Education needed for pregnant workers

There are some risks to fetus

The ideal time to screen for immunity and educate health care workers about infection control and pregnancy is at initial employment -- not following an exposure that could threaten the fetus, an epidemiologist reminds.

The initial education session should be followed by ongoing efforts to raise awareness that health care workers need not worry about the occupational infection risks during pregnancy if appropriate precautions are followed, says Rebecca Wurtz, MD, hospital epidemiologist at the Evanston (IL) Medical Center.

"The last thing on an employee's mind as she starts a new job may be a future pregnancy," Wurtz notes. "The information provided at employment may be forgotten at the time when it is most needed. Women should be reminded to mention their occupations to obstetrical health care providers, and once a quarter we provide a lunchtime conference on the pregnant health care worker and infection control."

Pregnant workers not immunocompromised

Outlining the issue recently in Washington, DC, at the annual conference of the Society for Healthcare Epidemiology of America (SHEA), Wurtz emphasized that pregnant workers are not immunocompromised and the health care setting poses few risks to the fetus that are not already found in the community. Thus she argues against general policies of removing pregnant women from patient care, given that infection control is rigorously followed and all appropriate immunizations are in place.

"There are no special or different infection control precautions that a health care worker should take because she is pregnant --basic rules of infection control apply," she said. "Pregnant women are generally young and healthy and are not at special risk for contracting occupational infections."

Even with appropriate immunizations and infection control measures in place, recurrent concerns about the infectious risk to pregnancy center chiefly around three viruses: varicella, cytomegalovirus (CMV) and parvovirus B19. Pregnant women generally are not more prone to infection with the viruses, but all three pose risk to the fetus if acquired by the mother.

"These are the viruses about which we get the most calls," she said.

Viruses of concern

Fortunately, for varicella there is both the recently available vaccine and a post-exposures varicella zoster immune globulin (VZIG). It is clearly desirable for women of childbearing age to be immune to varicella, but the vaccine should not be administered during pregnancy due to the theoretical risk to the fetus, Wurtz said.

"We screen our new employees at employment for varicella immunity and urge vaccination," she said. "The varicella vaccine should not be given to a pregnant woman or a to a woman contemplating pregnancy in the next three months because its risk is unknown."

When a varicella susceptible pregnant health care worker has a significant occupational exposure -- defined as prolonged face-to-face contact -- VZIG should be administered. It should be given in the same dose -- that is based on weight -- as for non-pregnant women, she noted.

"VZIG will prevent or mitigate clinical infection in adults but will not prevent viremia, and thus it may not prevent fetal infection," she told SHEA attendees. "There is evidence that it will reduce the risk of fetal infection."

CMV a formidable threat

As for CMV, the virus is considered such a formidable threat to the fetus that some epidemiologists have recommended removing pregnant workers from patient care in the third trimester. Transmitted mainly through infectious body fluids which come into contact with the hands and are inoculated into the nose and mouth, CMV is found in highest quantities in the saliva and respiratory secretions of infected infants and toddlers, Wurtz said. Thus the greatest occupational risk for infection may be in day care center workers, she noted.

In hospitals, there have been concerns that pediatric patients and immunocompromised adults could be potential reservoirs for CMV. However, exposures to pregnant health care workers may confer no greater risk of infection than those generally encountered in the community, and numerous studies have shown the risk of transmission from patients is remote, she emphasized.

"Studies in diverse settings have shown conclusively that CMV is rarely if ever transmitted from patients to health care workers," Wurtz said. "The widespread implementation of what we now call standard precautions makes it even less likely that a health care worker should be infected occupationally. The only special precaution to take is don't kiss your patients. While this may seem amusing or self-evident, there is a lot of hugging on a pediatric floor -- but kissing should be discouraged."

Take droplets precaution

Parvovirus B19 likewise poses a rare but real risk to the fetus, particularly if the mother is infected between the 10th and 20th week of pregnancy. Complicating control efforts, however, is the fact that most transmission of parvovirus occurs before illness is evident. Immunocompromised patients are more likely to be persistently viremic and shed parvovirus in larger quantities for a longer time. The virus is present in oral and respiratory secretions, but the exact modes of transmission are not clear, she said.

"The most common likely route of spread is by person-to-person contact, although fomites and droplet spread are possible," she said. "Some investigators of possible outbreaks of [parvovirus] in hospital settings have reported transmission from patients to health care workers, but others have not."

Again, recent studies have suggested the risk in the hospital and the community may be roughly comparable, particularly during community outbreaks.

"The seroconversion rate was equally high in all groups, suggesting what might have been labeled a nosocomial outbreak could actually reflect transmission in the community," Wurtz said.

CDC infection control guidelines recommend droplet precautions with parvovirus, consisting in essence of standard precautions, a private room for the patient, and health care workers wearing masks. However, unlike varicella, there are no specific interventions to make following exposure to parvovirus or CMV, other than following the person for illness and then initiating therapy for infection. *