Ebook Medical parasitology: Part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook Medical parasitology: Part 2
Ebook Medical parasitology: Part 2
Section IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis ar Ebook Medical parasitology: Part 2re diseases resulting from infection with parasitic tapeworms belonging to Taenia species. Approximately 45 species of Taenia have been identified; however, the two most commonly responsible for human infection are the pork tapeworm Taenia solium and the beef tapeworm Taenia saginata. Parasitic tape Ebook Medical parasitology: Part 2worm infections occur worldwide, causing sickness, malnutrition and often resulting in the death of their host. Infection with adult tapeworms of eithEbook Medical parasitology: Part 2
er T solium or T.saginata cause taeniasis in humans. The metacestode, or larval stage, of Taenia solium causes the tissue infection, cysticercosis. ClSection IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis ar Ebook Medical parasitology: Part 2ms, to severe life-threatening forms which are often fatal.Geographic Distribution and TransmissionTaenia infections are estimated to affect 100 million people worldwide, with major endemic areas located primarily in the developing countries of South America, Africa, India, China and Southeast Asia. Ebook Medical parasitology: Part 2 Ihe ingestion of cysticerci from raw or undercooked meat facilitates the transmission of T solium from pigs to humans and is presumably responsible fEbook Medical parasitology: Part 2
or the high prevalence of human cysticerosis in these regions. It is estimated that anywhere between 5-40% of individuals carrying the adult tapeworm Section IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis ar Ebook Medical parasitology: Part 2problem in California. Although this disease is mainly seen in migrant workers from Latin American, it has also been reported in ƯS residents who have not traveled to endemic countries.Life-CycleTie complete life-cycle of Taenia solium involves two hosts: the pig and the human, whereas that of Taeni Ebook Medical parasitology: Part 2a saginata involves the cow and the human (Fig. 20.1). Humans act as the definitive host and harbor the adult tapeworm in the small intestine. InfectiEbook Medical parasitology: Part 2
on is acquired either through the accidental ingestion of embryonated eggs passed in the feces of an individual infected with the adult tapeworm, or tSection IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis ar Ebook Medical parasitology: Part 2ive up to 25 years. Depending on the species of Taenia, an adult wormTaeniasis and CylicercosisÌ39Cysticerci of T. saginaỉđTaenia eggCysticerci oi T. folium; Infected m : inadequately cooked4. Ingested cysticerci reach intestine, attach and grow to adult tapeworms2. Eggs ingested, c yslicert i devel Ebook Medical parasitology: Part 2op in tissues and organs of intermediate hostd Tdenraeggs ÌÀ voided in ieces _Figure 20.1. Life cycles of the beef tapeworm, Taenia saginata and the pEbook Medical parasitology: Part 2
ork tapeworm, T. solium. Reproduced from: Nappi AJ, Vass E, eds. Parasites of Medical Importance. Austin: Landes Bioscience, 2002:61.20per day. The moSection IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis ar Ebook Medical parasitology: Part 2h booklets. The strombila consists of several segments (proglottids) with the gravid or egg-carrying proglottids located toward the posterior end of the worm (Fig. 20.2). Individual proglottids may contain as many as 40,000 eggs in T. solium or as many as 100,000 eggs in T. saginata.Both the proglot Ebook Medical parasitology: Part 2tids and the eggs are released with the feces of infected individuals and serve as a source of infection for pigs and cattle, which act as intermediatEbook Medical parasitology: Part 2
e hosts for these parasites. Following the ingestion of eggs, mature larvae (onchospheres) are released in the gut. These onchospheres enter the bloodSection IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis ar Ebook Medical parasitology: Part 2he host tissues for several years causing cysticercosis (Fig. 20.3). The consumption of raw or undercooked meat containing cysticerci facilitates the spread of infection from pigs to humans. In humans, cysticerci transform into adult tapeworms which persist in the small intestines for years causing Ebook Medical parasitology: Part 2taeniasis. The time between initial infection and the development of the adult worm occurs over a period of140Medical ParasitologyComparative MorpholoEbook Medical parasitology: Part 2
gy of Tacniarhynchus saginatus and Taenia soliumTaenia saginataTaenia soliumFigure 20.2. Morphology of Taenia saginafa and T. solium. Reproduced from:Section IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis ar Ebook Medical parasitology: Part 2the small intestine of the human host and has been shown to induce a Th2-type immune response characterized by high levels of IL-4 and IL-10 expression and an increase in immunoglobulin production, primarily IgG. Antibodies produced in response to parasite antigens appear to be somewhat effective in Ebook Medical parasitology: Part 2 the destruction of the early larval form, but offer little to no protection against cysticerci present within the tissues.Viable cysricerci produce lEbook Medical parasitology: Part 2
ittle to no inflammation within rhe surrounding tissues and their ability to suppress the host inflammatory response undoubtedly plays a major role inSection IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis ar Ebook Medical parasitology: Part 2en shown to induce a strong Ihl-type cell-mediated inflammatory response, characterized by high levels of interferon-gam ma and the formation of granulomas containing lymphocytes, eosinophils, granulocytes and plasma cells. Experimental data using a mouse model suggest that the development of a Til Ebook Medical parasitology: Part 21 cell-mediated inflammatory response controls parasite growth, whereas a Th2-type response increases levels of susceptibility to chronic infection.ThEbook Medical parasitology: Part 2
ese parasites have developed numerous methods for evading the host immune response. Although rhe ingested oncospheres which are capable of penetratingSection IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis arSection IIICestodesChapter 20Taeniasis and CyticercosisHannah Cummings, Luis I. Terrazas and Abhaỵ R. SatoskarBackgroundTaeniasis and cysticercosis arGọi ngay
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