Exam 3

Humans, canids, felines, bears, and otters

Mammal host (where worms reproduce)

Feces of the mammal host (definitive host)

Eggs are ingested by a freshwater crustacean (like copepod)

Crustacean (copepod)

Procercoid larvae

Minnow or other small freshwater fish

Procercoid larvae are released from crustacean and migrate into fish's flesh, where it develops into plerocercoid larvae

Plerocercoid larvae

Small second intermediate hosts are eaten by larger predator (mammals) raw or undercooked

Develop into immature adults and then into mature adult tapeworms, residing in small intestines

Small intestine of mammals

Two bilateral grooves (bothria) of their scolex

One of several tape-like proglottid segments regularly detach from the main body of the worm

Freshwater

20 years

Diphyllobothriasis

Diphyllobothrium latum

Generally mild,
diarrhea, abdominal pain, vomiting, weight loss, fatigue, constipation and discomfort

4 out of 5 cases are asymptomatic

Megaloblastic anemia: severe B12 deficiency due to parasite absorbing 80% or more of host B12 intake

Pernicious anemia

No, infection of many years is normally required to deplete the human body of B12 to the point that neurological symptoms appear

By identifying proglottid segments, or characteristic eggs in feces

Taenia solium

Pig eats the eggs or Travis proglottid of the tapeworm shed in the feces of a human

Oncosphere stage hatches in the intestines

Invades the intestinal wall and migrates to the striated muscle, the brain, liver, and other tissues;
oncosphere encysts in these tissues and waits to be eaten

Pig

Becomes cysticercus stage

Infected with cysticercus stage by eating raw or undercooked pork

As an intermediate host and as a definitive host

Human ingests raw / undercooked pork containing cysticercus stage

Attaches to the small intestine by scolex, or head, by using hooks and suckers on the head

Years

Humans ingest cysticercus stage and attaches to small intestine

Human ingests eggs shed in the feces of a human tapeworm carrier then become infected with oncosphere

Migrates out of the anus on its own or in feces

Drops on the ground and the proglottid dries up and releases the eggs inside

Wall around the egg is digested, oncosphere hatches in the intestine and invades intestinal wall, migrates to striated muscles as well as brain, liver, and other tissues

Develops into cysticercus; in humans, can cause sequence if they localize int eh brain, resulting in cysticercosis

T solium cysts cause serious sequelae that localizes in the brain

Ingestion of T solium eggs or proglottid rupture within the host intestine causing larvae to migrate into host tissue and cause cysticercosis

Cysticercosis

Wide spectrum including headaches, dizziness, and occasional seizure

Location, size, and number of parasite larvae in tissues, as well as host immune response.

MRI, CAT scan or Xray

Finding eggs or proglottid in stool

No only genus

By staining proglottid's uterus stained with India ink

Visible uterine branches (that can help identify the species)

T solium uteri only have 5-10 uterine branches on each side

Taenia saginata

Humans

Cattle

Finding eggs from parasite in stool sample

Eggs look like other eggs from genus Taenia, so no, not at species level

Every proglottid contains multiple eggs and uteri

India ink (to see uterine branches)

12 or more branches on each side

Malnourished patients (the tapeworm will take vital nutrients)

Patient is infected with adult stage of T solium or T saginata (by finding eggs or proglottids in the feces)

No!

Cysticercosis means the pt is having symptoms related to where the intermediate stage (the cysticercus) is located in the body, accomplished thru MRI Scan, CT Scan, or X-ray

Diagnosis of cysticercosis cannot be made by stool exam

Echinococcus granulosus

Canids (dogs, coyotes, wolves) as an adult

Herbivores, where it causes hydatid disease

Herbivores (intermediate hosts)

Immature proglottid
mature proglottid
Gravid proglottid

Four suckers on scolex (head), and rostellum with hooks

Passed in canids (dog's) feces

Herbivores, such as sheep, deer, moose, kangaroos, and wallabies that ingest dog feces or eggs

Petting a dog that had eggs on its fur

Eggs hatch into oncosphere larvae and penetrate through the intestines

Travel through the blood and form a type of bladder worm called hydatid cyst in host's tissues

Brood capsules

Protoscolices that are infective to the definitive host

Protoscolices

Dog eats tissues of an animal that has the hydatid cyst containing protoscolices, cyst wall is digested away

