Cyclophyllidean Tapeworms

Order Cyclophyllidea - Chapter 21

Major order of tapeworms of medical and veterinary importance

General Characteristics of the Order:

1. Scolex has __________________ and a _________________________ + hooks

2. Common genital pore is lateral

3. Single compact ________________________________ beneath ovary

Order Cyclophyllidea

4. Gravid proglottids are _______________________________; proglottid ruptures on land to disseminate eggs

5. Life cycle involves 2 hosts - intermediate host and definitive host

Tapeworms of medical and veterinary importance are found in 3 families.

The first family is the Family Taeniidae.

Taenia saginata = Taeniarhynchus saginatus

Beef tapeworm of humans - humans are the only definitive host and cattle are the only intermediate host

DISTRIBUTION -

Taenia saginata

ADULT MORPHOLOGY:

Scolex has 4 acetabula but lacks ___________________________________

Strobila commonly reaches lengths of 10 to 15 feet (record is 75 ft.) and may contain up to 2000 proglottids.

Taenia saginata

ADULT MORPHOLOGY:

Mature proglottids contain male and female organs

Testes

Vas deferens

Genital pore

Vagina

uterus

Ovary

Vitellarium

Taenia saginata

ADULT MORPHOLOGY:

Gravid proglottids are identified by presence of ____________________________ - diagnostic stage in human feces

Life Cycle of Taenia saginata

1. Adult tapeworm occurs in human ______________________

2. Gravid proglottid is shed in feces - may actively crawl about in feces.

3. Gravid proglottid ruptures on land during drying and releases eggs onto soil.


4. Grazing cow (intermediate host) ingests eggs.

5. Oncosphere hatches from egg in cow small intestine, penetrates intestine, and enters circulation.

6. Oncosphere reaches skeletal muscle and becomes a _____________________

(scolex surrounded by bladder)

- beef infected with cysticerci is commonly called _____________________

.Life Cycle of Taenia saginata


7. Human eats raw or poorly cooked beef containing cysticerci.

Scolex evaginates, attaches to wall of ileum, and begins strobilization.

Adult reaches maturity in 2-12 weeks.

Life Cycle Stages of Taenia saginata

Cysticercus with invaginated scolex

Cysticercus with evaginated scolexEgg has a striated

embryophore and inner oncosphere with 6 hooks

Scolex Mature proglottid Gravid proglottid (diagnostic in feces!)

Human Infections

EPIDEMIOLOGY - human infections associated with ________________________________________________________________________________________________

PATHOLOGY:

1.

2.

Parasite is never life-threatening.

DIAGNOSIS - identify gravid proglottid in feces with 15-20 lateral uterine arms.

Eggs are not diagnostic as they are typically not found in feces. Eggs cannot be distinquished from other taeniid tapeworms.

TREATMENT - ___________________________________ are effective

PREVENTION - __________________________________ _________________________________________________

Cysticerci in beef are large and are found during inspection of beef in packing plant. If found, carcass is condemned.

Human Infections

These were used as diet pills from 1900 to 1920.

Reappeared again in the 1970’s as a weight loss method.

Recently sold again as “Megaslim” and “Weight-B-Gone”

The Tapeworm Miracle Diet Pills are BackPosted on December 1, 2005 by Sam MarkensThe IndoMed company of southern San Francisco has produced a new product which has for some reason slipped past the FDA. Their new weight loss pill called Weight-B-Gone has some interesting side effects. This once a week pill, when ingested, will cause the patient to lose as much weight as they want on a steady basis while allowing them to eat whatever they want and as much as they like. The “catch” is that these pills contain a genetically engineered head of a Taenia saginata, otherwise known as the Beef Tapeworm.

Megaslim: the cheap alternative to diet and exercise. Michael SwaimStaff Writer

An FDA probe into Megaslim, the new “miracle diet medication,” revealed that the pills, which are sold out of a Wisconsin warehouse, are in fact nothing more than infant tapeworms.

