosis of toxoplasmosis is typically made by serologic testing. A test that measures immunoglobulin G (IgG) is used to determine if a person has been infected. If it is necessary to try to estimate the time of infection, which is of particular importance for pregnant women, a test which measures immunoglobulin M (IgM) is also used along with other tests such as an avidity test. Diagnosis can be made by direct observation of the parasite in stained tissue sections, cerebrospinal fluid (CSF), or other biopsy material. These techniques are used less frequently because of the difficulty of obtaining these specimens. Parasites can also be isolated from blood or other body fluids (for example, CSF) but this process can be difficult and requires considerable time. Molecular techniques that can detect the parasite's DNA in the amniotic fluid can be useful in cases of possible mother-to-child (congenital) transmission. Ocular disease is diagnosed based on the appearance of the lesions in the eye, symptoms, course of disease, and often serologic testing. rest Prevention & Control People who are healthy should follow the guidelines below to reduce risk of toxoplasmosis. If you have a weakened immune system, please see guidelines for Immunocompromised Persons. Reduce Risk from Food To prevent risk of toxoplasmosis and other infections from food: Cook food to safe temperatures. A food thermometer should be used to measure the internal temperature of cooked meat. Do not sample meat until it is cooked. USDA recommends the following for meat preparation. For Whole Cuts of Meat (excluding poultry) Cook to at least 145° F (63° C) as measured with a food thermometer placed in the thickest part of the meat, then allow the meat to rest* for three minutes before carving or consuming. For Ground Meat (excluding poultry) Cook to at least 160° F (71° C); ground meats do not require a rest* time. For All Poultry (whole cuts and ground) Cook to at least 165° F (74° C), and for whole poultry allow the meat to rest* for three minutes before carving or consuming. *According to USDA, "A 'rest time' is the amount of time the product remains at the final temperature, after it has been removed from a grill, oven, or other heat source. During the three minutes after meat is removed from the heat source, its temperature remains constant or continues to rise, which destroys pathogens." More on: Fight BAC: Safe Food Handling Freeze meat for several days at sub-zero (0° F) temperatures before cooking to greatly reduce chance of infection. Peel or wash fruits and vegetables thoroughly before eating. Wash counter tops carefully. Photo courtesy of USDA. Wash cutting boards, dishes, counters, utensils, and hands with hot soapy water after contact with raw meat, poultry, seafood, or unwashed fruits or vegetables. More on: Handwashing The U.S. Government and the meat industry continue their efforts to reduce T. gondii in meat. Reduce Risk from the Environment To prevent risk of toxoplasmosis from the environment: Avoid drinking untreated drinking water. Wear gloves when gardening and during any contact with soil or sand because it might be contaminated with cat feces that contain Toxoplasma. Wash hands with soap and warm water after gardening or contact with soil or sand. Teach children the importance of washing hands to prevent infection. Keep outdoor sandboxes covered. Have someone else clean the litter box. (CDC Photo) Feed cats only canned or dried commercial food or well-cooked table food, not raw or undercooked meats. Change the litter box daily if you own a cat. The Toxoplasma parasite does not become infectious until 1 to 5 days after it is shed in a cat's feces. If you are pregnant or immunocompromised: Avoid changing cat litter if possible. If no one else can perform the task, wear disposable gloves and wash your hands with soap and warm water afterwards. Keep cats indoors. Do not adopt or handle stray cats, especially kittens. Do not get a new cat while you are pregnant by :hayu