Fungus

Phylum Platyhelminthes

Class Trematoda
Subclass Digenea ( The trematodes with 2 generations in their life cycle ) indirect life cycle .
Subclass monogenea (Direct life cycle with one generation in their life cycle ex. Fish infection .
General characters of Digenetic trematodes :
1 – Leaf – like shaped unsegment, flat worms called Flukes.
2 – Size varies from 1 MM to several centimeters.
3 – The organs of attachment are two suckers oral and ventral suckers the last one known as acetabulum.
4 – Sexes are not separated , each worm is a hermaphrodite (Monoecious ), except the Schistosomes ( Dioecious ).
5 – Body cavity is absent.
6 – Alimentary canal is present , but incomplete the anus is absent.
7 – Excretory and nervous system are present .Excretory system consist of flame cells and collecting tubules which open posteriorly in to excretory pore.
8 – Reproductive system is highly developed.
9 – The worms are oviparous and the eggs with operculum except that of the Schistosoma .
FOUR KINDS OF FLUKES ARE PRESENT THESE ARE:
LIVER FLUKES. ex. Fasciola hepatica ,Fasciola gigantica and Clonorchis sinusis .
INTESTINAL FLUKES . EX . Fasciolopsis buski
( Giant intestinal fluke ) and Heretrophyes heterophyes .
LUNG FLUKES . ex . Paragonimus westermani .
BLOOD FLUKES Schistosoma spp .
LIVER FLUKES
Fasciola hepatica
It is known as sheep liver fluke. This disease is world –wide in distribution. The parasite infects herbivorous animals like sheep ,goat and cattle and occasionally Man .
Morphology : The adult worm is large leaf –like , unsegmented , 3 cm in length and 1.5 cm in breadth and brown or grey in colour, there are 2 suckers, The oral sucker is smaller than the ventral .The intestinal caeca is highly branched.
Life span in sheep is 5 years and in man about 10 years.
The ova is large, ovoid in shape brownish – yellow in colour.
Measuring 140 M by 80 M , and it is operculated.
Excreted with the bile to the duodenum and intestine and the faece.


Life Cycle:
Definitive host: Sheep, Goat, Cattle and Man, Sheep is considered the reservoir host for the infection

Intermediate host : Snail of the genus Lymnaea

The eggs pass out in the faeces of the definitive host , mature in water and from each egg a ciliated miracedium will be developed in 2 – 3 weeks .
The miracedia enter the body of the intermediate host ( Snail of the genus Lymnaea ) .
Inside this host the miracedia pass through the stages of Sporocyst , 2 generations of Redia and finally to Cercaria. The whole cycle takes from 1 – 2 month.
The cercaria after leaving the snail swim in the water and encyst on grasses and water plants forming Metacercaria .
The Metacercaria will be swallowed with the grass by the definitive host: sheep , goat , cattle and occasionally Man .
On entering the digestive tract , the Metacercaria excysts in the duodenum and migrate through intestinal wall to the peritoneal cavity and enter the liver capsule and settle in the bile ducts of the liver and develop to adult worms .This takes about 3 months .

Pathogenicity:

Infection of the liver with F. hepatica is known ( liver Rot ) Fascioliasis is prevalent in sheep ,goat and cattle in the middle and south parts of Iraq and to less extent in the north , heavy infection now a day in man reported in Iraq .
The infection causes great loss and mortality especially among sheep, goat and less in cattle.
Heavy infection of the liver causes liver cirrhosis and damage to the liver tissue.
It was once primarily thought of, as Veterinary problem but it has been estimated that 17 million people are infected and that 180 million are at the risk of infection.
The pathogen is wide spread, all over the world. Infection begins with consumption of water plants or bad or not washed vegetables.
Disease signs and symptoms in man:
Fascioliasis occurs in two stages:
The first stage, larval period is marked clinically by abdominal pain, fever, weight loss and articaria . Eosinophilia and elevations in liver transaminase. This stage can last for several months. Egg production during this stage is minimal.
The second stage, refers to biliary period, represents the maturation of larvae in to adult flukes that pass in to the biliary ducts. Symptoms during this phase are often subtle, vague and even asymptomatic. Patients may develop intermittent right upper quadrant pain, which can mimic cholecystitis . Ova are released.
Complications from chronic disease include anemia, cholangitis, biliary obstruction, jaundice and liver cirrhosis. Subcapsular liver hematomas and hemoperitoneum are also reported.
Ectopic sites include inguinal lymph nodes, subcutaneous skin , brain and eyes infection , no potential for malignancy of the biliary tract .
Diagnosis:
General stool examination by finding the eggs.
Radiological examination X –Ray.
Ultrasound ,and CT scan .
ELISA.
Treatment:
Triclabendazole , abenzimidazole is the first line treatment 10 mg / kg B.W. as a single dose . For more severe disease, an additional dose can be taken 12 hours later.
Prevention and Prophylaxis :
Early detection of the infection.
Public health measures and health care workers.
Improving sanitation, decreasing outdoor defecation.
Improvement of inspection and transport of vegetation.
Shedding of viable eggs.
Control snail populations.
Routine treatment of livestock .
Fasciola gigantica : Another species of Fascioliasis prevalent in Iraq .
Life cycle and hosts similar to that of F. hepatica.


