Prophylaxis of Infectious Diseases & Measures to Control

Them

Prevention & control include: Mass-scale measures aimed at improvement of

public health, prevention of infectious diseases spreading;

Medical measures aimed at reduction of infectious morbidity & eradication of some diseases;

Health education & involvement of population in prevention or restriction of infectious diseases spreading;

Prevention of infectious diseases importing from other countries

Prophylaxis

PreventiveAnt-

epidemic

The basic factors for an epidemic process development :

the source of infection; transmission mechanism; susceptibility of population

Control of infection source Active detection of the sick persons (clinical

examination, epidemical anamnesis, laboratory tests);

Isolation of patients (depends on clinical and medical prepositions – to a hospital or at home);

Treatment of patients (etiotropical, pathogenetic, symptomatic);

Discharging from a hospital after clinical recovering and negative laboratory tests.

Carriers should be revealed for medical examination and sanation.

If animals are the source of infection (zoonoses) veterinary measures should be taken.

Disruption of infection transmission pathways

General sanitary measures (community hygiene)

Health education of population Disinfection Sterilization Disinsection Deratization

Disinfection

Focal Preventive

Current Final

Preventive disinfection

Mechanical PhysicalChemical

Chlorine-,oxygen-

containing substances,

Phenols,Acids,Alkalis,

hydrogen peroxide,

formaldehyde

Boiling, Steam, UV radiation &

others

Biological

Sterilization complete eradication of pathogenic and

non-pathogenic microorganisms ( bacteria, viruses, fungi, spore forms) present on a surface, contained in a fluid, in medication, or in a environment. Can be achieved by applying the proper combinations of heat, chemicals, irradiation, high pressure, and filtration.

Sterilization is used for surgical, gynaecological, stomatological and other tools, dressing materials, linen, needles, syringes, etc. Nutrient media, laboratory ware, tools and instruments are sterilized in microbiology.

METHODS OF STERILIZATION

There are four sterilization methods used in medical and dental offices:

1. Steam (autoclave) sterilization 2. Chemical vapor sterilization 3. Dry heat sterilization 4. Ethylene oxide gas sterilization

Each of these methods, when used properly, will achieve sterilization. Effective sterilization is dependent upon the ability of the sterilant (e.g., saturated steam, heat or gas) to have direct contact with all surfaces of the device or product being sterilized, for a specified time at a set temperature. Proper techniques in cleaning, preparation, packaging, and placement of supplies in the sterilizer chamber are critical for successful sterilant contact.

Steam sterilizationMoist heat in the form of saturated steam under

pressure is the sterilant used in the steam sterilizer (autoclave). Steam sterilization is the least time

consuming, and the preferred, method of sterilization for heat and moisture stable medical devices. In steam

sterilization it is important that the ambient air in the chamber and contents be completely removed at

the beginning of the cycle so that the saturated steam can have direct contact with the items being

sterilized. There are three main types of steam sterilization cycles: gravity, pre-vacuum, and flash.

Chemical vapor sterilization

Unsaturated chemical vapor (a mixture of alcohol, water, ketones, and formaldehyde heated under

pressure) is a typical sterilant used in this method of sterilization. Because of the low moisture content

of unsaturated chemical vapor, it will not cause rust and corrosion on carbon steel instruments.

Dry heat sterilization

Hot air is the sterilant used in the dry heat sterilizer (hot air oven). It is a slow process because it depends upon higher temperatures to incinerate microorganisms. This method of sterilization is used for heat-stable, moisture-sensitive, or steam impermeable medical devices and products. The Cox dry heat sterilizer is a rapid cycle dry heat sterilizer and is typically run for six minutes at 375°.

Ethylene oxide sterilization

Ethylene oxide (EtO) is the sterilant used for gas sterilization. This method of sterilization is used for heat-sensitive items. EtO sterilization process is seldom used in office-based practice because of the long sterilization and aeration times required.

Disinsection

DestroyingPreventive

Mechanical Physical Biological ChemicalGenetic

Deratization (rodent control)

DestroyingPreventive

Mechanical

Biologycal

Chemical

Quarantine measures medical examination of persons who arrive into or

depart from a given country, their vehicles & belongings;

availability of special medical documentation (international certificate of vaccination, certificate of deratization & the like) must be checked;

revealing & isolation of persons with infectious diseases, and isolation of persons who require medical observation;

disinfection, disinsection, deratization of means of transportation, of cargo & luggage (for specisl indications).

Measures to increase opportunity

Specific – preventive vaccinations, immune globulins, serums;

Non-specific – improving of living and labour conditions, nutrition, physical training.

