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What every laboratorian should know about RSV.

Laboratorians' attention to resiratory syncytial virus (RSV) is warranted for two main reasons. First, prompt identification of the virus enhances patient care by permitting early intervention. Second, because the microorganism is easily transmitted, laboratory workers must learn to protect themselves, other hospital personnel, and patients from exposure to it

RSV is now recognized a major cause of respiratory illness in pediatric units. A though adults can also contract the virus, they tend to experience only ordinary symptoms of the common cold. In small children, however, the infection can lead to serious sequelae: severe bronchitis, pneumonia, and lifelong respiratory problems. The recently discovered ability of the antiviral agent ribavirin (Virazole) to treat RSV infection has changed hospital response to the virus. It is more important than ever for laboratorians to understand its dangers and how easily they can help restrict its transmission to other personnel and to visitors in the pediatric unit.

Most patients hospitalized with RSV are infants less than one year of age who were admitted with symptoms of lower respiratory tract illness. Infectedd infants shed high titers of the virus for prolonged periods. The result is a large human reservoir of the virus on the wards during RSV season, which spans the winter months. In our area of the Midwest, this lasts from approximately October through April. Viral excretion has been documented for three weeks and tonger in infants with lower respiratory tract illness. I

Because adults' immunity to RSV is limited, infection in hospital personnel can be extensive.

Lab workers can infect themselves by touching their own conjunctival or nasal mucosa with contaminated hands. RSV infection in adults tends to be manifested by signs and symptoms of a cold or influenza like illness that may be severe and debilitating. Symptomatic health care workers can readily transmit the virus to patients in their care.

Even exposed staff members who avoid RSV infection themselves can transmit the virus from patient to patient if their hands become contaminated from contact with secretions. Studies have shown that RSV resists drying and remains viable on crib rails and other environmental surfaces for up to six hours-up to 30 minutes on a used facial tissue. These fomites are suspected to play a role in viral transmission.(2)

* Protocol. Our community hospital, which had formerly followed category-specific isolation as formulated by the Centers for Disease Control, adopted body substance isolation (BSI) in 1988.3 At that time we decided to review our procedures with an eye to preventing the transmission of RSV in the hospital setting, restricting the potential exposure of our employees and family members to the drug used to combat it, and making the handling and testing of laboratory specimens safer. The remainder of this article presents the results of our extensive review of all these elements.

When our hospital used CDC's category-specific isolation, patients known or suspected to be infected with RSV were housed in private rooms and, when so ordered by a physician, placed in contact isolation. Personnel used gowns and gloves when touching infected materials. They washed their hands after touching the patient or potentially contaminated articles and before taking care of another patient. Articles contaminated with infected material were discarded or bagged and labeled before being sent for decontamination or disposed of. These measures had drawbacks that may have increased the risk for nosocomial transmission of the virus, especially during the peak RSV season, late fall to early spring.

One problem is the difficulty of identifying all RSV infections. Virtually any child admitted during the season could easily be carrying the virus. (Our pediatric nurses have become adept at identifying RSV infection by these children's characteristic cough, which the nurses compare with the whooping cough of pertussis.)

Another hindrance to infection control is that few hospitals have enough private rooms to accommodate all patients with RSV infections at the height of the yearly epidemic. Furthermore, isolation in itself does not prevent staff members from inoculating themselves or from carrying the virus on their hands and transferring it to patients in other rooms. It may be argued that having an easily accessible sink available, as is true in private rooms, predisposes hospital workers to wash their hands after patient contact. Yet physical isolation of the patient may also foster a false sense of security.

According to BSI, any body fluid may harbor any microorganism; therefore, isolation is directed at the body fluid rather than at the patient. BSI uses no formal system for warning staff members of a potential illness except in the case of illnesses transmitted through the respiratory route, such as measles, tuberculosis, and bacterial meningitis.

In BSI, as in any system of isolation, scrupulous hand washing should limit viral transmission by the hands. Nevertheless, the failure of personnel to wash their hands after every contact with patients has been well documented.(4) Since RSV is so easily transmitted by contact and the number of cases at our hospital during the peak season is high, we extended our hospitalwide BSI policy to include a measure we called contact precautions.

In our facility, nurses can initiate this precaution for any patient suspected or known to have a disease transmissible by contact with a highly resistant or easily transmitted microorganism. We use the same precaution for antibiotic resistant bacterial infections and for colonization with microorganisms such as methicillin-resistant Staphylococcus aureus or aminoglycoside-resistant gram-negative bacilli, including Serratia and Pseudomonas.

A special stop sign on the door asks visitors and hospital personnel to check with the nurse before entering the room. Visitors are reminded of the importance of good hygiene and hand washing and asked to avoid or limit visits into the pediatric unit if they have RSV symptoms. In an adult or older child, these may include sore throat, runny nose, coughing, congestion, fever, sneezing, wheezing, and sinus headache. Those who do enter must wear appropriate protective gear, including gown and gloves. Masks are not required to prevent transmission of the virus, but many employees choose to wear them.

During the peak season, all children admitted to our pediatric unit with respiratory tract symptoms-bronchiolitis, pneumonia, croup, and others-are considered likely carriers of RSV. These patients remain under contact precautions until lab studies are negative or until the physician indicates on the chart that precautions are to be discontinued.

While private rooms are preferable, children with diagnosed RSV infections can share a room; in fact, cohorting is common during the peak season. The door to the hall is kept closed as much as possible. This measure is intended not so much to contain the aerosolized virus as to prevent young patients from leaving their rooms and to be sure that visitors see the stop sign before entering. Each parent whose child is placed under contact precautions at our hospital receives a written guide from the ribavirin manufacturer that answers common concerns about isolation precautions in general and RSV in particular. Nevertheless, worried parents ask a lot of questions of any hospital worker who passes by, including the laboratorian who has come to obtain a specimen. They may wonder why it is necessary to gown up before entering the room, for example, and whether they should do so themselves in the hospital or at home.

