parasitologyparasitology

Medical Parasites:

- Protozoa 1- Platyhelminthes

- Helminthes: 2- Nemathelminthes

- Arthropoda 3- Nematomorpha 4- Acanthocephala 5- Annelida

WHO Classified of Helminthes WHO Classified of Helminthes According to transmission methodsAccording to transmission methods

1 -Soil transmitted Helminthes : Ascaris, Hook worms

2 -Snail t. H. : Trematoda( Schistosoma,….)

3 -Arthropods t. H. : Filaria, Dracanculus medinensis

4 -Food and Meat t. H. : Taenia saginata, Taenia solium

5 -Direct t. H. ( contagious H.): Enterobius vermicularis …,

Nematoda

General Discription

Morphology

Reproductive systemReproductive system

Digestive systemDigestive system

Bucal cavity

Classification of NematodaClassification of Nematoda

Nematoda: 1- Phasmidia (Secerenentea) 2- Aphasmida (Adenophora):

ويژگيهاي آفازميدا:

تحليل يافقدان پاپي هاي دمي--سيستم دفعي- ترشحي فاقد كانالهاي جانبي -

- مري سيلندري شكل واجد استيكوزوم يا تروفوزوم- تخمهاي بد ون سگمانته با پالكهاي قطبي

Styletعفونتزا و اغلب واجد L1- الرو مرحله - فاقد فاسميد

Order: EnoplidaOrder: Enoplida

1 -Super Family: Trichoridea Genus: - Trichuris

- Trichinella - Capillaria

- Anatrichosoma2 -Super Family: - Dioctophymatoidea

Genus: - Dioctophyma 3 -Super Family: - Mermithoidea

Super Family: TrichroideaSuper Family: Trichroideaويژگيهاي ويژگيهاي

مجزا - وماده نر جنسپهن - خلفي قسمت و ظريف قدامي قسمتواجد - نر آن 1كرم فاقد يا اسپيكولمونودلفيك - مادهاستيكوزوم - واجد مرييافته - تكامل بخوبي وركتوم روه

Trichuris trichiuraTrichuris trichiura( also called the human whipworm)( also called the human whipworm)

Life CycleLife Cycle

Geographic DistributionGeographic Distribution

The third most common round worm of humans  .

Worldwide, with infections more frequent in areas with tropical

weather and poor sanitation practices, and among children .

It is estimated that 800 million people are infected worldwide .

Clinical FeaturesClinical Features

Most frequently asymptomatic  .Heavy infections, especially in small children, can cause

gastrointestinal problems (abdominal pain, diarrhea, rectal prolapse) and possibly growth retardation

Whipworm in the gutWhipworm in the gut  

Prolapsed RectumProlapsed Rectum

Laboratory diagnosisLaboratory diagnosis

Microscopic identification of whipworm eggs in feces is evidence of infection .

TreatmentTreatment

Mebendazole is the drug of choice, with albendazole as an alternative

Causal Agents:Trichinellosis (trichinosis) is caused by nematodes (roundworms) of the genus Trichinella. 

In addition to the classical agent T. spiralis (found worldwide in many carnivorous and omnivorous animals), several other species of Trichinella are now recognized.

Trichinella sppTrichinella spp..

1- T. pseudospiralis (mammals and birds) worldwide),

2- T. nativa (Arctic bears)

3- T. nelsoni (African predators and scavengers)

4- T. britovi )carnivores of Europe and western Asia).

TrichinellaTrichinella--adultadult

TrichinellaTrichinella nativanativa

Life cycleLife cycle

Geographic DistributionGeographic Distribution

Worldwide.  Most common in parts of Europe and the United States.

Clinical FeaturesClinical FeaturesLight infections may be asymptomatic. 

Intestinal invasion can be accompanied by gastrointestinal symptoms (diarrhea, abdominal pain, vomiting). 

Larval migration into muscle tissues (one week after infection) can cause periorbital and facial edema, conjunctivitis, fever, myalgias, splinter hemorrhages, rashes, and blood eosinophilia. 

Occasional life-threatening manifestations include myocarditis, central nervous system involvement, and pneumonitis. 

Larval encystment in the muscles causes myalgia and weakness, followed by subsidence of symptoms.

                             

                               

Splinter hemorrhagesSplinter hemorrhages Swollen eyes Swollen eyes

AA, , BB:: Encysted larvae ofEncysted larvae of TrichinellaTrichinella in pressed muscle in pressed muscle tissue sampletissue sample..  The coiled larvae can be seen inside the   The coiled larvae can be seen inside the

cystscysts

                                                            

AB

Trichinella spiralisTrichinella spiralis encysted larvaencysted larva

                                 

 

CC, , DD:: Larvae ofLarvae of TrichinellaTrichinella, , freed from their cysts, freed from their cysts, typically coiled; lengthtypically coiled; length: : 0.8 to 1 mm0.8 to 1 mm..  

                                           

   

                                              

   

CD

Antibody DetectionAntibody Detection

Immunodiagnostic tests currently available in the U.S. include enzyme immunoassays (EIA). 

Antigen preparations may be crude antigens prepared from homogenates of Trichinella spiralis muscle larvae or excretory-secretory (ES) products produced by cultured larvae.

Laboratory DiagnosisLaboratory Diagnosis

The suspicion of trichinellosis (trichinosis), based on clinical symptoms and eosinophilia, can be confirmed by specific diagnostic tests, including antibody detection, muscle biopsy, and microscopy.

Trichuris trichiuraTrichuris trichiura( also called the human whipworm)( also called the human whipworm)

Life CycleLife Cycle

Capillaria sppCapillaria spp..