E. Jenner(1749 - 1823)

L. Pasture(1822 - 1895)

D. Samoylovych(1724 - 1810)

INNATE IMMUNITY

The innate immune system, also known as non-specific immune system and first line of defense, comprises the cells and mechanisms that defend the host from infection by other organisms in a non-specific manner. This means that the cells of the innate system recognize and respond to pathogens in a generic way, but unlike the adaptive immune system, it does not confer long-lasting or protective immunity to the host. Innate immune systems provide immediate defense against infection, and are found in all classes of plant and animal life.

The major functions of the vertebrate innate immune system include:

Recruiting immune cells to sites of infection, through the production of chemical factors, including specialized chemical mediators, called cytokines;

Activation of the complement cascade to identify bacteria, activate cells and to promote clearance of dead cells or antibody complexes;

The identification and removal of foreign substances present in organs, tissues, the blood and lymph, by specialized white blood cells;

Activation of the adaptive immune system through a process known as antigen presentation;

Acting as a physical and chemical barrier to infectious agents;

Cells of the innate immune response: mast cells, phagocytes, macrophages, neutrophils, dendritic cells, basophiles and eosinophiles, natural killer cells.

ADAPTIVE IMMUNITY

The adaptive immune system is composed of highly specialized, systemic cells and processes that eliminate or prevent pathogenic growth. The adaptive immune response provides the vertebrate immune system with the ability to recognize and remember specific pathogens (to generate immunity), and to mount stronger attacks each time the pathogen is encountered. It is adaptive immunity because the body's immune system prepares itself for future challenges.

Immunization

is the process by which an individual's immune system becomes fortified against an agent (known as the immunogen). When this system is exposed to molecules that are foreign to the body (non-self), it will orchestrate an immune response, but it can also develop the ability to quickly respond to a subsequent encounter (through immunological memory)

This is a function of the adaptive immune system. Therefore, by exposing an animal to an immunogen in a controlled way, its body can learn to protect itself: this is called active immunization. The most important elements of the immune system that are improved by immunization are the B cells (and the antibodies they produce) and T cells. Memory B cell and memory T cells are responsible for a swift response to a second encounter with a foreign molecule. Passive immunization is when these elements are introduced directly into the body, instead of when the body itself has to make these elements.

Types of immunoprophylaxis Planned — vaccination is performed regardless of incidence

of corresponding infectious disease.

Emergency — vaccination during epidemiological signs are performed:

During presentation of adverse epidemiological situations (especially severe infections, influenza),

When dealing with an unvaccinated (healthy) person who has had contact with a source of a pathogen,

When traveling of a person to an epidemiologically unfavorable territory,

Vaccination against tetanus and rabies.

Medical immunobiological preparations (MIBP)

Vaccines and antitoxins, which create an active immunity;

Immunoserums and immunoglobulins, that provide a passive defense;

Bacteriophages, which provide lysis of bacteria;

Cytokines (interferon and other biological immunostimulators).

ACTIVE IMMUNITY

entails the introduction of a foreign molecule into the body, which causes the body itself to generate immunity against the target. This immunity comes from the T cells and the B cells with their antibodies. Active immunization can occur naturally when a person comes in contact with, for example, a microbe. If the person has not yet come into contact with the microbe and has no pre-made antibodies for defense (like in passive immunization), the person becomes immunized. 

The immune system will eventually create antibodies and other defenses against the microbe. The next time, the immune response against this microbe can be very efficient; this is the case in many of the childhood infections that a person only contracts once, but then is immune. Artificial active immunization is where the microbe, or parts of it, are injected into the person before they are able to take it in naturally. If whole microbes are used, they are pre-treated, attenuated vaccine.

Requirements for vaccines and antitoxins

Specificity; Immunogenic; Absence of negative side-effects; Stable and prolonged preservation; Easy to use; High percentage of immunologic and

epidemic effectiveness; Low cost.

Type of Vaccines Live; Innactive; Chemical; Genetically-engineered; Vector-recombinant; Plants; DNA-plasmids; Mucosal vaccines.

Live Vaccines( tuberculosis, poliomyelitis, measles, epidemic parotitis,

influenza, rabies, brucelliosis, epidemic typhus, Q fever, yellow fever, anthrax, tularemia, plague)

Avirulent strains of microorganisms, rid of pathogenic ability with preserved immunogenesis.