It can be difficult for family members to understand that a child must be isolated in the hospital setting although similar precautions are unnecessary for themselves, including at home. The knowledgeable laboratory worker can explain that the virus is universal and that gowning up and isolating the child helps limit transmission to the other highly susceptible children on the ward.

When children's RSV symptoms are severe enough to require hospitalization, they may benefit from treatment with ribavirin, delivered through an aerosolized delivery system. The recommended length of treatment is 12 to 18 hours per day for three to seven days. A particulate film deposited in the oxyhood or oxygen tent may filter out into the room. This relatively uncontrolled dissemination of the aerosolized drug-provoked when a nurse opens the tent to attend to the patient, for example-makes it especially important for all personnel to take precautions while in the room, whether they have direct contact with the patient or not.

Masks are required when ribavirin treatment is in progress. Pregnant visitors and health care workers are asked not to enter the room because the drug is contraindicated during, the first trimester of pregnancy.(5) Soft contact lenses tend to absorb the particulate aerosol; therefore, anyone wearing them is asked to wear goggles in the room while treatment is in progress. We continually remind the hospital staff about the importance of checking in with the nurse each time they enter the room. We considered placing a different sign on the door during ribavirin treatment, but felt the need for personal contact between nursing and laboratory staff would provide an opportunity for the nurse to explain not only what to do but also why. Admittedly, personal communication may be more feasible in a small community hospital such as ours than in a large city hospital, where posting a distinctive sign might be more efficient. * Obtaining a specimen. The ability to screen for the RSV antigen quickly with immunoassays has made it possible to remove a tentatively diagnosed child far sooner than before. But ribavirin therapy is costly; a positive laboratory finding of RSV may be required to justify the expense to insurors. Physicians are eager for fast turnaround because the sooner they can begin drug therapy, the more effective it will be.

Since RSV replicates in the cells of the nasopharyngeal lining, the best specimen for detection is a nasal washing. When a physician orders an RSV screen, a laboratorian comes to the bedside with a vial of transport medium, usually containing a phosphate buffered saline or tryptose phosphate solution. Before entering the room, the laboratorian, like all visitors and hospital personnel, dons gown and gloves.

The nurse obtains a nasal washing specimen by inserting I to 2 ml of sterile normal saline into the child's nostrils and removing as much of the fluid as possible with a baby nasal bulb. The washings are placed in the prepared medium and transported back to the lab for testing as soon as possible. Under BSI, the specimen is transported in a plastic bag as an extra precaution in case of spillage. Just before leaving the room, the individual removes gown and gloves and washes his or her hands. Inverted gowns and gloves are disposed of in the regular trash disposal, since under BSI all trash is handled as though contagious. Instruments and phlebotomy equipment used in the room should remain there throughout the patient's stay. If not, they must be wiped down with disinfectant before reuse.

*o Lab test. Direct fluorescent antibody (DFA) staining of nasal washings, which some laboratorians prefer, can still be done. Newer immunoassay methods, however, may be as sensitive and may provide faster turnaround time. Both enzyme immunoassay and DFA screening methods are often backed up with a culture.

The lability of the virus makes it wise to keep specimens cool and to transport them to-the lab for inoculation immediately. Although culture identification is still the definitive means for recognizing RSV, studies have shown that screening methods may detect RSV antigen days after viral cultures have reverted to negative."

*Education. As with any procedure or technique, educated personnel are more apt to be compliant. The epidemiology and microbiology staffs should meet with other health care workers at the start of the RSV season and then intermittently for six months to explain the importance and physlologic basis of control measures and their role in preventing exposure. Microbiology personnel should work with personnel from the epidemiology department in educating the rest of the laboratory staff. In-services with handouts and question-and-answer sessions are particularly effective.

As is true for a great many aspects of infection control in an institution, the greatest aids are interdepartmental communication and cooperation. Effectively preventing nosocomial transmission of respiratory syncytial virus requires a frequent exchange of information, a clear understanding of hospital protocols, and enough knowledge of viral pathology to comprehend why going to all that trouble is worthwhile.

One day, when universal precautions are part of our lives and always followed to the letter, contact precautions such as those used for RSV will no longer be necessary. In the meantime, we need to do everything at our command to assure the safest possible atmosphere for hospital patients and personnel.

1. Snydman, D.R.; Greer, C.. Meissner, C.. et al. Prevention of nosocomial transmission of respiratory syncytial virus in a newborn nursery. Infect. Control Hosp. Epidemiol. 9(3): 105 108, 1988.

2. Hall, C.B. Douglas, R.G. Jr.; and German, J M. Possible transmission by tomites of respiratory syncytial virus. J. Infect. Dis. 141: 98 102,1980,

3. Luebbert, P.P. Body substance isolation: A comprehensive method for infection control. MLO 22(4): 35 40. April 1990.

4. Albert, R.K., and Condie, F. Handwashing patterns in medical intensive-care units. N. Engl. J. Med. 304:1465 1466, 1981.

5. Centers for Disease Control. Assessing exposures of health care personnel to aerosols of ribavirin in California.MMWP 37:560 563,1988.

6. Kadi, Z.; Dali, S. Bakouri, S.. et al. Rapid diagnosis of respiratory syncytial virus infection by antigen immunofluorescence detection with monoclonal antibodies and immunoglobulin M immunofluorescence test. J. Clin. Microbiol. Dec. 24(6):1038 1040, 1986,
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Title Annotation:respiratory syncytial virus
Author:Luebbert, Peggy Prinz
Publication:Medical Laboratory Observer
Date:Jan 1, 1991
Words:2232
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