2. DISEASE PREVENTION AND CONTROL
• Every disease has certain weak points susceptible to attack.
• The basic approach in controlling disease is to identify these weak
points and break the weakest links in the chain of transmission.
• This requires sound epidemiological knowledge of the disease - that is
its magnitude, distribution in time, place and person, multifactorial
causation, sources of infection and dynamics of transmission.
3. DISEASE PREVENTION AND CONTROL
• Frequently it may be necessary to institute more than one method of
control simultaneously.
• The choice of methods will depend upon factors such as availability of
proper tools and techniques, relative cost effectiveness, efficiency and
acceptability.
• Although effective control of a disease requires knowledge of its
multifactorial causation, removal or elimination of a single known essential
link or the weakest link may be sufficient to control a disease, even if
complete knowledge about the aetiology of the disease in question is
lacking.
• The classic example is that of John Snow controlling the cholera epidemic
in London, by removing the handle of the incriminated water pump.
4. DISEASE PREVENTION AND CONTROL
• Disease control involves all the measures designed to prevent or
reduce as much as possible the incidence, prevalence and
consequences of disease.
• This includes community participation, political support and
intersectoral coordination.
• Control measures should not be delayed because of incomplete or
lack of accurate knowledge of the aetiological agent.
5. DISEASE PREVENTION AND CONTROL
• Broadly these are measures, pending results of epidemiologic
investigation.
1. The reservoir or source of infection
2. The route(s) of transmission
3 . The susceptible host (people at risk)
• The activities of disease prevention and control are now included in
primary health care - it requires community participation
(involvement), political support and intersectoral coordination.
6. 1. Controlling the reservoir
• If the first link in the chain of causation (i .e ., the disease agent) is
deemed to be the weakest link, logically, the most desirable control
measure would be to eliminate the reservoir or source, if that could
be possible.
• Elimination of the reservoir may be pretty easy with the animal
reservoir (e.g. , bovine tuberculosis, brucellosis), but is not possible in
humans in whom the general measures of reservoir control comprise:
early diagnosis, notification, isolation, treatment, quarantine,
surveillance and disinfection - all directed to reduce the quantity of
the agent available for dissemination.
7. (1) EARLY DIAGNOSIS
The first step in the control of a communicable disease is
its rapid identification. It is the cornerstone on which the
edifice of disease control is built. It has been aptly said that
prompt detection of cases (and carriers) and their treatment
is like stamping out the "spark" rather than calling the fire
brigade to put out the fire caused by the spark. Frequently,
laboratory procedures may be required to confirm the
diagnosis.
8. (1) EARLY DIAGNOSIS
Early diagnosis is needed for (a) the treatment of patients
(b) for epidemiological investigations, e.g., to trace the
source of infection from the known or index case to the
unknown or the primary source of infection (c) to study the
time, place and person distribution (descriptive
epidemiology) and (d) for the institution of prevention and
control measures.
9. (2) NOTIFICATION
Once an infectious disease has been detected (or even
suspected), it should be notified to the local health authority,
whose responsibility is to put into operation control
measures. including the provision of medical care to
patients, perhaps in a hospital.
10. (2) NOTIFICATION
Certain diseases are statutorily notifiable . The diseases to
be notified vary from country to country; and even within
the same country. Usually, diseases which are considered to
be serious menaces to public health are included in the list
of notifiable diseases. Notifiable diseases may also include
non-communicable diseases and conditions such as cancer,
congenital defects, accidents, etc.
11. (2) NOTIFICATION
Notification is an important source of epidemiological
information. It enables early detection of disease outbreaks,
which permits immediate action to be taken by the health
authority to control their spread. The other uses of
notification are discussed elsewhere.
12. (2) NOTIFICATION
Notification of infectious diseases is often made by the
attending physician or the head of the family, but any one,
including the lay people (e.g., religious, political and
administrative leaders, teachers and others) can report, even
on suspicion. In all cases, the diagnosis is verified by the
local health authority.
