Faculty of Medicine, Dentistry and Health Sciences

I. Summary of the Policy

All students enrolled in the Faculty of Medicine, Dentistry and Health Sciences, and who will have patient contact during their course, are expected to comply with specific  requirements set out in the policy in order to proceed beyond their first year in the course. (In the case of Health Sciences students, this applies to the fourth year).

The specific  requirements are:

1. All students must attend a lecture given by the Infection Control Officer early in the year to explain the Policy and to provide information about particular infections. All students are required to sign for attendance at the lecture.

2. All students must have a blood sample taken to determine if they are immune to the   following infectious diseases, and vaccinated if they lack immunity:

1. Hepatitis B
2. Measles
3. Mumps
4. Rubella (German measles)
5. Varicella (chickenpox)

Refer to section II.1 for further details.

In addition to the above, prior to enrolment, dental students are required to provide the Faculty Office with laboratory evidence of absence of infection with hepatitis B. This must be in the form of a current lab report, performed in a NATA accredited Australian laboratory, showing negative hepatitis B surface antigen (HBsAg). Students infected with hepatitis B cannot be enrolled in Dentistry.

3. All students must provide documentary evidence of up-to-date immunisation against:

1. Diphtheria
2. Tetanus
3. Pertussis
4. Polio

Immunity against these infections cannot be determined by blood testing. If not vaccinated or if vaccination records are incomplete, vaccination may be necessary.

Refer to section II.2 for further details.

4. It is the responsibility of individual students throughout their course to be aware of their infection status for the blood borne viruses (BBVs) HIV, hepatitis B and hepatitis C. A student infected with one of these viruses must not perform exposure-prone procedures and must seek expert advice from a specialist in the field of infectious diseases.

Refer to section III for further details.

5.  All students must have a Mantoux test for evidence of past exposure to tuberculosis.

Refer to section II.3 for further details.

6.  Any student who has been in a hospital (either working or as a patient) outside Western Australia, in the 12 months prior to starting work in a Western Australian hospital, must have swabs taken to determine whether they are carriers of Methicillin-resistant Staphylococcus aureus (MRSA). Work in hospitals cannot be commenced until swabs are shown to be MRSA negative.

Refer to section II.4 for further details.

 7. Sharps injuries and other body fluid exposure incidents must be reported by the student involved to their supervisor immediately. The Infection Control Officer should also be notified via the Incident Report Form.

Refer to section VII.1 for further details.

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II. Further details regarding tests and vaccinations

1. Hepatitis B, measles, mumps, rubella and varicella

You must have evidence of immunity or otherwise to these infections, in the  form of   a recent laboratory report performed in a WA laboratory. The relevant tests are:

1. Hepatitis B surface antibody (HBsAb)
2. Measles IgG antibody
3. Mumps IgG antibody
4. Rubella IgG antibody
5. Varicella IgG antibody

The Faculty will arrange for students to have these blood samples taken and tested. This will be discussed further at the Infection Control Lecture and students will be informed through their year representatives of the dates and venue where this will be done.  Testing will not be done before the Infection Control Lecture is given. Depending on your results, you may need immunisation or boosting against these infections and retesting after 2 months.

Note that live virus vaccines (measles, mumps, rubella and varicella) should not be administered to those who are pregnant. If pregnancy is being planned, it should be delayed for at least 28 days after last being administered one of these vaccines.

A small number of people receiving the varicella vaccine may develop mild infection with the vaccine strain of the virus during the six weeks following administration. Those developing a rash during this period should not come into contact with patients for a week following the onset of the rash.

The cost of testing, but not vaccination, is met by the Faculty.

2. Diphtheria, tetanus, pertussis and polio

Blood testing for immunity to these agents is not routinely available. You should try to obtain your vaccination records from childhood or adolescence. Depending upon your past immunisation history, a Medical Officer at the University Medical Centre will determine whether you need to have a primary vaccination course or boosting against these infections. This process will be greatly assisted, and unnecessary vaccination avoided, if you have records of you past vaccinations. 

The cost of vaccination against these agents is the responsibility of the student.

It is important that the testing and vaccination is carried out early in the year so that the vaccinations can be given and immunity achieved before you start to have patient contact. Students of OHCWA must meet the requirements of the Policy  before the mid first semester break. Health Sciences students in fourth year must meet the requirements prior to their first patient contact.

3. Tuberculosis

Tuberculosis is becoming more common in this community. Students may be at risk of acquiring this infection if they come into contact with a patient who is coughing up this bacterium. All students are expected to undergo a Mantoux test (small subcutaneous injection) in order to detect evidence of possible past infection with tuberculosis.

