Helminth Parasite of GI Tract

Examples of Parasitic Nematodes Enterobius vermicularis- ???? Ascaris lumbricoides - ??? Toxacara canis, T. cati- ???? Necator americanus- ??? Trichuris trichiura- ???? Strongyloides stercoralis- ????? Trichinella sp.-

Examples of Parasitic Nematodes Enterobius vermicularis- human pin worm Ascaris lumbricoides -human roundworm Toxacara canis, T. cati- dog and cat round worm Necator americanus- human hookworm Trichuris trichiura- whipworm Strongyloides stercoralis- thread worm Trichinella sp.-

Treatment Drug Options (3) In the United States, ascariasis is generally treated for _____ days The drugs are effective and appear to have few side effects.

Treatment Drug Options Albendazole Mebendazole Pyrantel pamoate In the United States, ascariasis is generally treated for 1-3 days The drugs are effective and appear to have few side effects.

Ascaris lumbricoides Large ______________ (___cm in length) _______________ human parasite worldwide, including US ____ of world's population (1 billion people) are infected Can be seen in US, especially in poor communities along the ____________ _________ and _______________

Ascaris lumbricoides Large roundworm (30cm in length) Common human parasite worldwide, including US 25% of world's population (1 billion people) are infected Can be seen in US, especially in poor communities along the Mississippi delta and appalachia

Cestodes _____ worms Up to ___ _______ in length Complex life cycles

Cestodes Tape worms Up to 1 meter in length Complex life cycles

Clinical Features, Diagnosis, Treatment Most frequently ______________ Heavy infections, especially in small children, can cause ___________________ problems (abdominal pain, diarrhea, rectal prolapse) and possibly growth retardation. Diagnosis by microscopic identification of whipworm _____ in feces Treatment: _________________ is the drug of choice, with ________________ as an alternative

Clinical Features, Diagnosis, Treatment Most frequently asymptomatic. Heavy infections, especially in small children, can cause gastrointestinal problems (abdominal pain, diarrhea, rectal prolapse) and possibly growth retardation. Diagnosis by microscopic identification of whipworm eggs in feces Treatment: Mebendazole is the drug of choice, with albendazole as an alternative

Cestodes: Tapeworms, up to 1 meter in length, complex lifecycles Taenia species: Eggs ingested by ______ (T. solium) or __________ (T. saginata) → eggs hatch & larvae invade intestinal ______ & migrate to striated __________ → humans ingest raw or undercooked infected______ → tapeworm attaches to small intestine via ________ & reside → adults produce ________ _______ which migrate to anus & pass in stool; if eggs are ingested by human, causes ________ in CNS = neurocysticerosis (seizures, hydrocephalus, CN damage, visual impairment); diagnosed via demonstration of eggs or _____________ in feces, treated with _____________

Cestodes: Tapeworms, up to 1 meter in length, complex lifecycles Taenia species: Eggs ingested by pigs (T. solium) or cattle (T. saginata) → eggs hatch & larvae invade intestinal wall & migrate to striated muscles → humans ingest raw or undercooked infected meat → tapeworm attaches to small intestine via Scolex & reside → adults produce gravid proglottid which migrate to anus & pass in stool; if eggs are ingested by human, causes cysticerci in CNS = neurocysticerosis (seizures, hydrocephalus, CN damage, visual impairment); diagnosed via demonstration of eggs or proglottids in feces, treated with praziquantel

Clinical Features During the lung phase of _______ ___________, ______________ symptoms can occur (cough, dyspnea, hemoptysis, eosinophilic pneumonitis). Infections may cause ___________ __________ in children High worm burdens may cause ______________ pain and intestinal obstruction. Migrating adult worms may cause symptomatic occlusion of the ________ _______. In small numbers, adult worms may cause no acute symptoms.

Clinical Features During the lung phase of larval migration, pulmonary symptoms can occur (cough, dyspnea, hemoptysis, eosinophilic pneumonitis). Infections may cause stunted growth in children High worm burdens may cause abdominal pain and intestinal obstruction. Migrating adult worms may cause symptomatic occlusion of the biliary tract. In small numbers, adult worms may cause no acute symptoms.

