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Stricken sites give shots, but CDC questions need
In unrelated cases that shocked medical communities in Alabama and Michigan last year, two experienced and highly regarded laboratorians died suddenly after occupationally acquiring a pathogen for which there is an available vaccine: Neisseria meningitidis.
On July 15, 2000, a 35-year-old hospital laboratory technician in Huntsville, AL, was working in his yard when he began to feel nausea and pain that rapidly worsened. He died the next day after reporting to the emergency department of Crestwood Medical Center, where he was a microbiologist and laboratory safety officer. He had been working with a meningococcal isolate from a 12-year-old patient in the days prior to his death. (See case descriptions, pp. 48 and 50.) The isolate from the source patient was matched by a DNA fingerprint.
Five months later on Dec. 23, a 52-year-old female laboratory worker with 28 years experience at the Department of Community Health in Lansing, MI, began to feel ill after working with a patient specimen the previous day in the lab. Her condition rapidly deteriorated, and she died on Christmas Day. Isolates from the patient and the worker also were identical. "It’s shocking to think anything could happen that quickly," says Geralyn Lasher, director of communications at the Michigan Department of Health in Lansing. "We provided grief counseling for her co-workers."
No obvious breach in infection control was reported in either case, and the lab workers were described as experienced and competent professionals with good technique. One theory is that they generated an aerosol through manipulations of the pathogen in the lab and unknowingly inhaled it. Another possibility is that they contaminated their hands and then touched mucous membranes such as the eyes or nose. A third fatal meningococcal death in a laboratory worker in Idaho occurred in January 2001, but the case has not been confirmed as occupationally acquired pending genotyping comparisons with the patient specimen, Hospital Infection Control has learned.
The infecting pathogen in the two confirmed cases was N. meningitidis serogroup C. Though not 100% efficacious and limited to only certain groups of meningitis, the vaccine currently available in the United States covers groups A, C, Y, and W-135. Because the vaccine covers serogroup C — the type of meningitis that killed the laboratorians — the hard truth is that immunization could well have saved their lives.
But the epidemiological perspective, as is often the case, is more complicated. The current guidelines from the Centers for Disease Control and Prevention state "research, industrial, and clinical laboratory personnel who routinely are exposed to N. meningitidis in solutions that may be aerosolized should be considered for vaccination."1 Meningitis caused by N. meningitidis results in some 3,000 community-acquired infections annually in the United States, but many clinical laboratorians are not likely to encounter it "routinely" enough to warrant vaccination under the CDC recommendation.
"[Crestwood Medical Center] lab hadn’t seen a case of meningococcal meningitis come through in the last four or five years," says Brian Whitley, MPH, epidemiologist with the Alabama Depart-ment of Public Health in Montgomery. "So even if they were aggressive, it’s not likely they would have vaccinated anyone. They have made the decision to vaccinate their laboratory employees now."
Indeed, Suzanne Stanfield, RN, MSN, CIC, infection control coordinator at Crestwood,
says it is her opinion that it is time to offer the meningococcal vaccine to lab workers nationwide. "We are offering it to our laboratory workers," she tells HIC. "It’s not that expensive — about $75 a person."
In addition, in both the Alabama and Michigan labs, meningitis has been elevated in laboratory infection control terms beyond the current CDC recommendations for biosafety level 2. The labs now are dealing with the pathogen at biosafety level 3, which includes more stringent measures to prevent inhalation of aerosols.
"I don’t think there is any way the CDC could have known that its guidelines were not strict enough," Stanfield says. "But maybe the whole idea of specimen handling in laboratory settings needs to be re-looked at. Not only for this organism, but for other ones that also could be aerosolized."
State lab workers in Michigan also are being offered the vaccine, Lasher notes.
"That is not something that is recommended by the CDC, but we went above and beyond that to offer it as well," Lasher says. "As every other state laboratory in the nation, we were following the recommendations of the highest medical authority in the land, which is the CDC. We took these steps above and beyond that to err on the side of caution. We have had a great deal of support from the lab workers."
Why not immunize all?
As this issue of HIC went to press, the lab deaths were expected to be reported in an upcoming issue of the CDC’s Morbidity and Mortality Weekly Report (MMWR). In preparing the report, the CDC is discussing infection control changes for labs, but the agency may not make any recommendation for routine vaccination of lab workers. Instead, the CDC is considering bumping up meningococcal lab work to biosafety level 3 conditions — meaning a biosafety cabinet would be used to prevent aerosol exposures when working in meningococcal specimens. Current guidelines call for a class 2 biological safety cabinet to be used when mechanical manipulations that have high aerosol potential are performed.