The Mantoux test should not be done within 4 weeks following immunisation with the following live vaccines as they may suppress the tuberculin response and result in an inaccurate result:

• measles
• mumps
• rubella
• varicella

The Mantoux test should also be delayed for three weeks following a febrile illness for similar reasons.

The Faculty will arrange Mantoux testing for students. This will be discussed further at the Infection Control Lecture and students will be informed through their year representatives of the dates and venue where this will be done.

The cost of Mantoux testing is the responsibility of the student.

4. MRSA (Methicillin-resistant Staphylococcus aureus)

Because of its isolation and stringent screening procedures multiresistant strains of this bacterium have largely been kept out of hospitals in Western Australia. All hospitals in this state have policies to screen new staff for possible carriage of the bacterium. If you have been in a hospital anywhere outside Western Australia within the last 12 months, either working or as a patient, then you must be screened before working in a hospital in this state. This involves having a swab taken from your nose, throat and any broken skin and waiting 2-3 days for the results.

MRSA screening swabs can be performed through PathWest at the QEII Medical Centre, at either "E" Block: Mon-Thurs, 8am-5pm or "J" Block: Mon-Fri, 8am-5pm.

The cost of MRSA screening is the responsibility of the student.

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III. Students infected with blood-borne viruses (BBVs)

Students of the Faculty are expected to comply with the same policy applied by the Medical Board of Western Australia to medical practitioners. A copy of this policy is included in the Appendix 1. In short: 

• Students are expected to be aware of their infection status for HIV, hepatitis B and hepatitis C.
• Testing for infection with these viruses should be carried out should the student experience a potential exposure to these viruses (such as a sharps injury) or if the student engages in any behaviour likely to involve risk of infection.
• Students infected with a blood borne virus must not perform exposure prone invasive procedures on patients. These procedures are described in Appendix 2.

It is not a responsibility of the Faculty nor part of its Infection Control Policy to test or monitor students for evidence of infection for BBVs with the exception of testing required after sharps injuries or other potential exposures from patients. Refer to section VII.1.

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IV. Data collection

The Faculty Office will maintain a record of student compliance with the various components of the Infection Control Policy.

V. The Infection Control Officer

The Infection Control Officer (ICO) is a medically qualified member of the Faculty with specialist qualifications in the field of microbiology/infectious diseases. The ICO is there to give you advice at any time regarding concerns you might have about catching infections from patents; or conversely, about passing on an infection to a patient. You can contact the ICO through the Faculty Office should you need to.

The ICO is Dr Liam O'Connor, who can be contacted at QE II Medical Centre on 08 9346 2496 or through the Faculty Office on 08 9346 7323.

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VI. Confidentiality

The specific information obtained from the blood tests will be available only to the requesting medical officer at the University Medical Centre, the  Faculty Infection Control Officer or where necessary to the Associate Dean for Student Affairs, the Clinic Coordinator at the Oral Health Centre of Western Australia or the Sub-Dean of Health Sciences.

Students who approach the ICO for advice will have their queries treated with respect and confidentiality

There may be situations where infection in a student or patient has placed others at risk  and in order to deal with the situation other Faculty or hospital staff members may need to be informed. This will only be done after consultation between the ICO and the student concerned

Remember always that while confidential information is being collected, it is being done with the clear goal of protecting both students and patients from harmful situations.

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VII. Situations requiring action

 If you ever come into contact with one of the infectious diseases listed below, make a note  of:

• the date, time and duration of the contact
• the name of the contact (ie. if patient or classmate) - the nature of the contact

 The Infection Control Officer will need to have this information in order to best advise you  and others what to do.

1. Needlestick or other body fluid contact

 If you are accidentally pricked by a needle or sharp object which has been used on a  patient or possibly been used on a patient or if any body fluid from a patient makes contact  with your mouth or eyes, chapped skin or open wound on your body, cease work and  inform your immediate supervisor without delay. You, or your supervisor, should then  contact one of the following urgently:

 Students at Sir Charles Gairdner Hospital:

• In working hours contact SCGH Immunology Department: ex. 2833
• After hours page Immunology Registrar through switchboard: 08 9346 3333

Students at Princess Margaret Hospital/KEMH:

• In working hours contact Accidental Inoculation Nurse: page 2711
• After hours contact PMH Emergency Department: ex 8353 OR after hours Nurse Manager, page 8840

Students at Fremantle Hospital:

• In working hours contact Infection Control: page 4168
• After hours contact Emergency Department Senior Registrar/Consultant.

