Management of Outbreaks

This section deals with the measures that can be implemented in case of outbreaks of virus infections. The following topics will be covered:-

1. Control of Outbreaks of Viral Gastroenteritis
2. Prevention of transmission of blood-borne viruses from medical staff to patients
3. Outbreaks of Respiratory Virus Infections
4. Outbreaks of Enteric Viral Infections
5. Control of viruses that spread by direct inoculation
6. Management of rabies
7. Management of Viral Haemorrhagic Fever
8. Summary of control measures  

Control of Outbreaks of Viral Gastroenteritis

A. Outbreaks in hospitals and institutions

Small outbreaks of viral gastroenteritis are common in hospitals, especially among paediatric wards where rotaviruses and adenoviruses are usually involved. Large outbreaks involving adult wards are rare and small round structured viruses (SRSVs) are more likely to be involved. In such an outbreak situation, steps should be taken at the same time to establish the cause, mode of spread and control of the outbreak simultaneously.

Detailed information about the outbreak should be obtained. In particular, any factors common to those affected should be determined, such as whether they have consumed the same type of food, are the wards served by the same medical teams or other personnel, are any health workers involved. Fresh faecal specimens should be collected from an affected patient as soon as possible to ensure the maximum chance for detecting the pathogen. Faecal specimens should be sent for bacteriological and parasitical examination as well as virological examination. As a quick screen, the specimens could first be examined for the presence of rotaviruses or adenoviruses by EIA. The specimens should then be examined by electron microscopy or RT-PCR for Norwalk-like viruses if available. Only a small proportion of the specimens processed would be expected to yield a positive result. However, this is sufficient evidence to implicate SRSV as the agent. Other diarrhoeal viruses are occasionally involved in outbreaks in adults including caliciviruses, astroviruses, rotaviruses and adenoviruses. Normal electron microscopy should have little difficulty in detecting these viruses.

Diarrhoeal viruses are mainly spread by the faecal-oral route, either through infected foods such as shellfish or through an infected food handler. However, other modes of transmission are thought to be possible, in particular through aerosol sprays set up by vomitus. Food could be contaminated by this means or the viruses could be inhaled by other persons. Norwalk-like viruses have in particular been associated with airborne transmission. It is essential to determine whether any particular food consumed within last 5 days may be responsible. Whether any food handlers had been taken ill with gastroenteritis before or during the onset of the outbreak, whether any health workers working in any affected ward(s) were taken ill as they may play a role in the transmission of the virus to other wards. The plotting of an epidemic curve would determine whether the outbreak is a single source outbreak or involve person to person transmission.

Personal hygiene for both staff and patients should be emphasized, particularly hand-washing. Prompt removal of vomitus and diarrhoea is important in order to reduce the chance of environmental contamination. Affected persons should be isolated or cohorted together and enteric precautions instituted. This may be difficult in large outbreaks where there are difficulties in providing adequate facilities and staff for isolating cases. Any staff taken ill should refrain from coming to work. Transfer of staff from ward to ward should be avoided since this may spread infection to other wards. Implicated foods are likely to have been contaminated by the food handler. Food handlers who developed gastrointestinal symptoms should not be allowed to work. A scrupulously high standard of personal hygiene should be enforced for food handlers. Adequate toilet and hand washing facilities should be available which are regularly serviced. Work surfaces should be thoroughly cleaned to remove any environmental contamination. Attempts should be made to rethink food-handling practices to try to reduce the amount of handling of cooked or uncooked foods. It may be wise to take high-risk foods such as salads and sandwiches until the outbreak is clearly at an end. There are clearly a lot of problems involved in controlling outbreaks of viral gastroenteritis in hospitals, in particularly those associated with Norwalk-like viruses where outbreaks can rapidly involve several different wards through person to person spread. Fortunately, such outbreaks usually terminate spontaneously in 7 - 14 days and rarely lead to severe illness, even in those who are elderly or immunocompromised.  

B. Community Outbreaks

Outbreaks of viral gastroenteritis in the community usually involve adults, and Norwalk-like viruses or SRVs are by far the most likely agents to be involved. The majority of outbreaks involve food, in particular shellfish. The hazards of consuming shellfish are well known, especially those usually eaten uncooked such as oysters. Provided that the cooking process is correctly applied, there is no reason why molluscan shellfish cannot be rendered virologically safe. Non-shellfish food-borne outbreaks tend to involve food which tend to be handled extensively in the kitchen, such as salads and sandwiches, which suggest that a food handler is involved as the source. In some cases, several items are implicated whilst in others, it may not be possible to identify any association because multiple items are involved. It is thought that a food handler is infectious up to 48 hours after recovery. It has been assumed that the main means by which transmission occurs is by the faecal oral route involving poor hand hygiene. Another possibility is contamination of food by the airborne route through vomitus of an affected food handler or a waiter. Outbreaks involving potable water have been reported, with persons infected running into hundreds or even thousands. Outbreaks of Norwalk-like viruses have also been associated with swimming in lakes and swimming pools. It is thought that person to person transmission plays a important part in the maintenance of certain outbreaks such as those reported for successive voyages on cruise liners. Such instances may be due to heavy environmental contamination by vomitus and diarrhoea.