13. Under the International Health Regulations (IHR),
certain prescribed diseases are notified by the national
health authority to WHO. These can be divided into :
(a) Those diseases subject to International Health
Regulations (1969), Third Annotated Edition , 1983 -
cholera, plague and yellow fever.
(b) Diseases under surveillance by WHO - louse-borne
typhus fever, relapsing fever, paralytic polio, malaria,
viral influenza-A, SARS, smallpox etc.
Health administrations are required to notify to WHO
Geneva for any notification of communicable diseases under
international surveillance and International Health
Regulations.
14. (3) EPIDEMIOLOGICAL INVESTIGATIONS
An epidemiological investigation is called for whenever
there is a disease outbreak, the methodology for which is
given elsewhere. Broadly, the investigation
covers the identification of the source of infection and of the
factors influencing its spread in the community. These may
include geographical situation, climatic condition, social ,
cultural and behavioural patterns, and more importantly the
character of the agent, reservoir, the vectors and vehicles,
and the susceptible host populations.
15. (4) ISOLATION
Isolation is the oldest communicable disease control
measure. It is defined as "separation, for the period of
communicability of infected persons or animals from others
in such places and under such conditions, as to prevent or
limit the direct or indirect transmission of the infectious
agent from those infected to those who are susceptible, or
who may spread the agent to others". In general,
infections from human/animal sources can be controlled by
physical isolation of the case or carrier, and if necessary,
treatment until free from infection, provided cases and
carriers can be easily identified and carrier rates are low.
16. (4) ISOLATION
The purpose of isolation is to protect the community by
preventing transfer of infection from the reservoir to the
possible susceptible hosts. The type of isolation varies with
the mode of spread and severity of the disease. There are
several types of isolation - standard isolation , strict
isolation, protective isolation, high security isolation
17. (4) ISOLATION
For each patient, the relative risks to the patient and to
others should be assessed and the appropriate type of
isolation determined. Hospital isolation, wherever possible,
is better than home isolation. Isolation is particularly difficult
in rural areas. In some situations (e.g., cholera outbreaks)
the entire village or rural community may have to be
isolated. Isolation may also be achieved in some diseases by
"ring immunization", that is encircling the infected persons
with a barrier of immune persons through whom the
infection is unable to spread. This method when applied
worldwide in the 1960s and 1970s eradicated smallpox.
18. (4) ISOLATION
In North America, ring immunization is being applied in
measles control and eradication. The duration of isolation is
determined by the duration of communicability of
the disease and the effect of chemotherapy on infectivity
(Table).
19.
20. (4) ISOLATION
Isolation has a distinctive value in the control of some
infectious diseases, e.g. , diphtheria, cholera, streptococcal
respiratory disease, pneumonic plague, etc. In some
diseases where there is a large component of subclinical
infection and carrier state (polio, hepatitis A, and typhoid
fever), even the most rigid isolation will not prevent the
spread of the disease. It is also futile to impose isolation if
the disease is highly infectious before it is diagnosed as in
the case of mumps. Isolation has failed in the control of
diseases such as leprosy, tuberculosis and STD.
21. (4) ISOLATION
In the control of these diseases, the concept of physical isolation
has been replaced by chemical isolation, i.e. , rapid
treatment of cases in their own homes and rendering them
non-infectious as quickly as possible. Lastly, cases are
usually reported after the disease has spread widely. Taking
all these limitations into consideration, it may be stated that
isolation which is a "barrier approach" to the prevention
and control of infectious disease is not as successful as one
would imagine and may well give rise to a false sense of
security
22. (4) ISOLATION
In modern-day disease control, isolation is
more judiciously applied and in most cases replaced by
surveillance because of improvements in epidemiological
and disease control technologies. Today, isolation is
recommended only when the risk of transmission of the
infection is exceptionally serious.