Clinical Features Enterobiasis is frequently ______________. The most typical symptom is ___________ ____________, especially at night, which may lead to _____________ and bacterial _________________ Occasionally, invasion of the female genital tract with _____________ and pelvic or peritoneal _______________ can occur. Other symptoms include _________, irritability, and abdominal pain

Clinical Features Enterobiasis is frequently asymptomatic. The most typical symptom is perianal pruritus, especially at night, which may lead to excoriations and bacterial superinfection. Occasionally, invasion of the female genital tract with vulvovaginitis and pelvic or peritoneal granulomas can occur. Other symptoms include anorexia, irritability, and abdominal pain

Clinical Features of Hookworm Infection ______ deficiency _____________ (caused by blood loss at the site of intestinal attachment of the adult worms) is the most common symptom of hookworm infection, and can be accompanied by _____________ complications. NVD and nutritional/___________ symptoms Severe infections can cause delayed growth and poor intellectual development in children Local skin manifestations ("ground itch") can occur during penetration by the _____________ (___) larvae Respiratory symptoms can be observed during ______________ migration of the larvae.

Clinical Features of Hookworm Infection Iron deficiency anemia (caused by blood loss at the site of intestinal attachment of the adult worms) is the most common symptom of hookworm infection, and can be accompanied by cardiac complications. NVD and nutritional/metabolic symptoms Severe infections can cause delayed growth and poor intellectual development in children Local skin manifestations ("ground itch") can occur during penetration by the filariform (L3) larvae Respiratory symptoms can be observed during pulmonary migration of the larvae.

Clinical Features of Taenia Infections Taenia saginata Usually only produces only mild ______________ _____________ Occasionally, _________________ or _______________ can result from migrating ___________ Taenia solium Adult worms are even less frequently symptomatic than ___________ __________ The most important feature of Taenia solium __________ is the risk of development of _______________ from larval worms

Clinical Features of Taenia Infections Taenia saginata Usually only produces only mild abdominal symptoms. Occasionally, appendicitis or cholangitis can result from migrating proglottids. Taenia solium Adult worms are even less frequently symptomatic than Taenia saginata The most important feature of Taenia solium taeniasis is the risk of development of cysticercosis from larval worms

Csyticercus- Larval Form of Taenia Results from ingestion of Taenia _____ Egg hatches releasing an oncosphere that migrates to various tissues, develops into ________________ The cysticercus is a ________ __________ ____ about ___ ____ in length and contains an invaginated _________ Upon ingestion by definitive host, the scolex ______________ and begins development into an adult.

Csyticercus- Larval Form of Taenia Results from ingestion of Taenia eggs Egg hatches releasing an oncosphere that migrates to various tissues, develops into cysticercus The cysticercus is a fluid filled sac about 15 mm in length and contains an invaginated scolex. Upon ingestion by definitive host, the scolex evaginates and begins development into an adult.

Cutaneous Larval Migrans Dog hookworm ______________ _________ Larval worms of penetrate _____, migrate through dermis for ________ to months, then die Inflammation follows track of _______ ___________ Prevention (3)

Cutaneous Larval Migrans Dog hookworm Ancylostoma caninum Larval worms of penetrate skin, migrate through dermis for weeks to months, then die Inflammation follows track of larval migration Prevention Keep sandboxes covered Wear shoes Clean up dog and cat waste

Diagnosis and Treatment Microscopic identification of eggs collected in the perianal area is the method of choice for diagnosing enterobiasis. Use "_________ ______ test" (adhesive tape pushed against perianal skin) to collect eggs- works better that stool exam Treatment: (3)

Diagnosis and Treatment Microscopic identification of eggs collected in the perianal area is the method of choice for diagnosing enterobiasis. Use "Scotch tape test" (adhesive tape pushed against perianal skin) to collect eggs- works better that stool exam Treatment: Mebendazole or albendazole Pyrantel pamoate