Causal Agents:The nematode (roundworm) Capillaria philippinensis causes human intestinal capillariasis. 

Two other Capillaria species parasitize animals, with rare reported instances of human infections.  They are C. hepatica, which causes in humans hepatic capillariasis, and C. aerophila, which causes in humans pulmonary capillariasis.

The adults ofThe adults of Capillaria philippinensisCapillaria philippinensis (males(males: : 2.3 to 3.2 mm; females2.3 to 3.2 mm; females: : 2.5 to 4.3 mm2.5 to 4.3 mm ))

Larvae of Capillaria philippinensis

Capillaria philippinensisCapillaria philippinensis egg under light microscopyegg under light microscopy.. Roll over the image for a view of unembryonatedRoll over the image for a view of unembryonated

CC. . philippinensisphilippinensis eggs inside an adult femaleeggs inside an adult female. .

Life CycleLife Cycle

Geographic DistributionGeographic Distribution

Capillaria philippinensis is endemic in the Philippines and also occurs in Thailand.

  Rare cases have been reported from other Asian countries, the Middle East, and Colombia. 

Rare cases of human infections with C. hepatica and C. aerophila have been reported worldwide.

Capillaria aerophilaCapillaria aerophila

adult worms reside in the epithelium of the tracheo-bronchial tract of various animals.  Eggs are produced, coughed up, swallowed by the animal, and excreted in its feces.  The eggs become embryonated in the soil.  Ingestion of infective eggs completes the cycle.  Transport or paratenic hosts may also intervene in the cycle.

Capillaria hepaticaCapillaria hepatica

adult worms reside in the liver of various animals, especially rats.  The females produce eggs that are retained in the liver parenchyma.  When the infected animal is eaten by another animal, the eggs are released by digestion, excreted in the feces of the second animal, and become embryonated in the soil.  Alternately, the eggs can be released following the death and decomposition of the first animal, and mature in the soil.  Following ingestion by a subsequent host, these infective eggs release larvae in the intestine that migrate through the portal circulation to the liver, where they develop into adults.

Capillaria hepaticaCapillaria hepatica eggseggs

Capillaria hepaticaCapillaria hepatica eggs in tissueeggs in tissue..  The egg in  The egg in DD (higher (higher magnificationmagnification) ) has a typically striated shell and shallow polar has a typically striated shell and shallow polar prominencesprominences

CapillariaCapillaria hepatica hepatica eggs in livereggs in liver tissuetissue

Clinical FeaturesClinical Features

Intestinal capillariasis (caused by C. philippinensis) manifests as abdominal pain and diarrhea, which, if untreated, may become severe because of autoinfection. 

A protein-losing enteropathy can develop which may result in cachexia and death. 

Hepatic capillariasis (C. hepatica) manifests as an acute or subacute hepatitis with eosinophilia, with possible dissemination to other organs.  It may be fatal. 

Pulmonary capillariasis(C. aerophila) may present with fever, cough, asthma, and pneumonia, and also may be fatal.

Laboratory DiagnosisLaboratory Diagnosis

The specific diagnosis of C. philippinensis is established by finding eggs, larvae and/or adult worms in the stool, or in intestinal biopsies. 

Unembryonated eggs are the typical stage found in the feces.  In severe infections, embryonated eggs, larvae, and even adult worms can be found in the feces.

The specific diagnosis of C. hepatica infection is based on demonstrating the adult worms and/or eggs in liver tissue at biopsy or necropsy. 

(Note: identification of C. hepatica eggs in the stool is a spurious finding, which does not result from infection of the human host, but from ingestion by that host of livers from infected animals.)

The specific diagnosis of C. aerophila is based on demonstrating eggs in stool or in lung biopsy

Microscopy

Capillaria philippinensis eggs.  These unembryonated eggs are peanut shaped and measure 36 to 45 µm in length by 21 µm in width.  They have two inconspicuous polar "plugs" and a striated shell.

Dioctophyma renaleDioctophyma renale

Commonly called the giant kidney worm, Dioctophyma renale has been found most frequently in mustelids and in wild and domestic carnivores in practically all parts of the world.  Infrequent occurrences of the parasite have been recorded in pigs, horses, cattle and man

Adult worm showing enormous sizeAdult worm showing enormous size

Length20 to 100 cm

Drawing showing Drawing showing charactericscharacterics of a male's fleshy bursa of a male's fleshy bursa

Dioctophyma renaleDioctophyma renale egg egg

HabitatHabitat

Dioctophyma renale has a wide range of mammalian host species, such as dog, wolf, cheetah, mink, horse, swine and humans.

Fish-eating mammals are the most common hosts of D. renale because fish often serve as paratenic hosts after ingesting an infected annelid intermediate.

Any mammal that drinks water infested with infected annelid intermediate hosts, such as horses, has the potential of ingesting an infective third stage juvenile of D. renale.

AnnelidaAnnelidasegmented wormssegmented worms

                                               

               

 

                                     

ReproductionReproduction

Pathogenesis & clinical manifestationPathogenesis & clinical manifestation

Most hosts of D. renale, including humans, suffer from pressure necrosis caused by growing worms and their feeding activities. This reduces the infected kidney to a thin-walled, ineffective organ.

Loss of kidney function and uremic poisoning are severe side effects.

TreatmentTreatment

Treatment is limited to surgical removal of the parasite and the affected kidney.

                                   

                   

                                                                                 

 

Photography of canine dioctophymosisPhotography of canine dioctophymosis