Students at Royal Perth Hospital and other hospitals not listed above:

• In working hours contact the Immunology Clinical Nurse Specialist: ex. 3420
• After hours Immunology Registrar through switchboard: 9224 2244

It is important that you do not delay seeking advice and help following an exposure. In the situation where the source is known to be, or at high risk of being infective for HIV, your risk of acquiring this infection can be substantially reduced if you are administered antiretroviral drugs within several hours, the earlier the better.

Once you have done the above and appropriate management is underway, you must fill out an Incident Report Form (Appendix 3). You should give one copy to your supervisor and another to the Infection Control Officer.

2. Contact with rubella, chickenpox, shingles, mumps or measles

If you come into contact with a case of any of these infections (at home, amongst your friends or in a patient) you should contact the Infection Control Officer as soon as possible. As a result of compliance with the Policy you should be immune to these infections and at no risk of acquiring the infection and passing it on to patients or your classmates. However it is best to discuss this with the ICO to ensure that this is the case. Refer to sections VIII.1-4.

3. Contact with any illness with a rash

If you come into contact with anyone (at home, a friend, or a patient) who has an illness with a rash, you should try to find out what the cause of the infection is. If it is something that you believe you are not immune to you should contact the Infection Control Officer to discuss the situation.

4. Potential MRSA contact

If you come into contact with a patient with MRSA while in a hospital in WA you should  discuss the necessary course of action with the hospitals Infection Control Department.  You may need to have swabs taken to determine whether you have become a carrier. Refer also to section II.4.

5. Contact with Tuberculosis

 If you come into contact with a case of active pulmonary or laryngeal tuberculosis, then you  are at risk of acquiring this infection yourself. Tuberculosis patients who have been on  appropriate antimycobacterial therapy for several weeks are no longer infective to others.  Following contact with an infective patient you should contact the Infection Control Officer  immediately. You may need to have a Mantoux test performed and another in 2-3 months. Refer to section VIII.10.

6. Contact with Encapsulated Bacteria

If you have significant contact with somebody who has invasive disease with either Neisseria meningitidis or (less likely) Haemophilus influenzae you may be at risk of being colonised with this bacterium, subsequently becoming ill with it or passing it on to someone else. Significant contact is:

• kissing contact
• close household contact
• having your face, mouth or eyes come into contact with vomit or respiratory secretions from an infected patient

Following such a contact you can be protected by receiving prophylactic antibiotics, usually  in just a single dose. If you have such a contact you should get in touch with the Infection Control Officer immediately. Refer to section VIII.12.

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VIII. Reference information

This section contains information about a number of organisms and topics which are  relevant to a better understanding of the Infection Control Policy.

1. Measles

Measles is a virus which infects primarily the respiratory tract. It is not common because of widespread vaccination but cases are still seen in those without immunity who come into contact with a case, usually introduced from outside the community. It is highly infectious. The infection consists of fever, red eyes, runny nose, cough and a widespread red blotchy rash. Pneumonia may develop and middle ear infection is a common complication. Mortality is significant in those under 5 years.

Incubation period:  7 - 18 days, typically 10
Period of infectivity: from 4 days before rash onset, to 4 days after rash onset

2. Mumps

Mumps is a viral infection causing painful enlargement of the salivary glands (parotid, sublingual, submaxillary). It may also affect the testes, ovaries and mammary glands and uncommonly may result in sterility.

Incubation period: 14 - 25 days
Period of infectivity: from up to 7 days before parotitis onset to 9 days after onset

3. Rubella

 Rubella is an infection caused by a virus. It is a very common infection in childhood and in  this age group it usually causes no problems. Symptoms of the illness include fever,  tirednesss loss of appetite, swollen glands in the head and neck and a rash. When the  infection occurs in adults it may produce a more significant illnes. and complications like  arthritis and encephalitis (inflammation of the brain, a rare complication) are more common  than in children. The infection is most serious when it occurs in pregnant women because  it can be transmitted to the developing fetus with disastrous effects. If the affected baby is  born alive it may suffer from the congenital rubella syndrome, a collection of birth defects  including microcephaly (abnormally small head), mental retardation, abnormally small  eyes, blindness, deafness, bleeding disorders and abnormal heart valves. For this reason,  a pregnant woman who is not immune to rubella must avoid contact with the virus at all  costs. Even a woman who is immune should avoid contact as reinfections can sometimes occur.

Rubella is spread in the form of droplets from the respiratory tract. The incubation period  (time between first contact and first symptoms) ranges from 14 to 23 days. Infection may  be asymptomatic. It is important to realise that a person infected with the virus may be infectious to others even before the onset of symptoms. An infected person is infectious for  about a week before the onset of symptoms until at least 4 days after the onset of the rash.