Diagnosis and Treatment of Hookworms Microscopic identification of ______ in the stool is the most common method for diagnosing hookworm infection. Treatment: (3)

Diagnosis and Treatment of Hookworms Microscopic identification of eggs in the stool is the most common method for diagnosing hookworm infection. Treatment: albendazole, mebendazole or pyrantel pamoate

Diagnosis and Treatment of Neurocysticercosis Diagnosis aided by ___ and _____ Serologic tests for ___________________ antibodies Treatment: (2)

Diagnosis and Treatment of Neurocysticercosis Diagnosis aided by CT and MRI Serologic tests for anti-cysticercal antibodies Treatment: praziquantel, albendazole

Diagnosis, Treatment and Control of Taenia sp. Diagnosis: demonstration of ______ or ______________ in feces Treatment: _________ Control: Properly ____ ____

Diagnosis, Treatment and Control of Taenia sp. Diagnosis: demonstration of eggs or proglottids in feces Treatment: Praziquantel Control: Properly cook meat

Enterobius vermicularis The most common helminth infection in the United States Also called human ____________. Adult females: 8 to 13 mm, adult male: 2 to 5 mm.) ___________ are the _____ hosts of E. vermicularis. ______________ distribution Infections more frequent in school- or preschool- children and in ____________ ______________. ______________ appears to be more common in temperate than tropical countries.

Enterobius vermicularis The most common helminth infection in the United States Also called human pinworm. Adult females: 8 to 13 mm, adult male: 2 to 5 mm.) Humans are the only hosts of E. vermicularis. Worldwide distribution Infections more frequent in school- or preschool- children and in crowded conditions. Enterobiasis appears to be more common in temperate than tropical countries.

Diphyllobothrium latum The ______ tapeworm) ____________ human _____________ Diphyllobothriasis occurs primarily in the _____________ _________________ Freshwater fish infected with Diphyllobothrium sp. larva may be transported to and consumed in ______________ areas where active transmission does not occur

Diphyllobothrium latum The fish tapeworm) Largest human tapeworm. Diphyllobothriasis occurs primarily in the Northern Hemisphere Freshwater fish infected with Diphyllobothrium sp. larva may be transported to and consumed in geographic areas where active transmission does not occur

Diphyllobothrium latum: Fish tapeworm - eggs passed in feces → larvae ingested by ____________ → ingested by fish → humans eat undercooked ______ → reside in _______ _________ → eggs passed in feces → mostly asymptomatic, can have ________ ____ deficiency with pernicious anemia; diagnosed by microscopic identification of _____, treated with _____________

Diphyllobothrium latum: Fish tapeworm - eggs passed in feces → larvae ingested by crustacean → ingested by fish → humans eat undercooked fish → reside in small intestine → eggs passed in feces → mostly asymptomatic, can have vitamin B12 deficiency with pernicious anemia; diagnosed by microscopic identification of eggs, treated with praziquantel

Echinococcosis Human echinococcosis (hydatidosis, or hydatid disease) is caused by the ______ _______ of the tapeworm Echinococcus. Echinococcus granulosus is more common causes cystic echinococcosis, occurs worldwide, especially in ________, grazing areas where dogs ingest organs from infected animals. E. multilocularis causes ____________ _______________; E. multilocularis occurs in the northern hemisphere, including central Europe and the northern parts of Europe, Asia, and North America

Echinococcosis Human echinococcosis (hydatidosis, or hydatid disease) is caused by the larval stages of the tapeworm Echinococcus. Echinococcus granulosus is more common causes cystic echinococcosis, occurs worldwide, especially in rural, grazing areas where dogs ingest organs from infected animals. E. multilocularis causes alveolar echinococcosis; E. multilocularis occurs in the northern hemisphere, including central Europe and the northern parts of Europe, Asia, and North America

