Schistosomiasis (Bilharzia)

1. Schistosomiasis (Bilharzia) Mohammad Habboub HishamHajHamad

2. Definition: • Schistosomiasis or bilharzia is a disease affecting many people in developing countries. In the form of 'acute' schistosomiasis it is sometimes referred to as snail fever and cutaneous schistosomiasis.

3. Although it has a low mortality rate, schistosomiasis can be very debilitating. Bilharzia, or bilharziosis, is named after Theodor Bilharz, who first described the cause of urinary schistosomiasis in 1851.

4. There are five species of flatworms that cause schistosomiasis. Each causes different symptoms. Schistosomiasis may travel to different parts of the body, and its localization determines the person's symptoms. • Schistosomamansoni and Schistosomaintercalatum cause intestinal schistosomiasis. • Schistosomahaematobium causes urinary schistosomiasis. • Schistosomajaponicum and Schistosomamekongi cause Asian intestinal schistosomiasis.

5. Geographical distribution and epidemiology • The disease is found in Africa, the Caribbean Eastern South America, East Asia and in the Middle East. • Schistosomamansoni is found in parts of South America and the Caribbean, Africa, and the Middle East. • S.haematobium in Africa and the Middle East. • S.japonicum in the Far East. • S.mekongi and S.intercalatum are found focally in Southeast Asia and central West Africa, respectively.

6. Schistosomiasis map • Worldwide 207 million people have the disease with 120 million being symptomatic. Urbanization, pollution, and / or consequent destruction of snail habitat has reduced exposure, with a subsequent decrease in new infections

7. The most common way of getting schistosomiasis in developing countries is by wading or swimming in lakes, ponds and other bodies of water which are infested with the snails (usually of the Biomphalaria Bulinus, or Oncomelaniagenus) that are the natural reservoirs of the Schistosoma pathogen 

9. Schistosomiasis life cycle.  • Schistosomes have a trematode vertebrate-invertebrate lifecycle (infecting both a vertebrate and invertebrate), with humans being the definitive host • The life cycles of all human schistosomes are similar: parasite eggs are released into the environment from infected individuals. The eggs hatch on contact with fresh water to release the free-swimming miracidium

11. Pathology • schistosomiasis is a chronic disease. Pathology of S.mansoni and S.japonicum schistosomiasis includes: Katayama fever, hepatic perisinusoidal egg granulomas, Symmers' pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in the brain or spinal cord.

12. Pathology of S.haematobium schistosomiasis includes: hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in the brain or spinal cord. •  Bladder Cancer diagnosis and mortality are generally elevated in affected areas

13. Clinical features • Many infections are subclinically symptomatic, with mild anemia and malnutrition being common in endemic areas.Symptoms depend on where the eggs are: • Continuing infection may cause granulomatous reactions and fibrosis in the affected organs, which may result in manifestations that include: • Colonic polyposis with bloody diarrhea (Schistosomamansoni mostly); • Portal hypertension with hematemesis and splenomegaly(S. mansoni, S. japonicum; • Cystitis and ureteritis(S. haematobium) with hematuria, which can progress to bladder cancer; • Pulmonary hypertension(S. mansoni, S. japonicum, more rarely S. haematobium); • Glomerulonephritis; and central nervous system lesions.

14. Occasionally central nervous system lesions occur: cerebral granulomatous disease may be caused by ectopic S.japonicum eggs in the brain, and granulomatous lesions around ectopic eggs in the spinal cord fromS.mansoni and S.haematobium infections may result in a transverse myelitis with flaccid paraplegia. • Katayama Fever • Acute schistosomiasis (Katayama's fever) may occur weeks after the initial infection, especially by S.mansoni and S.japonicum. Manifestations include: • Abdominal pain • Cough • Diarrhea • Eosinophilia-extremely high eosinophil granulocyte count. • Fever • Fatigue • Hepatosplenomegaly-the enlargement of both the liver and the spleen.

15. Laboratory diagnosis • Microscopic identification of eggs in stool or urine is the most practical method for diagnosis • Tissue biopsy (rectal biopsy for all species and biopsy of the bladder for S. haematobium) • Antibody detection can be useful in both clinical management (eg, recent infections) and for epidemiologic surveys

16. Treatment • Schistosomiasis is readily treated using a single oral dose of the drug Praziquantel

17. Prevention through good design • The main focus of prevention is eliminating the water-borne snails which are natural reservoirs for the disease • This is usually done by identifying bodies of water, such as lakes, ponds, etc., Which are infested, forbidding or warning against swimming and adding niclosamide, acrolein, copper sulfate, etc., To the water in order to kill the snails.

18. Irrigations schemes can be designed to make it hard for the snails to colonize the water, and to reduce the contact with the local population.

19. Abdel Halim Hafez (1929 – 1977)

20. Thank you for your Attention