7. Finals Class Trematoda

CLASS TREMATODA

MONOECIOUS FLUKES LIVER FLUKES Fasciola hepatica and Fasciola gigantica Chlonorchis sinensis Opistorchis felineus and Opistorchis viverrini Dicrocoelium dendriticum INTESTINAL FLUKES Fasciolopsis buski Echinostoma ilocanum Heterophyes heterophyes Metagonimus yokogawai LUNG FLUKE Paragonimus westermani DIOECIOUS FLUKES BLOOD FLUKES Schistosoma japonicum Schistosoma mansoni Schistosoma haematobium

GENERAL CHARACTERISTICS

Broadly oval or _________________ in shape with an oral sucker, a

prepharyngeal tube, a pharynx, an esophagus, and a bifurcated intestinal

ceca which ends blindly except in the ___________________

They vary in size and shape. The most characteristic external structure

are the _______________________ (suckers)

Digestion is predominantly an _______________________

Respiration is essentially ____________________

Excretory system is bilaterally symmetrical and open at the posterior

end of the body with ____________________________

Nervous system is composed of a group of

______________________ disposed like saddle on the dorsum of

the pharynx or esophagus, and a main pair each of posteriorly and

anteriorly directed nerve trunks in the dorsal, ventral and lateral fields


They are hermaphrodites (monoecious) except for HUMAN

BLOOD FLUKES

The _______________________________ trematode is found

in the DEFINITIVE HOST

Both male and female reproductive organ system have one

common opening known as the ________________________

Male reproductive system is composed of the prostate enclosed by

____________________________________ followed by

dilatation known as SEMINAL VESSICLE, leading to ONE VAS

DEFERENS the bifurcate into 2 vas deferens which ends into a

PAIR OF TESTES

Female reproductive system consists of a sac-like structure called

the UTERUS which opens into the ____________________,

then the OOTYPE, then the OVIDUCT ending in a single ovary


All trematodes lay eggs which upon embryonation, give rise to a

ciliated embryo known as MIRACIDIUM. All eggs to trematodes

are provided with a lid called an OPERCULUM except for the

BLOOD FLUKES whose eggs are NON OPERCULATED

Trematodes need BODY OF WATER to complete the life cycle. All

require 2 INTERMEDIATE hosts except the BLOOD FLUKES

which only has one I.H.


LIFE CYCLE OF TREMATODES

◦ ________________ – adult fluke

◦ _________________-larva

◦ _________________ free swimming stage, ciliated embryo which hatches in water to penetrate the 1st IH

◦ __________________ sac-like structure with GERM BALLS which proliferate, found in snail host

◦ ________________ sac-like structure containing ORAL SUCKER, a pharynx, a birth pore, carcaria germ balls, and another generation of redia, also found in the snail host (1st IH)

◦ ___________________– stage in the life cycle which emerges from the snail host; all possess tail, therefore they are free swimming

◦ ___________________– found in 2nd IH


TYPES OF CERCARIA

◦ Lephocerous

A. Simple tailed

B. Keeled tailed

◦ Microcerous

◦ Fork-tailed – bifurcated at its dorsal end


IMPORTANT DIFFERENCES IN DEVELOPMENTS

1) Egg embryonated when laid----hatches on contact with water--

--miracidium actively enters appropriate mollusk----develops

into 1st generation sporocyst (S1)-----produce 2nd generation

sporocyst (S2) ----produce cercaria

2) Egg not embryonated when laid but matures in water and then

hatches----miracidium, after entering the mollusk, develops

into 1st generation sporocyst (S1)----produces redia----which

then produce cercaria


IMPORTAN DIFFERENCES IN DEVELOPMENTS

3) Egg not embryonated when laid but mature in water and h

hatches---miracidium, after actively entering the mollusk,

develops into redia---produces 2nd generation rediae----which

then produce cercariae.

4) Egg embryonated when laid but hatches only when ingested

by appropriate snail----miracidium develops into 1st generation

sporocyst (S1)----produces rediae----which then produce

cercariae


INTESTINAL CECA ◦ Branched:

◦ Simple:

◦ Simple but arranged in a zigzag fashion:

TESTES ◦ Branched and arranged in tandem:

◦ Deeply lobulated testes arranged in tandem or dumbell testes:

◦ Lobulated testes arranged side by side:

◦ Oval or round testes arranged side by side or slightly oblique:

◦ Lobular testes obliquely arranged:


OVARY

◦ Branched:

◦ Lobulated:

◦ Oval or round:

VITELLARIAE

◦ Highly branched:

