The development comes on the heels of the announcement Thursday by U.S. Department of Agriculture officials of a possible second case of mad cow disease in U.S. herds.
Richard Da Silva, 58, of Orange County, N.Y., died from Creutzfeldt Jakob disease, an incurable brain-wasting illness that strikes about one person per million.
Richard's wife Ann Marie Da Silva told UPI he underwent a check for the eye disease glaucoma in 2003, approximately a year before his death. The procedure involves the use of a tonometer, which contacts the cornea -- an eye tissue that can contain prions, the infectious agent thought to cause CJD.
Ann Marie's concern is that others who had the tonometer used on them could have gotten infected.
A 2003 study by British researchers suggests her concerns may be justified. A team led by J.W. Ironside from the National Creutzfeldt-Jakob Disease Surveillance Unit at the University of Edinburgh examined tonometer heads and found they can retain cornea tissue that could infect other people -- even after cleaning and decontaminating the instrument.
"Retained corneal epithelial cells, following the standard decontamination routine of tonometer prisms, may represent potential prion infectivity," the researchers wrote in the British Journal of Ophthalmology last year. "Once the infectious agent is on the cornea, it could theoretically infect the brain."
Prions, misfolded proteins thought to be the cause of mad cow, CJD and similar diseases, are notoriously difficult to destroy and are capable of withstanding most sterilization procedures.
Laura Manuelidis, an expert on these diseases and section chief of surgery in the neuropathology department at Yale University, agreed with the British researchers that tonometers represent a potential risk of passing CJD to other people.
Manuelidis told UPI she has been voicing her concern about the risks of corneas since 1977 when her own study, published in the New England Journal of Medicine, showed the eye tissue, if infected, could transmit CJD.
At the time the procedure was done on Richard Da Silva, about a year before he died, she said it was "absolutely" possible he was infectious.
The CJD Incidents Panel, a body of experts set up by the U.K. Department of Health, noted in a 2001 report that procedures involving the cornea are considered medium risk for transmitting CJD. The first two patients who have a contaminated eye instrument used on them have the highest risk of contracting the disease, the panel said.
In 1999, the U.K. Department of Health banned opticians from reusing equipment that came in contact with patients' eyes out of concern it could result in the transmission of variant CJD, the form of the disease humans can contract from consuming infected beef products.
Richard Da Silva was associated with a cluster of five other cases of CJD in southern New York that raised concerns about vCJD.
None of the cases have been determined to stem from mad cow disease, but concerns about the cattle illness in the United States could increase in light of the USDA announcement Thursday that a cow tested positive on initial tests for the disease. If confirmed, this would be the second U.S. case of the illness; the first was detected in a Washington cow last December. The USDA said the suspect animal disclosed Thursday did not enter the food chain. The USDA did not release further details about the cow, but said results from further lab tests to confirm the initial tests were expected within seven days.
Ann Marie Da Silva said she informed the New York Health Department and later the eye doctor who performed the procedure about her husband's illness and her concerns about the risk of transmitting CJD via the tonometer.
The optometrist -- whom she declined to name because she did not want to jeopardize his career -- "didn't even know what this disease was," she said.
"He said the health department never called him and I called them (the health department) back and they didn't seem concerned about it," she added. "I just kept getting angrier and angrier when I felt I was being dismissed."
She said the state health department "seems to have an attitude of don't ask, don't tell" about CJD.
"There's a stigma attached to it," she said. "Is it because they're so afraid the public will panic? I don't know, but I don't think that the answer is to push things under the rug."
New York State Department of Health spokeswoman Claire Pospisil told UPI she would look into whether the agency was concerned about the possibility of transmitting CJD via tonometers, but she had not called back prior to story publication.
Disposable tonometers are readily available and could avoid the risk of transmitting the disease, Ironside and colleagues noted in their study. Ann Marie Da Silva said she asked the optometrist whether he used disposable tonometers and "he said 'No, it's a reusable one.'"
Ironside's team also noted other ophthalmic instruments come into contact with the cornea and could represent a source of infection as they are either difficult to decontaminate or cannot withstand the harsh procedures necessary to inactivate prions. These include corneal burrs, diagnostic and therapeutic contact lenses and other coated lenses.
Terry Singletary, whose mother died from a type of CJD called Heidenhain Variant, told UPI health officials were not doing enough to prevent people from being infected by contaminated medical equipment.
"They've got to start taking this disease seriously and they simply aren't doing it," said Singletary, who is a member of CJD Watch and CJD Voice -- advocacy groups for CJD patients and their families.
U.S. Centers for Disease Control and Prevention spokeswoman Christine Pearson did not return a phone call from UPI seeking comment. The agency's Web site states the eye is one of three tissues, along with the brain and spinal cord, that are considered to have "high infectivity."
The Web site said more than 250 people worldwide have contracted CJD through contaminated surgical instruments and tissue transplants. This includes as many as four who were infected by corneal grafts. The agency noted no such cases have been reported since 1976, when sterilization procedures were instituted in healthcare facilities.
Ironside and colleagues noted in their study, however, many disinfection procedures used on optical instruments, such as tonometers, fail. They wrote their finding of cornea tissue on tonometers indicates that "no current cleaning and disinfection strategy is fully effective."
Singletary said CDC's assertion that no CJD cases from infected equipment or tissues have been detected since 1976 is misleading.
"They have absolutely no idea" whether any cases have occurred in this manner, he said, because CJD cases often aren't investigated and the agency has not required physicians nationwide report all cases of CJD.
"There's no national surveillance unit for CJD in the United States; people are dying who aren't autopsied, the CDC has no way of knowing" whether people have been infected via infected equipment or tissues, he said.
Ann Marie Da Silva said she has contacted several members of her state's congressional delegation about her concerns, including Rep. Sue Kelly, R-N.Y., and Sen. Charles Schumer, D-N.Y.
"Basically, what I want is to be a positive force in this, but I also want more of a dialogue going on with the public and the health department," she said.