NEW ORLEANS — Doctors don’t know why eating crawfish or buffalo fish sometimes causes the rare muscle-destroying illness that recently sickened three members of one Mississippi family. But they believe Haff disease is caused by eating bottom-feeders that have eaten the roots of a wetland plant called water hemlock.
The three people who became ill in early July after eating buffalo fish caught in the Yazoo River were Mississippi’s first cases, but Haff disease has been seen at least twice in Louisiana since 2000. And in 1997, seven people diagnosed with the disease in other states turned out to have eaten buffalo fish caught in Louisiana and Missouri.
No U.S. case has been fatal. Symptoms — muscle weakness and pain, dry mouth, chest pain, nausea, vomiting, confusion, and dark urine — generally appear within 12 hours of eating buffalo fish or crawfish.
The disease is caused by a toxin that destroys skeletal muscle tissue — possibly cicutoxin, which is found in water hemlock, though the connection to Haff disease has never been proved, epidemiologist Mallory Becnel wrote last year in the Louisiana Mortality and Morbidity Report.
As muscle cells break open, their contents pour into the blood. Treatment is mostly large amounts of intravenous fluid to keep the contents of the cells from clogging and destroying the kidneys.
Only about 30 cases of Haff disease have been reported in the United States since 1984, the Mississippi State Department of Health said last month, though water hemlock is found throughout North America.
“It’s a really common plant in wetlands and other wet places, roadside ditches,” said Gary N. Ervin, head of the plant ecology lab at Mississippi State University. Because it generally grows in shallow water or moist areas that may flood for part of the year, it might not be readily accessible to some types of fish but would be easy for crawfish to get at, he said.
Water hemlock also is called cowbane, beaver poison, muskrat weed or musquash poison. The toxin is found throughout the plant but is especially concentrated in the chambered, tuberous roots, according to the U.S. Forest Service. In the book “Weeds of the Northern U.S. and Canada: A Guide for Identification,” France Royer and Richard Dickinson describe water hemlock as the most toxic plant in North America.
In January 2012, a 62-year-old woman who had eaten buffalo fish went to a hospital because her arms, neck, back and chest were aching and she felt nauseated, Becnel wrote.
The chest pain can be mistaken for a heart attack, said Dr. Raoult Ratard, Louisiana’s state epidemiologist.
Seven people went to emergency rooms within one week in 2001 with chest pain, shortness of breath, nausea and sweating, according to an earlier article in in the Louisiana Mortality and Morbidity Report.
Ratard said the seven were fairly young. “At first it looked like heart attacks,” he said. But their blood didn’t show high levels of enzymes found in heart muscles and used to diagnose heart attacks. Their blood did have high levels of CPK, an enzyme found in all muscle cells. That indicated the muscle destruction called rhabdomyolysis.
All had bought crawfish from the same store in the Zachary area.
“By the time we knew about it, some other people had bought crawfish and nothing had happened,” Ratard said.
Five of the people were hospitalized. They recovered quickly, without remaining problems, LMMR reported.
People who think they have heart attacks probably make up the bulk of Haff disease diagnoses because the enzyme test isn’t common, said Dr. Brobson Lutz, former health director for the City of New Orleans.
“I suspect that, like most diseases, the cases that get reported are the tip of the iceberg and other people get mild symptoms that resolve spontaneously over a few hours. ... And if they did get into the emergency room, it’s unlikely a CPK test would be ordered unless there was some sort of chest pain,” he said.