Exam 3 Flashcards
3 classes of flatworms
Turbellaria
Trematoda
Cestoda
Life cycle stages
Egg-miracidium-sporocyst-redia-cercaria-metacercaria
Upon entering a snail the miracudium loses its cilia and transforms into a sac-like body called a
Sporocyst
Miracidum morphology- small elongate organism covered by
Cilia
Miracidium
At anterior end is the ____ that functions in contacting the snail intermediate host.
Apical papilla
Miracidium
The apical papilla contains openings from ____ When a snail is contacted the penetration glands secrete enzymes to aid in embedding the miracidium within the snails tissues
Apical gland
Miracidium
____ are common for photo reception
Eye spots
A mass of _____ lies in the posterior end. These cells divide asexually to form the next larval generation
Germinal cells
Sporocyst
- no mouth or digestive system
- germinal sacs; mother sporocyst - daughter sporocyst or redos or cercaria
In some digenetic trematodes, the germ cells in the mother sporocyst divide asexually to give rise to another generation of sporocyst s called _____ Mother sporocyst bursts to release these daughter sporocyst a
Daughter sporocyst
In other trematodes the germ cells of the mother sporocyst form a new larval stage called the
Redial stage
Each redia contains a ___ and short ____
Mouth
Intestine
___ in the mother rediae may develop into a second generation of rediae called ____ or may develop into ____ or ____
Host tissue
Germinal cells
Daughter redia
Cercaria
Where do Metacercaria occur
May occur within a second intermediate host or on aquatic vegetation
When the second intermeduate host or aquatic vegetation containing metacercaria ______ in the digestive tract and matures to the _____
Excyst
Adult stage
Family Diplostomidae
Alaria americana
Parasite of carnivorous animals
May involve multiple intermediate hosts forming a mesocercaria
Paratenic hosts
Paratenic host
Not essential but can help bridge the gap between intermediate host and the primary so that the parasite can finish its life cycle
Life cycle of Alaria americana
Alaria americana is a three- host trematode that lives as adults in the intestine of the dog definitive host. Eggs are passed in faeces and hatch in water, releasing miracidia which penetrate the helisomid freshwater snails (first intermediate host) and develop through the sporocyst stage into fercocircus cercaria that penetrates a tadpole (second intermediate host) and transforms into the unencysted stage called mesocercaria
Black spot
Uvulifer
Encysted parasite on minnows
Produce melamine that surrounds the cyst to make the black spot
Kingfisher bird
Life cycle of Uvulifer
Egg Miracidium Sporocyst (Snail) first intermediate Fircocircus cercaria free living Metacercaria Fish (second intermediate)
What was Shistosomiasis formerly known as
Bilharzia
German dude
Discovered the worm named it after himself
Name the three important species of Schistosoma infecting humans
Schistosoma mansoni
Schistosoma haematobium
Schistosoma japonicum
The slave trade introduced S. mansoni to South America but why not North America?
Aquatic snail intermediate host
Tropical climate
How is the Schistosoma parasite unique among digeneans?
Dioecious
Sexually dimorphic
Schistosoma Mansoni morphology
Most spines
6-8 testes
Smallest
Live in the veins around the urinary bladder
Schistosoma haematobium morphology
4-5 testes
Venules-veins
Schistosoma japonicum
Largest 7 testes No spines Produce the most eggs 1500-3000 eggs a day
How do female Schistosoma mature
The female is housed in the gynecophoral canal and most remain in contact with the male so that it can get the nutrients it needs to mature. If it doesn’t meet a male then it cannot mature or produce eggs and will die
Schistosoma life cycle
Schistosoma eggs are eliminated with feces or urine, depending on species image . Under appropriate conditions the eggs hatch and release miracidia image , which swim and penetrate specific snail intermediate hosts image . The stages in the snail include two generations of sporocysts image and the production of cercariae image . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host image , and shed their forked tails, becoming schistosomulae
Granulomas
Calcified nodules
How do you control Schistosoma?
Snail control
Adequate sewage treatment
Education
Medication
What is the drug used for the early stages of Schistosoma?
