JOHNS HOPKINS
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Department of Pathology
600 N. Wolfe Street / Baltimore MD 21287-7093
(410) 955-5077 / FAX (410) 614-8087
Division of Medical Microbiology
THE JOHNS HOPKINS MICROBIOLOGY NEWSLETTER Vol. 26 No. 03
Tuesday, February 13, 2007
A. Provided by Sharon Wallace, Division of Outbreak Investigation, Maryland Department of
Health and Mental Hygiene.
There is no information available at this time.
B. The Johns Hopkins Hospital, Department of Pathology, Information provided by,
Mark R. Lewin, M.D.
Clinical History:
A 40-year-old male from Trinidad presented to The Johns Hopkins Emergency Department for a
1-week history of nausea, vomiting, and abdominal pain. He had recently returned from a 3-week
visit to Trinidad, 1 month prior to his presentation. His symptoms began as myalgias and
arthralgias, which progressed to a sharp, constant right upper abdominal pain. During this time
the patient also noted fevers and chills. Over the past week, the patient began experiencing
anorexia, nausea, and vomiting. His liver function tests were abnormal and he underwent an
ERCP which was found to be normal.
Multiple cultures and stool O&P were negative. A serologic test for Fasciola hepatica (sheep
liver fluke) was positive.
Organism:
Fasciola hepatica, also known as the sheep liver fluke, is a trematode of herbivores that can
accidentally infect humans. F. hepatica occurs worldwide, but is particularly prevalent in
temperate areas of sheep and cattle-rearing. Humans most commonly become infected by eating
watercress or other freshwater plants grown in sheep-raising areas. Once ingested, the infective
metacercariae excyst in the duodenum, and the larvae penetrates the small intestine to enter the
peritoneal cavity. The larva then penetrates the liver capsule and migrates through the liver tissue
to enter the biliary tract where they mature into adults and begin egg production. The eggs are
released through the sphincter of Oddi and into the stool, where they can ultimately be detected.
The process from excystation to egg production takes approximately 12 weeks. For this reason, it
is not uncommon for the stool O & P to be negative during the first 3-4 months of infection.
Clinical Manifestations:
Clinical manifestations of F. hepatica can be divided into 3 phases: the acute (liver) phase,
chronic (biliary) phase, and the ectopic (pharyngeal) phase. The early phase of fascioliasis occurs
when the larvae migrates through the liver parenchyma. This migratory path undergoes necrosis
and fibrosis, which clinically manifests as fever, right upper quadrant pain and hepatomegaly.
Other common symptoms include myalgia, anorexia, nausea, vomiting, cough, urticaria, and
occasionally jaundice. The severity of liver damage and symptoms increases with parasite load.
Symptoms usually begin within 6-12 weeks of infection and commonly subside 6 weeks later.
Marked peripheral eosinophila is frequently present during this phase of infection.
The chronic phase of fascioliasis is typically asymptomatic, but symptoms can arise secondary to
common duct obstruction by the adult flukes, which can result in biliary colic, cholangitis and
obstructive jaundice. If the infection is particularly prolonged and heavy, sclerosis cholangitis and
biliary cirrhosis can result. Other symptoms include epigastric and right upper quadrant pain,
diarrhea, nausea, vomiting, wasting, hepatomegaly and jaundice. Eosinophilia is a variable finding
in this phase of the disease. The diagnosis of Fascioliasis should be entertained in patients with
prolonged abdominal pain or splenomegaly in the setting of peripheral eosinophilia.
Lab Diagnosis:
Microscopic identification of eggs is useful in the chronic (adult stage). Eggs may be recovered
from stool or material from duodenal or biliary drainage. The eggs are ellipsoidal with a small
barely distinct operculum. False fascioliasis (pseudofascioliasis) occurs when eggs are present in
the stool not from an infection, but from ingestion of infected livers containing the eggs. As the
acute manifestations of human fascioliasis may precede the appearance of eggs in the stool by
several weeks, immunodiagnostic tests are useful for the diagnosis of early infections. Specific
antibodies to Fasciola may be detectable 5-7 weeks before eggs appear in the stool. The current
tests are EIA combined with confirmation of positives by immunoblot. Sensitivity of the test
ranges from 95%-100%.
Treatment:
Unlike other fluke infections, Fasciola hepatica infections may not respond to praziquantal,
mebendazole, or albendazole. The drug of choice is triclabendazole.
References:
Parasites and Health—www.dpd.cdc.gov
Price et al. Fascioliasis: case reports and review. Clin Infec Dis 1993; 17: 426-430.
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