Schistosomiasis: Introduction and Overview

Trematodes and Related Diseases

• Genus Schistosoma causes diseases in humans, primarily affecting the intestine and liver.

Schistosoma Species and Urinary Tract Disease

• Schistosoma haematobium primarily causes urinary tract disease and female genital schistosomiasis.

Tropical Distribution of Schistosomes

• A critical factor for the tropical distribution of schistosomes is the presence of freshwater habitats, which support the life cycle of the snail intermediate hosts.

Habitat of S. mansoni

• S. mansoni resides in the mesenteric veins, specifically draining the intestine.

Affected Body Parts by Schistosomes

• Apart from the urinary system impacted by S. haematobium, human schistosomes primarily affect the liver, intestines, and sometimes the lungs.

Regional Increases in Schistosomiasis

• Factors contributing to regional increases in schistosomiasis, particularly in Africa, include poor sanitation, increased water contact, and the spread of snail populations.

Penetration Time of S. mansoni Cercariae

• It takes approximately minutes to hours for S. mansoni cercariae to penetrate unbroken skin.

Initial Clinical Manifestation

• The initial clinical manifestation caused by penetrating cercariae of S. mansoni is known as cercarial dermatitis, characterized by itchy rashes.

Immune Evasion of Adult Schistosomes

• Adult schistosomes avoid long-term exposure to host immune surveillance through mechanisms such as coating themselves with host antigens and releasing immunomodulatory substances.

Egg Deposition of S. mansoni

• Egg deposition occurs in the mesenteric veins and subsequently released into the intestinal lumen.

Hosts for Clinical Illness

• Clinical illness caused by schistosomiasis generally occurs in humans, who are the definitive hosts for these parasites.

Host Inflammatory Response Trigger

• The presence of eggs and their associated antigens in tissues triggers the host inflammatory response, leading to symptoms characteristic of schistosomiasis.

Learn about the different species of Schistosoma and the related diseases they cause in humans. Understand the impact on the urinary tract, female genitalia, intestine, and liver, as well as the chronic effects of schistosomiasis.