Infection with rubella produces immunity to further infections. In addition, immunity may be  achieved by vaccination. Rubella is currently part of the childhood vaccination schedule in  WA. Reinfection with rubella has been described but is uncommon and is more likely to  occur  in someone who has achieved immunity through vaccination rather than by natural infection.

Incubation period: 14 - 21 days
Period of infectivity: from 1 week before to 4 days after onset of rash

4. Varicella-Zoster

This virus causes chickenpox and shingles. Chickenpox is a common infection of children  and usually produces only tiredness, low grade fever, loss of appetite and a very itchy rash  consisting of small blisters.

Adults who become infected with this virus may suffer from  more severe symptoms and are more likely to get complications of pneumonitis (infection  of the lungs) or encephalitis. Once a person has been infected with this virus it stays in  their body forever, usually causing no further problems.

The virus remains hidden in the dorsal root ganglia, small structures of the nervous system close to the spine. In some  people, later in life, the virus can become reactivated and travel down the nerve to the skin  where it produces a red and blistery skin rash called shingles or zoster. This very painful  condition affects only that segment of the skin supplied by the nerve involved.

Two main groups of people should avoid contact with varicella-zoster virus (VZV) if they  are not immune to it. These are the immunocompromised (people whose immune systems  are impaired by things such as cancer or drugs or HIV infection) and pregnant women.

Immunocompromised people if infected by VZV can get an overwhelming and fatal  infection. Pregnant women if infected by the virus may experience a number of problems.

Firstly, they may get a more serious infection than nonpregnant people would, sometimes  resulting in a severe and potentially fatal pneumonitis.

Secondly, the developing fetus may  be infected and suffer from the fetal varicella syndrome, a collection of birth defects  including scarring of the skin, abnormally small limbs, abnormal eyes and mental retardation.

Thirdly, if a pregnant woman comes down with chickenpox within several days  before or after birth, her baby may suffer from a severe chickenpox infection after birth with a high mortality.

VZV is spread by respiratory droplets or by contact with virus from the skin rash. It is highly  infectious. The incubation period ranges from 2-3 weeks. The period of infectivity is from two days before the onset of the rash until 5 days after the appearance of the last lot of vesicles  (blisters).

 It should be noted that a non-immune person can get chickenpox from another case of  chickenpox or from someone with shingles. A person can only get shingles from  reactivation of their own latent VZ virus.

Immunity is gained from either natural infection or from vaccination.

Incubation period: 2 - 3 weeks, commonly14 16 days 
Period of infectivity: from up to 5 days before onset of rash until all lesions are crusted

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5. Diphtheria

This infection, caused by the bacterium Corynebacterium diphtheriae, is rarely seen in this community because of vaccination. The bacterium infects the superficial tissue of the nasopharynx and sometimes further down the airways. It results in production of a very thick exudate or membrane; this, and associated inflammatory swelling, may result in death by asphyxiation. It may uncommonly produce skin ulceration. The bacterium also produces a toxin which is absorbed into the body to produce effects in the heart, (myocarditis leading to heart failure) and peripheral nerves (difficulty breathing, swallowing; muscle weakness).

Incubation period: 2 - 5 days
Period of infectivity: 2 weeks, sometimes 4

6. Tetanus

This infection occurs when hardy spores of the bacterium Clostridium tetani are introduced into a wound contaminated by soil, faeces or other organic matter. Deep puncture type wounds provide the type of anaerobic environment which favours the growth of the bacteria in the soft tissues. The bacteria produce a powerful neurotoxin which blocks inhibitory nerve impulses to skeletal muscle. This results in unopposed muscle contraction manifesting as muscle spasms. Affected patients develop lockjaw (spasms of the jaw muscles), facial spasms, neck stiffness, difficulty swallowing, trunk and leg spasms and convulsions. Muscular spasm can result in the inability to breathe, one of the causes of death in those with the infection. The spasms can continue for months requiring prolonged intensive care management. Mortality is significant, particularly in those parts of the world where intensive hospital care is not available. The disease can be actively  vaccinated against using tetanus toxoid. In addition, tetanus immunoglobulin (TIG) can be used prophylactically in individuals who have not been vaccinated and who sustain a tetanus prone wound.

