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Tapeworm Research Paper

Cysticercosis is a disease caused by ingestion of the eggs of Taenia solium. Neurocysticercosis occurs when the tapeworm parasite infests the central nervous system (CNS). This infection is becoming increasingly common in places such as, Latin America, Central America, and Southeast Asia. Immigration has increased the area of infection and stopped the confinement to certain geographical areas. These infections occur via fecal-oral route and can come from fresh produce. Most of the infections can be stopped by proper hygiene practices, which is why many of the infections occur in developing countries.

Sometimes the tapeworm will leave the body without help from any medication, but treatment may be necessary in certain instances. History The earliest recorded instances of Taenia solium is in the History of Animals written by Aristotle around 350 BC. (Singh & Prabhakar, 2002) Its description was of ”measled pork” showing their knowledge of the pork tapeworm. Historical studies on this parasite show its roots stemming from antelopes and bovids. (Hoberg, Alkire, Queiroz, & Jones, 2001) It is believed that humans scavenged and preyed on these animals and spread the infection to domestic pigs with their own bodies.

An interesting fact about Jewish culture is that they were instructed by God to not eat pork due to its uncleanliness, one of the reasons to not eat pork could be due to this pork parasite. Cysticercosis was first described by Johannes Udalric Rumier in the mid 16th century. (Cox, 2002) He did not make the connection between a tapeworm parasite and the infection. Later, Friedrich Kuchenmeister made the connection, in the mid 19th century, by feeding pork infested with cysticerci to prisoners who were going to be executed. He recovered the bodies after their execution and discovered tapeworms in the intestinal tract.

A distinct connection between the tapeworms and the cysticercosis had been made. Disesase Neurocysticercosis specifically refers to the infection of the CNS and may be the most common infection of the CNS. This disease is caused by the ingestion of the eggs of Taenia solium. The eggs first enter the body orally and develop into larvae in the intestines. Once development has occurred, the larvae travel via the blood stream and infest the tissues. These infections are called cysticerci and can occur almost anywhere in the body.

In the brain, the larvae create cysts that are about 1-2 centimetres in diameter. These solid lumps can be seen through magnetic resonance imaging (MRI) scans. The cysticerci can affect the brain and be symptomatic. In developing countries, neurocysticercosis is the most common cause of seizers. Cysticerci are able to down regulate the host immune system so infection can occur in the brain. It secretes prostaglandins, paramyosin taeniastatin, and sulfated polysaccharides that will inhibit host cell cytokine production and complement activation, as well as minimalize inflammation around the cysticerci. Mansur, 2016)

Clinical symptoms usually arise due to degenerating cysts causing inflammation in the brain. After many months or years, the cysts may lose their ability to stop host defenses and symptoms will start to manifest. As the cysts degenerate further, they will be encased in granuloma which can lead to scarring and calcification. In some cases, an edema may develop due to the cysts called cysticercal encephalitis. This may develop into meningoencephalitis or granulomatous meningitis. Many more symptoms can present due to the location of the cysticerci.

Recorded instances of cysticerci in sylvian fissures of the brain have caused hydrocephalus, which is the blocking of cerebral spinal fluid (CSF) out of the brain. If the cysticerci are in the basal cisterns, basailar arachnoiditis may arise. Cysticerci may also infest around the spinal cord and cause cord compression and other symptoms related to the position. Usually cysticerci in this location do not cause many symptoms unless in large numbers. Other locations, such as arteries, may cause infarctions or large-vessel strokes which can cause extreme harm to the host.

Symptoms may include but are not limited to chronic headahces, vomiting, seizures, blindness, partial or complete loss of eyesight, dementia, hernia of the brain, convulsions, learning difficulties, confusion, excessive accumulation of CSF, inflammation of the CNS, pressure in head, and death. (Tseng, 2016) Transmission The usual transmission of Taenia solium is through the ingestion of cysts in undercooked pork causing taeniasis. This makes the human the intermediate host. The cysts will then excyst in the intestines and the eggs will be secreted through feces.