Echinococcosis: Eggs released from _________________→ intermediate host ingestion (ex. sheep) & egg hatches in small bowel & penetrates intestine migrating to various _______ (liver, lungs) forming a cyst; if humans ingest eggs can cause cysts in _____, _____, ______, etc; diagnosed by finding __________________ in aspiration of cysts & serologic tests, treatment is ____________ to remove cysts followed by _____________ or ______________

Echinococcosis: Eggs released from dogs/canids → intermediate host ingestion (ex. sheep) & egg hatches in small bowel & penetrates intestine migrating to various organs (liver, lungs) forming a cyst; if humans ingest eggs can cause cysts in liver, lung, brain, etc; diagnosed by finding protoscolecies in aspiration of cysts & serologic tests, treatment is surgery to remove cysts followed by albendazole or mebendazole

Life Cycle Adult worms live in the lumen of the ________ ____________. A female may produce approximately _________ eggs per day, which are passed with the _____. Unfertilized eggs may be ingested but are not __________. Fertile eggs embryonate and become infective after ___ days to several weeks , depending on the environmental conditions (optimum: moist, warm, shaded soil). After infective eggs are swallowed , the larvae hatch , invade the _________ __________, and are carried via the portal, then systemic circulation to the ______. The larvae mature further in the ______ (___ to __ days), penetrate the alveolar walls, ascend the bronchial tree to the throat, and are __________ . Upon reaching the _______ ____________, they develop into adult worms . Between __ and __ months are required from ingestion of the infective eggs to oviposition by the adult female. Adult worms can live __ to __ years

Life Cycle Adult worms live in the lumen of the small intestine. A female may produce approximately 200,000 eggs per day, which are passed with the feces . Unfertilized eggs may be ingested but are not infective. Fertile eggs embryonate and become infective after 18 days to several weeks , depending on the environmental conditions (optimum: moist, warm, shaded soil). After infective eggs are swallowed , the larvae hatch , invade the intestinal mucosa, and are carried via the portal, then systemic circulation to the lungs . The larvae mature further in the lungs (10 to 14 days), penetrate the alveolar walls, ascend the bronchial tree to the throat, and are swallowed . Upon reaching the small intestine, they develop into adult worms . Between 2 and 3 months are required from ingestion of the infective eggs to oviposition by the adult female. Adult worms can live 1 to 2 years

Life Cycle of D. latum Immature eggs are passed in ______ . Under appropriate conditions, the eggs mature (approximately 18 to 20 days) and yield oncospheres which develop into a _________ . After ingestion by a suitable freshwater ____________ (the copepod first intermediate host) the coracidia develop into procercoid larvae . Following ingestion of the copepod by a suitable second intermediate host, typically __________ and other small ___________ fish, the procercoid larvae are released from the crustacean and migrate into the ______ ______ where they develop into a plerocercoid larvae (sparganum) . The plerocercoid larvae are the infective stage for humans. Because humans do not generally eat ______________ minnows and similar small freshwater fish, these do not represent an important source of infection. Nevertheless, these small second intermediate hosts can be eaten by larger predator species, e.g., trout, perch, walleyed pike . In this case, the sparganum can migrate to the musculature of the larger predator fish and humans can acquire the disease by eating these later intermediate infected host fish raw or _____________ . After ingestion of the infected fish, the plerocercoid develop into immature adults and then into mature adult tapeworms which will reside in the small intestine. The adults of D. latum attach to the intestinal mucosa by means of the two bilateral groves (bothria) of their scolex . The adults can reach more than 10 m in length, with more than 3,000 proglottids. Immature eggs are discharged from the proglottids (up to 1,000,000 eggs per day per worm) and are passed in the feces . Eggs appear in the feces 5 to 6 weeks after infection. In addition to humans, many other mammals can also serve as definitive hosts for D. latum.

