Ninevah University medical colleges Department of medical microbiology
PhD. Dr. Ali Abbas Al KhalafTREMATODES
TREMATODES
Class Trematoda (Flukes) General characteristics Are leaf-shaped worms, which are generally flat and fleshy. Others have different shapes such as the threadlike Schistosomes. Are hermaphroditic except for Schistosoma, which has separate male and female. Snails are the first intermediate hosts. Some species require arthropods or fish as a second intermediate hosts.TREMATODES
Schistosoma (Blood Flukes) The causative agent of Schistosomiasis or Bilharzia. One of the most frequent tropical diseases. Occurrence depends on the presence of suitable intermediate hosts. The parasites that cause Schistosomiasis live in certain types of freshwater snails. German physician Th. Bilharz, discovered Schistosoma hematobium in human blood vessels in 1851. Occurs endemically in tropical and subtropical countries of Africa, South America, Asia and Middle East.TREMATODES
Schistosoma (Blood Flukes) Human infections result from contact with water (freshwater) and Schistosoma cercariae. Schistosoma hematobium causes urinary Schistosomiasis. S. mansoni, S. japonicum,S. intercalatum, and S. mekongi are the causative agents of intestinal Schistosomiasis and other forms of the disease. Schistosomiasis is an important cause of disease in many parts of the world, most commonly in places with poor sanitation.TREMATODES
Schistosoma (Blood Flukes) School-age children who live in these areas are most at risk because they tend to spend time swimming or bathing in water containing infectious cercariae. If you live in, or travel to, areas where schistosomiasis is found and are exposed to contaminated freshwater, you are at risk.TREMATODES
TREMATODES
Schistosoma (Blood Flukes) Morphology and life cycle The relatively thick male forms a tegumental fold in which the thread like female is enclosed. The adult parasites live in the lumen of veins. Adult worms in humans reside in the mesenteric venules in various locations.TREMATODES
Schistosoma (Blood Flukes) Morphology and life cycleTREMATODES
Schistosoma (Blood Flukes)Schistosome cercaria
TREMATODES
Schistosoma (Blood Flukes)Morphology and life cycle1-Sexually mature Schistosoma females layabout 100–3500 eggs a day containing animmature miracidium.2-The miracidium within six to 10 days, remains viable for about three weeks.TREMATODES
TREMATODESSchistosoma (Blood Flukes) Morphology and life cycle 6- Enzymes produced by the miracidium cause granuloma formation.
TREMATODES
Schistosoma (Blood Flukes)Pathology1- Pathology of S. mansoni and S. japonicums chistosomiasis includes: Katayama fever, hepatic perisinusoidal egg granulomas, Symmers’ pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord.
TREMATODES
TREMATODESSchistosoma (Blood Flukes) life cycle The cercariae upon contact with a human host, Enzyme secretion and vigorous movements enable them to penetrate the skin or less frequently the mucosa when ingested with drinking water. During the infection process, the cercaria loses its tail, sheds the surface glycocalyx, forms a new tegument, and transforms into the schistosomulum.
TREMATODES
Schistosoma (Blood Flukes)TREMATODES
Schistosoma (Blood Flukes)TREMATODES
Schistosoma (Blood Flukes) Migration of Schistosomes in the Human Body Infection Schistosomula penetrates subcutaneous tissues, find venous capillaries or lymph vessels, migrate through the venous circulatory system into the right ventricle of the heart and the lungs. It travels hematogenously into the intrahepatic portal vein branches where development into adult worms takes place as wells as male-female pairing just prior to sexual maturity.TREMATODES
Schistosoma (Blood Flukes) Pathogenesis and clinical manifestations The infection can be divided into the following phases: 1-Penetration phase :penetration of cercariae into the skin occures. without reaction or, especially in cases of repeated exposure with skin lesions (erythema, papules), which disappear within a few days.TREMATODES
Schistosoma (Blood Flukes) Pathogenesis and clinical manifestations 2-Acute phase, about two to ten weeks after a severe initial infection, the symptoms like, fever, headache, limb pains, urticaria, bronchitis, upper abdominal pain, swelling of the liver and spleen, lymph nodes, intestinal disturbances, and eosinophilia (Katayama syndrome) appear.
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Schistosoma (Blood Flukes) Pathogenesis and clinical manifestations. Katayama Fever (Syndrome) Due to release of Schistosoma antigens, the serum antibody levels (IgM, IgG, IgA) rise rapidly and immune complexes are formed (is characterized by increased circulating immune complexes and eosinophils). that can cause renal glomerulopathies. 3- Chronic phase: The most significant phase in pathogenic terms begins after an incubation period of about two months with oviposition by the Schistosoma females. The miracidia grow in the egg which remain viable for about three weeks, produce antigens which are secreted through the eggshell into the tissue.TREMATODES
Schistosoma (Blood Flukes)Pathogenesis and clinical manifestations.After antigenic stimulation, T lymphocytes secrete cytokines which contribute to produce granulomatous reaction and ”pseudotubercles” above all macrophages, neutrophilic and eosinophilic granulocytes, as well as fibroblasts and aggregate around eggs.TREMATODES
Schistosoma (Blood Flukes) Pathogenesis and clinical manifestations. Granulomatous proliferations extends into the lumen of the urinary bladder or intestine. The granulomas are replaced by connective tissue, producing more and more fibrous changes and scarring.TREMATODES
Schistosoma (Blood Flukes) Clinical manifestation The main forms of schistosomiasis are differentiated according to the localization of the lesions: 1- Urinary schistosomiasis (urinary bilharziasis) 2- Intestinal schistosomiasis (intestinal bilharziasis) 3- Hepatosplenic schistosomiasis 4- Cerebral and pulmonary schistosomiasis 5- Cercarial dermatitis.TREMATODES
TREMATODESSchistosoma (Blood Flukes) Diagnosis Detection of microhematuria with test strips is an important diagnostic tool in bladder schistosomiasis. Clinical examination with portable ultrasonic imaging equipment has proved to be a highly sensitive method of detecting lesions in the liver and urogenital tract in epidemiological studies.
TREMATODES
Schistosoma (Blood Flukes) Treatment:- The drug of choice for treatment of schistosomiaisi is Praziquantel, which is highly effective against all Schistosoma species and is well tolerated. When a village reports more than 50 percent of children have blood in their urine, everyone in the village receives treatment.