THURSDAY, Aug. 19, 2004 (HealthDayNews) -- U.S. health officials acknowledged Thursday the very slight possibility that West Nile virus may have been transmitted through dialysis last summer.
According to the U.S. Centers for Disease Control and Prevention (CDC), the case involved three people with kidney disease in Georgia. Two of them were the only people in their county who had confirmed cases of West Nile virus last year. Both had dialysis at the same place on the same machine on the same day. Sandwiched between them on the same machine was a third patient whose test results for the virus came back inconclusive. All three lived fairly close to each other.
And while health officials have closed the book on the case without a clear resolution, it does raise another flag on transmission.
West Nile is generally transmitted to humans by infected mosquitoes. But it has also been shown to be transmitted through blood transfusions, organ transplantations, from mother to fetus and possibly through breast milk.
"This is a new disease in the United States and we're learning about it. We're trying to figure out how it transmits so we can figure out if people are safe," said Richard Quartarone, a spokesman for the Georgia Division of Public Health in Atlanta. "This was coming off of the first year of doing blood gets, and we were starting to see the possibility of people's blood coming into contact with each other."
At least one expert thinks it's unlikely the virus was spread through dialysis.
"Theoretically, it's very unlikely. The evidence for any transmission is very circumstantial and not proved," said Dr. L. Lee Hamm, chief of nephrology and hypertension at Tulane University School of Medicine in New Orleans. "I don't think dialysis patients should be concerned about getting their dialysis."
The case was reported in the Aug. 19 issue of the CDC's Morbidity and Mortality Weekly Report.
On the day in question last August, a 77-year-old man with hypertension and end-stage kidney disease -- identified as "Patient A" -- received dialysis first. Eight days later, he was hospitalized with a fever, chills and confusion. Test results showed he was suffering from West Nile. He was discharged from the hospital nine days later.
"Patient B," who received dialysis second, was a 71-year-old woman with end-stage kidney disease, type 2 diabetes and hypertension. She had no symptoms of illness during late August or early September and her tests for West Nile were inconclusive, Quartarone said.
The last of the three to receive dialysis was "Patient C," a 60-year-old man with type 2 diabetes, hypertension, alcoholism and prostate cancer as well as end-stage kidney disease. Nineteen days after the dialysis, he was hospitalized with fever, chills and an "altered mental state," according to the report. Tests came up positive for West Nile. He died 20 days after being admitted to the hospital.
Health officials investigated the dialysis center and found no problems with infection control. For transmission to take place, a needle or other component of the process would have had to be dirty.
"They were doing everything right, cleaning the machine, new needles, new tubes, new dialyzers between each patient," Quartarone said. "They seemed to have a good history of infection control."
The CDC report pointed out that, in the past, transmission of hepatitis in dialysis patients had been caused by cross-contamination of supplies, equipment, or medication and problems with infection-control. Outside of the United States, transmission of HIV between dialysis patients has occurred as a result of reusing needles, dialyzers and improper injection practices.
More likely, health officials said, patients "A" and "C" were bitten by the same group of mosquitoes because they lived just two-tenths of a mile from each other. "Patient B" lived about one mile away from them. Although no West Nile virus-positive mosquitoes were identified in that area, there were signs of poor preventive measures, such as missing window screens and standing water, the CDC report said.
And, they added, patients on dialysis are also more susceptible to infections in general.
Health officials are no longer investigating the case, so it's unlikely they'll ever have a final answer.
Quartarone said the state health department was leaning toward the geographical explanation of events. But there's still a lesson to be learned, he added.
"Hopefully, this will give a heightened sense of suspicion when people are doing case investigations on West Nile to ask those kinds of slightly off-the-wall questions," Quartarone said. "It is most likely mosquitoes, but don't close down other considerations."
This year, West Nile is particularly problematic in Arizona, which now has 42 percent of the cases reported nationwide. California, Colorado, Florida, New Mexico, and South Dakota have been hit hard, as well.
As of Aug. 17, the CDC said, there were reports of 689 human cases of West Nile, and 20 deaths so far this year.
California and Louisiana had five deaths each, Arizona had three, Texas had two, and there has been one death each in Colorado, Florida, Iowa, Mississippi and Ohio.
For more on West Nile, visit the Centers for Disease Control and Prevention.