Urinary schistosomiasis(S. haematobium)
The disease caused by S. haematobium is called bilharziasis, urinary schistosomiasis, or endemic haematuria.After the worms mature in the liver, they migrate from that organ, and reach the vesical, prostatic and uterine plexuses by way of the hemorrhoidal veins.
The eggs are deposited in the wall of bladder and lower ureters (LUT) or to a lesser extent in the uterus, vaginal wall, prostate, rectum or other organs.
1-In acute stage , eggs invade the bladder wall and escape into lumen of the bladder causing symptoms as terminal haematuria (is the classical presenting feature). Urinary symptoms usually are not seen for three to six months after infection and may not develop for a year or more.
2-In late stage, fibrosis and thickening of the bladder wall occur. So lesions of this stage (late) is acellular and fibrotic which called sandy patches (patchy fibrotic thickening of badder mucosa and submucosa). Bladder wall may calcified and defrmed.
The uterine cervix is the most common site of S. haematobium infection in women, and granulomatous inflammation of the cervix is a common manifestation.
In males, heavy infections may involve the urethra, prostate, seminal vesicles, and even the spermatic cord and penis.
Genital schistosomiasis may increase the risk of acquiring HIV infection and could predispose to cervical cancer.
Intestinal schistosomiasis (S. mansoni and S.japonicum)
1-Eggs of S. mansoni and S. japonicum may be deposited at any point in the corresponding venules leading to the inferior and superior mesenteric veins respectively.2-In early stage, (cellular granulomatous reaction) local damage to intestial wall caused by egg deposition and escape into the lumen of intestine and form the dysentric type of manifestation.
3-in late stage: Acellular fibrotic lesion :
a-fibrosis, thickening of bowel wall and pseudotumers.
b-Adhesions to other loops of bowel.
c-Intestinal Polyps may form from mass of eggs deposited in the submucosa.
d-Fibrosis of the submucosa in the areas of egg deposition explains the decrease in egg passage in chronic infection.
Ectopic lesions
1-Hepatic schistosomiasis: Although the intestines are involved primarily in S. mansoni and S. japonicum infections, but egg embolism (escaped mesenteric eggs to portal veins) results in secondary involvement of the liver and form the hepatosplenic type of manifestation.Hepatosplenic involvement is the most important cause of morbidity in S. mansoni and S. japonicum infections which may present anaemia, jaundice, thrombocytopenia.
In hepatosplenic schistosomiasis, anemia results from:
1-bleeding. 2-hypersplenism. 3-anemia of chronic disease. 4-the ingestion of RBCs by adult worms.
2- Pulmonary schistosomiasis: after portal hypertension caused by S. mansoni and
S. japonicum, collateral pathways shunt parasite eggs to the lungs. In S. haematobium, egg can migrate directly to lungs and induce pulmonary inflammation.3- Neuroschistosomiasis: result from migration of adult parasites and the resultant entry of eggs into cerebral (S. japonicum) or vertebral venous plexus (S. mansoni and S. haematobium).
Association of schistosomes with other diseases
1- Salmonellosis: An association between chronic salmonellosis (persistent salmonella bacteremia) and schistosomiasis caused by S. mansoni and S. japonicum, has been reported from many areas.2- Hepatitis: co-infections with hepatitis B and C have been reported.
3- Nephritic syndrome : is occasionally seen in both S. mansoni and S. haematobium infections.
4- Cancer: S. haematobium infection results in sequmous metaplasia of the urinary bladder and ureter mucosa.
Diagnosis
1- Finding of eggs:
A-Eggs of S. haematobium in urine (rarely in stool)
B-Eggs of S. mansoni and S. japonicum in stool.
2- Egg-hatching technique.
3- Cystoscopy, proctoscopy and colonoscopy.
4-Biopsy .
5-Serological tests: CFT, FAT, IHT, LAT.
6-PCR (polymerase chain reaction).
7-Aldehyde test: positive due to high serum globulins (hypergammalobulinemia).
8-Intradermal skin test (schistosomian skin test): become positive after few months of infection.