23. ( 5) TREATMENT
Many communicable diseases have been tamed by
effective drugs. The object of treatment is to kill the
infectious agent when it is still in the reservoir, i.e. , before it
is disseminated. Treatment reduces the communicability of
disease, cuts short the duration of illness and prevents
development of secondary cases. In some diseases (e.g. ,
syphilis, tuberculosis, and leprosy), early diagnosis and
treatment is of primary importance in interrupting
transmission. Treatment is a lso extended to carriers.
24. ( 5) TREATMENT
Treatment can take the form of individual treatment or
mass treatment. In the latter category, all the people in the
community are administered the drugs whether they have
the disease or not (e.g., trachoma). If the treatment is
inadequate or inappropriate, it may induce drug resistance
in the infectious agent and may frustrate attempts to control
the disease by chemotherapy. It is well to remember that no
disease has ever been conquered through attempting to treat
every affected individual. Yaws is a shining example.
25. (6) QUARANTINE
Quarantine has been defined as "the limitation of
freedom of movement of such well persons or domestic
animals exposed to communicable disease for a period of
time not longer than the longest usual incubation period of
the disease, in such manner as to prevent effective contact
with those not so exposed". Quarantine measures are
also "applied by a health authority to a ship, an aircraft, a
train, road vehicle, other means of transport or container, to
prevent the spread of disease, reservoirs of disease or
vectors of disease".
26. (6) QUARANTINE
Quarantine may comprise (a) absolute quarantine, as
defined above; (b) modified quarantine, e.g., a selective
partial limitation of freedom of movement, such as exclusion
of children from school; and (c) segregation which has been
defined as "the separation for special consideration, control
of observation of some part of a group of persons (or
domestic animals) from the others to facilitate control of a
communicable disease, e .g., removal of susceptible children
to homes of immune persons".
27. (6) QUARANTINE
In contrast to isolation , quarantine applies to restrictions
on the healthy contacts of an infectious disease. Quarantine
which was once a popular method of disease control has
now declined in popularity. With better techniques of
early diagnosis and treatment, quarantine, as a method of
disease control, has become outdated. It has been replaced
by active surveillance.
28. 2 . Interruption of transmission
A major aspect of communicable disease control relates
to "breaking the chain of transmission" or interruption of
transmission (Fig.). This may mean changing some
components of man's environment to prevent the infective
agent from a patient or carrier from entering the body of
susceptible person. For example, water can be a medium for
the transmission of many diseases such as typhoid,
dysentery, hepatitis A, cholera and gastroenteritis. Water
treatment will eliminate these diseases. Depending upon the
level of pollution, this may vary from simple chlorination to
complex treatment.
29. 2 . Interruption of transmission
However, control of the source of
contamination is an important long-term measure. Foodborne
disease is particularly prevalent in areas having low
standards of sanitation. Clean practices such as handwashing,
adequate cooking, prompt refrigeration of
prepared foods and withdrawal of contaminated foods will
prevent most food-borne illnesses. When the disease
is vector- borne, control measures should be directed
primarily at the vector and its breeding places. Vector
control also includes destruction of stray dogs, control of
cattle, pets and other animals to minimize spread of
infection among them, and from them to man.
30. 2 . Interruption of transmission
On the other hand, episodes of infection either by droplets or droplet
nuclei are not usually controlled effectively by attempting to
interrupt their mode of spread; reliance is placed on early
diagnosis and treatment of patients, personal hygiene and
proper handling of secretions and excretions. In short,
blocking the routes of transmission imply an attack on
environmental factors, that is, to bring about an adjusted
equilibrium between host and environment through
encouraging some ecological influences and inhibiting
others.
31. 3 . The susceptible host
The third link in the chain of transmission is the
susceptible host or people at risk. They may be protected by
one or more of the following strategies.
32. (1) ACTIVE IMMUNIZATION
One effective way of controlling the spread of infection is to
strengthen the host defences. Under certain circumstances this
may be accomplished by active immunization, which is one of
the most powerful and cost-effective weapons of modern
medicine. There are some infectious diseases whose control is
solely based on active immunization, e .g., polio, tetanus,
diphtheria and measles. Vaccination against these diseases is
given as a routine during infancy and early childhood,
with periodic boosters to maintain adequate levels
of immunity.
