Diphtheria is an acute infectious disease caused by Corynebacterium diphtheriae, affecting the upper respiratory tract and occasionally the skin. It is characterised by an inflammatory exudate which forms a greyish membrane in the respiratory tract which may cause obstruction.
The incubation period is from 2 to 5 days. The disease is usually communicable for up to two weeks, but carriers may shed organisms for longer. A toxin is produced by diphtheria bacilli which affects particularly the myocardial, nervous and adrenal tissue.
Spread is by droplet infection an dthrough contact with articles (fomites) soiled by infected persons.
The last notified case of diphtheria in Malta was in 1969. This success has been mainly the result of a comprehensive immunisation programme against the disease. The current documented coverage rate for immunisation of children at 2 years of age stands at 83%. It is hoped that the WHO target of 95% will be reached by the end of 1996.
Diphtheria immunisation is carried out by using diphtheria toxoid and protects by stimulating the production of antitoxin which provides immunity to the effects of the toxin.
The recommended vaccines for immunisation are:
For immunisation of infants and children up to ten years, ads. Dip/Tet/Per or ads Dip/Tet vaccines should be used as follows:
If a course is interrupted it may be resumed; there is no need to start again.
A booster dose using the ads Dip/Tet preparation for adults should be administered at the age of 16 years.
Individuals exposed to such a risk should be given a complete course or a reinforcing dose according to their age and immunisation history as follows:
Swelling and redness at the injection site are common. Malaise, transient fever and headache may also occur. A small painless nodule may form at the injection site but usually disappears without sequelae. Severe anaphylactic reactions are rare. Neurological reactions have been reported occasionally.
See contraindications under General Considerations.
Vaccines should be stored at 2 to 8 degrees Celsius.
Tuberculosis in man is caused by infection with Mycobacterium tuberculosis or Mycobacterium bovis and may affect any part of the body. In most new cases it involves the respiratory system, non-respiratory forms are more common in the immunocompromised.
The incubation period from infection to a demonstrable primary lesion or significant tuberculin reaction, is about 4 to 12 weeks.
The initial infection usually goes unnoticed; tuberculin sensitivity appears within a few weeks. Lesions commonly heal, leaving no residual changes except occasional pulmonary or tracheobronchial lymph node calcifications. About 95% of those initially infected enter this latent phase from which there is lifelong risk of reactivation. In about 5% , the initial infection may progress directly to pulmonary tuberculosis or by lymphohaematogenous dissemination of bacilli, to pulmonary, miliary, meningeal or other extra pulmonary involvement. Serious outcome of the initial infection is more frequent in infants, adoloscents and young adults.
Extra pulmonary tuberculosis is much less common than pulmonary. It may affect any organ or tissue and includes tuberculous meningitis , miliary tuberculosis and involvement of lymph nodes, pleura, pericardium, kidneys, bones and joints, larynx, skin, intestines, peritoneum and eyes.
Progressive pulmonary tuberculosis arises from reinfection or reactivation of a latent focus remaining from the primary infection.
Clinical status is based mainly on the presence or absence of tubercle bacilli in the sputum and also on the nature of changes seen on chest radiographs. Fatigue, fever and weight loss may occur early, while localising symptoms of cough, chest pain, haemoptysis and hoarsness become prominent in advanced stages.
Spread is by droplet infection, which is most likely when the index case is sputum smear-positive for the bacillus.
In Malta on average some 20 to 25 cases of tuberculosis are notified per year, the majority of these being pulmonary. They occur mainly in the adult population. Vaccination against tuberculosis is carried out on all school children at the age of 12 - 13 years.
The recommended vaccine for immunisation is: Bacillus Calmette-Guerin (BCG) vaccine
The BCG vaccine is a live attenuated strain derived from Mycobacterium bovis. It gives good protection against tuberculosis, lasting at least 15 years. This vaccine is only available from the Immunisation Section in the Department of Primary Health Care.
RECOMMENDATIONS
The following groups are recommended for immunisation with BCG vaccine:BOOSTER DOSES
Subjects who give a history of previous BCG immunisation should only be re-immunised if there is no characteristic scar and they are tuberculin negative.CONTACTS
Contacts of a sputum-positive index case may initially have a negative tuberculin skin test but still be in the early stages of infection. This is because tuberculin sensitivity has not yet developed. Although immunisation will do no harm, it should be delayed and the skin test repeated six weeks later. Immunisation is then carried out only if this second test is negative. If the skin test is positive, the patient has converted and must be referred for consideration of prophylactic chemotherapy.Children under five years of age who are contacts of a smear positive case should be given chemoprophylaxis and then immunised with BCG on completion of the course. Newly born babies who are contacts should have prophylactic isoniazid chemotherapy and the tuberculin test repeated after 3-6 months. If positive, chemotherapy is continued; if negative BCG vaccine is given provided they are no longer in contact with infectious tuberculosis. Newly born contacts of other cases should be immunised immediately.
HIV-positive individuals who come into contact with a smear-positive case, should be referred for consideration of chemoprophylaxis.
