Schistosomiasis(bilharzia) By Dr. Karl

Sometimes referred to as bilharzias, bilharziasis, or snail fever, is a parasitic disease caused by trematode(flukes) flatworms of the genus Schistosoma. Belong to Phylum Platyhelminthes

History schistosomiasis was discovered by Theodore Bilharz, a German surgeon working in Cairo, who first identified the etiological agent Schistosoma hematobium in 1851 The first doctor who described the entire disease cycle was Pirajá da Silva in 1908. It was a common cause of death for Ancient Egyptians in the Greco-Roman Period.

classification Schistosoma mansoni Schistosoma hematobium Schistosoma japonicum S. intercalatum S. mekongi ***Trichobilharzia ocellata (cause swimmers itch) Four species routinely infect the human host, and several others rarely do so.

Schistosoma eggs (haematobium with terminal stings - mansoni with lateral stings)

Epidemiology It is endemic to at least 76 tropical and sub- tropical countries. more than 200 million people are infected worldwide. In terms of impact this disease is second only to malaria as the most devastating parasitic disease. Schistosomiasis is considered one of the Neglected Tropical Diseases (NTDs)

The disease is found in tropical countries in Africa, the Caribbean, eastern South America, Southeast Asia and in the Middle East. Schistosoma mansoni is found in parts of South America and the Caribbean, Africa, and the Middle East; S. haematobium in Africa and the Middle East; and S. japonicum in the Far East. S. mekongi and S. intercalatum are found locally in Southeast Asia and central West Africa, respectively

Transmission Risk Factor- Wading and swimming in fresh water in tropical regions You get a schistosoma infection through contact with contaminated water. The parasite in its infective stages is called a cercaria. It swims freely in open bodies of water.

cercaria

Skin vesicles on the forearm, created by the penetration of Schistosoma

pathophysiology

Schistosomiasis is due to immunologic reactions to Schistosoma eggs trapped in tissues. Antigens released from the egg stimulate a granulomatous reaction involving T cells, macrophages, and eosinophils that results in clinical disease Initially, the inflammatory reaction is readily reversible. In the latter stages of the disease, the pathology is associated with collagen deposition and fibrosis, resulting in organ damage that may be only partially reversible.

Photomicrography of bladder in S. hematobium infection, showing clusters of the parasite eggs with intense eosinophilia

Host

All snail species susceptible to infection with Schistosoma mansoni and S. haematobium belong to the family Planorbidae in the subclass Pulmonata. Schistosoma mansoni infects snails in the genus Biomphalaria, and these can also become infected with S. mansoni-S. intercalatum hybrids, S. rodhaini and S. eduardiense. Schistosoma haematobium infects pulmonate snails of the genus Bulinus. Oncomelania for S japonicum Tricula (Neotricula aperta) for S mekongi

Clinical Presentation Symptoms and signs depend on the number and location of eggs trapped in the tissues.

Eggs can end up in the skin, brain, muscle, adrenal glands, and eyes Eggs can end up in the skin, brain, muscle, adrenal glands, and eyes. As the eggs penetrate the urinary system, they can find their way to the female genital region and form granulomas in the uterus, fallopian tube, and ovaries. Central nervous system (CNS) involvement occurs because of embolization of eggs from the portal mesenteric system to the brain and spinal cord via the paravertebral venous plexus.

location Intestinal Urinary S. mansoni S. japonicum S. intercalatum S. mekongi S. hematobium

S. japonicum eggs in hepatic portal tract

Acute schistosomiasis Katayama syndrome- is a systemic, serum sickness-like illness that develops after several weeks in some, but not most, individuals with new schistosomal infections. is associated with marked peripheral eosinophilia and circulating immune complexes most common with S japonicum and S mansoni infections is most likely to occur in heavily infected individuals after primary infection

present usually 4-8 weeks after(exposure to S japonicum or S mansoni) contact with infested water Fever, lethargy, malaise, and myalgia are the most common symptoms Less common symptoms cough, headache, anorexia rash (urticarial or papular) Right upper quadrant pain and bloody diarrhea may also occur patients may present with focal neurological deficits.