"We’re currently in discussion as to what specific recommendations we are going to make regarding laboratory handling of meningococcal isolates," says Jim Sejvar, MD, medical epidemiologist in the CDC’s meningitis and special pathogens branch. "You have to keep in mind, although this is obviously a worrisome thing — in fact, I suspect that it is more frequent than we are finding out — it is still a relatively rare occurrence."
Based on figures that are likely an undercount, there have been 33 cases of laboratory-acquired meningitis since 1965, Sejvar found in reviewing the literature and appealing for case reports on the Internet. About a third of those cases were fatal, he says.
"I went back about 15 years and, in addition to the ones that are already in the literature, [found] 17 additional cases," he says. "As far as I can ascertain, there are 16 cases in the literature. There are outlying cases in the early 1900s, but for the most part, those are [since] 1965. In general, these cases are not associated with mishaps. They’re just associated with circumstance — and probably not absolutely perfect laboratory technique. In none of these cases was there an obvious breach in protocol."
Given that, why not err on the side of safety and recommend the vaccine for all lab workers who may work with the pathogen? From a public health perspective — despite the dramatic nature of the two recently confirmed cases — the CDC is reluctant to issue nationwide vaccination orders for meningitis of all clinical lab workers based on a real but rare risk.
"There is a difference between having a hospital suggest the vaccine to their laboratories and passing what would be, in effect, a federal mandate for that to occur," Sejvar says. "At this point, we don’t think that we can justify that particular recommendation across the board based on the relatively low risk. Ideally, what we are trying to do is to identify those particular laboratorians or those particular procedures that carry with them excess risk and recommend vaccination [in those cases]. I wholeheartedly support what Michigan and Alabama have decided, but it is much more difficult to do that at the federal level."
Regardless, any such recommendation would have to include input from the CDC’s Advisory Committee on Immunization Practices (ACIP), which may well take up the matter at its next meeting June 20-21, 2001, at the CDC, he says.
William Schaffner, MD, a liaison member for the American Hospital Association on the ACIP panel, recalls the discussions prior to issuance of the 1997 guidelines on the meningococcal vaccine. First, the meningococcal vaccine was not recommended on a more widespread basis to the public because it is not effective in children under the age of two, who are more likely to acquire the infection.
There were also questions about the booster schedule and concerns that the vaccine does not cover serotype B meningitis, which historically has accounted for a large proportion of cases in the United States.
"So in that sense, it was an imperfect vaccine," Schaffner says. "That doesn’t mean that it is not a good vaccine. It has been used on U.S. military recruits for 15 to 20 years, and it has been very effective in eliminating recruiting camp meningococcal outbreaks. There seems to be some increasing outbreaks on college campuses, and that’s why the vaccine is now recommended particularly for freshmen who are going to be living in dormitories."
At the time of prior ACIP discussions, however, the committee decided there was not sufficient data on the risk to clinical laboratory workers to warrant a recommendation for universal vaccination, he recalls. However, ACIP may well take up the issue again as the lab deaths raise questions and concerns, he says. "We now have these reports, which have raised the question that there may be others out there that we don’t know about," says Schaffner, chairman of the department of preventive medicine at Vanderbilt University School of Medicine in Nashville.
Word of the cases prompted concern among laboratorians at Vanderbilt, and the infection control committee offered voluntary immunization after a discussion, he says. "We gave the vaccine to our laboratorians at their request." He says. "It is a safe and effective vaccine, but there are issues here that we need to acknowledge. For example, the appropriate booster schedule for the meningococcal vaccine, if there should be one, is a bit uncertain. So if you have, for example, a laboratory technologist who contemplates a 15- to 20-year career in the laboratory, then there has to be a program to make sure that those people are periodically boosted."
Stanfield says her program is discussing boosting the lab workers every three to five years. Such details will no doubt be the subject of many infection control committee discussions after the CDC releases its official account of the cases and any new recommendations.
"Once that MMWR article is published, I think there will be discussions all over the country about the appropriateness of using the vaccine," Schaffner says.
1. Centers for Disease Control and Prevention. Control and prevention of meningococcal disease: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1997; 46:1-51.