Incubation period: 3 - 21 days, average 10
Period of infectivity: Not transmitted from person to person

7. Pertussis 

Pertussis, or whooping cough, is a respiratory infection caused by the bacterium Bordetella pertussis. Bacterial toxins damage the ciliated cells of the trachea, resulting in a severe coughing illness which may persist for months. Classical whooping cough is described in young children as having three stages: the catarrhal stage in which increased upper respiratory tract secretions are present, the paroxysmal stage, in which severe bouts of coughing may lead to respiratory arrest, and the convalescent phase, in which coughing episodes persist for months before gradually diminishing. The mortality of whooping cough is significant, particularly in infants less than 1 year of age. In recent years, whooping cough has become increasingly recognised as an adult infection. Routine vaccination of children between 2 months and 4 years of age has shifted the peak incidence of the infection into the adolescent years but with the majority of cases spread across adulthood. This results from a waning of vaccine induced immunity. A booster is now given to 15-17 year olds. Whooping cough in adults does not usually manifest in the classical manner described in infected children and may thus be unrecognised. Maintenance of adult immunity is important, as infected adults are source of life threatening infection to infants who have not yet been vaccinated.

Incubation period: 7 - 20 days
Period of infectivity: highest during catarrhal stage (up to a week before coughing paroxysms) and during the following 3 weeks; for 5 days after commencement of effective antibiotics

8. Polio

Polio is a paralytic disease caused by a member of the enterovirus group. The infection is spread by the faecal-oral route and is common in developing countries where poor social conditions and low standards of hygiene are prevalent. A generation ago the infection was common in Western communities but it has essentially been eradicated in such populations by vaccination. In its most common form the illness consists of symptoms of meningitis which are then followed by the onset of muscle pain and paralysis. This may range from weakness of a single muscle to complete quadriplegia. Disability is common after symptomatic infection, but the bulbar form of the disease results in high mortality due to respiratory and circulatory collapse. Maintenance of immunity in health care workers is important, particularly those contemplating working in developing countries.

Incubation period: 3 - 35 days, commonly 7-14
Period of infectivity: difficult to assess but most infectious for several days before and after onset of symptoms; virus may be found in faeces for 3-6 weeks after infection

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9. Blood borne viral infections

 Included in this group are a number of viruses which circulate in the blood of an infected  person, in some cases for many years, and which can be transmitted to other people  when they come into contact with this infected blood. The main viruses of importance in  this group are the human immunodeficiency virus (HIV), hepatitis B virus (HBV) and  hepatitis C virus (HCV). Health care workers are potentially at risk of acquiring these  infections as they are in frequent contact with blood and other body fluids which may  contain the viruses (Refer to Section VIII.13 on Standard Precautions).

a) Human Immunodeficiency Virus

This virus is found in the blood of an infected person and in the following bodily fluids:  breast milk, semen, cervical and vaginal fluids, saliva, tears, cerebrospinal fluid, urine,  alveolar fluid and joint fluid, However, not all of these fluids have been implicated in the  transmission of the virus. Most cases of transmission have been associated with blood  (contaminated blood transfusions, blood products, contaminated needles in IV drug users) and with sexual intercourse. In developing countries, mother to infant transmission is a  significant mode of transmission.

In the occupational setting, health care workers have become infected with HIV primarily from contact with blood or blood-containing bodily fluids. This is most likely to occur following penetration of the skin by a needle ("needle stick injury) or by another sharp  instrument which is contaminated with blood from an infected patient, or by contact of such  infected blood with mucous membranes (eyes, mouth) or nonintact skin.

The estimated risk  of acquiring HIV infection from a needlestick injury from an infected patient is 0.3%. Following mucous membrane contact with infected blood the estimated risk of infection is  0.09%.

Following HIV infection the virus may enter a number of different cells in the body, but  those most susceptible are lymphocytes, a type of white blood cell important in the immune  response. Following entry of the virus into these cells, the genetic material of the virus  inserts itself into the genetic material of the cell. After 3 to 6 months antibodies against HIV  are produced by the infected human host and these may be measured by laboratory tests.  The period following infection and the point in time when these antibodies can be detected  is called the "window period". At the time of the appearance of these antibodies the host  may experience a nonspecific flu-like illness called the seroconversion illness.

The effect of HIV infection on the host is that the cells of the immune system are gradually destroyed, leaving the host less able to fight off infections and particular types of cancer. For a period averaging ten years, the latent period, the untreated patient may remain outwardly well while the virus continues to replicate and destroy the immune system. When the immune system is damaged beyond a particular point the host begins to experience infections, often caused by microorganisms which do not usually cause problems in people with healthy immune systems. In addition, unusual types of cancers may be seen when these events begin to take place, the patient is said to have AIDS, the Acquired Immunodeficiency Syndrome.