The first aspect of control must be to interrupt person to person transmission. This may be very difficult in view of the information emerging about airborne transmission. Prompt removal of vomitus and diarrhoea should reduce environmental contamination. Contamination of shellfish probably occurs as a result of culturing in sewage polluted areas. Re-siting of shellfish beds and/or reduction of sewage pollution are clearly the fundamental steps. Another alternative is to move shellfish to cleaner waters for several weeks to reduce the level of contamination. Consideration should also be given to the removal of viruses from sewage effluent by treatments such as chlorination, ozone or UV light. Properly cooked shellfish should pose no infection risk but this is not applicable to oysters which are often eaten raw. In the prevention of outbreaks caused by food handlers, the most important aspect is to have a system that ensures that food handlers who develop acute GI infection do not continue to work. They should be able to report such illness and take time off work without financial penalty. A scrupulously high standard of hygiene should be enforced for food handlers. The workplace must have adequate toilet and hand washing facilities that are regularly cleaned and serviced. It may be advisable to rethink food handling practices to try to reduce the amount of handling of cooked foods or foods which are eaten uncooked. It is advisable to reduce the chance of contamination of other foods by oysters

In the case of ongoing food-borne outbreaks, potentially contaminated items present in the kitchen such as salads or cakes should be removed. Work surfaces should be thoroughly cleaned and disinfected. It is important to ensure that food handlers taken ill be excluded from work for at least 48 hours after recovery. The problems posed in trying to control SRSV outbreaks have been demonstrated by incidents on cruise liners. The rapid turnaround between cruises, with regular influxes of new susceptible persons, has resulted in repeated outbreaks on successive cruises.

Prevention of Transmission of Blood-Borne Viruses from Medical Staff to Patients

Outbreaks of hepatitis B associated with eAg positive surgeons have been recognized regularly in the UK at the rate of around once a year. This is much higher than that reported for other industrialized countries and could reflect increased vigilance in the UK because of relatively low incidence. The surgeon involved in the majority of outbreaks was thought to be technically competent and had not reported by needlestick injuries. Revised guidelines were issued on HBV infection and health care workers in August 1993. The guidance requires that health care workers who perform "exposure prone procedures" should be vaccinated, that the immune response to the vaccine should be documented, that those with a post-vaccination titre of HBsAb of <10mIU/ml should be investigated further. Those found to be HBsAg and eAg positive should cease to perform exposure prone procedures. Operative procedures are described as exposure prone if there is a risk of injury to the health care worker, which result in the exposure of the patient’s open tissues to blood or body fluids of the worker. Typically, such procedures include surgical or dental operations in which the worker’s gloved hands may be in contact with sharp instruments, needles, and sharp tissues inside a patient’s open body cavity, wound, or confined anatomical space where the hand or fingertips may not be visible at all times.

1. Outbreak Investigation

An outbreak in the UK between 1992 and 1993 where an eAg positive cardiothoracic surgeon was involved in two clusters in two separate hospitals (four cases in the first hospital, and two cases in the second). He was not detected during investigation of the first outbreak because he provided a false specimen. He was only detected following investigation of the second outbreak when the specimens were obtained directly from the surgeon and other health workers involved. The two blood specimens, and a third which he provided earlier to an occupational health department were found to be from different individuals after haptoglobin and alpha-1 antitrypsin grouping. HBV from the six cases proved to be virtually identical to the source surgeon after comparison of the nucleotide sequences and subtyping of HBsAg (all were found to be adr, which was uncommon in the UK).

Patients upon whom the infected surgeon had performed an exposure prone procedure on were identified from hospital operating theatre records. The family doctors of the patients were asked to obtain blood specimens from the patient. A single blood was requested from patients who had been exposed more than 6 months earlier, and two blood specimens (within 3 months of exposure and at least after 6 months after exposure) were obtained from patients exposed more recently. When a patient was found to have serological markers of HBV infection, stored specimens from the patient before surgery were retrieved and tested in parallel. Partners of patients found to be infected were offered serological testing, and, if appropriate, HBV vaccine. Enquiries were made on the presence of any risk factors for HBV infection other than the operation. 18 out of 307 patients tested had serological evidence of recent infection (seroconversion demonstrated or the presence of anti-HbC IgM), of which nine were still HbsAg positive. However one of these patients had a HBV subtype (ayw) which was different from the infected surgeon and thus could not have acquired it from surgery. The other eight had sequences identical or virtually identical with the infected surgeon. Nine patients were determined to have acquired infection acquired at an undetermined time because they were anti-HbC IgM negative and no pre-operative specimen was available. Therefore it could not be ruled that these patients may have acquired HBV infection from surgery. Seven patients were demonstrated to have been infected before surgery. Overall, the rate of transmission to susceptible patients was about 6%.