Life Cycle of D. latum Immature eggs are passed in feces . Under appropriate conditions, the eggs mature (approximately 18 to 20 days) and yield oncospheres which develop into a coracidia . After ingestion by a suitable freshwater crustacean (the copepod first intermediate host) the coracidia develop into procercoid larvae . Following ingestion of the copepod by a suitable second intermediate host, typically minnows and other small freshwater fish, the procercoid larvae are released from the crustacean and migrate into the fish flesh where they develop into a plerocercoid larvae (sparganum) . The plerocercoid larvae are the infective stage for humans. Because humans do not generally eat undercooked minnows and similar small freshwater fish, these do not represent an important source of infection. Nevertheless, these small second intermediate hosts can be eaten by larger predator species, e.g., trout, perch, walleyed pike . In this case, the sparganum can migrate to the musculature of the larger predator fish and humans can acquire the disease by eating these later intermediate infected host fish raw or undercooked . After ingestion of the infected fish, the plerocercoid develop into immature adults and then into mature adult tapeworms which will reside in the small intestine. The adults of D. latum attach to the intestinal mucosa by means of the two bilateral groves (bothria) of their scolex . The adults can reach more than 10 m in length, with more than 3,000 proglottids. Immature eggs are discharged from the proglottids (up to 1,000,000 eggs per day per worm) and are passed in the feces . Eggs appear in the feces 5 to 6 weeks after infection. In addition to humans, many other mammals can also serve as definitive hosts for D. latum.

Life Cycle of Enterobius vermicularis Eggs are deposited on ________ ___________ . Self-infection occurs by transferring infective eggs to the mouth with hands that have scratched the perianal area . __________________ transmission can also occur. May also be acquired through surfaces in the environment that are contaminated with __________ eggs (e.g., curtains, carpeting, contaminated clothes or bed linens). Following ingestion of infective eggs, the larvae hatch in the _______ ________ and the adults establish themselves in the _______ . The time interval from ingestion of infective eggs to oviposition by the adult __________ is about one month. The life span of the adults is about two _________ Gravid females migrate _______________ outside the anus and oviposit while crawling on the skin of the perianal area . The ____________ contained inside the eggs develop (the eggs become infective) in 4 to 6 hours under optimal conditions

Life Cycle of Enterobius vermicularis Eggs are deposited on perianal folds . Self-infection occurs by transferring infective eggs to the mouth with hands that have scratched the perianal area . Person-to-person transmission can also occur. May also be acquired through surfaces in the environment that are contaminated with pinworm eggs (e.g., curtains, carpeting, contaminated clothes or bed linens). Following ingestion of infective eggs, the larvae hatch in the small intestine and the adults establish themselves in the colon . The time interval from ingestion of infective eggs to oviposition by the adult females is about one month. The life span of the adults is about two months. Gravid females migrate nocturnally outside the anus and oviposit while crawling on the skin of the perianal area . The larvae contained inside the eggs develop (the eggs become infective) in 4 to 6 hours under optimal conditions

Life Cycle of Hookworms Eggs are passed in the _______ , and under favorable conditions (moisture, warmth, shade), larvae hatch in __ to __ days. The released ____________ _________ grow in the feces and/or the soil , and after 5 to 10 days (and two molts) they become become filariform (third-stage) larvae that are infective. These infective larvae can survive ___ to __ weeks in favorable environmental conditions. On contact with the human host, the larvae penetrate the skin and are carried through the veins to the _______ and then to the _______. They penetrate into the ____________ _________, ascend the bronchial tree to the pharynx, and are swallowed . The larvae reach the small intestine, where they reside and mature into adults. Adult worms live in the _______ of the _________ __________, where they attach to the intestinal wall with resultant blood loss by the host . Most adult worms are eliminated in ___ to ___ years, but longevity records can reach several years. Some A. duodenale larvae, following penetration of the host ______, can become dormant (in the intestine or muscle). In addition, infection by A. duodenale may probably also occur by the ______ and transmammary route. N. americanus, however, requires a ___________________ migration phase.