Chronic Intestinal Schistosomiasis disease onset is insidious- Patients with symptomatic chronic schistosomiasis may present months to years after primary exposure portal hypertension with splenomegaly oesophagial varices, hypersplenism, ascitis, dyspepsia, flatulence, and pain are present in the left hypochondrium pulmonary hypertension CNS lesions: spine - transverse myelitis cerebral – seizures (S. japonicum) -Dizziness, nausea, and increased intracranial pressure, Visual scintillation from occipital mass

intestinal polyposis: intestinal granulomatosis: contractures of colon, intusseception, melena, Generalized lymphadenopathy Female genital schistosomiasis- Postcoital bleeding, Genital ulceration, Irregular menstruation, Pelvic pain Cardiopulmonary schistosomiasis - larval pneumonitis with a cough, mild wheezing, and a low-grade fever, while in schistosomal cor pulmonale, easy fatigability, palpitations, dyspnea on exertion, and hemoptysis

Splenomegaly due to bilharziosis: a drawing of the contour before ablation and the spleen after excision

Tortuous Varicosities in Chronic Schistosomiasis

Cercarial dermatitis of humans ("swimmer's itch", "Badedermatitis", "Weiherhippel") Trichobilharzia ocellata

Urinary schistosomiasis Schistosoma haematobium

Schistosoma near urethra

Presentation hematuria (terminal) urinary frequency pyuria pyelonephritis obstructive uropathy cancer of bladder (squamous cell) distant metastases (spinal column) (pulmonary hypertension)

diagnostics

symptoms mimic any acute viral, bacterial, or malarial illness. Obtaining a careful travel history, including drinking water sources and recreational activities, is important. Symptoms are likely secondary to immune complex formation following egg deposition in tissues; the illness resembles serum sickness.

Diagnosis: intestinal schistosomiasis 1. History of freshwater exposure 2. Stool for O&P (egg counts and viability) 3. Serology-- Elisa and Western Blot 4. Antigen capture 5. Eosinophilia 6. Rectal snips or biopsies 7. Liver biopsy 8. Ultrasound or CT of abdomen

Laboratory debris in urine eggs in urine (overnight-millipore) I.V.P. abnormalities cystoscopy serology

Schistosoma Mansoni in the Cecum ( Magnification Colonoscope.) This 34 year-old male, a routine colonoscopy was performed a Schistosoma Mansoni was found at the cecum.

Management

Management strategies: A. Treatment of local irritation (swimmers itch) B. Treatment of allergic reaction to cercarial entry (fever, rash, myalgia, pneumonitis - Katayama fever) C. Control of egg laying to prevent complications D. Treatment of complications

Swimmers itch & Katayama fever: Anti-allergic (chlopheniramine), paracetamol, steroids (prednisone or hydrocortisone)

Control of egg laying & complications: Praziquantel: Effective against all 3 forms ↑ entry of Ca++ to cell memb, paralyze, detach & kill Taken after meal without chewing (bitter) May increase symptoms of Katayama fever (↑ allergic reaction due to dead cestodes) Oxamniquine: Effective only for S. mansoni Metrifonate: Only for S. haematobium

Outlook (Prognosis Treatment before significant damage or severe complications occur usually produces good results.

Complications

Hemospermia Squamous cell bladder cancer Sepsis (Salmonella) Pulmonary hypertension Cor pulmonale Neuroschistosomiasis - Transverse myelitis, paralysis, and cerebral microinfarcts Infertility

Severe anemia Low ̶ birth-weight babies Spontaneous abortion Higher risk for ectopic pregnancies End-organ disease Portal hypertension Obstructive uropathy Pregnancy complications from vulvar or fallopian granuloma Carcinoma of the liver, bladder, or gallbladder

Prevention Avoid swimming or bathing in contaminated or potentially contaminated water Avoid bodies of water of unknown safety Snails are an intermediate host for the parasite. Getting rid of snails in bodies of water used by humans would help prevent infection.