BenefitsBenefits : :— Complete and prolonged immune response after the

introduction of the preparation— Single dose injections — have a long enough (more than a year) period of validity,

freezing does not affect the effectiveness. Short-comingsShort-comings : :

— requires strict maintenance of temperature during storage (4-

8 °С),

— possibility of reversion into another strain, which is associated

with serious complications in the postvaccination period. Do not contain preservatives, working with them it is important

to maintain strict aseptic guidelines.

Dead (inactive) corpuscular vaccines hepatitis A, herpes, influenza, pertussis, tick-borne encephalitis,

leptospirosis, poliomyelitis, cholera, typhoid fever, rabies

Chemically or physically decontaminated microorganisms.

In addition to defensive (protective) antigens, the vaccines contain a considerable amount of bacterial cells (virions), which is associated with the reactivity of the preparation.

Vaccines are to be stored at 4-8 С. Lower effectiveness when compared with live

vaccines, repeated injections are required to build up a strong enough immunity.

Chemical Vaccines

Contain surface antigen determinants (considerably less additional substances);

Resistant to environmental factors; very safe with the ability to use in different

associated infections.; Weak reactivity and immunogenesis, requires

the vaccines to be infused multiple times.

Genetically-engineered vaccines

Are obtained with biotechnology by translocating genes, which code surface antigens of known pathogens, into attenuated strains of viruses, bacteria, yeast or eukaryot.

Recombinant vaccines are safe and effective, may be used to produce complex vaccines, which provide immunity against multiple infections.

DNA-Vaccines

Plasmid DNA, which codes the surface antigens.

Immune response is similar to that of a live vaccine.

No chance of a reversion into a wild strain. These are the vaccines of the future against

HIV, rabies, influenza, hepatitis B & C, herpes, HPV, tuberculosis, malaria, ect.

Plant transgenetic vaccines The principle based on using transgenic

plants, which contain translocated genes of microorganisms. Consumption of these plants have shown to cause synthesis of specific antibodies in experimental animals.

Benefits— Oral ability to immunize; More cost-effective than using vaccines.

Mucosal VaccinesPreparations, which provide synthesis of

antibodies against proteins of adhesive bacterial cells (vibrions), as a result of which colonies of these pathogens cannot form on mucosal membranes (cholera, toxigenic strains of E. coli, HSV, pneumococcus).

After introduction intranasally and peros they provide a high titer of synthesis of IgA.

AnatoxinsDecontaminated bacterial exotoxins with preserved antigenic

and immunogenic properties. Used for active prophylaxis of toxigenic infections; Inherently high prophylactic effectiveness with a two-dose

infusion, which reaches 95-100 %, also maintains a strong immune memory;

Relatively low reactivity; Provides the development of antitoxic immunity (slightly

less than the immunity after a disease); Do not protect from carrier susceptibility Widely used against diphtheria, tetanus, gangrene,

botulism, cholera, staphylococcal and Pseudomonas infection.

Complex VaccinesA combination (mixing) of vaccines, — using two-camber syringes with repeated

injections in case of incompatible antigens.

DTaP (diptheria tetanus and pertussis) vaccine, Influvac – influenza vaccine, meningococcal, pneumococcal, poliomyelitis

PHASES OF DEVELOPMENT OF POST-VACCINE IMMUNITY

Characteristic for the synthesis of antibodies and the development of cellular immunity.

First, latent phase – interval from the infusion of antigen to the appearance of antibodies, cytotoxic cells and mediators of latent hypersensitivity (persists for a couple day).

Second, growth phase – increase of antibodies and immunocompetent cells in the blood (from 4 days to 6 weeks).

Phase of regression of immunity – very fast at the beginning, then slows down, over a period of time from a couple years to decades.

Methods of introduction of vaccines

Intramuscular — vaccines are injected into the deltoid muscle for adults, and for children younger than 18 months– into the quadricept femoris muscle.

Subcutaneous— into the subscapular region or in the upper third of the arm.

Intracutaneous – into the upper external surface of the arm (BCG) or in the internal middle surface of the forearm(tuberculin, other allergens).

Scarification – in the internal surface of the forearm (used during vaccinating with live viruses against – plaque, contrax, Q fever, brucellosis, tularemia.

Peroral – introduced as a liquid (poliomyelitis) or tablet (smallpox, cholera, the plague) form.

Methods of introduction of vaccines

Intracutaneous Intramuscular

Methods of introduction of vaccines

Subcutaneously Perorally

Immunization against polio (OPV)

BCG (Bacille Calmette-Guérin) vaccine

PASSIVE IMMUNITY

Passive immunization is where pre-synthesized elements of the immune system are transferred to a person so that the body does not need to produce these elements itself. Currently, antibodies can be used for passive immunization. This method of immunization begins to work very quickly, but it is short lasting, because the antibodies are naturally broken down, and if there are no B cells to produce more antibodies, they will disappear. Passive immunization occurs physiologically, when antibodies are transferred from mother to fetus during pregnancy, to protect the fetus before and shortly after birth.