Clonorchis sinusis : (Chinese liver fluke ) :

The habitat of the adult worm is the biliary tract of the liver in man, cats, dogs and pigs. The disease is prevalent in China and South –East Asian countries.

Morphology:

The fluke is elongated flat worm, size from 1 – 2 .5 cm in length by 2 -3 mm in breadth.
The oral sucker is slightly larger than the ventral sucker. Blind intestinal caeca is not branched. The life span of the adult worm is 25 – 30 years.
Characters of the eggs:
1 – Bile strained in colour, flask – shaped and operculated.
2 – Possess a terminal spine.
3 – Size is small, 35 m BY 20 m.
4 – When ovum posited it contains ciliated miracidium .
5 – It is infective to the intermediate host snail.
Life cycle:
Definitive host: Man, Pigs, Cats and Dogs.
Intermediate host: Two intermediate hosts required :
1 – Snail genus ( Bithyniinae ) .
2 – Cyprinoid Fish.
Eggs containing miracidium are passed with faeces of the definitive host on the grass or water ingested by the snail, the miracidium penetrates the intestinal wall and enters the vascular space where it passes through the stages of sporocyst , redia and cercaria , the cercaria leaving the snail in to water and attack a fresh water fish of the family Cyprinidae , the cercaria cost off their tail and encyst as metacercaria in the flesh and scales of the fish .
The infection of man and other animals occurs by ingestion of undercooked meat of the fish.
Excystation occurs in the duodenum and the larvae migrate through the bile duct to the liver, where it becomes mature in about one month.
Pathology and symptomatology
The patient suffers from pain in the right upper abdomen with slight fever and persistant diarrhea.
Biliary colic with vomiting and cough .In heavy infection the patient presents with hepatomegaly and the adult worm causes damage to the bile duct – epithelium and fibrosis.


Intestinal flukes:

Fasciola buski (Giant intestinal fluke ) ;

It is the largest trematode parasitizing man .It is prevalent in south –East Asia.
The adult worm lives in the small intestine of man and pig .The normal host is the pig which is considered the reservoir host of infection.
Morphology:
The adults measure 7.5 cm in length and 2 cm in width .The ventral sucker is larger than the oral sucker.
The intestinal caeca is not branched.
The egg is similar to that of F. hepatica but slightly larger.
Life cycle: Definitive host: Man or Pig.
Intermediat host: snail of genus Segmentina .
The life cycle is similar to that of F. hepatica.
Infection occurs by eating vegetables carrying metacercaria .
Pathogenicity;
The infection causes superficial ulceration of the small intestine associated with diarrhea, heavy infection causes anemia, vomiting and eosinophilia .
Laboratory diagnosis:
By general stool examination to find the eggs or in duodenal aspirate.
Heterophyes heterophyes :
A common parasite of Egypt .The fluke lives in the small intestine of man.

Morphology;

Very small worm measuring 2 mm. in length and o.4 mm. in width. Narrow anteriorly and broad rounding posteriorly (flask or conical shape). In addition to two suckers oral and ventral there is genital sucker .The integument is spinoused . The ovary is branched and the tests two in numbers. The ovum is small 30 M by 16 M in size, operculated and it has a knob like opposite to the operculum. The live span in man is 2 months
Life – cycle of Heterophyes heterophyes :
Definitive hosts: are Man, Dogs, Cats and Fox.
Itermediate hosts: Snail Perevella conica and a fish .
The egg contains fully developed miracidium ingested by the snail and inside the snail passes in to the stage of sporocyst , and 2 stages of redia , the cercaria leaves the snail and encysts in the flesh of second intermediate host ( The mullet fish ) man get infection by eating under cooked meat of the fish .
Pathogenicity:
The disease is known as Heterophyiasis , characterised by colic pain with mucus diarrhea .


Laboratory diagnosis: by finding the egg in stool examination.
THE LUNG FLUKE:
Paragonimus westermani :
The disease is known as Oriental Lung Fluke. It is prevalent in south East Asian countries. The adult worm lives in the Lung of man, dogs and cats.
Morphology:
The shape is oval, the anterior end is broader than the posterior end, it measures about 1cm. in length and 5 cm. in width, the integument is spinoused the excretory vesicle extend from the posterior to the anterior end dividing the body in to two halves, the intestine caeca is not branched. The genital organ consist of two testes and two ovaries, the egg is oval and operculated , golden brown in colour .
Life cycle:
Definitive hosts: Man, Cats , Dogs Tigers .
Intermediate host: The first one is snail of the genus (Melania ) , and the second one is the fresh water Crab or Cray-Fish , the eggs come out with the sputum or faeces . In water hatch in to miracidium which enter the snail ( first host ) , pass in to sporocyst , 2 stages of redia and then cercaria which leave the snail and enter the second intermediate host the Crab or Cray –fish to form the encysted cercaria or metacercaria . Man get infection by eating the under cooked or fresh Cray-fish excitation occurs in the duodenum and the larvae migrate through the intestinal wall and reach the lung where they become mature.
Pathogenicity:
The patient suffers from productive cough resembling that of Tuberculosis associated with chest pain, low grade fever and night sweating. The migration of the young worm in the lung causes extensive inflammatory reaction, and the adult worm surrounds by a thick wall (1 cm. in thickness) with only a small hole for the passage of the eggs.
Laboratory diagnosis:
By finding the worm in the faeces .