Randall Corman, CEO of Fly By Night Inc., the company which manufactures the pills, has been under legal investigation since several of his patients complained of “cramping, gas, and tapeworms.” Corman defended the legitimacy of these pills, saying, “the vast majority of my clients have been overjoyed with their results.” Corman has also set up a “testimonials” page on his website, where former patients can write in to voice their opinions of his new drug.

Mary Shechter of Minnesota had this to say: “Megaslim has changed my life. Now, I eat pizza and donuts for three meals a day, and I still lose weight! When friends ask me what my secret is, I have to giggle, just thinking of that cute little tapeworm, feasting away on my intestinal wall.”

Corman suspended the infant tapeworms in gelatin and began selling them as diet pills earlier this year. His advertisement, which ran in a local newspaper, promised “fast, noticeable results” and “only minor parasitic infestation.” It is with this that the FDA has taken issue.

According to Jeremy Franklin, head of the FDA’s investigation into Megaslim, a tapeworm infestation is anything but “minor.” “Tapeworms are not to be taken lightly,” he told reporters Tuesday. “Once infected with a worm, a subject can experience diarrhea, gastral cramps, weakness, fatigue, malnutrition, and a dangerously sexy waistline. Though adorable, tapeworms should be considered a serious health risk.”

Following the FDA’s study, Corman and Franklin met with litigators and have since come to a settlement in the case. After agreeing to add “may cause tapeworms” to the list of side-effects, the FDA has officially approved Megaslim for sale and dispersal to the general public. Corman, overjoyed with the decision, says he is looking forward to “thinner citizens, fatter worms, and ten percent of the sale revenue.”

Miracle Diet Pills Really Just Tapeworm Eggs

Taenia solium

Pork tapeworm of humans - humans are the only definitive host and pigs are the intermediate host

This parasite is much more dangerous than the beef tapeworm, as humans can also serve as ___________________________________ _______________________________________________________

DISTRIBUTION - _______________________________________________________

Common in Slavic countries of Europe and Central & South America

Infections in U.S. commonly associated with migrant workers from Central and South America

Taenia solium

ADULT MORPHOLOGY:

Scolex with 4 acetabula and rostellum with 2 circles of hooks.

Strobila commonly reaches lengths of 6-10 feet and contain up to 1000 proglottids.

Taenia solium

ADULT MORPHOLOGY:

Mature proglottids are similar to T. saginatus.

Gravid proglottids contain _________________________________________ - diagnostic stage in human feces.

Life Cycle Stages of Taenia solium


Egg has a striated embryophore and inner oncosphere with 6 hooks

Scolex Mature proglottid Gravid proglottid (diagnostic in feces!)

Life Cycle of Taenia solium

Life cycle is similar to the beef tapeworm:

1. Adult tapeworm occurs in _____________ _____________________

2. Gravid proglottid is shed in feces.

3. Gravid proglottid ruptures on land, releasing eggs onto soil.


4. Pig intermediate host ingests eggs.

5. In pig, oncosphere hatches from egg and enters circulation.

6. Oncosphere reaches skeletal muscle and becomes a ____________________

- pork infected with cysticerci is ____________________


7. Human eats raw or poorly cooked pork containing cysticerci.

Adult tapeworm develops in small intestine.



Cysticercus with evaginated scolex

Measly pork

Life Cycle of Taenia solium - Cysticercosis

Humans can also serve as accidental intermediate hosts of the cysticerci - disease is called ____________________________


Humans can also serve as accidental intermediate hosts of the cysticerci - disease is called ____________________________

Methods of human infection:

1. ingest ___________________ via fecal contamination from a human infected with adult tapeworm.

• Don’t have to eat pork - recent infections of Jewish people in NY from Mexican housekeepers/cooks

2. autoinfection - caused by________________________________

• human is host of adult which releases gravid proglottids

• gravid proglottids rupture in stomach or duodenum releasing eggs


1. When eggs enter small intestine, _______________________ hatch, penetrate intestine, and enter circulation.

2. Oncospheres are carried to many organ where they become _______________________

Cysticerci commonly occur in 2 regions:

• _______________________ _________________________ (little pathology)

• ________________________ - results in disorder called neurocysticercosis

Pathology of Taenia solium

Adults - symptoms similar to T. saginatus - _________________________________________________

Neurocysticercosis - very dangerous and potentially fatal!