Tightening of guidelines - as a result of the lessons learnt from the above outbreaks, it is now recommended that when investigating a case of acute hepatitis B in a patient who had undergone surgery in the six months before becoming ill, blood specimens should be obtained from all members of the surgical team even if occupational health records are available. Furthermore, blood specimens from health workers should be obtained by directly observed sampling and tested for HBsAg. Molecular biology techniques may play a useful role in determining the source of infection.

2. Hepatitis B

The introduction of the Department of Health guidelines on HBV infection in health care workers in 1993 led to all health workers undertaking exposure prone procedures being testing for immunity to HBV. Those who were not immune were tested for markers of HBV infection and re-vaccinated if negative. Two trainee surgeons employed by two district general hospitals in the same area were found to be eAg positive HBV carriers. Neither surgeon gave a history of injury at work. The surgeons were suspended from work, counseled, and further blood specimens were taken to confirm the diagnosis and for further investigation. An infection control team, made up of public health physicians, a virologist, a surgeon, and hospital chief executive was convened. The surgeons were examined carefully by the occupational health department to assess the risk of occupational transmission, such as injuries at work, history of jaundice or hepatitis, chronic skin lesions, injecting drug, overseas work, past vaccination, received dental treatment or other operations.

The patient administration system of the hospital was asked to identify all patients that the surgeons had operated on. Patients were counseled individually at home, and blood taken for HBV testing. Patients operated on within 8 weeks earlier were given an accelerated course of vaccine (0, 1, 2, and 12) in the hope that, even if infection had already occurred, severe illness and the development of a carrier state might be prevented. The family doctors of the patients were informed of the management decision and were asked to provide another blood specimen six months after the operation. A press statement was released without giving any personal details about the surgeons or their patients. However it described how long the surgeons had been employed, why they were tested, and at what hospitals the surgeons had worked at. The statement also stated that the surgeons had stopped operating and that all their patients had been counseled. Two of the sixteen patients on whom one of these surgeons had performed exposure prone procedures were shown to have acquired infection from that surgeon. The HBV nucleotide sequences were shown to be identical to the source surgeon by single stranded conforma3tion polymorphism (SSCP). The partners of these patients were also counseled and given HBIG and vaccine.  

3. HIV

To date, there has only been a single report concerning the transmission of HIV infection to 5 patients by a Florida dentist. The mechanism of this transmission remains speculative as the dentist died before his techniques could be verified. It is not possible to quantify the risk of transmission from health care worker to patient, but it must be extremely low given that large volumes of blood would need to enter the patient’s bloodstream. The GMC recommends that all staff who think that they have been at risk of infection should be confidentially tested for HIV infection. Testing for HBV and possibly HCV should also be encouraged. Should HIV infection be detected, counseling and expert advice should be sought. If the health care worker is HIV or eAg positive, then he should stop performing invasive procedures i.e.

1. Surgical entry into tissues, cavities, or organs
2. Repair of major traumatic injuries
3. Cardiac catheterisation and angiography
4. Vaginal or Caesarean deliveries or other obstetric procedures during which bleeding may occur.
5. Dental procedures where bleeding may occur

Should a health worker who had performed invasive procedure be found to be HIV-positive. Enquiries should be made to determine the possible risk of him having transmitted his infection to patients, such as whether he had sustained any injuries while operating, chronic skin lesions etc. The procedures and the role he played in them should be reviewed. It may be advisable to trace those patients, counsel them and offer anti-HIV testing. Postexposure prophylaxis would not be indicated given the very low risk and also the fact that it is probably ineffective after 36-48 hours.

4. Hepatitis C

Although not as infectious as HBV, there had been reports of HCV infection transmitted from infected surgeon to patient. Although, there are no clear guidelines at present, it is likely, that HCV positive surgeons will be asked to refrain form performing exposure-prone procedures as in the case of HBV and HIV positive surgeons. There are no indications for mass screening of surgeons. Instead, those who are at increased risk should be encouraged to come forward for HCV as well as HIV and HBV testing and counseled if found to be positive.

Outbreaks of Respiratory Virus Infections

In general, patients with respiratory virus infections should be isolated in single cubicles or cohorted with respiratory precautions. The room should be under negative pressure. Gloves and gowns (or plastic aprons) should be worn on entering the room. The value of filter masks is highly debatable, but should be worn when handling the patient. Hand washing must be carried out on leaving the room. The number of staff attending the patient should be restricted. Disinfection of surfaces may be carried out by 1000 ppm hypochlorite. Viruses under this category include varicella-zoster, measles, mumps, rubella, parvovirus, influenza, parainfluenza, and RSV. Where possible, nursing of patients should be carried out by staff known to be immune eg. for VZV, mumps, measles, and rubella. For this reason, It would be invaluable to have a record of staff immunity to childhood illnesses kept either by the sister in charge or by the occupational health department.

