infection basics on transmission and prevention

INFECTIONBasics on Transmission and Prevention

Dr.T.V.Rao MD

Dr.T.V.Rao MD 1

HOW TO CLASSIFY DISEASES

• Acute Diseases– Acute diseases are those conditions in which the

peak severity of symptoms occurs within three months (usually sooner), and recovery in those who survive is usually complete

• Chronic Diseases– Chronic diseases or conditions are those in which

symptoms continue longer than three months and in some cases for the remainder of the person’s life. Recovery is slow and sometimes incomplete.

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CLASSIFYING DISEASES (cont’d.)• Communicable (Infectious) Diseases

– Diseases for which biological agents or their products are the cause and which are transmissible from one individual to another

– The disease process begins when the causative agent is able to lodge and grow or reproduce within the body

– The process of lodgment and growth of a microorganism or virus in the host is termed infection

• Non-communicable (Noninfectious) Diseases/Illnessses– Those diseases or illnesses that cannot be transmitted from an infected

person to a susceptible, healthy one– Several, or even many, factors may contribute to the development of a

given non-communicable health condition– The contributing factors may be genetic, environmental, or behavioral in

nature

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Classification of DiseasesTypes of Diseases_____ Examples______________

• Acute Diseases– Communicable Common cold, pneumonia, mumps,

measles, pertussis, typhoid fever, flu

– Non-communicable Appendicitis, poisoning, trauma (e.g., (incl. trauma) due to automobile accidence, fires,

etc.)

• Chronic Diseases– Communicable Lyme disease, tuberculosis, AIDS,

syphilis, rheumatic fever following streptococcal infections,

herpes– Non-communicable Diabetes, coronary heart disease,

osteoarthritis, cirrhosis of the liver dur to alcoholism, hyptertensionDr.T.V.Rao MD 4

in·fec·tiondictionary means

• a. Invasion by and multiplication of pathogenic microorganisms in a bodily part or tissue, which may produce subsequent tissue injury and progress to overt disease through a variety of cellular or toxic mechanisms.

• b. An instance of being infected.• c. An agent or a contaminated substance

responsible for one's becoming infected.• d. The pathological state resulting from having been

infected.Dr.T.V.Rao MD 5

Definitions• Disease and Infectious Disease–Disease •Any deviation from a condition of good health and well-being

–Infectious Disease ·A disease condition caused by the presence or growth of infectious microorganisms or parasites

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Definitions• Pathogenicity and Virulence – Pathogenicity

• The ability of a microbe to cause disease • This term is often used to describe or

compare species– Virulence

• The degree of pathogenicity in a microorganism • This term is often used to describe or

compare strains within a species Dr.T.V.Rao MD 7

• Infection is the invasion of a host organism's bodily tissues by disease-causing organisms, their multiplication, and the reaction of host tissues to these organisms and the toxins they produce. Infections are caused by microorganisms such as viruses, prions, bacteria, and Viroids, and larger organisms like parasites and fungi.

Infection means

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Spanish Flu (1918) changes the understanding of Communicable Diseases with millions effected and

killing many

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COURSE OF INFECTIOUS DISEASEs• Exposure/Invasion of Host• Incubation -- period of time

between exposure and onset of symptoms -- e.g., interval between HIV infection and development of AIDS can be as long as 10-15 years

• Host reaction• Disease runs course --

treatment, recovery/death (most people don’t die from infectious diseases)

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Causative Agents effecting humans

Bacteria VirusesFungiProtozoaHelminth

sPrions

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INCUBATION PERIOD• Varies by disease• Salmonella -- 12-72 hours after infection; symptoms usually resolve

in 5-7 days, unless infected person is in a very weakened health status

• Measles (rubeola) -- approx. 10-12 days (prodomal -- i.e., interval between the earliest symptoms and the appearance of the rash or fever -- rash onset, on average, 14 days

• HIV -- 6 weeks upward to months; interval between HIV infection and development of AIDS can be as long as 10-15 years

• 2-6 weeks after infection in many, but not all, diseases, most people develop antibodies against reinfection

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MODES OF COMMUNICABLE DISEASE TRANSMISSION

• Direct Transmission• Indirect

Transmission

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Definitions• Acute infection vs. chronic infection – Acute Infection • An infection characterized by sudden onset, rapid

progression, and often with severe symptoms

–Chronic Infection • An infection characterized by delayed onset and

slow progression

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Definitions• Primary infection vs. secondary infection – Primary Infection

• An infection that develops in an otherwise healthy individual

– Secondary Infection • An infection that develops in an

individual who is already infected with a different pathogen

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Definitions• Localized infection vs. systemic infection – Localized Infection

•An infection that is restricted to a specific location or region within the body of the host