◦ Finely granular vitelline follicles:

◦ Medium sized vitelline follicles:

◦ Polygonal:


MANNER OF TRANSMISSION Ingestion of ______________________through

improperly cooked 2nd IH

Skin penetration by __________________in flukes

CONTROL AND PREVENTION Chemotherapy of cases discovered in the human

population

Disinfection of excreta or their sanitary disposal

Anti-molluscal campaigns

Education of the population to refrain from bathing in “infected” water and from eating improperly prepared foods

MONOECIOUS FLUKES

LIVER

FLUKES

Fasciola hepatica

COMMON NAME

◦ ________________________________

DISEASE

◦ Fascioliasis, _________________

GEOGRAPHICAL DISTRIBUTION Fascioliasis occurs worldwide. Human infections with F.

hepatica are found in areas where sheep and cattle are raised,

and where humans consume raw watercress, including Europe,

the Middle East, and Asia.

Fasciola hepatica MORPHOLOGY

Fasciola hepatica PATHOGENESIS, PATHOLOGY, AND

SYMPTOMATOLOGY

◦ IMMATURE ADULTS

Ectopic lesions in the intestinal _____________________

◦ MATURE ADULTS

Irritation and inflammation of the bile duct including biliary obstruction due

to pressure toxic metabolites

Development of parenchymal atrophy and periportal cirrhosis

Enlarged tender liver, jaundice, diarrhea, and anemia

S/S: sever headache, irregular fever, chills, diarrhea, urticarial rashes, stabbing

substernal pain, right upper quadrant pain that radiate to back and shoulder,

vomitting. In the latter course, there is tenderness and enlargement of the

liver with jaundice, which is hepato-cellular and obstructive in type,

leukocytosis, with 60% eosinophilia

Fasciola hepatica _________________________________________

◦ Laryngopharyngitis due to eating raw infected sheep or goat liver; the young

adullt flukes attached to the pharynx, larynx, eustachian tube and palate; S/S

include dyspnea, dysphagia, deafness, and asphyxia

_________________________

◦ An ectopic foci wherein the flukes lodged themselves in the subcutaneous tissue

causing an oval or round reddish-brown discoloration with associated pain and

itchy sensation

_________________________

◦ Due to ingestion of infected liver with passage of eggs in the feces. Ruled out by

keeping patient on a liver-free diet fro at least 3 days. If eggs continue to pass

out, infection is probably genuine

Fasciola hepatica DIAGNOSIS

◦ DFS

◦ Concentration and sedimentation methods

◦ Biliary drainage

TREATMENT

◦ Triclabendazole is the treatment of choice

PREVENTION

◦ Eliminate molluscan host with 1: 50,000 solution of cupric sulfate

◦ Proper drainage of pasture

◦ Sanitary protection of water beds

◦ Eradication of parasite in reservoir host which is the sheep

◦ Avoid eating raw salad (water cress)

Fascioliasis is endemic in the Philippines, and is common among_________________

Fasciola gigantica

DISEASE

◦ Fascioliasis

GEOGRAPHICAL DISTRIBUTION

◦ Infections with F. gigantica have been reported, more rarely, in

Asia, Africa, and Hawaii

MORPHOLOGY

◦ Refer to laboratory manual

Fasciola gigantica INTERMEDIATE HOST

◦ The species of Fasciola can become adapted to new intermediate

hosts under certain conditions based on laboratory trials.

◦ It has been reported that the most important intermediate host

for Fasciola gigantica is Radix auricularia

◦ Lymnaea rufescens and Lymnaea acuminata are the host snails in

the Indian Subcontinent

◦ Radix rubiginosa and Radix natalensis are the hosts in Malaysia

and in Africa respectively; and the synonymous Lymnaea cailliaudi

is the intermediate host in east Africa

Fasciola gigantica DEFINITE HOSTS

Fasciola gigantica is a causative agents (together with Fasciola

hepatica) of fascioliasis in

____________________________________________

worldwide

The parasite infects ________________________ and can

also be seen regionally in goats, sheep, and donkeys.

Fascioliasis

Disease Most of the clinical knowledge about fascioliasis is based on cases

caused by Fasciola hepatica. However, the same principles and

clinical features are thought to apply to F. gigantica.

Fasciola parasites do not multiply in people. Therefore, the parasite

burden depends on the inoculum, including the potential for

reinfection.

Clinical manifestations reflect host factors and the parasite burden,

the large sizes of Fasciola eggs and of adults flukes in and of

themselves can be problematic.