Life Cycle of Hookworms Eggs are passed in the stool , and under favorable conditions (moisture, warmth, shade), larvae hatch in 1 to 2 days. The released rhabditiform larvae grow in the feces and/or the soil , and after 5 to 10 days (and two molts) they become become filariform (third-stage) larvae that are infective. These infective larvae can survive 3 to 4 weeks in favorable environmental conditions. On contact with the human host, the larvae penetrate the skin and are carried through the veins to the heart and then to the lungs. They penetrate into the pulmonary alveoli, ascend the bronchial tree to the pharynx, and are swallowed . The larvae reach the small intestine, where they reside and mature into adults. Adult worms live in the lumen of the small intestine, where they attach to the intestinal wall with resultant blood loss by the host . Most adult worms are eliminated in 1 to 2 years, but longevity records can reach several years. Some A. duodenale larvae, following penetration of the host skin, can become dormant (in the intestine or muscle). In addition, infection by A. duodenale may probably also occur by the oral and transmammary route. N. americanus, however, requires a transpulmonary migration phase.

Life Cycle of Taenia solium Humans are the only definitive hosts for Taenia saginata and Taenia solium. Eggs or ______ ___________ are passed with feces ; the eggs can survive for days to months in the environment. Cattle (________) and pigs (______) become infected by ingesting vegetation contaminated with eggs or ________ _________. In the animal's intestine, the ____________ hatch , invade the intestinal wall, and migrate to the ____________ muscles, where they develop into cysticerci. A cysticercus can survive for several years in the animal. Humans become infected by ingesting raw or undercooked infected meat . In the human intestine, the ______________ develops over 2 months into an adult tapeworm, which can survive for years. The adult tapeworms attach to the small intestine by their ______ and reside in the small intestine . Length of adult worms is usually 5 m or less for T. saginata (however it may reach up to 25 m) and 2 to 7 m for T. solium. The adults produce______________ which mature, become gravid, detach from the tapeworm, and migrate to the _______ or are passed in the stool (approximately 6 per day). T. saginata adults usually have ______ to __________ proglottids, while T. solium adults have an average of _______ proglottids. The eggs contained in the gravid proglottids are released after the proglottids are passed with the feces. T. saginata may produce up to ____________ and T. solium may produce ________ eggs per proglottid respectively.

Life Cycle of Taenia solium Humans are the only definitive hosts for Taenia saginata and Taenia solium. Eggs or gravid proglottids are passed with feces ; the eggs can survive for days to months in the environment. Cattle (T. saginata) and pigs (T. solium) become infected by ingesting vegetation contaminated with eggs or gravid proglottids . In the animal's intestine, the oncospheres hatch , invade the intestinal wall, and migrate to the striated muscles, where they develop into cysticerci. A cysticercus can survive for several years in the animal. Humans become infected by ingesting raw or undercooked infected meat . In the human intestine, the cysticercus develops over 2 months into an adult tapeworm, which can survive for years. The adult tapeworms attach to the small intestine by their scolex and reside in the small intestine . Length of adult worms is usually 5 m or less for T. saginata (however it may reach up to 25 m) and 2 to 7 m for T. solium. The adults produce proglottids which mature, become gravid, detach from the tapeworm, and migrate to the anus or are passed in the stool (approximately 6 per day). T. saginata adults usually have 1,000 to 2,000 proglottids, while T. solium adults have an average of 1,000 proglottids. The eggs contained in the gravid proglottids are released after the proglottids are passed with the feces. T. saginata may produce up to 100,000 and T. solium may produce 50,000 eggs per proglottid respectively.

Life Cycle of Trichinella spiralis Trichinellosis is acquired by ingesting meat containing _____ (encysted larvae) of Trichinella. After exposure to _________ ____ and ________, the larvae are released from the cysts and invade the small bowel ___________ where they develop into adult worms (female 2.2 mm in length, males 1.2 mm; life span in the small bowel: 4 weeks). After 1 week, the females release ________ that migrate to the _________ ___________ where they encyst . Encystment is completed in 4 to 5 weeks and the encysted larvae may remain viable for several years. Ingestion of the encysted larvae perpetuates the _______ Rats and rodents are primarily responsible for maintaining the ________________ of this infection. Carnivorous/omnivorous animals, such as pigs or bears, feed on infected rodents or meat from other animals. Different animal hosts are implicated in the life cycle of the different species of ____________. Humans are accidentally infected when eating improperly processed meat of these ______________ ____________ (or eating food contaminated with such meat).