1. Chickenpox

Outbreaks of chickenpox is of particular concern in wards with immunocompromized patients, particularly paediatric oncology wards with leukaemic children, adult oncology wards, and bone marrow transplant recipients. It is also of concern in obstetric wards and neonatal wards. In the case of obstetric wards, the main concern is that chickenpox is likely to be more severe in pregnant women, and therefore, if supplies permit, susceptible women should be given ZIG. Any baby born whose mother developed the rash of chickenpox within 7 days of delivery should also be given ZIG and possibly acyclovir. Acyclovir is thought to be safe for the fetus. The following are guidelines for dealing with potential contacts of chickenpox in susceptible wards.

1. Patients with uncomplicated chickenpox do not require admission to hospital. If admission is required, then the patient should be put in respiratory isolation. The same applies to patients with other conditions who develop chickenpox while in hospital. For patients with shingles, contact isolation would be sufficient.
2. Other patients on the ward should be assessed for immunity for VZV; usually, a past history of a chickenpox-like illness diagnosed by the General Practitioner is sufficient; however, IgG antibody screening of all patients would be preferable, especially for those individuals who are predisposed to severe chickenpox.
3. Those found to be negative should be discharged home if their condition allows. If they must remain in hospital, they should be cohorted together and put in respiratory isolation during the period of infectivity (10-21 days following contact), until the incubation period has passed. Essentially, these patients must not have contact with immunosuppressed patients.
4. ZIG should be given to seronegative patients who are susceptible to severe VZV disease such as leukaemic children, immunocompromised individuals, pregnant women, and neonates. In the latter case, it may also be reasonable to give IV acyclovir since ZIG is not completely effective in preventing neonatal chickenpox, although this has not been properly evaluated. These patients who are given ZIG and isolated should be isolated for at least 28 days since ZIG is known to prolong the incubation period. If ZIG is not available, oral acyclovir may be used instead for a period of 3 weeks. Live vaccine may also be given to children with leukaemia in haematological remission.
5. Nursing should be carried out by immune staff only. A register of staff immunity is important in view of the susceptibility of 5-10% of the adult population (higher in developing countries). Staff should be assessed for past immunity to VZV, if negative, they should either refrain from work for 21 days (US guidelines), or remain in the same ward, or transferred to other wards with immunocompetent patients doing work which requires less patient contact.
6. With the availability of the vaccine, it may be advisable to screen all staff in high risk wards and immunized if found to be negative. The problem is whilst this is easy for staff permanently based on the ward, there is also a high turnover of non-permanent staff such as doctors, domestics, porters etc. There is now active discussion on the possibility of screening and administering the vaccine to medical and nursing students. It may be advisable to vaccinate all susceptible leukaemic children who are in haematological remission before admission to hospital.
7. It may be advisable not to admit non-immune children during the period of the outbreak, up to 3 weeks after the last diagnosed case of chickenpox.

2. Measles

Measles outbreaks are most deleterious in wards with immunocompromised children or adults e.g. children with leukaemia and BMT patients. Measles is definitely as dangerous as VZV in that setting. Measles can cause severe disease in babies who are undernourished, immunocompromised, or suffering from chronic debilitating disease. Therefore babies with the above conditions, or who had recently recovered from a severe illness should be protected by HNIG.

1. Patients with uncomplicated measles do not require admission to hospital, if admission is required, then they should be put in respiratory isolation so that they may be isolated from the immunosuppressed, babies, and non-immune staff and patients. Patients with measles diagnosed in hospital should be sent home where possible if their condition allows.
2. Nursing should be carried out by immune staff, either in cohorts or in individual rooms during the period of infectivity (4 days preceding to 2 days following the appearance of the rash)
3. HNIG should be given to all severely immunocompromised children irrespective of their immunization status since it has been reported that severe measles infection can occur in those who had been immunized and had a documented low-level antibody response. Two doses HNIG should be given 48 hours apart, the actual dose depending on the age of the patient. Therefore, the routine screening of children for measles antibody before admission is probably unjustified since there would be no difference in the management. The same argument applies to the screening of patients for immunity before the administration of HNIG.
4. Immunocompetent children under 12 months in whom there is a particular reason to avoid measles, such as a recent severe illness, or a chronic debilitating disease can also be given immunoglobulin. MMR vaccine should then be given after an interval of at least 3 months, at around the usual age.
5. The use of live-attenuated vaccine for postexposure prophylaxis is contraindicated in immunocompromised patients. The same protocol applies to immunocompromised adults who come into contact with measles. However, work from Japan suggests that vaccination of leukaemic children in remission is safe and induces a protective immune response.
6. The live vaccine can be used as postexposure prophylaxis in immunocompetent children and adults who had not been immunized since the incubation period of vaccine measles is 7 days compared with 10 days for clinical measles. All immunocompetent non-immune staff and children in contact with the index case should be vaccinated immediately, within 72 hours, unless a valid contraindication exists. HNIG would be unnecessary in those cases.
7. Non-immune staff and patients for whom vaccination is too late and who had been a contact with the index case must be regarded as potentially infectious from the 7th day of the first contact to the 14th day of the last contact. During this time, they should be kept away from susceptible patients.
8. It would be invaluable to have a record of staff immunity to childhood illnesses kept either by the sister in charge or by the occupational health department. Failing a definite medical history, laboratory confirmation may be useful although this service is not normally available from most virology laboratories.