• When cysticerci die in the brain, they elicit a severe inflammatory reaction and destroy brain tissue.

• ______________________________________ occur

• Death? ______________________________________

Neurocysticercosis - fatal cases

DIAGNOSIS - adults are identified by finding gravid proglottid with ________________________________ in human feces.

Cysticerci are identified by X-ray, CAT scan, and MRI.

TREATMENT - ______________________ is useful against adults

___________________________________ is somewhat effective against cysticerci if brain damage is not severe.

http://www.emedicine.com/cgi-bin/foxweb.exe/makezoom@/em/makezoom?picture=%5Cwebsites%5Cemedicine%5Cneuro%5Cimages%5CLarge%5C41241778figure1.jpg&template=izoom2

PREVENTION

1. ____________________________________________ (Infections in U.S. are rare as pigs do not scavenge on human fecal wastes.)

2. __________________________________________________

(this also prevents trichinosis!)

3. _________________________________________________

http://animal.discovery.com/videos/monsters-inside-me-pork-tapeworm.html

Finding of infected pigs raises a red flag!

Taenia spp. of veterinary importance

Taenia pisiformis

Common parasite in the small intestine of ________________ __________________________________________________

In Wisconsin?

Adults are 1-3 feet long.

Adults are asymptomatic in canid definitive host.

Taenia pisiformis

Cysticerci occur in the liver and on mesenteries in the abdominal cavity of __________________________

cysticerci

oncosphere

egg Adult in fox

Taenia multiceps

Parasite in the small intestine of _____________________________________

Intermediate host is __________________________________

Larval form that develops in sheep is a ________________________________ (has many scoleces within one bladder)

Coenuri in sheep occur in brain and spinal cord and cause _____________________________________resulting in "gid" or "staggers"

Taenia taeniaformis

Adult tapeworm in small intestine of ____________________ which is asymptomatic.

Intermediate hosts are _________________________________

Larval form is called a ________________________________

Echinococcus spp.

Small taeniid tapeworms that infect ______________________ as definitive hosts.

Humans can serve as __________________________________ of the larval form called the hydatid cyst.

________________________________ is a very serious human disease in many parts of the world.

2 important species

Echinococcus granulosus

ADULT MORPHOLOGY - small tapeworm - 3-6 mm long

• consists of scolex, neck, immature proglottid, mature proglottid, and gravid proglottid

Life Cycle of Echinococcus granulosus

1. Adult occurs in ______________________________________________

2. Gravid proglottid detaches and ruptures as it passes through digestive tract. Eggs are released in the feces.

3. Eggs are released on soil and are ingested by intermediate host -______________________________________________

Life Cycle of Echinococcus granulosus

4. ____________________ hatches in herbivore's intestine, penetrates gut, enters circulation, and reaches liver, lungs, or brain

5. Oncosphere transforms into a ______________________________________________

6. When herbivore is eaten by canid, _______________________develop into adult tapeworms in the canid small intestine.

Unilocular Hydatid Cyst of Echinococcus granulosus

Unilocular hydatid cyst is a large circular structure (up to 6 inches in diameter)

Composed of 2 outer layers: 1. _____________________ 2._____________________

Germinal layer gives rise by asexual means to millions of _________________________ and brood capsules which produce additional protoscolices.

Cyst is filled with __________________________ containing the protoscolices


Unilocular hydatid cyst is a large circular to sausage-shaped structure (up to 6 inches in diameter)


Unilocular hydatid cyst is a large circular structure (up to 6 inches in diameter)

2 outer layers: 1. laminated layer 2. germinal layer

Protoscolices

Hydatid fluid

Human Infections of Echinococcus granulosus

HUMAN INFECTIONS are caused by ___________________ ___________________________________________________

• infected dog licks anus with eggs, then licks person's face.

• In Kenya, primitive tribe eats dog intestine lightly roasted on stick -

these persons have highest incidence of hydatidosis in world.