Life Cycle of Trichinella spiralis Trichinellosis is acquired by ingesting meat containing cysts (encysted larvae) of Trichinella. After exposure to gastric acid and pepsin, the larvae are released from the cysts and invade the small bowel mucosa where they develop into adult worms (female 2.2 mm in length, males 1.2 mm; life span in the small bowel: 4 weeks). After 1 week, the females release larvae that migrate to the striated muscles where they encyst . Encystment is completed in 4 to 5 weeks and the encysted larvae may remain viable for several years. Ingestion of the encysted larvae perpetuates the cycle. Rats and rodents are primarily responsible for maintaining the endemicity of this infection. Carnivorous/omnivorous animals, such as pigs or bears, feed on infected rodents or meat from other animals. Different animal hosts are implicated in the life cycle of the different species of Trichinella. Humans are accidentally infected when eating improperly processed meat of these carnivorous animals (or eating food contaminated with such meat).

Life Cycle of Trichuris trichiura Also called whip worm The ___________ eggs are passed with the stool. In the soil, eggs become ___________ in 15 to 30 days. After ingestion (soil-contaminated hands or food), the eggs hatch in the small intestine, and release larvae that mature and establish themselves as adults in the _______. The adult worms (approximately 4 cm in length) live in the _______ and ____________ ________, their anterior portions penetrating the mucosa. The females begin to oviposit ___ to ___ days after infection. Female worms in the cecum shed between 3,000 and __________ eggs per day. The life span of the adults is about ___ year.

Life Cycle of Trichuris trichiura Also called whip worm The unembryonated eggs are passed with the stool. In the soil, eggs become infective in 15 to 30 days. After ingestion (soil-contaminated hands or food), the eggs hatch in the small intestine, and release larvae that mature and establish themselves as adults in the colon. The adult worms (approximately 4 cm in length) live in the cecum and ascending colon, their anterior portions penetrating the mucosa. The females begin to oviposit 60 to 70 days after infection. Female worms in the cecum shed between 3,000 and 20,000 eggs per day. The life span of the adults is about 1 year.

Microscopic identification of ______ in the stool is the most common method for diagnosing intestinal ascariasis.

Microscopic identification of eggs in the stool is the most common method for diagnosing intestinal ascariasis.

Necator americanus and Ancylostoma duodenale The human _________________ include two species, Ancylostoma duodenale and Necator americanus. Worldwide distribution, mostly in areas with ________, ______ climate. Hookworms of animals can penetrate the human skin causing ________________ _________ ________, but do not develop any further (A. braziliense, A. caninum)

Necator americanus and Ancylostoma duodenale The human hookworms include two species, Ancylostoma duodenale and Necator americanus. Worldwide distribution, mostly in areas with moist, warm climate. Hookworms of animals can penetrate the human skin causing cutaneous larva migrans, but do not develop any further (A. braziliense, A. caninum)

Nematodes _________ worms Macroscopic adults; microscopic eggs and larvae Various species infect intestines, blood, lymphatics and tissues

Nematodes Round worms Macroscopic adults; microscopic eggs and larvae Various species infect intestines, blood, lymphatics and tissues

Neurocysticercosis Cysticerci in ____, cause: (4)

Neurocysticercosis Cysticerci in CNS, cause: seizures, hydrocephalis, cranial nerve damage, visual impairment

Parasitic Cestodes Taenia saginata- ???? Taenia solium- ????? Echinococcus granulosis Echinococcus multilocularis Diphyllobothrium latum- ????