3. RSV

Prevention of the nosocomial spread of RSV infection is of prime importance, as many hospitalized infants have underlying conditions which make them susceptible to severe RSV infection. A number of hospital outbreaks of RSV infection have been described in infants, the immunosuppressed, and the elderly.

1. Affected patients identified clinically as having RSV must be isolated immediately in single cubicle or cohorted for the duration of virus shedding which corresponds to the duration of the symptoms. This period last up to 7 days in healthy children, but can be much longer in the immunosuppressed, leukaemic children, and adults.
2. Hand washing is the most important measure that can be used in the prevention of infection since the virus is mainly spread by close contact. Gowns and gloves should be worn.
3. The routine use of gowns and masks has not be shown to be of additional benefit. The use of gowns may be advisable during periods of close contact in which the infant's secretions are apt to contaminate the clothing. Since RSV primarily infects via the eyes and nose, masks are of limited value. Eye-nose goggles have been reported to be of benefit.
4. Recognition and cleaning of objects contaminated with infant secretions should be carried out as soon as possible.
5. Infected infants should be isolated and cohorted, preferably as far as possible to infants with underlying chronic diseases who are susceptible to severe RSV infection.
6. Nursing personnel should be assigned to care for either infected infants or uninfected infants, but not both simultaneously.
7. During epidemic periods, the numbers of patient contacts and visitors should be limited.
8. Elective admission of infants with high-risk conditions should be avoided during epidemic periods.
9. IV RSV immunoglobulin is now licensed by the FDA in the US for the prevention of RSV infection in children < 24 months with bronchopulmonary dysplasia or premature birth (<=35 weeks)

4. Influenza

Influenza is a particularly worrying problem in nursing homes where individuals with chronic debilitating disease are especially susceptible to severe life-threatening influenza infection.

1. Those diagnosed or suspected as having influenza should be cohorted together in one or two rooms, preferably with negative ventilation. The door to the room should be closed.
2. Hygienic practices among the staff, especially hand washing should be emphasized. Gowns, gloves, and masks are probably unnecessary unless there is prolonged contact with the patient.
3. Staff taken ill should not report to work
4. Amantidine prophylaxis should to given to al the other inmates and staff, together with the current vaccine formulation.
5. Amantidine prophylaxis should be for a period of at least 2 weeks, in order to allow antibody to the vaccine to develop.
6. Longer period of amantidine prophylaxis, up to 6 weeks or for the duration of the outbreak, should be considered for those who could not tolerate the vaccine due to sensitivity to egg protein, or those who are severely debilitated, since the vaccine is only 70% effective. It is thought that prolonged indiscriminate amantidine usage may lead to the emergence of amantidine-resistant viruses.
7. Rimantadine may be used in place of amantidine for prophylaxis and the treatment of uncomplicated influenza A infections, although it has fewer neurological symptoms, it is probably not as effective as amantidine.
8. Zanamivir can be used instead of amantidine for the prophylaxis and treatment of influenza. Being a neuraminidase inhibitor, it has considerably fewer side effects than amantidine and could thus be considered for use in family contacts.

5. Rubella

Despite the vaccination program, a small proportion of women of childbearing age is still susceptible to rubella. Therefore, outbreaks of rubella occurring in hospital wards or outpatients affecting susceptible pregnant women is still a possibility.

1. Affected patients should be sent home or isolated from pregnant women during the infectious period (1 week prior to the appearance of the rash to 10 days after its onset). Babies with congenital rubella should be nursed in standard isolation.
2. Nursing should be carried out by immune staff.
3. The immune status of staff and patients on the ward should be determined following the contact. Records of immunity may be available from occupational health or from antenatal clinic records. Where the result was negative or the records were not available, then immune status testing should be carried out. Those who are negative on initial testing should be retested at least 7 days later (or weekly up to 4 weeks) to see whether there is seroconversion together with the appearance of IgM.
4. Non-immune staff and patients who may be infectious should not have contact with pregnant women during the infectious period (1 week before first contact to 2 weeks after last contact)
5. In cases where the rubella infection is thought to have occurred some weeks prior to testing or is thought to be reinfection, avidity testing may be carried out.