ADVERSE REACTIONS
Local reactions:
Severe injection site reactions, large ulcers and abscesses are most commonly caused by faulty injection technique where part or all of the dose is administered too deeply (subcutaneously instead of intradermally). The immunisation of individuals who are tuberculin positive may also give rise to such reactions. To avoid these, doctors and nurses who carry out tuberculin skin tests and administer BCG vaccine are trained in the interpretation of the results of tuberculin tests as well as in the technique of intradermal injection with syringe and needle.
Keloid formation at the injection site is not uncommon
Local reactions
General reactions:
These are rare and mostly consist of adenitis with or without suppuration and discharge. A minor degree of adenitis with or without suppuration and discharge. A minor degree of adenitis may occur in the weeks following immunisation and should not be regarded as a complication. Very rarely a lupoid type of local lesion has been reported.
CONTRAINDICATIONS
STORAGE
The freeze dried vaccine should be protected from light, stored between 2 to 8 degrees Celsius and never frozen. It has a shelf life of 12 to 18 months and should not be used after the expiry date stated on the lable.
INTERPRETATION OF THE HEAF TEST
The reaction is graded 0 - 4 according to the degree of induration produced (erythema alone should be ignored).
Grades 0 and 1 are regarded as negative. Individuals who have not previously received BCG immunisation may be offered immunisation in the absence of contraindications. Those who give a history of previous BCG should only be re-immunised if there is no evidence of a characteristic scar.
Those with a grade 2 reaction are positive. They are hypersensitive to tuberculin protein and should not be given BCG vaccine. When the immunisation is performed as part of a routine health prevention programme such as the schools programme, no further action is required. In other circumstances (e.g. immigrants, contacts of tuberculosis etc.) subjects with a grade 2 reaction who have not previously had a BCG immunisation should be referred to the chest clinic.
All those who show a strong positive reaction to tuberculin (grade 3 or 4) should be referred for further investigation and supervision (which may include prophylactic chemotherapy). This includes subjects previously immunised with BCG.
FACTORS AFFECTING THE TUBERCULIN TEST
The reaction to tuberculin protein may be suppressed by the following factors:
Subjects who have a negative test but who may have had an upper respiratory tract or other viral infection at the time of testing should be retested 2-3 weeks after the clinical recovery before being given BCG. Tuberculin testing should not be carried out within three weeks of receiving a live viral vaccine. Immunisation programmes should be arranged so that tuberculin testing is carried out before live viral vaccines are given.
The following factors may also affect the consistency of tuberculin testing or add to its variability:
IMMUNISATION REACTION
Normally a local reaction develops at the immunisation site within 2 to 6 weeks, beginning
as a small papule which increases in size for a few weeks widening into a circular area up to
7mm in diameter with scaling, crusting and occasional bruising. Occasionally a shallow ulcer
up to 10mm in diameter develops. It is not necessary to protect the site from becoming wet during washing
and bathing, but should any ozzing occur, a temporary dry dressing may be applied until a scab
forms. It is essential that air should not be excluded. If absolutely essential
an impervious dressing may be applied but only for a short period (e.g. to permmit swimming)
as it may delay healing and cause a large scar. The lesion slowly subsides over several months and eventually
heals leaving only a small scar.
Tetanus is an acute illness caused by Clostridium tetani, characterised by muscle rigidity with superimposed agonising contractions. It is induced by the toxin of the tetanus bacilli which grow anaerobically at the site of the injury.
The incubation period is between 4 and 21 days, commonly about 10 days.
Tetanus spores are present in soil and may be introduced into the body during injury, often through a puncture wound, but also through burns of trivial, unnoticed wounds.
People considered to be at high risk of contracting the infection include:
It is in the context of infection risk that tetanus vaccination is recommended to all.
In spite of the availability of effective vaccination, tetanus has not yet been totally eradicated from our islands. Over the past 5 years there were six reported cases of tetanus occuring in adults following field or household garden trauma. It is therefore essential to vaccinate people of all ages against this serious and potentially fatal condition.
Immunisation with tetanus toxoid protects by stimulating the production of antitoxin which provides immunity against the effects of the toxin.
Active immunisation is indicated for all persons above two months of age. For primary immunisation the following schedule is recommended:
If a course is interrupted, it may be resumed; there is no need to start again irrespective of the time interval.
In the case of children, a booster dose of adsorbed diphtheria/tetanus should be given after an interval of at least 3 years from the last dose of the primary course. A further reinforcing dose of adsorbed adult diphtheria / tetanus vaccine is recommended for those aged 15-19 years or before leaving school.
In adults, a reinforcing dose ten years after the primary course and again ten years later maintains a satisfactory level of protection which will probably be life-long.
Local reactions, such as pain, redness, and swelling round the injection site may occur and persist for several days. general reactions, which are uncommon, include headache, lethargy, malaise, myalgia and pyrexia.
Passive immunisation using homologous anti tetanus immunoglobulin should be given to individuals with a tetanus-prone type of wound who either give no history of having been previously immunised or who have had their last dose of the primary course or booster dose more than ten years prior to the time of the injury. Immunoglobulin should be given together with a full course or a booster dose of vaccine, injected at different sites.
If the wound is less than 24 hours old, a dose of 250 i.u. should be used. For wounds older than 24 hours, a dose of 500 i.u. is used.
The vaccine should be stored and kept at temperatures between 2 and 8 degrees celsius and should be checked for sedimentation. Opened vials should be discarded within 48 hours of opening.