To date there is no vaccine effective against HIV. A number of antiviral drugs have been shown to slow the replication of the virus and to improve the health of those infected. Following a risk exposure such as a needle stick injury from an infected patient, the use of these drugs alone or in combination for a period of several weeks can reduce the odds of infection in the recipient by 80 per cent. This is more likely to be effective if the drugs are given early after the exposure rather than later, so it is important to seek advice as soon as possible after such an injury.

Incubation period: Variable; to seroconversion illness, 5 70 days, typically 22 days; to onset of AIDS, typically 10 years.
Period of infectivity: Variable: from shortly after infection and for duration of life; influenced by viral load and effectiveness of treatment.

b) Hepatitis B Virus

This blood borne virus is more likely to be encountered by healthcare workers than is HIV, and it is also many more times infectious than is HIV. Fortunately however, infection with HBV can be prevented by vaccination.

HBV is a virus which infects the cells of the liver. Most infections do not cause symptoms, and in those who become ill with hepatitis most recover within 6 months Symptoms of hepatitis may be severe or mild and include headache, malaise, fever, nausea, vomiting, jaundice and abdominal pain. About 1% of cases may be fulminant, that is severe liver failure and seizures, often leading to death. A small number of cases, perhaps 10%, will become chronically infected and of this group some will develop cirrhosis (a serious form of liver damage) and some will develop fatal cancer of the liver. Those with chronic infection are the major source of transmission to others.

As the virus replicates in the liver it spills out into the bloodstream and it can be detected here and in a number of body fluids. These are semen, cervicovaginal secretions, breast milk, salvia, urine, bile, sweat, tears, cerebrospinal fluid and joint fluid. HBV is transmitted by similar routes to HIV although is much more infectious.

The most common routes of transmission are sexual intercourse, sharing of contaminated needles by intravenous drug users and from mother to infant. The virus may be transmitted on objects such as toothbrushes, eating utensils, razors, baby bottles and toys. Transmission in the hospital setting may occur from patient to healthcare worker and vice versa, and from patient to patient on contaminated equipment. The risk of transmission following a needlestick injury from an infected patient is estimated to be from 27-40 per cent if the patient is HBeAg positive (refer to infomation below).

A number of tests are used to diagnose hepatitis B or to show immunity to it. During active infection, two components of the virus are usually looked for in the blood, surface antigen (HBsAg) and 'e' antigen (HBeAg). Both of these indicate that the patient is actively infected and infectious to others. The presence of HBeAg indicates high infectivity. As disease resolves these components disappear from the blood and antibodies to them appear, namely HBsAb and HBeAb. Another antibody, HBcAb, is directed against the 'core' antigen which is found in the liver during active infection but not in the blood.

Those who become chronically infected do not clear the surface antigen (HBsAg) from their blood and do not develop antibody to surface antigen (HBsAb). They may also have HBeAg in the blood.

Infection with HBV can be effectively prevented by the use of a vaccine The material used in the vaccine is in fact HBsAg, made in the laboratory by a harmless yeast which has been genetically engineered to produce this viral protein. The vaccine gives rise to HBsAb in those vaccinated. The course of vaccination consists of 3 injections, the second 1 month after the first and the third one at 6 months. Although the vaccine produces protective levels of HBsAb in over 90% of individuals, failure to respond to the vaccine occurs in some and is related to increasing age, obesity, smoking and injection in the buttock rather than the upper arm.

For those who do not have immunity to hepatitis B and who receive a needlestick injury or other risk exposure, protection from infection is available by other means. If a risk is thought to exist, then the person receiving the needlestick can be injected with hepatitis B immune globulin (HBIG). This is HBsAb derived from the serum of people who already have high levels of HBsAb, and the process is known as passive immunisation. Administration of HBIG must be carried out within 72 hours of the exposure to be fully effective, and it is followed by a course of the vaccine. The aim of this Policy is to ensure that all students will be immune to hepatitis B in advance of any such injury occurring, so that the process of passive immunisation is not necessary.

Incubation period:  45 180 days, average 60 90 days
Period of infectivity: As long as HBsAg is present in blood; from many weeks before onset of symptoms and during the period of the acute illness; for the duration of viral carriage in those chronically infected.

c) Hepatitis C Virus

This virus has been discovered relatively recently, although cases of so called non-A, non-B hepatitis have been known about for many years. Most cases of non-A, non-B hepatitis are now known to be caused by HCV. Hepatitis C is transmitted mainly by contaminated blood or blood products, and many cases in the community were acquired from blood transfusions in the days before specific tests were available to screen blood donations for this virus. Another group at risk of acquiring hepatitis C infection is intravenous drug users sharing contaminated needles. Many people with the infection have no history of blood transfusion or IV drug use. Sexual transmission is not thought to be responsible for many cases. The infection may be transmitted from mother to baby but the rate of transmission is not high.