• Use of nurse dogs to lick children clean in tribes in Africa

Once the egg is ingested, oncosphere hatches, penetrates intestine, enters circulation, and comes to rest in ________________________

where it forms the ______________________

Pathology of Echinococcus granulosus

Adults in canid cause no pathology.

Hydatidosis in human:

1. ___________________________________________ form around unilocular hydatid in liver, lungs, or brain.

2. ________________________________________- pressure effects cause tissue damage and failure.

3. Rupture of hydatid results in fatal __________________________________ (due to hydatid fluid)

4. Calcification of hydatid occurs after many years.

5. Hydatid cysts in bone marrow cause ________________________________.

Unilocular hydatid cyst grows slowly in human. It may be many years before cyst enlarges enough to cause problems.


Unilocular hydatid cyst in the lung

Note pressure effects exerted by cyst that crowds and destroys lung tissue


6 inch unilocular hydatid cyst that killed a 7 year-old-girl in Colorado

Diagnosis of Echinococcus granulosus

DIAGNOSIS:

IN DOGS: identify eggs in feces. Eggs are characterized by dense striated __________________________ surrounding __________________________.

• Eggs, however, cannot be distinquished from any other taeniid.

.

embryophore

oncosphere

Diagnosis of Echinococcus granulosus

IN HUMAN INFECTIONS: X-rays, CAT scan, and MRI will detect the hydatid cysts.

Treatment of Echinococcus granulosus

TREATMENT - ______________________________________ Surgeon must be careful not to rupture cyst! Why?

Surgical removal of 3 unilocular hydatid cysts from a Kenyan woman

Distribution of Echinococcus granulosus

DISTRIBUTION - associated with range of intermediate hosts:

• ______________________________________ of world

• northern distribution associated with _______________________________

In the U. S. parasite occurs in southwestern states; in Wisconsin?

Echinococcus multilocularis

This species has recently been reported in __________________ in the upper Midwest (North and South Dakota, Minnesota, Iowa, and southern Wisconsin). Recently identified in Illinois and Ohio.

Echinococcus multilocularis

Humans can serve as __________________________________

___________________________________________________

• Many human cases have been reported in Alaska.

• First human case in lower 48 states was reported in 1979 in a Minnesota woman.

Echinococcus multilocularis in Minnesota

Life Cycle of Echinococcus multilocularis

1. Adult tapeworm occurs in _______________________________________________

Dogs, cats, and coyotes can also serve as definitive hosts.

• Adult is small - 1-2 mm long

2. Eggs are released in feces and are ingested by _____________________________________________________________________

_______________________ develops in liver and body cavity of rodent.

Alveolar hydatid has the ability to metastasize and infiltrate surrounding tissues like a cancer.

3. Fox becomes infected by eating rodent intermediate host containing alveolar hydatid host.

4. Human becomes accidental intermediate by _______________________________________________________________


Alveolar hydatid cyst in a mouse - cyst metastasizes from the liver to fill the body cavity


Alveolar hydatid cyst in the liver. Note the laminated layer, germinal layer, protoscolices.

PATHOLOGY involves _____________________________________________________

_________________________________________________________________________

Comparison of unilocular and alveolar hydatid cysts


DIAGNOSIS of the alveolar hydatid is difficult in human infections. It is often mistaken for a malignant liver tumor.

TREATMENT involves _______________________________________ Difficult to get entire cyst and recurrences occur 20-40% of the time.

Extensive liver cysts are inoperable and require _________________________________________

HUMAN INFECTIONS are rare but anyone handling ________________ (trappers, skinners) are at greatest risk for infection.

Distribution of Echinococcus multilocularis

The parasite has a circumpolar distribution in ________________________________________________________________________________________________________

Family Hymenolepidae

Large family of tapeworms in birds and mammals

Characterized by proglottids that are wider then long; mature proglottids contain 3 testes.

Hymenolepis diminuta

Cosmopolitan parasite in the ______________________________

Human infections are rare but have been reported in Egypt and India.

Adult of Hymenolepis diminuta

Scolex with 4 acetabula and rostellum lacking hooks

3 testes/proglottid

Strobila reaches lengths of 1 to 3 feet.

