d. Signs and Symptoms of Blood Flukes. Blood flukes live in the final host
over a span of several years. Eggs produce minute granulomata and scars in organs
where they lodge or are deposited. The symptoms experienced by humans depend on
the location of the parasite in the human host.
(1) Clinical stages. Generally, three clinical stages of infection can be
delineated. In the first phase, there is an itchy erythematous or petechial rash at the
sites of penetrates of the cercariae, the free-swimming larvae; this lasts from two to five
days. In the second clinical phase, four to five weeks later, the symptoms are primarily
allergic and of varied severity. There may be fever, urticaria, malaise, respiratory
symptoms, and the liver and the spleen may be temporarily enlarged. In two to eight
weeks, the person becomes asymptomatic. The final clinical phase, which can occur
six months to several years after infection, is characterized by diarrhea, dysentery,
intestinal tumors, portal hypertension, and hepatic insufficiency. It should be noted that
these parasites can live for many years. Some people with light infections are
asymptomatic and never have signs or symptoms of parasitic disease.
(2) Course and severity. Remember that the course and severity of the
disease caused by the blood fluke depends on three elements:
The number of adult worms present.
(b) The number of eggs produced.
The sites of the lesions the worms cause.
(3) Intestinal blood flukes. Early symptoms are diarrhea, dysentery, and
abdominal pain. Symptoms of later stages include anorexia, weight loss, polypoid
intestinal tumors. Signs of portal hypertension and hepatic insufficiency are also in
(4) Urinary blood flukes. In the urinary form of the disease, the patient may
have the signs/symptoms of ureteral and renal damage ending in fatal uremia. The
infected human might die of bladder carcinoma many years after being infected.
(5) Oriental blood flukes. Symptoms are similar to those of intestinal blood
flukes, but the disease is more serious. Complications that come from chronic infection
can be fatal.
e. Treatment. The drug of choice for all three species of blood fluke--intestinal
blood fluke, urinary blood fluke, and Oriental blood fluke--is praziquantel. Alternative
drugs are as follows:
Intestinal blood fluke disease--oxamniquine.