The illness caused by HCV is very similar to that caused by HBV. However, HCV is of major concern because 50-70% of infections will become chronic infections, unlike the 10 per cent chronic infection rate with HBV. As in the case of chronic HBV infection, chronic HCV infection may lead to cirrhosis and hepatocellular carcinoma.

Laboratory tests for HCV are relatively limited in their scope. Following infection there is a window period before antibodies to HCV can be detected in the blood, and this averages 6 - 8 weeks. The presence of HCV antibodies in a blood test gives no indication as to when the infection occurred or whether the infection is active or inactive. Another test is available to detect HCV genetic material in the blood (the PCR test), and the presence of this indicates active viral replication in the liver.

There is no vaccine against HCV nor any form of passive immunisation.

Incubation period:  2 weeks to 6 months, commonly 6 - 9 weeks.
Period of infectivity: For several weeks before onset of symptoms and for duration of infection in chronic carriers.

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10. Mycobacterium tuberculosis

M. tuberculosis is the cause of tuberculosis (TB), a bacterial infection usually involving the lungs but which may spread to many other tissues of the body. This bacterium is spread from actively infected patients in respiratory droplets, produced by coughing, sneezing or talking. The bacterium is highly infectious and may float in the air in the vicinity of an infected patient for a period of time even if the patient has left the area.

It is estimated that a third of the world's population is currently infected with M. tuberculosis, most cases occurring in the developing world where spread is enhanced by crowded living conditions and disease results from poor resistance. In nineteenth century Europe tuberculosis was responsible for 30% of all adult deaths but the prevalence of disease has been steadily decreasing in developed countries in this century. In 1985 however epidemiologists were surprised to find that this trend was reversed and that tuberculosis was on the rise. This was attributed largely to the AIDS epidemic and to an increasing population of homeless poor in some developed countries. For these reasons, tuberculosis is still of concern to healthcare workers in this community. Another reason for concern is the increasing resistance of M. tuberculosis to the drugs used to treat it.

Tuberculosis is a chronic disease and may exist in the host for many years without causing symptoms. This can make infection difficult to diagnose unless the disease has reached a fairly advanced state. One of the tests which is used to help detect previous infection with M. tuberculosis is the Mantoux or tuberculin test. In this test a small dose of purified protein derived from M. tuberculosis is injected superficially under the skin. In those who have been previously infected by the bacterium the immune system will produce a reaction at the injection site consisting of redness and swelling, The diameter of the area of swelling is measured 48 hours after the injection and if it is above a certain value then this indicates past infection, which may still be active. False positive reactions may be seen in people infected with nontuberculous species of mycobacteria. Previous administration of BCG (Bacillus Calmette-Guerin) vaccination may also result in a reaction at the site of a Mantoux test.

BCG is a vaccine consisting of live Calmette-Guerin bacilli which are attenuated Mycobacterium bovis bacteria. The vaccine is mainly useful in infants and children in parts of the world where the risk of infection is high. It does not prevent infection with M. tuberculosis but in these children it is effective in preventing clinically apparent disease and particularly deaths from tuberculous meningitis. Its usefulness in other populations is debated, particularly as the overall efficacy of the vaccine has been estimated to be only 50 per cent. Additionally, administration of the vaccine makes interpretation of a subsequent Mantoux test difficult, as the test will usually become positive and thus not useful in those suspected of being infected with TB.

Incubation period:  To first demonstrable lung lesion or Mantoux seroconversion, 2 10 weeks.
Period of infectivity: As long as viable bacteria are present in sputum, potentially for years. Infectivity ceases within several weeks of effective antimicrobial therapy commencing.

11. Methicillin-resistant Staphylococcus aureus (MRSA)

Staphylococcus aureus is a common bacterium which lives harmlessly on the bodies of many healthy people. It is often referred to by the press as the Golden Staph". S. aureus is also a virulent and dangerous pathogen and commonly causes infections such as boils and other skin infections, abscesses in many soft tissues, bone and joint infections, and infections of the blood to mention only a few. Most strains of S. aureus are resistant to penicillin because they can produce an enzyme called beta-lactamase which can destroy this antibiotic Antibiotics such as methicillin, flucloxacillin and cephalexin have been produced which are resistant to this bacterial enzyme, making treatment of the above infections possible.

