Schistosomiasis

that characterize chronic schistosomiasis.10

Patients may be asymptomatic, or present dysu-

Urinary schistosomiasis is caused by the blood

ria, hematuria, frequency, colic, incontinence,

retention, and stones (Lehman 1973).

trematode Schistosoma

haematobium. It

is

Obstructive uropathy is also a long-term

endemic to areas of the Middle East and most of

sequelaeof urinaryschistosomiasis.Hydroureter

Africa with 90 million infected worldwide, and

usually precedes hydronephrosis and is typi-

has become more prevalent in the USA with the

cally bilaterally asymmetrical (Lehman 1973).

increased international travel.10

As the obstructive uropathy progresses and

The life cycle of S. haematobium in the human

ascends to hydronephrosis, long-term dilation

host begins with the deposition of ciliated lar-

leads to atrophy

and

finally renal failure

vae into fresh water from eggs excreted through

(Lehman 1973).

urine and feces of infected human hosts. The

Chronic urinary schistosomiasis also pro-

larvae use an intermediate host, Bulinus snails,

duces bladder hyperplasia, metaplasia, dyspla-

to produce cercariae in freshwater which, using

sia, and eventually cancer. Metaplasia and

vibratory locomotion, penetrate the unbroken

dysplasia are usually associated with bladder

skin of human hosts to become a schistosomu-

cancer caused by

the

chronic inflammatory

lum. Following maturation of 80–110 days, the

state. Squamous

cell

carcinomas make up

schistosomulum microembolize to the liver and

50–90% of bladder cancer lesions, with adeno-

lung before settling into the pelvic and perivesi-

carcinoma accounting for 5–15%. Most are exo-

cal venous plexus where paired male and female

phytic,but 25% can be endophytic and ulcerative.

worms now their adult size of 1.5 cm adhere to

They tend to occur most frequently on the pos-

the endothelial

lining of

veins

and

begin

to

terior and lateral

walls, typically sparing the

release eggs into the blood stream. These eggs

trigone.47 Unlike other squamous cell carcino-

are ovoid, distinctly terminally spined, and

mas, those associated with schistosomiasis tend

80–150 mm in length. Twenty percent of these

to be well differentiated, have a good prognosis,

eggs will cross directly into the bladder or rec-

and have low metastatic potential.45

tum where they will be excreted to continue the

In addition to malignant sequelae, the blad-

cycle of infection. The presence of terminally

der can develop painful ulcers with the slough-

spined eggs in the urine or feces is the gold

ing of necrotic papules. More common with

standard for the diagnosis of schistosomiasis.

chronic schistosomiasis, patients may present

Adult worms have a typical life span of 3–6

with suprapubic or pelvic pain and dysuria.47

years, but have been demonstrated to live up to

During the very late stages of the disease pro-

3 decades, and may release as many as 100 eggs

cess, the detrusor can become indurated and

per pair daily. During active infection, eggs of

thicken, markedly

reducing bladder capacity

all stages are excreted, but in active or cured

causing the patient abdominal pain and voiding

infections, only

degenerated

eggs

will

be

dysfunction. As with bladder cancers, the trigo-

excreted.10,44

nal region is typically spared.10

S. haematobium eggs can invade epididymal

Clinical Manifestations

structures and ejaculatory ducts, and blood and

eggs may be present in the ejaculate even before

The clinical sequelae of schistosomiasis come

the urine. A painful scrotal mass may be mis-

from the eggs which cause significant cellular

taken for cancer and only discovered after

and humoral host responses that result in the

orchiectomy. Women with schistosomiasis may

granulomatous encasement of eggs.45 This

manifest eggs on routine Papanicolaou smear

inflammatory reaction results in the presence of

due to asymptomatic cervicitis or vaginitis.45

hyperemic, large, bulky polyps surrounding

Patients with urinary schistosomiasis may

localized areas of large egg burden within host

also have concurrent superinfections with a

tissue.46 As the eggs are destroyed and urinary

variety of pathogens. In endemic regions,

excretion of eggs ceases, calcification and

chronic infections with Salmonella commonly

fibrosis occurs resulting in tan colored flat

recur and are resistant to antimicrobial therapy

mucosal lesions, known as the “sandy patches”

alone (Lehman 1973).