6. Parvovirus

1. Infectious patients should be isolated and contact prevented with individuals at risk of aplastic anaemia and pregnant women.
2. IVIG given periodically can be used for the treatment of aplastic anaemia
3. In theory, HNIG can also be used for post-exposure prophylaxis although this has not been tested.

Outbreaks of Enteric Viral Infections

1. Diarrhoeal Viruses

Most admissions from the community for viral diarrhoea, other than in a food-related outbreak, occur in winter usually in children under 3 years old. Rotavirus account for over 50% of episodes of acute viral diarrhoea in children.

1. Standard "enteric precautions" or otherwise known as "faecal-oral" isolation is required for patients with viral diarrhoea. Cohort nursing is acceptable as long as no patients are admitted to the cohort unless infection is proven.
2. In infants and children, shedding of rotavirus, adenovirus, and astrovirus continues for many days following resolution of the symptoms and therefore they should continued to be isolated for 5 days after the symptoms have cleared.
3. In adults, less virus is shed once the acute episode has passed. Therefore, they do not need to be isolated once their symptoms have cleared.
4. Nursing personnel should be assigned to care for either infected infants or uninfected infants, but not both simultaneously.
5. Eradication of rotavirus from a long-stay geriatric ward or neonatal unit may be impossible partly as a result of recolonization of the ward by chronic carriers such that even closure and cleaning are ineffective

2. Polio

Since the advent of polio vaccination, the majority of reported cases of paralytic poliomyelitis were due to vaccine strain virus. However, cases of paralytic poliomyelitis are still reported from time to time.

1. The polio isolate should be examined further to determine whether it is vaccine or wild type. Initial testing may include the RCT 40 testing. Reference testing may involve the use of monoclonal antibodies and/or sequence analysis.
2. Detailed history should be obtained; such as vaccination history, contact with any persons who may have been vaccinated recently
3. The patient should be isolated with enteric precautions, preferably contact isolation, since high-dependency nursing will probably be required, and also that polio may be transmitted through nasopharyngeal secretions
4. If wild virus is confirmed, then a single dose of OPV should be given to all persons in the immediate neighborhood of the case, regardless of a previous history of immunization against poliomyelitis. Individuals with genuine contraindications such as immunodeficiency should be given IPV. In previously unimmunized individuals, the 3-dose course must be completed.
5. If there is laboratory confirmation that a vaccine-derived polio virus is responsible for the case, immunization of further possible contacts is unnecessary since no outbreaks associated with vaccine virus have been reported to date. If the source of the outbreaks uncertain, it should be assumed to be a "wild" virus and appropriate measures instituted.

3. Coxsackie and Echoviruses

In normal wards, enteric precautions would be sufficient after the diagnosis of a coxsackie or echovirus infection, paying particular attention to hand washing, disinfection of surfaces with hypochlorite 1000 ppm, heat disinfection of bedpans and instruments. However, coxsackie or echoviruses may cause severe problems in a neonatal ward.

1. Pregnant women with a flu-like illness a few days before delivery should be isolated with enteric precautions.
2. She should be investigated for enterovirus infection e.g. throats swabs, stools, and possibly blood for serological tests
3. Her baby should be put in contact isolation after birth, and given HNIG or IVIG if born within 7 days of maternal symptoms.
4. The baby should be examined for enterovirus infection
5. Other babies in the neonatal wards should be given HNIG or IVIG if supplies permit. (In fact, it is now routine to give all premature babies weekly IVIG, IVIG is probably preferable in babies because of the ease of administration once an IV line is in place.)

4. Hepatitis A

1. Standard precautions should apply to patients with hepatitis A. It may be advisable to put patients with a poor standard of hygiene in a side room.
2. Staff constantly exposed to patients with hepatitis A should be advised to be tested for immunity and vaccinated if non-immune.
3. By the time jaundice appears, hepatitis A excretion is probably well past its peak and may even be undetectable. Therefore, HNIG would not be of any use in these circumstances.
4. However, postexposure prophylaxis may be considered in schools and institutions where personal hygiene may be poor.
5. Hepatitis A vaccine may be given at the same time but its efficacy in postexposure prophylaxis is uncertain at present
6. During an outbreak in an institution, good hygiene practices such as hand washing should be practiced.

Control of Viruses that Spread by Direct Inoculation

1. HSV

Outbreaks of HSV infection have been described in neonates which were confirmed by DNA fingerprinting.