If the human ingests the eggs, cysticercosis will occur and the human will then be the definite host for the parasite. Humans can be infected by eggs via the fecal-oral route or through auto-reinfection, incases of taeniasis, and most commonly in improperly washed fresh produce. The eggs are sticky and can reside under the fingernails of infected food handlers. Even areas that do not usually have this parasite can be infected if the water or food is contaminated. Infected individuals are likely to spread the infection to others in the same household and to other in close proximity. Mansur, 2016)

Epidemiology In the United States, about 1,000 cases are reported annually. Most occur among Latin American immigrants in California, Arizona, and Texas. The second most common occurence of cysticercosis are reported in individuals who travel to areas of endemic disease. In the world, approximately 50-100 million people are infected with cysticercosis, which is linked to neurocysticercosis being one of the leading causes of adult-onset seizures worldwide. (Bittencourt et al. , 1996)

The most prevalent areas of disease are Central and South America, China, India, and Africa. Wu, Qian, Huang, & Hong, 2012) In Latin America and rural South American communities, the seroprevalence is as high as 5-25%. In developing countries, up to 50% of adult-onset seizures can be attributed to neurocysticercosis. In Los Angeles, California, it was found to be around 10%. (Wallin & Kurtzke, 2004) From 1990-2002, the United States had 221 deaths due to cysticercosis. (Sorvillo, DeGiorgio, & Waterman, 2007) Mortality is low in first world countries due to modern medicine and surgical care, but without surgical treatment, many infections are potentially life threatening.

However, certain locations of cysticerci growth are unable to be surgically removed and are associated with a high 10-year fatality rate. Most of the infections occur in Hispanic individuals and secondly Asian individuals due to endemic areas. Despite these statistics, infection has been related to exposure rather than genetic predisposition. Other commonalities are that cysticercosis has been more commonly found in children and young females. This could be due to the lack of immune capability but the cause has not been distinguished.

The age group for infected individuals spans from 10-40, but the infection has been described in all age groups. Life Cycle Taenia solium is under the phylum Platyhelminthes and class Cestoidea. It is referred to as the pig tapeworm and is considered a flatworm. The scolex, head, of the tapeworm has for suckers and two rows of hooklets. The adult tapeworm is flat, white in color, and measures about 2-3 meters in length but can grow up to 8 meters. Its body is made of a chain of segments called proglottids. Each proglottid contains 7-13 uterine branches and a genital pore.

Its normal life cycle is a pig as a definite host and its prey as the intermediate host. Humans are the intermediate host in cases of taeniasis, but in cases of cysticercosis, humans take the place of the pig as the definitive host. The normal life cycle of Taenia solium will start with the ingestion of eggs by the pigs. In the intestines of the pig, the eggs will develop into larvae and travel to the tissues via blood vessels. Once encysted in the tissues, humans become infected by eating raw or undercooked infected meat. The cysticerci will develop in the intestines and become an adult tapeworm.

The adults will attach to the calls of the intestines and grow gravid proglottids. The mature gravid proglottids will detach from the tapeworm and be passed in feces. The gravid proglottids in feces release their eggs, which are infective. In cases of cysticercosis, man becomes the accidental definitive host and takes the place of the pig in the life cycle. (“CDC – Taeniasis – Biology”, 2016) Lab Diagnosis The traditional method for diagnosis would be eggs in the stool samples of the patient, but in cases of cysticercosis, only a small minority of patients will present eggs in stool.

For definite diagnosis, biopsy of infected tissue is gathered and serological tests are run. Antibodies created by the body against cysticerci can be found in serum and tested for through enzyme linked immunotransfer blot (EITB) or enzyme linked immunosorbent assay (ELISA). Other tests, such as MRI scans or CT scans, can also be used to detect cysticerci but may not be diagnostic. (Cavalcante et al. , 2006) Treatment Treatment is dependent on the development of the cysticerci. Both the treatment for the parasite and present symptoms are included. If the parasite is dead, treatment is focused on the symptoms.

If the parasite is still viable, immunosuppressants are given prior to starting the use of anticysticercal drugs. Depending on the location of the cysticerci, surgery is recommended. Each individual response is different and the course of action is decided upon by the doctor. (“CDC – Cysticercosis”, 2016) Prevention and Control The main prevention of infection will be to use proper food handling techniques. For example: cooking meat thoroughly, washing fresh produce carefully, and staying clear of potentially contaminated water/food. Pig farming is carefully regulated in the United States and has strict guidelines for farming and processing.

This is much more difficult in developing countries due to lack of regulation, which creates limitations on how to regulate the infections. Vaccines are the focus of research at the moment. Many vaccines are created through the use of antigen from cysticercus cellulosae. (Lightowlers, 2010) This type of vaccine has been produced to protect against the different types of Taenia solium. The problem with vaccination is that each pig must be injected individually and does not incorporate free-range pigs. One of the easiest ways for humans to not get infected by this parasite is to stop possible contact to the parasite.

Conclusion Neurocysticercosis is caused by the ingestion of eggs of Taenia solium. This disease can be prevented by proper food handling techniques and precaution when traveling. Due to modern medicine and surgical intervention, there is low mortality rate due to neurocysticercosis. Despite the safety net given by medicine, it is best to stay away from sources of infection due to complication that may occur. There are plans in place to eradicate this parasite but it is highly unlikely that it will completely subside. Therefore, take care in your eating habits.

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