The Biology of Schistosomiasis By Tricia Stone Marielle

The Biology of Schistosomiasis By: Tricia Stone, Marielle Remillard & Tracy Wright

Schistosomes l l l macroscopic parasite from the genus Schistosoma characterized by significant sexual dimorphism Schistosoma=split body

Types of Schistosomes l Three species affect humans: 1. ) S. mansoni: large intestine 2. ) S. japonicum: small intestine 3. ) S. haematobium: urinary bladder

Life Cycle feces and urine miracidia intermediate fresh water snail host

Intermediate Snail Hosts l l l S. mansoni: Biomphalaria (Africa) S. haematobium: Bulinus (Africa) S. japonicum: Oncomelania (Asia) Biomphalaria Bulinus Oncomelania

Life Cycle intermediate fresh water snail host cercariae

Life Cycle in the Human YUMMY!! cercariae human host

Life Cycle in the Human schistosomulum human host

Life Cycle in the Human schistosomulum human host adult schistosome

Life Cycle in the Human eggs adult schistosome excreted in the feces and urine

Life Cycle

Stage 1: Migratory Phase l l l moves through the body to target tissue begins with penetration through egg production often symptomless possible rash and itchy skin some upper respiratory complications (i. e. cough)

Stage 2: Acute Phase l l l 4 -10 weeks after infection begins with egg production Symptoms: - fever - headache - diarrhea - fatigue - nonspecific abdominal pain

Stage 3: Chronic Phase l prolonged infection (up to 10 years) symptoms: - cirrhosis of the liver - kidney damage - bleeding of upper bowel - urinary bladder damage - enlargement of liver and spleen

“Slippery Little Suckers Aren’t They…” ~ l Julia Roberts (Pretty Woman) Innate Immunity l l penetration of skin Specific Immunity l adults take on host antigens

Incidence

Risk Factors l l l 200 million infected globally 20 million with chronic schistosomiasis 600 million at risk -extreme poverty -lack of public health facilities -unsanitary conditions -unawareness among the people

Prevention l l l avoid swimming in fresh water in countries where schistosomiasis is prevalent. drink clean water scrape body down after accidental exposure water-resistant creams Snail Control

Diagnosis and Treatment l Diagnosis l l blood tests examination of stool and urine samples to detect eggs l Treatment l Drugs l Praziquantel - effective in the treatment of all forms of schistosomiasis, with virtually no side effects * l Oxamniquine - used exclusively to treat intestinal schistosomiasis in Africa and South America * l Metrifonate - effective for the treatment of urinary schistosomiasis l Vaccination l Research efforts are directed at finding a vaccine, but no success *obtained from W. H. O.

Interested in More? ? ? l l l http: //www. wellcome. ac. uk/en/labnotes 5/animation_popups/schisto. html http: //www. cdc. gov/ncidod/dpd/parasites/schistosomiasis/default. htm http: //en. wikipedia. org/wiki/Schistosomiasis http: //www-micro. msb. le. ac. uk/224/Schisto. html http: //www. path. cam. ac. uk/~schisto/

Questions? ? ?