33. (1) ACTIVE IMMUNIZATION
Then there are immunizations against certain
diseases which are offered to high-risk groups or
restricted to definite geographic areas where the disease is
endemic or a public health problem (e.g., yellow fever).
Unfortunately we do not have vaccines for every infectious
disease (e.g. , malaria, diarrhoeal diseases). Diseases for which
improved or less costly vaccines are needed include
tuberculosis, pertussis, meningococcal meningitis, hepatitis B,
rabies, Japanese encephalitis, etc.
34.
35.
36.
37.
38. (1) ACTIVE IMMUNIZATION
Immunization is a mass means of protecting the greatest
number of people. By reducing the number of susceptibles
in the community, it augments "herd immunity" making the
infection more difficult to spread. It also reduces the risk for
those individuals who have escaped vaccination or those
who have not developed satisfactory protection. It is well to
bear in mind that immunizations are not all 100 per cent
effective, particularly when an individual is exposed to a
large dose of pathogenic organisms.
39. (1) ACTIVE IMMUNIZATION
Immunization has to be planned according to the needs
of the situation. Every country has its own immunization
schedule, so does each medical society and each paediatric
society, adding to confusion. Thus there is an infinite
number of immunization schedules, each having its merits
and demerits. If each vaccine were to be given separately, a
minimum of at least 14 visits would be needed to the immunization clinic.
The current trend is to combine
immunizing agents into small packages and thus reduce the
number of injections an individual must receive.
40. (1) ACTIVE IMMUNIZATION
A well thought-out immunization schedule must be
(a) epidemiologically relevant, that is, vaccinations should be
included only against diseases which are public health
problems and against which an effective vaccine exists
(bl immunologically effective: children must be vaccinated at
an age when they can benefit from it, i.e. , when they are
capable of forming defences and when they have lost the
antibodies transmitted by the mother.
41. (1) ACTIVE IMMUNIZATION
Above all, children
must be vaccinated at the right time, that is before they are
exposed to possible infection. An immunization may not be
effective if given within too short an interval between
subsequent doses (c) operationally feasible : this includes cost
and ability to achieve a high percentage of coverage which is
a key factor in an effective immunization programme.
42. (1) ACTIVE IMMUNIZATION
The schedule must minimize the number of visits, by simultaneous
administration of vaccines, and (dl socially acceptable : the
schedule must take into account the local customs, beliefs and
practices, seasonal and climatic factors and daily work
pattern of the community. One important factor is to reduce
long waiting time for patients whose sole purpose in visiting
the clinic was to be immunized.
43. Universal Immunization Programme (UIP)
In May 1974, the WHO officially launched a global
immunization programme, known as Expanded Programme
on Immunization (EPI) to protect all children of the world
against six vaccine-preventable diseases, namely -
diphtheria, whooping cough, tetanus, polio, tuberculosis and
measles by the year 2000. EPI was launched in India in
January 1978.
44. Universal Immunization Programme (UIP)
The Programme is now called Universal Child
Immunization , 1990-that's the name given to a declaration
sponsored by UNICEF as part of the United Nations' 40th
anniversary in October 1985. It is aimed at adding impetus
to the global programme of EPI.
The Indian version, the Universal Immunization
Programme, was launched on November 19, 1985 and was
dedicated to the memory of Smt. Indira Gandhi. The
National Health Policy was aimed at achieving universal
immunization coverage of the eligible population by 1990.
46. 1. National Immunization Schedule
The National Immunization Schedule is given in Table.
The first visit may be made when the infant is 6 weeks
old; the second and third visits, at intervals of 1-2 months.
Oral polio vaccine may be given concurrently with
pentavalent vaccine. BCG can be given with any of the three
doses but the site for the injection should be different. The
schedule also covers immunization of women during
pregnancy against tetanus.
