In 1992-93, Cuba experienced an epidemic of optic neuropathy (degeneration of the optic nerve) that ultimately affected more than 45,000 people (425 per 100,000). The search for causes of the rapid spread of both optic and peripheral neuropathy ruled out the existence of an infectious disease or possible toxic causes (food, water, pesticides). Treatment with vitamins proved successful, pointing to nutritional causes. Changes in diet in the early 1990s, partly a result of both the loss of Soviet aid and the US embargo, had resulted in reduced consumption of meat, diary products, breads, fats, cereals, and coffee.
The average Cuban diet thus consisted mainly of rice, beans, cabbage, cassava, and herbal teas, with sugar added to meals and drinking water to increase calorie intake. In addition, a high percentage of smokers were affected (93 percent), as low levels of B12 and B6 which usually break down the cyanide and other toxins found in cigar and cigarette smoke are not present. The result is a "nutritional toxic" insult. It was noted that this disease has also been common to POWs and was evident in Cuba during the Spanish-American War (when there was also an American embargo).
Currently, there is a network of diagnostic centers to monitor and detect possible new levels of optic neuropathy. It was pointed out that lack of medical diagnostic resources has also been one consequence of the US embargo.
Yet the international collaboration that helped solve the optic neuropathy problem was also the first example of bilateral governmental cooperation between Cuba and the US (the Centers for Disease Control) on a public health issue. The value of such international cooperation was summed up for a Cuban physician by a Nobel laureate who said of the optic neuropathy experience: "there's good news and bad news about the epidemic. The good news is that the disease probably won't come back. The bad news is, you may never know exactly what hit you." Thus, this type of international cooperation and dissemination of information is especially valuable as the disease could well occur elsewhere, with little warning.
Questions were asked about the absence of optic neuropathy in other countries suffering nutritional deficits. The response was that the important variable in Cuba (as among POWs) was the sharp drop in vitamin intake and changes in diet in 1992-93, not just the vitamin deficit per se.
Public Health Systems in Developing Countries. http://www.pugwash.org/