Parasitic Cestodes Taenia saginata- beef tapeworm Taenia solium- pork tapeworm Echinococcus granulosis Echinococcus multilocularis Diphyllobothrium latum- fish tapeworm

Taenia sp. Long-lived parasites (up to 25 years) Can grow to ____m or more in length Tania saginatum: _____ tapeworm ___________ distribution ______ are intermediate host ______ are definitive host Taenia solium : ______ tapeworm Worldwide distribution; especially in poorer areas where people live close to pigs; rare in ________ __________ Pigs- _____________ host Humans-___________ host

Taenia sp. Long-lived parasites (up to 25 years) Can grow to 5-7m or more in length Tania saginatum: Beef tapeworm Worldwide distribution Cattle are intermediate host Humans are definitive host Taenia solium : Pork tapeworm Worldwide distribution; especially in poorer areas where people live close to pigs; rare in Muslim countries Pigs- intermediate host Humans-definitive host

Trichinella spiralis Zoonotic disease following infection with Trichinella sp. (T. spiralis, T nativa, others) ___________ distribution Animal reservoirs: ????? Humans infected by eating __________ _________ in meat of infected __________ Formerly, most infections resulted from undercooked _____ Most US infections (60%) result from eating ______ meat

Trichinella spiralis Zoonotic disease following infection with Trichinella sp. (T. spiralis, T nativa, others) Worldwide distribution Animal reservoirs: pigs, bears, many omnivorous animals Humans infected by eating encysted larvae in meat of infected animals Formerly, most infections resulted from undercooked pork Most US infections (60%) result from eating bear meat

Trichinellosis: Clinical Findings Diarrhea, abdominal pain, vomiting may occur during ____________ __________ phase Larval migration phase can cause ____________ and facial ___________, _______________, fever, myalgias, __________ hemorrhages, rashes, and _______________ _____________. Larval encystment in the muscles causes myalgia and ___________ ______________ Laboratory findings: eosinophilia, elevated muscle enzymes (_____, ____) History of consumption of __________________ ______ Symptoms generally last _____ weeks

Trichinellosis: Clinical Findings Diarrhea, abdominal pain, vomiting may occur during intestinal invasion phase Larval migration phase can cause periorbital and facial edema, conjunctivitis, fever, myalgias, splinter hemorrhages, rashes, and peripheral eosinophilia. Larval encystment in the muscles causes myalgia and muscle weakness Laboratory findings: eosinophilia, elevated muscle enzymes (LDH, CPK) History of consumption of undercooked meat Symptoms generally last 5-6 weeks

Trichinellosis: Diagnosis, Treatment Diagnosis: Clinical findings plus ___________ suggestive of Trichinellosis Serology and/or __________ ____________ confirms diagnosis Treatment: albendazole, mebendazole plus _______________ to control inflammation in serious cases

Trichinellosis: Diagnosis, Treatment Diagnosis: Clinical findings plus history suggestive of Trichinellosis Serology and/or muscle biopsy confirms diagnosis Treatment: albendazole, mebendazole plus corticosteroids to control inflammation in serious cases

Trichuris trichiura Also called the human _____________ Worldwide, with infections more frequent in areas with _________ ____________ and poor _____________ practices, and among children. _____ million people are infected worldwide. Trichuriasis occurs in the ____________ United States.

Trichuris trichiura Also called the human whipworm Worldwide, with infections more frequent in areas with tropical weather and poor sanitation practices, and among children. 800 million people are infected worldwide. Trichuriasis occurs in the southern United States.

Visceral larval migrans: Toxacara sp Toxacara canus, Toxacara cati- ________ worms of ___ and ___ Predominantly infect _________ _________ Visceral larval migrans results from human ingestion of _______ Larvae hatch in stomach, wander throughout body including ____ and _____ Fever, anorexia, weight loss, cough, wheezing, rashes, ______________________, and ___________________________.

Visceral larval migrans: Toxacara sp Toxacara canus, Toxacara cati- round worms of dog and cat Predominantly infect young animals Visceral larval migrans results from human ingestion of eggs Larvae hatch in stomach, wander throughout body including CNS and eyes Fever, anorexia, weight loss, cough, wheezing, rashes, hepatosplenomegaly, and hypereosinophilia.