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Medicine and Health

Toxoplasma Gondii

Infection and Organism

Toxoplasma gondii is a parasite that lives dormant in as many as 60 million Americans as well as household pets and is one of the most significant contributors to foodborne illness (Centers for Disease Control). Toxoplasmosis may be caused by the consumption of raw meats, blood transfusions, organ transplantation, and the poor handling of cat litter which has been infected with these parasites (PubMed Health). This parasite was discovered back in 1908 and many people who are carriers are never actually infected with Toxoplasmosis, although the parasite may lay dormant for many years (Hokelek). However, when the disease develops, it presents with much danger, particularly for pregnant women and those persons who have compromised immune systems a as a result of HIV infection (Centers for Disease Control). Therefore, if symptoms are prevalent, diagnosis must be determined and treatment must begin as quickly as possible to improve the chance of recovery for these patients in an effective manner (Centers for Disease Control).

Pathogenesis

Toxoplasma gondii is characterized by two distinct life cycles: 1) sexual in cats; and 2) asexual in other types of mammals (Hokelek). Tachyzoites are formed during the acute stage, with bradyzoites at the cyst formation stage and cats are infected with the parasite through the consumption of raw meat or mice, where the reproduction cycle begins (Hokelek). Sporozoites are released into fecal matter and are infectious for up to one year in environments where humidity is evident (Hokelek). The parasite’s ability to attach to its hosts is characterized by the attachment of a vacuole to the plasma membrane; however, the host cell does not appear to undergo any real physical changes during the parasite attachment process (Hokelek). When tissue cysts form in host organisms, they are evident throughout the lifespan of the organism and may not create any type of inflammatory response in these hosts; rather, they may lie dormant for extended periods of time without leading to additional infection within this population group (Hokelek).

Transmission

Domestic cats often serve as parasite hosts and their fecal matter carries the parasitic cells through the environment, which may be picked up by humans during the handling of infected cat litter in the home (Centers for Disease Control). Furthermore, other warm blooded animals carry the toxin, and parasitic cysts are found in the tissue cells of infected animals that are then consumed as meat by humans when said meat is not cooked properly at the appropriate temperatures (Centers for Disease Control). Other forms of transmission include blood transfusions and from mother to fetus through the placenta (Centers for Disease Control). Under these conditions, the parasite invades human tissue and forms cysts in such areas as the brain, skeletal muscle, and eyes (Centers for Disease Control). Upon invasion of these tissues and subsequent cyst formation, tissues may be altered and subsequent complications begin to arise, including the potential for severe symptoms and potential organ and tissue damage (Centers for Disease Control).

Treatment

Those patients who are carriers of the parasite and do not have any symptoms of the condition do not require any form of treatment, especially if they are healthy to begin with (PubMed Health). For those who require treatment due to various symptoms, typical methods include antibiotic therapies and anti-malarial drugs to ensure that the infection is reduced and continued symptoms and permanent damage are minimized (PubMed Health). Common drugs that are prescribed include sulfadiazine and pyrimethamine (Centers for Disease Control). For women who are pregnant, treatment may be effective but is not likely to completely eradicate the parasite because it may be present in a dormant phase (Centers for Disease Control).Finally, for those patients who are immunocompromised due to HIV/AIDS or another condition, it may be necessary to administer prescription drug therapy for a lengthy period of time (Centers for Disease Control).

For patients who enter the emergency room for evaluation and treatment, it is necessary to identify symptoms and to determine the plan of care that is required (Hokelek). If the patient has any type of airway obstruction, this must be cleared as quickly as possible, and circulation problems must also be addressed (Hokelek). During the evaluation phase, patients must also undergo neuroimaging as necessary to determine if there are any neurological concerns, such as altered state of memory or headaches (Hokelek). Patients must be evaluated from a comprehensive point of view, including all possible differential diagnoses, in order to determine if the diagnosis of Toxoplasmosis is appropriate, since its symptoms vary and may mimic the symptoms associated with other conditions (Hokelek). These circumstances provide additional evidence that Toxoplasmosis may be difficult to diagnose solely based on symptoms and that other factors must be considered in order to determine a definitive diagnosis, such as the proper testing mechanisms and blood sampling techniques (Hokelek). These efforts are critical to determine an accurate diagnosis and treatment plan for any patient that is diagnosed with Toxoplasmosis to ensure that all other concerns are also identified that could compromise treatment and recovery in different ways, such as pregnancy and HIV infection for some patients (Hokelek).