They can compound the tissue damage and increase the abdominal

pain when larval flukes migrate through the liver and can

predispose to biliary obstruction during the chronic phase.

Fascioliasis Both the acute and chronic phases of infection can be symptomatic

or symptom free.

Nonspecific clinical features of both phases can include:

◦ fever, which can be intermittent

◦ malaise

◦ abdominal pain, in the right upper quadrant, epigastrium, or more

diffuse/generalized

◦ other abdominal symptoms (such as anorexia, nausea, vomiting, diarrhea,

change in bowel habits, and weight loss) and signs (such as

hepatomegaly and jaundice)

◦ eosinophilia, which is more prominent and less variable during the acute

phase than in the chronic phase

◦ anemia, especially in children; and

◦ transaminitis (during the chronic phase, laboratory testing also can

indicate hepatobiliary obstruction)

Fascioliasis

_________________________________ The _________________ is also referred to as the

________________________________________________

Immature larval flukes migrate through the intestinal wall, the peritoneal cavity, the liver capsule, and hepatic tissue and, ultimately, to the bile ducts.

Lasts up to 2 to 4 months and ends when the larvae reach and mature in the bile ducts.

Larval migration, especially through the liver, can result in tissue destruction, inflammation, local or systemic toxic/allergic reactions, and internal bleeding.

Symptoms, in addition to those listed above, can include urticaria, cough, and shortness of breath. This phase can be life-threatening in sheep infected with large inocula of parasites. However, severe illness is uncommon in people, although some young children may have intense abdominal pain.

Fascioliasis __________________________________________ The chronic phase is also referred to as

___________________________________________________The chronic phase begins when immature larvae reach the bile ducts, mature into adult flukes, and start producing eggs. The eggs are passed from the bile ducts into the intestine and then into feces. During this phase, the patient may be asymptomatic for months, years, or indefinitely. The only finding on routine blood testing may be peripheral eosinophilia, which typically is less prominent than during the acute phase.

Some experts differentiate between an asymptomatic latent phase and a symptomatic obstructive phase, which only some patients experience. The symptoms, if any, may be similar to those during the acute phase or may be more focal/discrete, reflecting: ◦ cholangitis and biliary obstruction, which can be intermittent;

◦ cholecystitis and gallstones;

◦ pancreatitis; and

◦ cirrhosis.

On the basis of limited data, the life span of adult flukes in people may be 5 to 10 years, perhaps even longer.

Fascioliasis __________________________________

Fasciola parasites usually go to the liver and bile ducts. However,

larval flukes also can migrate to ectopic (aberrant) sites, such as the

lungs, subcutaneous tissue, genitourinary tract, or brain. Fasciola

parasites at ectopic sites may or may not mature into adult flukes.

For example, subadult worms may emerge through the skin.

In addition, Fasciola hepatica and F. gigantica have been reported to

cause pharyngeal infection in people who ate raw sheep or goat

liver that contained immature flukes. In this unusual scenario, the

larval flukes emerge from the liver and attach to the pharyngeal

mucosa.

Pharyngeal fascioliasis (and other parasitic infections) acquired in

this manner from raw liver is also known as halzoun (a local,

Middle Eastern term). The clinical features can include dysphagia,

dyspnea, bleeding, and airway obstruction.

Chlonorchis sinensis COMMON NAME

◦ _________________________________________

DISEASE

◦ Chlonorchiasis


◦ Endemic areas are in Asia including Korea, China, Taiwan, and Vietnam.

◦ Clonorchiasis has been reported in non endemic areas (including the United

States). In such cases, the infection is found in Asian immigrants, or following

ingestion of imported, undercooked or pickled freshwater fish containing

metacercariae.

HABITAT

◦ _________________________________ passages

Chlonorchis sinensis MORPHOLOGY

◦ Adult

Measure from 10-25 mm, spatulate organism, attenuated anteriorly and rounded posteriorly

Integument is ASPINOSE

Oral sucker is slightly larger than the ventral sucker

Most characteristic feature: _________________________________________which are situated one behind the other in the posterior 3rd of the body, with large branches extending into the lateral fields

Vitellaria are delicate, granular aggregrates in the lateral field

◦ Eggs

Measure about 27-35 u

Broadly ovoidal with a moderately thick light yellow brown shell provided with a distinct convex operculum which fits into a rimmed extension of the shell

Thick posterior and with a ____________________________________________________

__________________when laid

Contain mature __________________

Chlonorchis sinensis

Chlonorchis sinensis MODE OF TRANSMISSION

◦ Ingestion of __________________through improperly cooked infected

freshwater fish

1ST INTERMEDIATE HOST

◦ Melanoides tuberculatus, Corithidia, Thiara, and Bulimus

2ND INTERMEDIATE HOST

◦ Fresh water fishes (Bangus, tilapia, Kanduli, etc)