Praziquantel
Night soil
Human waste as fertilizer
Illegal in the US
Runoff into water passing parasites
Fasciola hepatica
Probably the most studied of the trematodes Oral cone and shoulders Regiment with spines Adult in bile passages Watercress
Life cycle of Fasciola hepatica
-Water- Operculated egg in feces Egg embryonates in water -Snails- Miracidium penetrates snail Sporocyst 1st gen redia 2nd gen redia -WaterPlants- Free swimming cercaria -Herbivores/man- Metacercaria ~ingested Excysts in duodenum ~penetrates duodenum wall ~enters peritoneal cavity ~penetrates liver ~settles in biliary passages
Symptoms and pathology of Fasciola hepatica
- chills, fever m, backache, cirrhotic liver, inflammation and edema in bile duct
- migrating juveniles cause abscesses
- eggs in fecal matter
- Halzoun from infected liver consumption
Other Fasciolid species
Fasciola gigantica
Fasciolopsis buski - 2 times bigger than hepatica
Dicrocoelium dentriticum
Lance like liver fluke
Rarely infects humans; bile duct/ gallbladder in sheep and cattle
Unusual in that no aquatic life stage occurs
Morphology of Dicrocoelium dendriticum Characteristic feature is the \_\_\_\_\_ -testes are lined in tandem -posterior to the testes is \_\_\_\_\_ Posterior portion of body consists of a \_\_\_\_
Pointed on both ends (lance)
And dilobed testes
Ovary
Uterus
Life cycle of Dicrocoelium
Eggs
Eggs ingested by snail
(Miracidum, sporocyst, redia, cercaria, inside snail tissue)
Cercariae are released from the snail via the respiratory pore in a slime bail
Metacercariae on ants
Cattle
Chinese liver fluke
Clonorchis sinensis
How do you get Clonorchis sinensis
Eating raw or undercooked fish
Life cycle of Clonorchis sinensis
Egg hatches in water -snail first intermediate host Miracidum, sporocyst, redia (in snail) Cercaria Encysted Metacercaria in fish musculature -fish second intermediate host Consumption of infected fish Excysting Metacercaria Excysted Metacercaria Adult
Two types of life cycles what are they
Order Cyclophyllidea
Order Psiedophyllidea
Pseudophyllidea pattern
Egg Coracidium Procercoid Plerocercoid Adult cestode
Cyclophyllidea
Egg Oncosphere - Cysticercus -Cysticercoid -Coenurus -Hydatid Adult cestode
Broad fish tapeworm
Diphyllobothrium latum
Life cycle of Diphyllobothrium latum
Egg release coracidia
Coracidia are ingested by copepods
Coracidia becomes Procercoid larvae
Copepod is ingested by fish, release larvae
Procercoid larvae become Plerocercoid larvae
Humans ingest fish and plerocercoid
Beef tapeworm
Taenia saginata
Life cycle of Taenia saginata
Eggs in feces Ingested by specific intermediate host Hecacanth embryo released in intestine of host Penetrates mucosa to tissue Develops into cysticercus -Cow Human ingests undercooked meat Cysticercus dissolved in intestine Scolex released Attaches to intestine Develops into adult
Taenia solium
Pork tapeworm
Life cycle of Taenia solium
Eggs in feces Ingested by specific intermediate host Hecacanth embryo released in intestine of host Penetrates mucosa to tissue Develops into cysticercus -Pig Human ingests undercooked meat Cysticercus dissolved in intestine Scolex released Attaches to intestine Develops into adult
Echinococcus granulosis
Small species Canines are usually primary host Wide variety of intermediate hosts Rossellini with hooks Usually only 3 proglottids Forms unilocular hydatid cyst in intermediate host
Life cycle of Echinoccocus granulosis
Egg in feces
Oncosphere hatches penetrates intestinal wall
Hydatid cyst in liver, lungs etc
Protoscolex from cyst
Scolex attaches to intestine
Adult in small intestine
-ingestion of eggs in feces (sheep, goats etc)
Ingestion of cysts in organs (dogs/carnivores
Name the layers of the Hydatid cyst from outside to the inside
Adventitial layer
Laminated layer
Germinal layer
Echinococcus multilocularis
Adult occurs in large canids
Small rodents serve as intermediate hosts
Primarily in Europe but also in tundra areas
Produces a multilocular Hydatid cyst whose outer layer can metastasize into host tissue
Zoonotic- relies on predator prey relationship
Germinal layer can spread to other organs and can be confused with cancer
Larval stage is the problem
Dwarf tapeworm
Hymenolepis nana
Hymenolepis nana life cycle
Eggs are immediately infective when passed with the stool and cannot survive more than 10 days in the external environment. When eggs are ingested by an arthropod intermediate host (various species of beetles and fleas may serve as intermediate hosts), they develop into cysticercoids, which can infect humans or rodents upon ingestion and develop into adults in the small intestine
Flea- has to infect larval stage cause no chewing parts
Auto infection can bypass intermediate hosts all together
Dog tapeworm
Dipylidium caninum
Dipylidium caninum
Eggs ingested by intermediate host- _____
_____ develops in the body cavity of louse or flea
When flea or louse is ingested by dog or human cysticercoid becomes adult in small intestine
Larval flea transformed into adult flea
Cysticercoid
Cysticercoid
Fleshy tail
Inverted scolex