Prevention

In order to prevent Toxoplasma gondii, it is necessary to reduce any possible spread of parasitic contamination by cooking all meats thoroughly at the recommended temperatures and to freeze meat as required (Centers for Disease Control). Handwashing before and after handling meat products is also critical, and if a cat is in the home, the litter box should be cleaned daily to prevent the possible spread of contaminant parasites (Centers for Disease Control). Finally, when working with soil and in gardens, use gloves to reduce possible contamination through soil (Centers for Disease Control). For a specific patient population who receive transplants, Toxoplasmosis is of primary concern in the following manner: “Among organ transplant recipients, toxoplasmosis is most commonly seen in heart recipients. Thus, the serostatus of all heart donors and recipients should be checked prior to transplantation. Cardiac transplant patients who have detectable anti-Toxoplasma IgG or who are recipients of hearts from seropositive donors should receive prophylaxis” (BMJ Group). Therefore, it is necessary to develop a strategic prevention approach that will include testing for this population group and will consider the challenges of balancing the risks of Toxoplasmosis during transplantation with the benefits of this practice to achieve greater patient outcomes (BMJ Group). Furthermore, patients with HIV should be screened for this condition because of their immunocompromised systems; however, for patients who are taking antiretroviral therapies, there is a reduced risk of serious complications as a result of Toxoplasmosis for this group because their level of immunity is under control (BMJ Group).

Regardless of the circumstances involving suspected cases of Toxoplasmosis, it is important to make all possible efforts to prevent this condition as best as possible because it may lead to severe complications over a relatively brief period of time. Successful prevention strategies will enable possible carriers of the T. gondii parasite to prevent disease formation. It is important to recognize the benefits of regular hand washing and other hygiene practices in preventing the incidence of Toxoplasmosis so that those persons who face the greatest risk of exposure and activation are not affected. The chosen strategy must evolve through the utilization of expanded knowledge and information regarding this condition to reduce the number of cases that are identified within specific communities. From a clinical perspective, it is important to recognize these limitations and to employ a variety of medical techniques that will be effective in supporting those population groups at the highest risk of infection for Toxoplasmosis, particularly pregnant women and HIV patients or others who have compromised immune systems and experience difficulties when fighting different types of infections.

Laboratory Procedures/Testing

Typically, blood testing will determine if T gondii parasites are present in the bloodstream and require further evaluation and possible treatment (Hokelek). In addition, the polymerase chain reaction assay is typically performed as a common testing practice that is used to determine diagnosis through the evaluation of cerebrospinal fluid, amniotic fluid, blood, and bronchoalveolar fluid to determine if these parasites are present in different numbers (Hokelek). In this instance, it is important to perform the appropriate procedures that will identify if these parasites are evident, such as brain biopsy, lumbar puncture, bronchoalveolar lavage, and amniocentesis in pregnant patients who may present with the disease (Hokelek). Furthermore, “Ocular disease is diagnosed based on the appearance of the lesions in the eye, symptoms, course of disease, and often serologic testing” (Centers for Disease Control).  Each of these tests and tools, as appropriate, are likely indicators of Toxoplasmosis in patients and therefore, indicate whether or not treatment is required for the patient in question (Centers for Disease Control). These diagnostic tools establish a framework for the creation of new ideas and approaches using modern techniques to better manage the treatment phase of Toxoplasmosis and the prevention of long term organ or tissue damage, such as ocular damage that may cause blindness or other serious eye problems for patients who do not seek treatment in an effective manner (Centers for Disease Control).

Conclusion

Toxoplasmosis is a complex condition that is caused by the development of tissue cysts associated with Toxoplasma gondii, a unique parasite that is found in many warm blooded mammals and is carried through uncooked meat or through feline fecal matter, as well as through the handling of some farm animals. With these examples in mind, the risk to human beings may be very high, even if symptoms do not always appear to be present in an immediate fashion. From a clinical point of view, it is necessary to understand the pathogenesis of this condition, the parasitic organisms which cause it, how it invades host cells and forms tissue cysts, whether or not symptoms are present in these cases, and how the condition is diagnosed and treated to reduce additional risks to this patient population. For some population groups, such as pregnant women and HIV patients, there is a higher risk with a diagnosis of Toxoplasmosis because of the sensitivity of these conditions; therefore, it is important to seek medical treatment as quickly as possible. The risk of this condition if left untreated are significant; as a result, if the disease is suspected, diagnostic tools must be used effectively to determine the severity of the condition and if any other concerns are evident that require immediate attention.

Photographs

From Hokelek

http://emedicine.medscape.com/article/229969-overview

From Centers for Disease Control

http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Toxoplasmosis_il.htm

From Centers for Disease Control

http://www.cdc.gov/parasites/toxoplasmosis/

From Centers for Disease Control

http://www.cdc.gov/parasites/toxoplasmosis/biology.html

 

Works Cited

BMJ Group. “Best Practice: Toxoplasmosis.” 16 April 2013:

http://bestpractice.bmj.com/best-practice/monograph/557/prevention/screening.html

Centers for Disease Control. “Parasites – Toxoplasmosis (Toxoplasma infection). 16 April                     2013: http://www.cdc.gov/parasites/toxoplasmosis/

http://www.cdc.gov/parasites/toxoplasmosis/biology.html

Centers for Disease Control. “Toxoplasmosis.” 16 April 2013:

http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Toxoplasmosis_il.htm

Hokelek, Murat. “Toxoplasmosis: background.” 16 April 2013:

http://emedicine.medscape.com/article/229969-overview

PubMed Health. “Toxoplasmosis.” 16 April 2013:

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001661/