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 agentpossibly in homemade rumthat 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 armya 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 situationswhenever 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.