Chlonorchis sinensis EPIDEMIOLOGY AND PATHOGENESIS

◦ Human infection is characterized by proliferation of the bile duct

epithelium and of the surrounding connective tissue due to irritation,

inflammation of the biliary passages resulting in liver cirrhosis,

destroying liver parenchyma and obstructing portal blood flow

◦ Toxemia is due to decreased detoxifying ability of the liver

◦ Symptoms are divided into 3 stages:

1) _______________________– mild infection

2) _________________________– epigastric pain, producing GIT disturbances

like diarrhea, indigestion, anorexia, irregular appetite, fullness of abdomen,

hepatomegaly and tenderness, abdominal pain, leukocytes with 40% eosinophilia

3) ______________________– producing portal cirrhosis, jaundice, anemia,

edema, and ascitis

Chlonorchis sinensis DIAGNOSIS

◦ DFS

◦ Duodenal aspirate

◦ Non-specific immunological tests

TREATMENT

◦ Praziquantel

PREVENTION

◦ Prevention centers on adequate cooking of fish and proper disposal of human

waste

◦ Add __________________as sterilizing agent in fresh night soil endemic areas

Opistorchis felineus COMMON NAME

◦ __________________

DISEASE

◦ Opistorchiasis


◦ O. felineus is found mainly in

_______________________________

HABITAT

◦ Distal ___________ passages

Opistorchis felineus MORPHOLOGY

◦ Adult:

Measures from 7-12 mm

________________in shape with a subterminal oral sucker

Ventral sucker is almost of equal size as the oral sucker

Diagnostic feature: ________________________arranged obliquely to

each other

On the lateral field of the worm are transversely compressed vitelline follicles

Simple intestinal ceca

◦ Ova/ Egg:

Measures 30 x 10 u

Elongatedly oval in shape and resembles the C. sinensis ova in shape

Absence of prominent shoulder rim

Opistorchis felineus

Opistorchis felineus 1st INTERMEDIATE HOST

◦ Melanoides tuberculatus

2nd INTERMEDIATE HOST

◦ Fresh water fish (_____________)

PATHOGENESIS 30-60 worms

No serious damage

If _________: enlargement of liver with tenderness, passive congestion of the spleen, gastric disturbances, pancreatic involvement, cystic dilatation of biliary duct and thickening due to increase fibrous growth leading to cirrhosis and portal hypertension

_________ can be built in the egg

Simulate _________with subsequent __________

S/S include: anemia, abdominal fullness, diarrhea, vomitting, urticaria, enlargement of the liver, jaundice, flatulence, leukocytosis with eosinophilia

Opistorchis felineus DIAGNOSIS

◦ DFS

◦ Duodenal aspirate

TREATMENT

◦ Praziquantel

PREVENTION

◦ Same with C. sinensis

***** ___________ is associated more with O. felineus than with C. sinensis

****_____________ is associated more with C. sinensis than with O. felineus

Opistorchis viverrini COMMON NAME

DISEASE

◦ Does not cause nay specific symptoms


◦ O. viverrini is found mainly in northeast

MORPHOLOGY

◦ Similar with O. felineus except for its greater proximity of the

ovary and testes, fewer clusters of aggregated vitellaria

Opistorchis viverrini LIFE CYCLE: Same with the O. felineus

Dicrocoelium dendriticum COMMON NAME

DISEASE

◦ Dicrocoeliasis


◦ Europe, northern Asia, America and northern Africa

MORPHOLOGY

◦ Refer to laboratory manual

Dicrocoelium dendriticum

PATHOGENESIS

◦ Most infections are light and asymptomatic. In heavier infections, symptoms may include cholecystitis, liver abscesses and upper abdominal pain.

DIAGNOSIS

◦ Microscopic identification of eggs in the stool or duodenal fluid. If eggs are found only in stool, it could represent spurious passage following the ingestion of infected animal liver. Additional specimens should be collected to confirm a true infection.

TREATMENT

In humans, the diagnosis of dicrocoeliasis is typically spurious based on parasite eggs that are passed in the feces after consumption of infected animal liver. True infections are rare. Infection has been treated successfully with praziquantel, 25 mg/kg three times orally daily for 2 days. Praziquantel is not approved for treatment of children less than 4 years old. Niclosamide is effective but is not available in the United States.

Documents

7. Finals Class Trematoda