Baffling Blindness Afflicts Thousands in
Cuba
Medical Researchers Believe Nutrition May Be Partly at
Fault
By Sandy Rovner
Washington Post Staff Writer
Washington Post, June 1, 1993, Health section, page 7
A mysterious epidemic has afflicted
the vision of thousands of Cubans in the past 18 months, prompting
increasing international attention and medical investigation.
The disorder, which is not fatal, has
affected mostly adult men and caused some cases of blindness.
In addition to the vision problems, it has also caused loss of
sensation in the arms and legs.
At the request of the Cuban government,
two international teams of scientists, one organized by the New
York-based international vision organization Project Orbis, the
other by the World Health Organization, spent from five days
to two weeks in Cuba recently. The teams were made up of neurologists,
ophthalmologists, nutritionists and virologists, including Nobel
laureate Carleton Gajdusek from the National Institute of Neurological
Disorders and Stroke.
They took cultures, examined patients
and debriefed Cuban scientific experts but came to no firm conclusions
about the ailment.
 |
| Benito Perez gets an eye exam from Maritza Valdez, a physician at Havana's Clinic La Lisa. Perez, 64, is one of an estimated 34,000 Cubans experiencing sudden vision damage. Health officials speculate that the mystery disease may be caused by a combination of malnutrition and vitamin deficiencies resultiing from the nation's acute economic crises. (AFP PHOTO) |
There is a general consensus, some
of the scientists said, that widespread malnutrition, caused
by Cuba's deteriorating economy, plays a major role in the illness,
as does some toxic agent—possibly in homemade rum—that
has not been identified. The scientists also agree that the pattern
of the epidemic's spread shows no sign that it is contagious.
For example, one doctor who would not
allow his name to be used said, "there are very few cases
in the same family; very few cases among children; no cases in
high schools, which, in Cuba, are boarding schools; and only
one case in the army—a general." Moreover, no foreigners
in Cuba have contracted the illness, the doctor said.
As of May 24, the Cuban government was
reporting 34,000 cases, but the U.S. scientists believe many
of these cases may represent other ailments. Still, even if only
half the cases fit the strict diagnostic protocol the scientists
have tentatively established, "the epidemic is unique in
the speed of its onset and the large numbers of those stricken,"
a member of the Pan American team said.
Cuban health officials believe that patients
are beginning to respond to a variety of therapies, including
a nationwide distribution of vitamins and other food supplements.
Cuban scientists are also trying a variety of drug therapies,
including interferon.
The Pan American Health Organization
issued a formal statement last week noting its team had found
that "epidemiologic and laboratory studies carried out to
date have not proven any environmental, genetic, nutritional,
infectious or toxicological cause for the epidemic."
Initially, Cuban scientists believed
the epidemic was caused by a virus and they isolated one they
thought might be responsible in some patients. But they were
not able to determine its actual relationship to the illness.
Nonetheless, according to David M. Asher,
one of three virologists from the National Institutes of Health
on the Pan American team, "It's one of those situations—whenever
a virus comes up, you can't just shrug it off." The NIH
scientists are analyzing the isolated virus and may have information
on it "in several weeks," Asher said.
Alfredo A. Sadun, a neuro-ophthalmologist
from the University of Southern California School of Medicine
and the Doheny Eye Institute, who was recruited by Project Orbis
for its Cuba team, believes that he has unraveled at least part
of the mystery.
He said that patients he examined had
optic nerve fiber injury that is similar to that found in several
other central nervous system diseases involving damage to the
mitochondria, the energy-producing part of cells. Damage to the
mitochondria often surfaces as problems with the eyes and the
spinal cord, he said.
In order for the mitochondria to produce
energy, the body needs large quantities of folate, or folic acid,
which is found in many fruits and vegetables and in animal liver,
both of which are in increasingly short supply in Cuba. Folate
is also used by the body to eliminate toxins such as the methanol
found in minute quantities in alcoholic beverages.
"Normally," said Sadun, "small
amounts of methanol wouldn't bother you, but because the Cubans
have a low folate level because of their poor diet, the little
folate that's left is being sucked out of the system to be used
to detoxify the methanol."
Another toxin that injures the energy-producing
system is cyanide, Sadun said. Small amounts of cyanide are found
in unprocessed or poorly processed sugar cane, a key component
of rum.
He hypothesizes that the combination
of methanol and cyanide in the homemade rum has created this
widespread condition. Rum is rationed in Cuba and widely bootlegged,
Sadun said he was told by patients.
Tobacco is also a source of cyanide and,
he said, 95 percent of adult Cuban males are smokers.
The epidemic began in late 1991 in a
tobacco-growing region west of Havana. It gradually moved east
as first men, then women and some children, mostly adolescents,
began to turn up with vision loss in varying degrees and loss
of sensation in arms and legs.
Sadun noted that a similar epidemic in
Jamaica in the 1940s, eventually named Jamaican Optic Neuropathy,
was traced to the habit of eating the root of the cassava, which
is covered with cyanide. Several hundred Jamaicans went blind,
Sadun said. Other similar outbreaks in Mexico and in some African
countries were traced to either yucca or cassava.
Sudun predicted that the epidemic would
abate within the next few weeks because the government has begun
widespread distribution of nutritional supplements. He said that
some of the patients would never recover their vision because
the nerve fibers were dead and do not regenerate.
"However....some of the fibers will
recover" with proper nutritional care, he said.
Another group of scientists who went
to Cuba earlier last month joined with former U.S. Atty. Gen.
Ramsey Clark last week in charging that the U.S. trade embargo
of Cuba, which was tightened last year, was a culprit in the
epidemic. But most of the scientists are avoiding any reference
to political ramifications.
The team members said Cuban President
Fidel Castro was concerned about the epidemic, and they were
impressed with his grasp of the medical problems. He attended
all the evening meetings and some of the other sessions the scientists
held while in Cuba.
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