47.
48.
49.
50. 1. National Immunization Schedule
The Indian Academy of Paediatrics recommends
inclusion of more vaccines in the immunization schedule.
These vaccines are not included in the UIP because of
financial constraints. The immunization schedule approved
by the IAP is as follows :
51.
52. 1. National Immunization Schedule
Pentavalent vaccine has replaced DPT, He patitis B and
Hib conjugate vaccine in NIS, therefore DPT, Hepatitis and
Hib conjugate vaccine should not be given at 6, 10 and 14
weeks if pentavalent vaccine is being used.
54. 2. WHO EPI Schedule
The next table summarizes the WHO recommendations for
routine vaccination for children. The purpose is to assist
health planners to develop an appropriate country specific
immunization schedule based on local conditions. The
health care workers should refer to their national
immunization schedules.
55.
56.
57. 2. WHO EPI Schedule
The WHO EPI Global Advisory Committee has strongly
recommended BCG and Polio vaccine to be given at birth or
at first contact, in countries where tuberculosis and polio
have not been controlled. In all countries routine
immunization with DPT and oral polio vaccine can be safely
and effectively initiated at 6 weeks of age. New vaccines are
being added for the vaccination schedule e.g., hepatitis B,
rubella, Rota virus vaccine Hib, pneumococcal and
Japanese encephalitis vaccines are now included in several
country's programmes.
58. 2. WHO EPI Schedule
The immunization schedule may be altered to suit the local
needs of individuals and groups. Interruption of the schedule
with a delay between doses does not interfere with the final
immunity achieved. There is no basis for the mistaken belief
that if a second (or third) dose in an immunization is delayed,
the immunization schedule must be started all over again. The ages
shown in Table for the various immunizations are considered the best.
However, if there is any delay in starting the first dose the site for the
injection should be different, the periods may be adjusted accordingly.
59. 2. WHO EPI Schedule
Immunization is frequently postponed if children are ill or
malnourished. This is not acceptable in the light of present
knowledge. In fact, it is particularly important to immunize
children with malnutrition. Low grade fever, mild respiratory
infections or diarrhoea and other minor illnesses should not
be considered as contraindications to immunization. These
are the very children who are most in need of immunization.
They are most likely to die should they acquire a vaccinepreventable
disease.
60. 2. WHO EPI Schedule
Since the success of EPI is now being seen to have
important long-term effects on the traditional
epidemiological patterns of major infectious diseases, often
raising the average age of incidence, the adolescent age
group of 10-19 years represent an important additional
target group for immunization. In the pre-immunization era,
large proportion of adults had disease induced immunity to
common infections, now majority of individuals have
vaccine induced immunity, which may or may not have the
same long-term stability. Questions therefore arise as to
policy and strategy implications for post-infancy
immunization programmes.
61. 2. WHO EPI Schedule
The WHO Scientific Advisory Group of Experts to EPI
has indicated the need to expand immunization activities
beyond infancy, either as part of routine immunization
services or as part of disease elimination or eradication
measure.
62. 2. WHO EPI Schedule
Adolescence presents certain challenges for immunization
in relation to lifestyle and other social issues, while a lso
offering special opportunities, such as a vaccine delivery in
the setting of educational institutions. The vaccines of
interest are MR and MMR as part of measles outbreak
prevention or elimination campaign, Td as booster dose for
neonatal tetanus elimination, hepatitis B, influenza, varicella
and HPV vaccines etc.
63. (2) PASSIVE IMMUNIZATION
Three types of preparations are available for passive
immunity - (a) Normal human immunoglobulin, (b) Specific
(hyperimmune) human immunoglobulin, and (c) antisera or
anti-toxins.
64. (2) PASSIVE IMMUNIZATION
Passive immunization is a short-term expedient useful
only when exposure to infection has just occurred or is
imminent within the next few days. The duration of
immunity induced is short and variable (1-6 weeks) .
Undesirable reactions may occur, especially if antiserum is of
non-human origin.