However. there are strains of S. aureus which are resistant to even these special antibiotics and sometimes to a range of other antibiotics too. When they cause infection they may be very difficult to treat. These strains are common around the world and in the Eastern States of Australia but they are less of a problem in Western Australia because of its isolation and because of effective measures aimed at keeping them out of the state.

There are a number of types of MRSA named according to the range of antibiotics to which they are resistant and their epidemic potential within a hospital.

Some strains of MRSA have a tendency to spread if introduced into a hospital environment. The introduction of one of these strains into a hospital proves very costly. Contacts and carriers need to be traced and treated where necessary to eradicate carriage of the organisms and in the case of staff carriage may result in many weeks off work. It has been necessary in the past to close wards until the organism can be removed from the environment using labour intensive and expensive cleaning techniques. Not only does the spread of MRSA generate large costs but it creates the risk of hospitalised patients developing S. aureus infections which may be very difficult to treat.

For these reasons, any patient, staff member or student who has been in a hospital outside the state in the preceding 12 months needs to have swabs taken to check for the presence of MRSA before they can start work in the hospital. Patients are held in isolation until their swabs are shown to be negative.

12. Encapsulated Bacteria

Certain bacteria are surrounded by capsules which help them to evade the host's immune defences, making these bacteria more able to produce serious infections. Two major organisms of concern are Neisseria meningitidis and Haemophilus influenzae type b. Serious disease with the latter is rarely encountered in this community now as it is vaccinated against in childhood. Neisseria meningitidis is a cause of life threatening septicaemia and meningitis which may occur in outbreaks. Invasive infection by these organisms is usually preceded by a period of asymptomatic nasopharyngeal carriage, although carriage does not mean that invasive disease will always follow. Carriers are responsible for passing the infection to others, who may develop invasive disease. The infections they produce may be severe and life threatening, particularly in debilitated people those with impaired immune systems and those who have had their spleens removed following trauma or for medical reasons. 

Health care providers frequently come into contact with patients suffering from infections with these bacteria and run the risk of being colonised themselves and becoming carriers. They may then pass the organism on to others or may themselves suffer from invasive infection. In the case of N. meningitidis and H. influenzae type b, health care workers and others who have had significant contact with a case of invasive disease may be given a very short course of antibiotics in order to eradicate the carrier state if it has been established. People who are considered to be significant contacts are:

• kissing contacts within the preceding 10 days
• household contacts within the preceding 10 days
• those who have had vomit or respiratory secretions from an active case splashed onto their faces

N. meningitidis incubation period:  2-10 days, commonly 3-4 days
N. meningitidis period of infectivity: As long as bacteria are present in nasopharyngeal secretions; ceases within 24 hrs of commencing appropriate antibiotic therapy.

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13. Standard Precautions and Additional Precautions

Standard Precautions are work practices required for a basic level of infection control. They include good hygiene practices, particularly washing and drying hands before and after patient contact, may include the use of protective barriers such as gloves, gowns, plastic aprons, masks, eye shields or goggles, appropriate handling and disposal of sharps and other contaminated or infectious waste, and use of aseptic techniques

Standard Precautions are recommended for the treatment and care of all patients, regardless of their perceived infectious status, and in the handling of:

• blood
• all other body fluids, secretions and excretions (excluding sweat) regardless of whether they contain visible blood
• non-intact skin
• mucous membranes

Standard Precautions also apply to dried blood and other body fluids.

The main goal of following Standard Precautions is to minimise the risk of acquiring blood borne viruses from contact with patients. In order to make such work practices effective, it must be assumed that all patients are potentially infected with such viruses. To only follow these precautions with those patients who are known to be infected gives a false sense of security and engenders risky work practices.

Additional Precautions

Additional Precautions are used for patients known or suspected to be infected or colonised with epidemiologically important or highly transmissible pathogens that can cause infection:

• by airborne transmission (eg. Mycobacterium tuberculosis, measles virus, chickenpox virus)
• by droplet transmission (eg. mumps, rubella, pertussis, influenza)
• by direct or indirect contact with dry skin (eg. colonisation with MRSA), or with contaminated surfaces
• by any combination of these routes.

Additional Precautions are designed to interrupt transmission of infection by these routes and should be used in addition to Standard Precautions when transmission of infection might not be contained by using Standard Precautions alone. Additional Precautions may be specific to the situation for which they are required or may be combined where microorganisms have multiple routes of transmission.

Additional Precautions implies a two tiered approach to infection control, and assumes that in cases where transmission of infection may not be contained by Standard Precautions alone. Additional Precautions will be applied in addition to Standard Precautions.

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