Adventure Doc Schistosomes

keeping you healthy for life's adventures

Erik McLaughlin MD, MPH

Also known as Bilharziasis. This Trematode/blood fluke infection may lead to portal hypertension, liver fibrosis or bladder cancers, depending on location and length of infection. Eggs enter a freshwater pool, mature in snails and then become free swimming. They directly penetrate skin when it contacts infected water. Two species have a preference for mesenteric veins (Schistosoma Mansoni and S. Japonicium). Schistosoma Hematobium is generally found in the bladder.

S. Mansoni is seen in Africa, South America and parts of Caribbean. S. Hematobium is found in Africa and Middle East. S. Japonicium is found mainly in China and Phillipines.

Transmission/ Incubation:

Transmitted by direct contact with infected water, allowing penetration of free-swimming cercariae. Eggs are deposited in water from infected person’s urine or feces.

Avoidance of infected water, wearing of waterproof boots if wading, topical application of a 70% alcohol solution immediately after contact with infected water and vigorous drying

Demonstration of eggs in Kato fecal smear or in urine. Urine filtration often facilitates demonstration. Various attempts are underway to have a rapid antigen analysis card for either blood or urine.

Praziquantel single dose of 40mg/kg for S. Mansoni and S. Japonicium. A 60mg/kg dose may be used for S. Hematobium.

Characteristic lateral spine

These are blood flukes and have two sexes, male and female. These parasites like to live in the bladder or mesenteric veins of the abdomen. There are several types of Schistosomiasis: Schistosoma Mansoni and S. Japonicium like to live in the mesenteric veins of the abdomen. Schistosoma Haematobium likes to live in the bladder.
These parasites clog the veins or bladder that they live in.

The life cycle of this parasite requires a snail to mature within. The eggs are passed from an infected individual, either in feces or urine. These eggs hatch miracidae (baby schistosomes) that mature within a snail, that lives in the water. Once they grow up a bit, they leave the snail and swim freely in the fresh water. These are known as cercariae (teenage schistosomes). These bad guys directly penetrate your skin while you are swimming or wading in the water.

To keep this from happening, wear waterproof boots while wading in the water. If you contact the water, vigorously dry skin and immediately rinse your body off with 70% alcohol solution after drying off, to kill the cercariae before they penetrate. This illness is found in Africa, Saudi Arabian peninsula, South America, the Middle East and some Caribbean islands. S. Mekongi and S. Intercalatum are two addition species worth mentioning. Katayama fever (systemic manifestation) is rare, but may occur 3-5 weeks after primary exposure.

Iodine or Chlorine may be used to disinfect water prior to bathing, laundry or drinking. Enure 3-4 hours for treatment, prior to use.