65. (2) PASSIVE IMMUNIZATION
Passive immunization has a limited value in the mass
control of disease. It is recommended for non-immune
persons under special circumstances. The commonly
employed passive immunization procedures are listed in
Tables.
66. (3) COMBINED PASSIVE AND ACTIVE
IMMUNIZATION
In some diseases (e.g., tetanus, diphtheria, rabies)
passive immunization is often undertaken in conjunction
with inactivated vaccine products, to provide both
immediate (but temporary) passive immunity and slowly
developing active immunity. If the injections are given at
separate sites, the immune response to the active agent, may
or may not be impaired by immunoglobulin
67. (3) COMBINED PASSIVE AND ACTIVE
IMMUNIZATION
But, according to current recommendations
immunoglobulin should not be given within 3 weeks before,
or until 2 weeks after administration of a live attenuated
vaccine. For example, the antibody response to live
attenuated measles vaccine is diminished in persons who
receive immunoglobulin concurrently. However, there
are exceptions to this rule, as for example, the simultaneous
administration of hepatitis B vaccine and hepatitis B
immunoglobulin.
68. (4) CHEMOPROPHYLAXIS
Chemoprophylaxis implies the protection from, or prevention of, disease.
This may be achieved by causal prophylaxis, or by clinical prophylaxis :
(i) Causal prophylaxis implies the complete prevention of
infection by the early elimination of the invading or migrating causal agent.
For example, there is causal prophylaxis available against malaria.
(ii) Clinical prophylaxis implies the prevention of clinical symptoms; it does
not necessarily mean elimination of infection.
The indications for chemoprophylaxis are given as in next table.
69.
70. (5) NON-SPECIFIC MEASURES
Most of the non-specific measures to interrupt pathways
of transmission are of general applicability. Improvements in
the quality of life (e.g., better housing, water supply,
sanitation , nutrition, education) fall into this category. Nonspecific
measures will also include "legislative measures",
wherever needed, to formulate integrated programme and
permit effective programme implementation. In fact, these
non-specific factors have played a dominant role in the
decline of tuberculosis, cholera, leprosy and child mortality
in the industrialized world, long before the introduction of
specific control measures.
71. (5) NON-SPECIFIC MEASURES
Another important non-specific
measure is community involvement in disease surveillance,
disease control and other public health activities. If
community involvement is not an integral part of public
hea lth programmes, they are unlikely to succeed. Laws,
regulations and policy measures alone will not bring the
desired results
72. (5) NON-SPECIFIC MEASURES
It is well worth considering some obstacles and new
developments in the control of infectious diseases in
developing countries. First and foremost is the scarcity of
funds, lack of an effective health infrastructure, public health
laboratory facilities, equipment, supplies, trained personnel
(e.g. , epidemiologists) and public awareness needed for the
investigation and control of communicable diseases. This
handicap is shared by all developing countries.
73. (5) NON-SPECIFIC MEASURES
A development which has been supported by WHO is
integration of communicable disease control into primary
health care. This integration has been successfully carried
out. Some authorities emphasize the need for maintaining
intensive vertical programmes for the control of the highly
prevalent and controllable diseases such as malaria,
tuberculosis and leprosy until their frequency has been
reduced to low levels. The failure of the malaria eradication
programmes emphasize this point.
74. (5) NON-SPECIFIC MEASURES
Finally a major obstacle to disease control is human
behaviour. Medical technology is often ineffective in
changing behaviour. In this regard, health education
remains the only approach to enlist public co-operation and
to induce relevant changes in the behaviour and life-styles of
people. Such changes could, in themselves, be powerful
methods of disease control.
75. Surveillance
Surveillance must follow control measures. It has been
defined as "the continuous scrutiny of all aspects of
occurrence and spread of disease that are pertinent to
effective control". Surveillance goes beyond the
passive reporting of cases. It includes laboratory
confirmation of presumptive diagnosis; finding out the
source of infection, routes of transmission , identification of
all cases and susceptible contacts; and still others who are at
risk in order finally to prevent the further spread of the
disease. Serological surveillance identifies patterns of
current and past infection.