Artificial passive immunization is normally administered by injection and is used if there has been a recent outbreak of a particular disease or as an emergency treatment for toxicity (for example, for tetanus). The antibodies can be produced in animals ("serum therapy") although there is a high chance of anaphylactic shock because of immunity against animal serum itself. Thus, humanized antibodies produced in vitro by cell culture are used instead if available.

Preparations for creating a passive immunity

Homogenous immunoglobulin — preparations containing specific

immunoglobulin (up to 95 % IgG) for specific pathogens (tetanus, influenza, botulism, tick-borne encephalitis) or against multiple pathogens of infectious diseases (human immunoglobulin). Obtained from the serum or plasma of healthy people.

introduced intramuscularly or intravenously, the half-life is approximately 4 weeks.

Heterogenous serum– preparations for prophylaxis and treatment of viral

(rabies, tick-borne encephalitis), bacterial (leptospirosis, anthrax), toxic (diphteria, botulism) infections.

Are obtained from the blood of animals vaccinated multiple times,

Introduced intramuscularly using the method of Bezredka, taking into account the risk for severe complications (anaphylactic shock, serum disease)

Have a shorter half-life in the organism.

Contraindications to prophylactic vaccination

Acute fever Recently sustained infections Chronic diseases Second half of pregnancy, first nursing

period Allergic diseases and states Oncology pathology

Postvaccination reactions These are the clinical and laboratory signs of

unstable pathological (functional) changes in the organism, which appear in relation to vaccination.

Reactions may be local and general, in this account severe.

A severe local reaction at the injection site is edema of soft tissues greater than 50mm in diameter, infiltrate greater than 20mm in diameter, hyperemia greater than 80mm in diameter.

Severe general reaction are characterized by an increase of body temperature to ≥ 39оС.

Postvaccination reactions Increase of body temperature < 39º С; Increase of body temperature ≥ 39° С (severe

general); Pain, edema of soft tissues ≥ 50 мм, hyperemia at

the injection site ≥80 mm, infiltrate ≥20 mm (severe local);

Lymphoadenopathy; Headache; Irritability, sleep disturbance; Rash of non-allergic etiology; Anorexia, stomach pain, dyspepsia, diarrhea; Catarrhal phenomena; Myalgia, artralgia; Transitory thrombocytopenia.

Postvaccination complications– are stable functional and morphological changes in

the body, beyond the physiological norms and lead to significant violations in health (frequency– 1:100 000 vaccinations):

Post-injection abcess; Anaphylactic shock or reaction; Allergic reaction (Quinke edema, syndrome of Steven-

Johnson, Layel); Febrile syndrome; Afebrile seizure; Cold subcutaneous abcess; Trophic ulcer greater than 10 mm; Regional lymphadenitis; Keloid scar; Generalized BCG-infection, osteomyelitis, osteitis.

Anaphylactic shock– characterized by a sudden drop of arterial pressure and disturbance of cardiac fuction. Appears, as a rule, in the first 30 minutes after vaccination, requires resuscitation.

Seizures without increased body temperature (afebrile seizures) – appears during DTaP vaccinations (1 out of 30-40 thousand vaccines). In contrast to febrile seizures, appear the irritation of definite areas of the brain and meninges with vaccine antigens.

Encephalitic reaction (serous meningitis) – has a frequency of 1:10000 vaccinations against measles and parotitis. Develops as a result of irritation of the meninges by vaccine viruses. Characterized by headaches, neurological symptoms, and sudden disappearance without any long-term effects.

Postvaccination complications

Keloid scar after vaccination

Postvaccination complications

Vaccination eczema

Multiform exudative erythema in a 1 year-old child after vaccination against small-pox

ErythemaInnoculation of virus on the left eyelid

Postvaccination complications (serum disease)

PROPHYLAXIS FOR POSTVACCINE COMPLICATIONS

Strictly following the guidelines of vaccinating; Careful selection of people for vaccinations

including contraindications; Following the instructions of transporting and

storing vaccines; Observing proper dosage of drugs and

intervals between vaccination.

Ant-epidemic measures in the focus

Examination by epidemiologist or a rural physician;

Final disinfection; Taking of material for microbiologic

investigation; Observation during the incubation period; Health education of population.

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