–Systemic Infection •An infection that has spread to several

regions or areas in the body of the host

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• Opportunistic infection– An infection caused

by microorganisms that are commonly found in the host’s environment This term is often used to refer to infections caused by organisms in the normal flora

Definitions

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DIRECT TRANSMISSION• Immediate transfer of the disease agent by

direct contact between the infected and the susceptible individuals

• Occurs through such acts as touching, biting, kissing, sexual intercourse, or by direct projection (droplet spread) by coughing or sneezing within a distance of one meter

• Examples of diseases for which transmission is usually direct are AIDS, syphilis, gonorrhea, and the common cold

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INDIRECT TRANSMISSION• May be one of three types: air-borne, vehicle-borne, or

vector-borne• Air-borne transmission -- transmission of microbial

aerosols to a suitable port of entry, usually the respiratory tract– Microbial aerosols are suspensions of dust or droplet

nuclei made up wholly or in part by microorganisms -- may be suspended and infective for long periods of time

– Examples of air-borne diseases include tuberculosis, influenza, histoplasmosis, and legionellosis

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INDIRECT TRANSMISSION (cont’d.)• Vehicle-borne transmission -- contaminated materials or objects

(fomites) serve as vehicles, nonliving objects by which communicable agents are transferred to a susceptible host– The agent may or may not have multiplied or developed on the

vehicle– Examples of vehicles include toys, handkerchiefs, soiled clothes,

bedding, food service utensils, and surgical instruments– Also considered vehicles are water, milk, food (e.g., common

vehicles), or biological products such as blood, serum, plasma, organs and tissues

– Almost any disease can be transmitted by vehicles, including those for which the primary mode of transmission is direct, such as dysentery and hepatitis

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INDIRECT TRANSMISSION (cont’d.)

• Vector-borne transmission -- disease transfer by a living organism, such as a mosquito, fly, or tick– Transmission may be mechanical, via the contaminated

mouth parts or feet of the vector, or biological, involving multiplication or developmental changes of the agent in the vector before transmission occurs

– In mechanical transmission, multiplication and development of the disease do not usually occur -- e.g., organisms that cause dysentery, polio, cholera, and typhoid fever have been isolated from such insects as cockroaches and house flies and could presumably be deposited on food prepared for human consumption

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– In biological transmission , multiplication and/or developmental changes of the disease agent occur in the vector before transmission occurs

– Biological transmission is much more important than mechanical transmission in terms of its impact on public/community health

– Examples of biological vectors include mosquitoes, fleas, ticks, lice, flies and other insects

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–Mosquitoes are extremely important vectors of human diseases -- e.g., they transmit the viruses that cause yellow fever and dengué fever as well as 200 other viruses -- they also transmit malaria, which infects 100 million people in the world each year (most in tropical areas), killing at least 1 million of them each year

– Ticks are another important biological vector, transmitting Rocky Mountain spotted fever, relapsing fever, and Lyme disease

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• Redness• Swelling• Tenderness• Warmth• Drainage• Red streaks

leading away from wound

Signs & Symptoms of Infection

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DISEASE AND INJURY PREVENTIONAND CONTROL

• Prevention– Includes individual, clinical, or personal health services such

as immunizations, screening for high blood pressure and follow-up services, or the use of Pap smears to detect the precursors to cancer of the cervix

• Protection– Includes the activities of organizations, both public and

private, to reduce exposure to hazards such as polluted water, contaminated food, traffic accidents, mosquitoes, or use of electric saws without safety devices

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Beginning of infection control Programmes

• Modern hospital infection control programs first began in the 1950s in England, where the primary focus of these programs was to prevent and control hospital-acquired staphylococcal outbreaks.

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PREVENTION OF COMMUNICABLE DISEASES

• Primary Prevention– In the chain of infection model, primary prevention

strategies are evident at each link of the chain– Successful application of each strategy can be seen as

weakening the link -- with the ultimate goal of interrupting the disease transmission cycle

–Community measures -- e.g., chlorination of the water supply, inspection of restaurants, immunization programs that reach all citizens, maintenance of a well-functioning sewer system, proper disposal of solid waste, and control of vectors and rodents

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PREVENTION OF COMMUNICABLE DISEASES (cont’d.)

