Physicians at Washington University School of Medicine in St. Louis have diagnosed a rare parasitic infection in six people who had consumed raw crayfish from streams and rivers in Missouri. The cases occurred over the past three years, but three have been diagnosed since last September; the latest in April. Before these six, only seven such cases had ever been reported in North America, where the parasite, Paragonimus kellicotti, is common in crayfish.
"The infection, called paragonimiasis, is very rare, so it's extremely unusual to see this many cases in one medical center in a relatively short period of time," says Washington University infectious diseases specialist Gary Weil, MD, professor of medicine and of molecular microbiology, who treated some of the patients. "We are almost certain there are other people out there with the infection who haven't been diagnosed. That's why we want to get the word out."
Paragonimiasis causes fever, cough, chest pain, shortness of breath and extreme fatigue. The infection is generally not fatal, and it is easily treated if properly diagnosed. But the illness is so unusual that most doctors are not aware of it. Most of the patients had received multiple treatments for pneumonia and undergone invasive procedures before they were referred to Barnes-Jewish Hospital or St. Louis Children's Hospital at Washington University Medical Center.
"Some of these invasive procedures could have been avoided if the patients had received a prompt diagnosis," says Michael Lane, MD, an infectious diseases fellow at the School of Medicine who treated some of the patients. "We hope more doctors will now have this infection on their radar screens for patients with an unexplained lingering fever, cough and fatigue."
Once the diagnosis is made, paragonimiasis is easily treated with an oral drug, praziquantel, taken three times a day for only two days. Symptoms begin to improve within a few days and are typically gone within seven to 10 days. All the patients have completely recovered, even one patient who temporarily lost his vision when parasites invaded the brain.
The recent infections, which occurred in patients ages 10-32, have prompted the Missouri Department of Health & Senior Services to issue a health advisory alerting doctors across the state. The department also printed posters warning people not to eat raw crayfish and placed them in campgrounds and canoe rental businesses near popular Missouri streams. Thoroughly cooking crayfish kills the parasite and does not pose a health risk.
Paragonimiasis is far more common in East Asia, where many thousands of cases are diagnosed annually in people who consume raw or undercooked crab that contain Paragonimus westermani, a cousin to the parasite in North American crayfish.
While the U.S. Centers for Disease Control and Prevention has an antibody test to identify Paragonimus westermani infection, the test is not sensitive for patients with P. kellicotti parasite, and this makes diagnosis a real challenge. Diagnostic clues include elevated levels of white blood cells called eosinophils. These cells typically are elevated in patients with worm parasites, but they can also occur in more common illnesses, including cancer, autoimmune disease and allergy. X-rays also show excess fluid around the lungs and sometimes the heart.
"You have to be a bit of a detective and be open to all the clues," says Washington University infectious diseases specialist Thomas Bailey, MD, professor of medicine, who diagnosed and treated the first case at the School of Medicine.
As a case in point, the first patient who sought treatment at Washington University had had a fever and cough for several weeks. His chest X-ray showed fluid around the lungs, and blood tests showed elevated levels of eosinophils.
The "aha moment" for Bailey occurred when the patient's wife mentioned that his symptoms developed about a week after he ate raw crayfish from a Missouri river, and Bailey recalled that in Asia eating raw or undercooked crabs can lead to a paragonimus infection. With a quick search of the medical literature, Bailey learned that rare cases of North American paragonimiasis had been described in patients eating raw crayfish. The scenario fit perfectly with his patient.
"That's the interesting thing about being an infectious diseases doctor," Bailey says. "Every time you see a new patient you have to be open to the possibility that the diagnosis could be something highly unusual."
Crayfish are common throughout North America, where hundreds of species live in rivers, streams, lakes and ponds. The parasite P. kellicotti has a complex life cycle. It lives in snails and crayfish but only causes a dangerous infection if it ingested by mammals, including dogs, cats and humans, who eat it raw.
No one knows why more cases of paragonimiasis are being diagnosed now, but doctors and researchers at Washington University are studying the parasite and hope to develop a better diagnostic test for the infection. For now, the message for physicians is to consider paragonimiasis in patients with cough, fever and eosinophilia. The simple message for the public is: "Do not eat raw crayfish," Weil says.
Physicians at Washington University School of Medicine published a review article last year that includes information about the first three cases of paragonimiasis they diagnosed: Lane MA, Barsanti MC, Santos CA, Yeung M, Lubner SJ and Weil GJ. Review Article: Human Paragonimiasis in North America following Ingestion of Raw Crayfish. Clinical Infectious Diseases. Sept. 15, 2009.
Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.
Judy Martin | EurekAlert!
Biofilm discovery suggests new way to prevent dangerous infections
23.05.2017 | University of Texas at Austin
Another reason to exercise: Burning bone fat -- a key to better bone health
19.05.2017 | University of North Carolina Health Care
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
24.05.2017 | Physics and Astronomy
24.05.2017 | Physics and Astronomy
24.05.2017 | Event News