1. Mothers with either genital or buccal HSV and her infant should be nursed separately from other patients, with gowns and gloves to be worn by attending staff.
2. Although there is little evidence for postpartum transmission as a cause of neonatal herpes, the mother should be encouraged to wash her hands before handling the patient and to wear a protective gown.
3. Staff with lesions (oral or whitlows) should cover their lesions and not care for patients at risk of serious infection ie. the young, those who are debilitated, immunocompromised, and those who suffer from eczema.
4. Patients with herpetic lesions should be nursed separately. Those with widespread lesions should be nursed in standard isolation.
5. Oral acyclovir should be offered to patients and staff with herpetic whitlows or severe localized lesions. Patients at risk of developing severe herpes infection may need IV acyclovir for 1 week or longer.  

2. Adenovirus

Nosocomial outbreaks of adenovirus pneumonia and URTI, especially caused by types 3 and 7, have been described, as have epidemic conjunctivitis.

1. Patients with pneumonia should be nursed in standard isolation.
2. Patients with eye infections should be discharged home as soon as possible.
3. Staff with eye infections should not have contact with patients for the duration of viral shedding which lasts for 10 days.  

3. CMV

There is no evidence that CMV is acquired nosocomially. Studies in hospital nurses caring for children have not shown any evidence of increased infection rates when compared with women of similar ages working in other occupations. Nonetheless, it would seem prudent to minimize the risks of cross-infection by careful attention to infection control measures in any patient known to be excreting CMV. Gloves and aprons should be worn and careful hand washing implemented. In case of pregnant women in contact with known CMV excretors, the following should be advised.

1. There is no scientific reason why women of childbearing age or pregnant women should be excluded from contact with known excretors of CMV who constitute only a small part of the pool of infection.
2. There is no indication for routine serological screening of female staff taking care of children or adults who may be excreting CMV, because there is no evidence that CMV is an occupational hazard.
3. The most appropriate means whereby pregnant women can protect themselves from acquiring CMV is by attention to good hygiene, especially hand washing. For instance, a pregnant teacher working with disabled children should avoid teaching methods that may involve the transfer of the child’s saliva to her mouth.
4. Immune status screening may be offered to the worried pregnant women. Those who are seorpositive will be at a far lesser risk of giving birth to a child with cytomegalic inclusion disease should transplacental infection occurs.
5. Pregnant women known to have had primary infection may be followed up by fetal blood, amniotic fluid, and chorionic villus sampling.

Management of Rabies

Rabies is an acute viral infection resulting in encephalomyelitis and almost invariably in death. The incubation period is usually between 2 to 8 weeks (range 9 days to 2 years). Infection is usually through the bite of a rabid animal. Rarely, transmission of the virus can also occur through mucous membranes. Person to person spread of the disease is extremely rare but there had been instances of transmission through corneal grafts.

Pre-exposure prophylaxis

Pre-exposure prophylaxis should be offered to all those whose work may lead to potential contact with rabid animals. It should be given to all health workers caring for a patient with confirmed or suspected rabies. Three 1 ml doses (0, 7, 28) by deep subcutaneous or i.m, is normally used. The vaccine may also be given in smaller doses by the intradermal route (0.1 ml) with the same intervals. The intradermal route may also be used for the rapid immunization of staff caring for a patient with rabies by giving 0.1 ml into each limb (0.4 ml in all) on the first day of exposure to the patient. Intradermal immunization is only reliable if the whole of the 0.1 ml dose is given into the dermis and should only be given by a person experienced in the technique. The use of the intradermal route is not covered by the manufacturer’s license. Booster doses of the vaccine should be given every 2 to 3 years. The three-dose course gives virtually 100% protection and thus routine post-immunization testing is unnecessary. However, serological testing is advised for those who work with live virus and this should be carried out every 6 months.

Post-exposure prophylaxis

In the event of a possible exposure, the following protocol should be observed in the UK;-

1. The wound should be thoroughly cleaned
2. The animal involved should be observed for 10 days, if no signs develop, then no further action is necessary. It is not necessary to commence postexposure prophylaxis since UK is a rabies free area. However, if the wound is very severe and near the CNS eg. the face, then post-exposure prophylaxis may be started and stopped if the animal remains normal after the observation period.
3. If the animal is a stray or a wild animal and observation is impossible, advice should be taken from a local doctor or CCDC who will know whether rabies occur in the locality and thus whether post-exposure prophylaxis is advised. It may be advisable to give a course of vaccine without immunoglobulin in such cases.
4. If the exposure occurred abroad, postexposure prophylaxis should be started as soon as possible while enquiries are made about the prevalence of rabies in the country concerned, and where possible, the condition and ownership of the biting animal.
5. Unimmunized individuals should be given 1.0 ml of HDCV by deep subcutaneous or i.m. infection on days 0, 3, 7, 14, 30, and 90. The vaccine should be given into the deltoid region. Rabies-specific immunoglobulin should be given; up to half the dose is infiltrated in and around the wound and the rest given by im injection.
6. Previously immunized individuals should be given two 1.0 ml doses of HDCV into the deltoid. Immunoglobulin treatment is not needed.