– Personal/Individual actions -- hand washing, proper cooking of foods, adequate clothing and housing, use of condoms, obtaining all of the available immunizations against specific diseases

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• Secondary Prevention– Community effort includes measures taken to control or

limit the extend of a disease outbreak/epidemic -- e.g., maintaining records of cases and compliance with regulations requiring the reporting of notifiable diseases, investigating cases and contacts, those who may have become infected through contact with cases

– Individual effort includes either (1) self-diagnosis and self-treatment with nonprescription medications or home remedies, or (2) diagnosis and treatment with an antibiotic or other physician-prescribed medicine

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– Occasionally, secondary disease control measures may include isolation or quarantine

– Isolation = separation, for the period of communicability, of infected persons or animals from others so as to prevent the direct or indirect transmission of the communicable agent to a susceptible person/host

– Quarantine = limitation of the freedom of movement of well persons or animals that have been exposed to a communicable disease until the incubation period has passed

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– Further measures may include disinfection -- the killing of communicable agents outside the the host, and mass treatment with antibiotics

– Public health education and health promotion should also be used as both primary and secondary preventive measures

– Timely laboratory Diagnosis stop of many Infections

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• Tertiary Prevention– Convalescence from infection, recovery to full or partial health,

and return to normal activity– In some cases, such as paralytic polio, return to normal activity

may not be possible, even with extensive physical therapy– At the community level, proper removal of infected items such as

clothing, disinfection, and burial of the dead, for example– Tertiary prevention may also involve the reapplication of primary

and secondary measures to prevent further cases -- e.g., in Japan and South Korea, people with colds or flu wear gauze masks in public to reduce the spread of the disease

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An approach to infection control in developing countries

Infection Control Team/ Infection Control ProgrammeAudit (process) & outcome Surveillance

EvidenceBased Practice

Cost effective

To reduce infection rate to‘irreducible minimum’.

Divert resourcesWasteful practices

Unsafepractices

Educating our Health Care Workers

• Education programs for employees and volunteers are one method to ensure competent infection control practices. It is a unique challenge since employees represent a wide range of expertise and educational background. The ICP must become knowledgeable in adult education principles and use educational tools and techniques that will motivate and sustain behavioral change. Much has been written about the education of healthcare workers (HCWs). Some of the tools used to educate HCWs successfully include newsletter, posters and videos

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TOOLS AVAILABLE TO THE “STATE” FOR THE CONTROL OF COMMUNICABLE DISEASE

• REPORTING -- Physicians and other health professionals must report specified diseases to a designated authority, usually to local or state health authority

• LABORATORY REPORTING -- In many states, licensed laboratories must report positive results for certain diseases to the health department, even though a diagnosis may not have been established

• SURVEILLANCE -- The systematic measurement of health status and risk factors

• MONITORING -- Involves the ongoing assessment of a condition after intervention has been initiated

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• LABORATORY ANALYSIS -- Involves public health laboratories with authority for the study and detection of infectious diseases

• CONTACT INVESTIGATION -- Once a case of a particular disease has been diagnosed, personnel from the health department are authorized to interview the victim to establish a list of possible contact. (A practice of considerable debate recently because of AIDS.)

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• TREATMENT -- Public health agencies are required to provide treatment services for specified infectious diseases. (In many cities, special hospitals were built for this purpose.) Local health departments are also required to provide services for people infected with sexually transmitted diseases or tuberculosis. These services are not regarded as welfare services but rather as tools to prevent the spread of dangerous communicable diseases. It is important to note, however, that the state cannot require treatment. The state can only force treatment if it can prove that the victim is (1) gravely disabled, and (2) a danger to self or others because of the disability

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• ISOLATION -- Means separation of infected people from non-infected people during the period of communicability. Follows the “least restrictive” principle

• IMMUNIZATION -- All states have requirements for the immunization of children against certain infectious diseases -- most common are diphtheria, pertussis (whooping cough), tetanus, rubella (German measles), and polio. The controlling agency is usually the school system, which is required to prevent entry of any child who has not been properly immunized

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• INVESTIGATIONS -- In addition to the specific authorities noted above, most health departments are required to investigate unusual occurrences of disease or injury. This includes the authority to review medical records, to perform laboratory investigations, to examine patients, and to interview both patients and others who may have been exposed to the disease or injury. (The public health authorities may require court authorization to undertake these investigations.)

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Our Vision to Future • Infection control

programs must maintain training records of employees. The minimum training required is annual OSHA blood borne pathogen, tuberculosis prevention and control and new employee orientation.

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Impact of Infectious Diseases• Economic

– Loss of revenue for the family– Loss of productivity for the employer

• Contagion– Other children in child care– Families– Caregivers/teachers and their families

• Disruption– Alternative caregivers– Other colleagues filling in for missing

parent at work• Health care

– Many office visits to get “sick notes”– Inappropriate use of antibiotics– Added responsibility of

administering medication in child care

Impact of Infectious Diseases

• All members of society are affected

Hand washing still continues to be best option to prevent infections

11/04/2023Dr.T.V.Rao MD 43

HAND WASHING STIIL SAVES MANY LIVES FROM INFECTIONS

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Visit me for more articles of interest on infectious diseases ……

11/04/2023Dr.T.V.Rao MD 45

• Programme Created by Dr.T.V.Rao MD for Medical and Health care workers in

the Developing World • Email

• [email protected]

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infection basics on transmission and prevention

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