76. Surveillance
Included in surveillance are
systematic collection of pertinent morbidity and mortality
data, the orderly consolidation of these data, special field
investigations and rapid dissemination of this information to
those responsible for control or prevention. Once control
measures have been instituted, their effectiveness should be
evaluated. If they have not been successful, the reason(s) for
failure should be identified, the existing measures modified
and evaluation continued. The ultimate objective of
surveillance is prevention.
77. Surveillance
Surveillance may comprise :
(a) Individual surveillance : This is surveillance of infected persons until they
are no longer a significant risk to other individuals,
(b) Local population surveillance : e.g. , surveillance of malaria,
(c) National population surveillance : e .g. , surveillance of smallpox after the
disease has been eradicated, and
(d) International surveillance : At the international level, the WHO maintains
surveillance of important diseases (e.g. , influenza, malaria, polio, etc.) and
gives timely warning to all national governments.
78. Surveillance
Surveillance, if properly pursued,
can provide the health agencies with an overall intelligence
and disease- accounting capability. Surveillance is an
essential pre-requisite to the rational design and evaluation
of any disease control programme.
80. Semmelweis (1818- 1865) demonstrated the value of
handwashing with antiseptic solutions, when he obtained
considerable reduction in the death rate from puerperal
fever. Lister (1827-1912) was also successful in reducing the
number of wound infections by prophylactic application of
an antiseptic (carbolic acid) to wounds. The importance of
antiseptics and disinfectants has not diminished in this
"golden age of antibiotics" . Their uses range from control of
communicable diseases to sterilization of sophisticated
instruments, and treatment of fungal and bacterial infections
of the skin and mucous membrane.
82. Disinfectant : Usually a chemical agent (but sometimes
a physical agent) that destroys disease causing pathogens or
other harmful microorganisms, but might not kill bacterial
spores. It refers to substances applied to inanimate objects.
83. Disinfection: Thermal or chemical destruction of
pathogen and other types of microorganisms. Disinfection is
less lethal than sterilization because it destroys most
recognized pathogenic microorganisms but not necessarily
all microbia l forms (e.g., bacterial spores).
84. Sterilization : Validated process used to render a
product free of a ll forms of viable microorganisms including
bacterial spores. Sterilizer is the apparatus used to sterilize
medical devices, equipment or supplies by direct exposure
to the sterilizing agent.
85. Antiseptic : Substance that prevents or arrests the
growth or action of micro-organisms by inhibiting their
activity or by destroying them. The term is used especially
for preparations applied topically to living tissue.
87. Sanitizer : Agent that reduces the number of bacterial
contaminants to safe levels as judged by public health
requirements. Commonly used with substances applied to
inanimate objects.
88. Sterile : State of being free from all living microorganisms.
89. Hospital disinfectant : Disinfectant
registered for use in hospitals,
clinics, dental offices or any other
medicalrelated facility. Efficacy is
demonstrated against Salmonella
choleraesuis, Staphylococcus
aureus, and Pseudomonas
aeruginosa.
90. Germicide : Agent that destroys
micro-organisms,
especially pathogenic
organisms.
91. Detergent : Surface cleaning agent that makes no
antimicrobial claims on the label. They comprise a
hydrophilic component and a lipohilic component.
It acts by lowering surface tension e.g. soap which
removes bacteria along with dirt.
92. Cleaning : Removal, usually with detergent and water
or enzyme cleaner and water, of adherent visible soil, blood,
protein substances, micro-organisms and other debris from
the surfaces, crevices, serrations, joints, and lumens of
instruments, devices and equipment by a manual or
mechanical process that prepares the items for safe handling
and/or further decontamination.
93. Deodorant : Deodarant is a substance
which suppresses or neutralizes bad
odours, e.g., lime and bleaching powder.
