Schistosomiasis Miracidia produces enzymes and secretions while in the egg. Ag/Ab reaction to miracidial secretions through egg, resulting in egg granuloma the Hoeppli phenomenon! Ag/Ab

How many eggs make it to the lumen? 2/3 of those that enter tissue do not leave. Many eggs do not enter tissue Swept away in blood stream Liver and spleen are first organs Then Lungs Other organs Eggs look like Psuedotubercles 100, 000 eggs/gram!

Pathology and Symptoms Migratory Phase Penetration to Egg production Symptomless Dermal rash

Pathology and Symptoms 2. Acute Phase Egg Production Chills, fever, fatigue, headache, malaise Much exposure to antigens Granulomas surround eggs Eosinophils, neutrophils, macrophages 1-2 weeks fibroblasts enter granuloma Psuedotubercles-fibrous granulomas

Pathology and Symptoms 3. Chronic Phase Asymptomatic S. haematobium Blood in the urine Pain with urination Loss of bladder function Bladder cancer? Eggs don’t metastasize?

Pathology and Symptoms 3. Chronic Phase S. japonicum, S. mansoni Mild, chronic dysentery Abdominal pain 8% infections develop liver fibrosis that impedes blood flow Cirrhosis of liver Long term problems Hepatosplenomeagly Long term: loss of tissue function

Ascites

Schistosoma japonicum Anterior mesenteric veins Small intestine Interfere with absorption Stunting Eggs can go to brain Smaller Brain lesions 25 year old

Pathology Adults cause no pathology Pathology due to eggs “hide” from immune system Absorb host antigens Pathology due to eggs

Diagnosis Schistosoma mansoni and S. japonicum? Schistosoma haematobium? Small number of eggs Serodiagnosis

Treatment Praziquantel Prognosis Effective Much of fibrosis can be reversed Severe damage irreversible

Epidemiology How do you get infected with a species of Schistosoma?

Epidemiology What causes people to come into contact with water?

Work: Fisherman, agricultural workers, housework

Bathing and Play

Traditions Ablution

How do eggs get into water supply?

What else do you need?

Snails Schistosoma mansoni Schistosoma japonicum Biomphilaria glabrata Schistosoma japonicum Oncomelania Schistosoma heamatobium Bulinus

Snail Habitat Any freshwater Eutrophic bodies of water Shallow areas near shore Associated with Aquatic plants Decaying organic debris

Seasonal Transmission Transmission can occur only during certain seasons Snail abundance Dry season Some species burrow into mud

Human Manipulations Agricultural projects Unintended consequences Improve agriculture Unintended consequences Increase snail habitat Zimbabwe: $10 million irrigation project abandoned Aswan High Dam in Egypt

Aswan High Dam Increased snail habitat Increased Schistosomiasis Below dam Varied by significant increases From 5%-35% Above dam From 5% in 1968 to 77% in 1993

Reservoir Hosts Schistosoma haematobium Schistosoma mansoni None known Schistosoma mansoni Many mammals: monkeys and rodents Schistosoma japonicum Least host specific Many mammals

Control Infected People Uninfected People Occupation Behavior Habitat Sewage Occupation Behavior Bathing Season Habitat Infected People contact Uninfected People contact

# 1 Control How do you get rid of snails? Remove by hand Molluscicide Biological control Eliminate habitat Do these work? Too many snails Molluscicides ineffective Oncomelania Biological control sometimes effective People need water, too

Control Infected People Uninfected People Occupation Behavior Habitat Sewage Occupation Behavior Bathing Season Habitat Infected People contact Uninfected People contact

#2 Control How do you prevent eggs from contaminating water supplies? Sewage treatment Eliminate night soil Education Why doesn’t this work? Expensive Reservoir hosts

Control Infected People Uninfected People Occupation Behavior Habitat Sewage Occupation Behavior Bathing Season Habitat Infected People contact Uninfected People contact

# 3 Control How do you prevent people from contacting cercariae? Education Protective gear (waders, boots) Provide non-contaminated water Vaccines Why don’t these methods work? People need water Fishermen, Agricultural workers can’t avoid 60% world calories from rice Protective gear hot and cumbersome Ablution Cost of clean water Vaccines unsuccessful

Control Infected People Uninfected People Occupation Behavior Habitat Sewage Occupation Behavior Bathing Season Habitat Infected People contact Uninfected People contact

# 4 Control How can you eliminate the parasite? Drug treatment Genetically modified snails Do these work? Cost Dose of praziquantel = $0.20 No genetically modified snails yet

Cercarial Dermatitis/ Swimmer’s Itch 10 species (U.S.)

Trichobilharzia sp.

Matt’s leg with cercarial dermatitis or “swimmers’s itch” caused by cercariae of avian blood flukes.

Furcocercous cercariae diagnostic for Schistosomes.

Cercarial Dermatitis/ Swimmer’s Itch Inflammatory response Pus-filled pimples Itching and pain 4 days

Dendritobilharzia spp. Live in the dorsal aorta of ducks!

Ducks can infect snails that can infect swans!

Eggs can enter CNS via arterial circulation causing CNS disease!