Protoscolices evaginate and attach themselves to the villi of the small intestines;
then mature into adult worms

Size of softball or basketball that may contain several smaller 'balloons' inside the main cyst

Organs like liver, brain, and lungs
NOT in subcutaneous tissue

Liver or other organ enlargement
booklets in sputum
possible anaphylactic shock (when immune system reacts to ruptured cysts)

Ultrasound, MRI, or serologic testing (like enzyme immunoassays (EIA), Indirect fluorescent antibody (IFA), or indirect Hemagglutination (IHA) tests)

Immunoblot assay

With surgery;
special care must be taken not to nick the cyst or the patient will die of anaphylactic shock

Keep dogs from being infected by preventing them from eating infected offal (guts) of infected animals like sheep

Avoid ingesting food or other substances contaminated with dog feces

Intermediate host is optional, and very tiny

When eaten by a person or rodent, hatches in duodenum of the small intestine

In duodenum

Oncospheres penetrate the mucosa and lie in the lymph channels of the villi; then develops into cysticercoid

Emerges into the lumen of the small intestine where it attaches and matures

Direct — doesn't involve intermediate host
indirect — involves a larval flea or beetle

Larval flea or beetle

Larval flea or beetle ingests the eggs that then hatch and become oncospheres and then cysticercoid

Human ingests the larval flea or beetle, then the cysticercoid stage is swallowed and matures to an adult in small intestine

When insect larvae are preset in flour and consumed with flour; also when accidentally ingesting rodent feces with eggs in it, associated with contaminated flour

Small intestine ; which come out in the feces of either rodents or humans

Finding the eggs in human feces

White blobs of cysticerci in meat (seen with naked eye)

Nematode (roundworms)

When an infective egg is ingested in fecally contained food or water

In intestine, larval worm is released from egg and penetrates the wall of the duodenum and enters blood stream

Carried to the hear, and enters pulmonary circulation, where it breaks free in alveoli, where it grows and molts

In 3 weeks, the larvae pass from respiratory system to be coughed up, swallowed, and thus returned to the small intestine

Mature to adult male and female; female lays thousands of eggs that are passed out with feces

Fertilized eggs land in soil and become infectious after 2 weeks in soil

10+ years

1. Blocks intestines
2. Poor cognitive development in kids
3. Parasite pneumonia
4. Verminous intoxication*

1. In heavy infections, nematodes block intestine
2. Heavy infestations in children associated with poor cognitive development and stunted growth
3. Heavy infections can cause pneumonia
4. VERMINOUS INTOXICATION

Finding the eggs or adults in the stool

Enterobius vermicularis

Pinworm

Human gastrointestinal tract of a single human host

Eggs are ingested and hatch in the duodenum (first part of small intestine)

Migrate through the small intestine towards the colon; during this migration, they mount TWICE and become adults

Settle in the large intestine, attaching to the mucosa and ingest intestinal contents; almost entire body of gravid female becomes filled with eggs

Approx 5 weeks after initial ingestion of pinworm eggs by human host

Gravid female pinworms migrates through the colon towards the rectum, emerge from anus and while moving on the skin near anus, the female pinworms deposits eggs

Female laying eggs causes itching to patients

Eggs are sticky, attach to the underwear, sheets, and under fingernails. Eggs are inhaled ad swallowed or ingested and the lifecycle starts again

Eggs are extremely sticky, easy to attach themselves to many surfaces, including walls

Finding the eggs outside the anus using a sticky paddle applied to anus; if eggs present, stick the paddle and observe under the microscope

Trichuris trichiura

Whipworm

Female T trichiura produces thousands of eggs a day that are deposited from human feces to soil

After 2-3 weeks, they become embryonated and enters the infective stage

Embryonated infective eggs are ingested and hatch in small intestine

In the small intestine

Larvae penetrate the villi and continue to develop in the small intestine

Move to the cecum and penetrate the mucosa, and there they complete development to adult worms in large intestine; attach to mucosa and suck blood

3 months

5 years

By ingesting fecally contaminated food or water that contains the eggs

1. Light infestation (<100 worms) asymptomatic
2. Heavy infestations - bloody diarrhea
3. Long-standing blood loss may lead to iron-deficiency anemia
4. Rectal prolapse (severe)
5. Vitamin A deficiency

Finding the distinctive lemon shaped eggs in stool using a concentration technique