Every year, more than 200,000 deaths are recorded in Sub-Saharan Africa due to Schistosomiasis caused by these trematodes.
Different species of this trematode exist, and they include Schistosoma japonicum, Schistosoma haematobium and Schistosoma mansoni.
But today, our focus will be on Schistosoma haematobium.
S.haematobium is endemic in 54 countries and is commonly termed a blood fluke.
Table of Contents
Mode of transmission
When one comes in contact with infected water by this parasite, its cercariae(larval stage) passes from an intermediate host(usually a snail) – I know, right? Don’t panic; it doesn’t mean you should stop eating your delicious snails.
When this larval stage penetrates the skin, it migrates to the liver and rectum and resides there while maturing into an adult fluke.
The female lays eggs in the bladder, and over 20-200,000 eggs are passed out daily in the urine of infected individuals.
Life Cycle
Schistosoma Haematobium Life Cycle
Schistosoma haematobium, a cunning parasite that manipulates humans and snails to survive. Its life cycle is a dance of infection, reproduction and reinfection.
The Egg
An infected person’s urine releases S. haematobium eggs into freshwater, where they hatch into miracidia, tiny larvae seeking snail hosts.
Snail Invasion
Miracidia infect Bulinus snails, transforming into sporocysts. These reproduce frantically, producing cercariae, the infective stage.
Human Invasion
Free-swimming cercariae await human contact. When skin contact occurs, they penetrate, entering the bloodstream as schistosomulae.
Maturity
Schistosomulae journey to the bladder, mature into adult worms, pair up and reproduce. Eggs either exit via urine or lodge in tissues, causing inflammation.
The Cycle Repeats
Eggs re-enter freshwater, seeking new snail hosts. This endless cycle thrives in areas with limited clean water access.
Contributors to Prevalence
- Migration of Refugees
- Construction of Irrigation Schemes
The eggs are responsible for triggering host response which then result in:
Clinical features
- Vaginal bleeding
- Bloody Urine
- Malaise and fever
- Chronic abdominal pain
- Miscarriage if pregnant
Laboratory Findings
- Haematuria(Red Blood Cells in urine)
- Eosinophila in urine
- Proteinuria
Mode of prevention and control
- Water should be treated occasionally
- Providing safe water supplies in villages
- Providing safe recreational bathing sites for children
- Frequent water bodies Sanitation
- Avoid stagnant or contaminated water.
The pictorial life cycle shown below is adapted from CDC