Management of patient diagnosed or suspected of having rabies

1. The patient should be put under strict isolation, particular attention should be paid to nasopharyngeal secretions and saliva. Blood is most unlikely to be infectious.
2. Staff caring for the patient should be immunized against rabies.

Viral Haemorrhagic Fever

In Africa, transmission of VHF has been associated with the reuse of unsterile needles and syringes and inadequate barrier nursing procedures for blood, other body fluids, secretions and excretions. The risks associated with various body fluids have not been well defined as most caregivers who acquired infection had multiple contacts with multiple fluids. The exact risk of airborne transmission is uncertain but must be very low, since to date, no cases of airborne infection involving humans had been documented. However this must be considered to be a possibility especially in patients with advanced stages of disease. Moreover, airborne transmission of VHF had been demonstrated in monkeys. The risk of person-to-person transmission is highest in the latter stages of the illness, which are characterized by vomiting, diarrhoea, shock, and haemorrhage. VHF infection has not been reported in persons whose contact occurred during the incubation period, the incubation period generally ranging from 2 days to 3 weeks.

The WHO made recommendations in September 1995 for management of suspected cases of viral haemorrhagic fever. These recommendations apply to patients who, within 3 weeks before the onset of fever, either (1) traveled in the specific local area of a country where VHF has recently occurred, (2) those who had direct contact with the blood, other body fluids, secretions or excretions of a patient or animal with VHF, (3) worked in a laboratory or animal facility that handles haemorrhagic fever viruses. The likelihood of acquiring VHF is considered to be extremely low in persons who do not meet any of the criteria.

1. Standard precautions are generally sufficient for patients in the early stages of the disease undergoing evaluation, since they are unlikely to have symptoms such as vomiting, diarrhoea, and haemorrhage which increases the risk of person-to-person transmission. If the patient has respiratory symptoms such as cough, then face shields or masks, and eye protection (goggles or eyeglass with sideshields) should be worn by caregivers.
2. The patient should be placed in a private room. A negative pressure room is not required during the early stages of the illness. Non-essential staff and visitors should be restricted from entering the room. Caretakers should use barrier precautions to prevent skin or mucous membrane exposure to blood and other body fluids. Gloves and gowns should be worn by all persons entering the room. In addition, face masks and shields should be worn by all persons coming within 1 metre of the patient to prevent contact with blood, other body fluids, secretions and excretions. Foot protection may be advised if there is copious amount of blood, vomit, or faeces present in the environment.
3. Patients with suspected VHF who have a prominent cough, vomiting, diarrhoea, or haemorrhage should be placed in a negative-pressure room in order to prevent possible exposure to airborne particles. Persons entering the room should wear personal protective respirators.
4. Measure to prevent precutaneous injuries should be emphasized.
5. Laboratory testing should be kept to a minimum. Specimens should be put in durable leak-proof containers which are then placed in plastic bags. The laboratory staff should be alerted and the transport of the specimen to the laboratory should be carried out by a single person. Specimens used in laboratory tests should be pre-treated with 10ul per ml of blood with PEG (10% Triton X-100). Specimens in clinical laboratory may be handled in a class II biological safety cabinet. Virus isolation must be done at biosafety level 4.
6. Contaminated surfaces or objects may be disinfected using standard procedures with bleach or other usual hospital disinfectants active against enveloped viruses.
7. Soiled linen should be placed in clearly labelled leak-proof bags and transported directly to a decontamination area. Decontamination may be done by autoclave or even incinerated. However, linens can be laundered using a normal hot water cycle with bleach if universal precautions to prevent exposure are precisely followed.
8. Although there is no evidence for transmission of VHF to humans through exposure to contaminated sewage, the following measures should be followed to reduce the risk. Blood, suctioned fluids, secretions and excretions should be treated before disposal either by autoclave, treated in a chemical toilet, or disinfected with household bleach for at least 5 minutes before flushing or disposal.
9. Solid clinical wastes, including needles, syringes, and tubings, should either be incinerated, or preferably autoclaved before incineration. They can also be disinfected by a disinfectant before disposed of according to local regulations.
10. If the patient dies, than handling of the body should be kept down to a minimum. The corpse should not be embalmed but wrapped in a sealed leak-proof material. Cremation is recommended but if burial is used, then a sealed casket is recommended. Autopsies should not be carried out unless strictly necessary. If carried out, then special containment precautions must be followed.
11. Persons with percutaneous or mucocutaneous exposures to blood, body fluids, secretions, and excretions should immediately wash Autopsies should not be carried out unless strictly necessary. If carried out, then special containment precautions must be followed.
12. Persons with percutaneous or mucocutaneous exposures to blood, body fluids, secretions, and excretions should immediately wash the affected surface with soap and water. Mucous membranes such as the eye should be irrigated. Exposed persons should receive medical evaluation and follow-up management.

Summary of Infection Control Measures