Life Cycle of Hymenolepis diminuta

1. Adult tapeworm in ____________________________________

2. Gravid proglottids rupture in large intestine and eggs are released in the feces.

Life Cycle of Hymenolepis diminuta

3. Eggs are ingested by ______________________________________

4. Oncosphere transforms into a ___________________ in body cavity of the beetle.

5. Grain beetle is eaten by rat. Cysticercoid develops into the adult.

Life Cycle Stages of Hymenolepis diminuta

Cysticercoid Grain Beetle intermediate

Human Infections of Hymenolepis diminuta

Human infections are associated with _______________________________________________________________________________________________

Diagnosis of Hymenolepis diminuta

Identification of eggs in the feces.

Eggs are characterized by thick, translucent ______________________ surrounding _______________________with 6 hooks.

Importance of Hymenolepis diminuta

Hymenolepis diminuta is easily maintained in laboratory rats

Subject of numerous experimental studies and EM studies

Hymenolepis (=Vampirolepis) nana

Known as the _____________________________________ - probably the most common tapeworm parasite of humans.

Commonly infects children.

Tapeworm is cosmopolitan in distribution.

Prevalence of 1% in humans in the southern U.S.

Hymenolepis (=Vampirolepis) nana

DEFINITIVE HOSTS - ___________________ ______________________________________

ADULT MORPHOLOGY - scolex with 4 acetabula and rostellum with circle of hooks

Strobila reaches length of 40 mm (1 - 1 ¼ in.)

Proglottids wider than long and contain 3 testes

Life Cycle of Hymenolepis nana

1. Adult tapeworm in __________________________

2. Egg egg released in feces.

3. Egg ingested by optional intermediate host - ___________________________

4. _________________________ develops in insect body cavity and is infective to human or rat definitive host.

Life Cycle of Hymenolepis nana

5. Autoinfection is more common:

• egg is ingested by the human

• egg hatches in small intestine and becomes a ________________________ inside a _________________ ________________________

6. After a week, cysticercoid emerges and becomes an adult in human small intestine.

Hymenolepis nana

Cysticercoids in villi of small intestine in autoinfection

Hymenolepis nana

PATHOLOGY - Infections of a few tapeworms are _____________________

• In heavy infections associated with autoinfection, worms cause ______________________________________________________. Never life-threatening.

DIAGNOSIS - ID ova in feces

• similar to H. diminuta but smaller

TREATMENT - ______________________

Family Dilepidae

Dipylidium caninum

Double-pored tapeworm of __________________.

Cosmopolitan distribution.

Other definitive hosts are _____________________________

Adult of Dipylidium caninum

Scolex with tiny hooks on rostellun

Mature proglottids recognized by presence of 2 sets of reproductive organs. Genital pores occur on each side of proglottid.

Gravid proglottids are cucumber-shaped and contain many egg sacs.


Strobila is about 1 foot long. Gravid proglottids are easily recognized by cucumber-shape.

Scolex with rostellum containing tiny hooks and 4 acetabula.


Mature proglottid

Testes

Vas deferens

Genital pore

Vagina

Ovary

Vitellarium

Testes


Gravid proglottid - _______________________________

• cucumber shape (tapered at ends) with 2 genital pores

• contains egg packets

• motile and may crawl out of dog’s anus

Egg packet

Life Cycle of Dipylidium caninum

1. Adult tapeworm in ____________________________________________

2. Gravid proglottid (diagnostic stage) released in feces

3. Eggs in packets are released from gravid proglottid as it dries.

Life Cycle of Dipylidium caninum

4. Egg ingested by intermediate host - ____________________________________________

5. _____________________ develops in the body cavity of louse or flea. 6. When flea or louse is ingested by dog or human, cysticercoid becomes adult in small intestine.

Human Infections of Dipylidium caninum

Human infections common in children associated with pets.

Why?

PATHOLOGY - Few worms are __________________________

Heavy infections result in _______________________________________

TREATMENT - ____________________________________

Cyclophyllidean Tapeworms

Documents

Transcript of Cyclophyllidean Tapeworms